Article

The ecology, silviculture and biogeography of mahogany (Swietenia macrophylla): A critical review of the evidence

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Recent studies of Swietenia macrophylla King argue that natural regeneration of this highly valued tree is episodic and occurs only after infrequent catastrophic disturbance. An analysis of 14 population size-distributions in natural forests shows that population structure varies across this species' range. In forests that are in successional transition from open deciduous forest to evergreen forest there is often prolific regeneration. We show that in this type of forest in southern Pará (Brazil) patches of even-sized trees are small. Large-scale disturbance may be necessary for regeneration only in evergreen forests where little light penetrates through the canopy. The transition zone between evergreen and deciduous forest in Pará is moving south, and we propose that mahogany populations to the north are in the process of competitive exclusion. Sustainable harvesting of mahogany must take account of the successional stage of the forest.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The species is widely distributed from Mexico and the Caribbean to northern Argentina. It is common in seasonally dry, semi-deciduous forests but less common in evergreen forest types (Cintron 1990;Lamb 1968), where it is mainly found on seasonally flooded lowland along watercourses (Gentry, no date;Pennington, 2006) and in the transitional zone between evergreen forest and savannah forest (cf Brown et al, 2003). In Guyana, the species is rare to locally occasional in mora forest along creeks, seasonal forest and poor types of rain forest (Fanshawe 1961). ...
... Swietenia macrophylla occurs at high densities within forest stands that have regenerated following severe disturbance (Whitmore 1998); dense patches of mahogany have been found in forests that have been subjected to past fires and hurricanes (Lamb 1966;Snook 1993), gully erosion and logjam-induced flooding (Gullison et al. 1996) as well as on abandoned agricultural fields (Stevenson 1927) and along roadsides (Snook 1993). These disturbances are thought to allow mahogany to regenerate as single-aged cohorts every few decades or centuries (Gullison et al. 1996;Snook 1996), which has led to the assumption that mahogany requires catastrophic disturbance in order to persist in forest ecosystems (Brown et al., 2003). It is highly likely that population structure and dynamics of C. odorata are comparable S. macrophylla. ...
... However, it appears that there is a difference in the C. odorata (and Swietenia macrophylla) population dynamics in Central America compared to South America. In Central America waves of regeneration of these two species are apparently provoked by hurricanes and other catastrophic events, resulting in comparatively high local densities, while in South America, the two species mainly occur in low densities in semi-deciduous forests (Brown et al. 2003), forests with rather open canopies along watercourses Gentry, no date) and in the transitional zone between evergreen forest and cerrado in the Brazilian Amazon (Brown et al., 2003). For South America, Brown et al. (2003) found no evidence that successful regeneration of mahogany depends on periodic catastrophic disturbances, as suggested by Snook (1996). ...
... The large geographic range of Big-leaf mahogany in South and Central America (LAMB, 1966;MAYHEW;NEWTON, 1998;GROGAN et al., 2002) suggests that the species may be tolerant to a wide range of environmental conditions. Light environment is critical for successful establishment both under natural and plantation conditions MIZE, 1993;GARCÍA et al., 1993;MACARIO-MENDOZA, 1995;HALL, 1996;MORRIS et al., 2000;BROWN et al., 2003). However, in native forests big-leaf mahogany can survive for several years in a suppressed state in partial shade (GARCÍA et al., 1993;GULLISON et al., 1996), whereas in plantations the species regenerates without apparent restrictions FU, 2003). ...
... However, in native forests big-leaf mahogany can survive for several years in a suppressed state in partial shade (GARCÍA et al., 1993;GULLISON et al., 1996), whereas in plantations the species regenerates without apparent restrictions FU, 2003). Successful establishment in the field then seems to be more a function of leaf herbivory and water availability (MAYHEW; NEWTON, 1988;GROGAN et al., 2002;BROWN et al., 2003). Within its geographic range the species thrives in a variety of soil types differing significantly in fertility (GULLISON et al., 1996;SNOOK, 1996;GROGAN et al., 2002;BROWN et al., 2003;WHITMORE, 2003). ...
... Successful establishment in the field then seems to be more a function of leaf herbivory and water availability (MAYHEW; NEWTON, 1988;GROGAN et al., 2002;BROWN et al., 2003). Within its geographic range the species thrives in a variety of soil types differing significantly in fertility (GULLISON et al., 1996;SNOOK, 1996;GROGAN et al., 2002;BROWN et al., 2003;WHITMORE, 2003). There are evidences of genetic differentiation of populations within its geographic range, underscoring the need for protection of natural habitats and development of conservation of the genotypes ex situ (NEWTON et al., 1993;LEMES et al., 2003). ...
Article
Full-text available
Analisou-se a composição nutricional e isotópica (C e N) de folhas de mogno (. Swietenia macrophylla King) em plantações estabelecidas em solos e climas contrastantes na América Central (Quintana Roo, Yucatán, México) e na América do Sul (Pará, Brasil). O objetivo foi determinar a adaptabilidade dessa espécie para grandes diferenças na disponibilidade de nutrientes e regimes de chuva. As concentrações de nutrientes das folhas e solos foram determinadas espectrofotometricamente, e razões isotópicas foram medidas utilizando espectrometria de massa. No Pará, os solos foram mais arenosos e ácidos, recebendo acima de 2.000 mm de chuva, enquanto em Quintana Roo os solos foram predominantemente argilosos, com pH neutro a alcalino, devido ao substrato calcário subjacente, com cerca de 1.300 mm de chuva. A razão área/peso foliar foi semelhante para ambos os sítios de estudo, mas em Quintana Roo as folhas foram significativamente menores. Concentrações de N e K em folhas adultas foram semelhantes. A concentração de Ca foi apenas ligeiramente inferior no Pará, apesar das grandes diferenças na disponibilidade de Ca. Folhas desse sítio possuíam concentrações ligeiramente maiores de P e menores de Al. Diferenças na eficiência do uso da água medida pela δ13C foram insignificantes, e o principal efeito da menor precipitação em Quintana Roo parece ser uma redução na área foliar. Assinatura isotópica do N (δ 15N) foi mais positiva no Pará, que em Quintana Roo, sugerindo maiores taxas de desnitrificação no primeiro sítio de estudo. Os resultados revelaram comportamento calciotrófico e uma notável capacidade do mogno para compensar as grandes diferenças de textura e disponibilidade de nutrientes do solo.
... Forest management can play an important role in regenerating this species, which is light-demanding and has higher fruit production in open conditions (Mayhew and Newton 1998, Boshier et al. 2004, Grogan et al. 2005. However, the type of management applied must take into account both the successional stage and ecological zone of the forest (Brown et al. 2003). While S. macrophylla can regenerate after catastrophic disturbance (e.g., hurricanes that open the forests and give seed trees the space to deliver seeds) (Snook 1996), it is not necessary for the species persistence in semi-deciduous forest, where much greater penetration of light permits dense recruitment. ...
... While S. macrophylla can regenerate after catastrophic disturbance (e.g., hurricanes that open the forests and give seed trees the space to deliver seeds) (Snook 1996), it is not necessary for the species persistence in semi-deciduous forest, where much greater penetration of light permits dense recruitment. Brown et al. (2003) argue that in late-succession wet forest, S. macrophylla typically occurs at low densities, persisting as relict populations in the process of competitive exclusion. There are few seedlings and saplings, and only rarely do they survive and grow to form advance regeneration. ...
... In drier forests and those at earlier successional stages, population densities of mahogany tend to be higher with more juveniles relative to adults, and more prolific advanced regeneration (Stevenson 1927, Baima 2001. Here, reduced impact logging will be sufficient to stimulate natural regeneration of S. macrophylla, which should benefit from small-scale disturbance (Brown et al. 2003). ...
... Árbol hasta de 50 metros de altura y hasta 3 m de diámetro (Brown et al. 2003). De copa amplia y abierta con ramas insertas en la parte alta del fuste, el cual es recto, cilíndrico y desarrolla aletones (Figura 17). ...
... Su fibra es recta aunque en algunos casos es ligeramente ondulada, con grano medio a fino. Es una madera de alta durabilidad natural, fácil trabajabilidad y alta estabilidad dimensional (Brown et al. 2003). Su brillo de mediano a alto, veteado suave, no presenta olor característico y su sabor es ligeramente amargo (Mendieta et al. 1999). ...
... La Caoba es una especie demandante de luz, que regenera bien en claros recién abiertos (Snook et al. 2005, Van Rheenen et al. 2004; algunos estudios sugieren que la regeneración natural es episódica y asociada a grandes disturbios (Whitmore 1973, García et al. 1993, Snook 1996, Grogan et al 2002. En la región de Pará, Brasil, se encontró que la regeneración en bosques semi-deciduos es muy prolífera comparada con la de los bosques siempre verdes; en este caso se evidencia que el factor luz define en gran medida su éxito (Brown et al. 2003). Un estudio realizado por Brown et al. (2003) muestra que la regeneración es similar entre bosques aprovechados y bosques no aprovechados y el factor determinante del éxito de su regeneración parece estar asociado más al tipo de bosque. ...
... Recent events has also revealed that pollution is becoming an enormous threat to human and ecosystem health and a great problem to the survival of the living biodiversity species mostly higher animals with humans as the central focus. As urban expansion continuous, environmental pollutions (air, water, soil, including sound and mental pollution) are likely to increase and new challenges might also emerge (Brown et al., 2003;and Zhenga, 2013).The planting of trees and shrubs is an effective means of controlling pollution and improving the environment the world. There are different ways and means to mitigate the urban environmental pollution and planting of trees is an effective means and equally recognized throughout the world (Geist and Lambin 2002;Zhenga, 2013). ...
... As trees grow in size and shape and their biomass increases, they absorb carbon from the atmosphere and store it in the plant tissues resulting in growth of different parts (Eggleston et al., 2006). Cardille and Foley (2003) and Geist and Lambin (2002) noted one strategy for enhancing the value of the trees and shrubs is to increase the concentration of economically important, indigenous tree species by planting seeds or seedlings (enrichment planting) for future environmental sustainability (Brown et al., 2003;Montagnini and Jordan, 2005). This can be accomplished with the urban green infrastructure. ...
... The study further indicated the importance of greenery design and quality in pollution abatement, by maintaining large and more continuous tree cover in urban setups (Nowak, 2006). Moreover, as many of the identified trees are still young, their environmental advantages and benefits will appreciate significantly overtime when the trees attain their final dimensions and size permissible by site conditions (Miller et al., 2015;Nowak, 2010 andBeckett et al., 1998). ...
Article
Full-text available
Urban green space is a collection of trees and shrubs growing in urban area. Green plants are well known for their abilities to reduce air and noise pollution. It is important that plants used for the development of urban landscaping must be tolerant to air pollutants. There must be some criteria to select tolerant plants for urban landscaping design and for that two indices viz. Air Pollution Tolerance Index (APTI) and carbon sequestration can be a good tool. Thus this study was carried out to assess the efficiency of urban trees (Tabebuia rosea, Polyalthia longifolia, Delonix regia and Raphia farinifera) and shrubs (Ficus spp) to tolerate air pollution and potential for carbon sequestration in Akure, Ondo State, Nigeria in 2015. The sites were sampled from Akure City Major Road, from Oloko Junction to Oba-Ile. The plant species identified at the sample area were Ficus spp, Tabebuia rosea, Polyalthia longifolia, Delonix regia and Raphia farinifera. The assessment of the ascorbic acid, pH, relative water content and total chlorophyll content of the leaves of the identified plant species was done to determine the APTI. The APTI of the plant ranged from 5.11 to 9.31 with Tabebuia rosea having the highest value which indicates it's high tolerance of air pollutants from the assessment and Raffia farinifera with the lowest value and least tolerant. The biomass of the trees species were estimated for the quantification of the amount of carbon sequestered and the absorbed CO2 in the plant. Tabebuia rosea also had the highest carbon sequestered (10,074 kg) and Delonix regia having the lowest of 4,702.50 kg.
... However, also small scale regeneration has been observed (Grogan et al. 2003). Brown et al. (2003) suggest that this is presumably accounted for by local variation in environmental factors such as soil fertility, light penetration and moisture availability. It is likely that such differences could explain the fact that mahogany population structure differs across its natural range. ...
... This study hypothesizes that intensive forest management regimes stimulate natural regeneration and performance of mahogany by increasing light penetration and reducing competing vegetation ( figure 1a). Regeneration success is understood to be strongly light dependent (Grogan et al. 2003;Brown et al. 2003;Snook et al. 2005;Negreros-Castillo et al. 2003) and, as light availability will increase with management intensity (due to partial clearings or canopy openings), so will the survival of mahogany seedlings. In addition, mahogany seeds will probably be dispersed longer distances in more intensively managed (i.e. more open) forests. ...
... She reported that the presence of long-lived and generally poorly regenerating tree species such as mahogany may reflect this former cultivation. On Although it is not clear whether soil type may influence the germination of mahogany seeds as well, evidence suggests that soil moisture is the main factor triggering seed germination (Brown et al. 2003;Gerhardt 1996). Based on the water holding capacities of organic humus, we therefore hypothesise that germination will be better on highly humic soils. ...
... The large geographic range of Big-leaf mahogany in South and Central America (LAMB, 1966; MAYHEW; NEWTON, 1998; GROGAN et al., 2002) suggests that the species may be tolerant to a wide range of environmental conditions. Light environment is critical for successful establishment both under natural and plantation conditions (NEGREROS-CASTILLO; MIZE, GARCÍA et al., 1993; MACARIO-MENDOZA, 1995; HALL, 1996; MORRIS et al., 2000; BROWN et al., 2003). However, in native forests big-leaf mahogany can survive for several years in a suppressed state in partial shade (GARCÍA et al., 1993; GULLISON et al., 1996), whereas in plantations the species regenerates without apparent restrictions (LUGO; FU, 2003). ...
... However, in native forests big-leaf mahogany can survive for several years in a suppressed state in partial shade (GARCÍA et al., 1993; GULLISON et al., 1996), whereas in plantations the species regenerates without apparent restrictions (LUGO; FU, 2003). Successful establishment in the field then seems to be more a function of leaf herbivory and water availability (MAYHEW; NEWTON, 1988; GROGAN et al., 2002; BROWN et al., 2003). Within its geographic range the species thrives in a variety of soil types differing significantly in fertility (GULLISON et al., 1996; SNOOK, 1996; GROGAN et al., 2002; BROWN et al., 2003; WHITMORE, 2003). ...
... Successful establishment in the field then seems to be more a function of leaf herbivory and water availability (MAYHEW; NEWTON, 1988; GROGAN et al., 2002; BROWN et al., 2003). Within its geographic range the species thrives in a variety of soil types differing significantly in fertility (GULLISON et al., 1996; SNOOK, 1996; GROGAN et al., 2002; BROWN et al., 2003; WHITMORE, 2003). There are evidences of genetic differentiation of populations within its geographic range, underscoring the need for protection of natural habitats and development of conservation of the genotypes ex situ (NEWTON et al., 1993; LEMES et al., 2003). ...
Article
Full-text available
We analyzed the nutritional composition and isotope ratios (C and N) of big-leaf mahogany (Swietenia macrophylla King) leaves in plantations established on contrasting soils and climates in Central America (State of Quintana Roo, Yucatán, México) and South America (State of Pará, Brazil). The objective was to determine the adaptability of this species to large differences in nutrient availability and rainfall regimes. Nutrient concentrations of leaves and soils were determined spectrophotometrically, and isotope ratios were measured using mass spectrometric techniques.In Pará soils were sandier, and acidic, receiving above 2000 mm of rain, whereas in Quintana Roo soils were predominantly clayey, with neutral to alkaline pH due to the underlying calcareous substrate, with about 1300 mm of rain. Leaf area/weight ratio was similar for both sites, but leaves from Quintana Roo were significantly smaller. Average N and K concentrations of adult leaves were similar, whereas Ca concentration was only slightly lower in Pará in spite of large differences in Ca availability. Leaves from this site had slightly higher P and lower Al concentrations. Differences in water use efficiency as measured by the natural abundance of 13 C were negligible, the main effect of lower rainfall in Quintana Roo seemed to be a reduction in leaf area. The N isotope signature (δ 15 N) was more positive in Pará than in Quintana Roo, suggesting higher denitrification rates in the former. Results reveal a calciotrophic behavior and a remarkable capacity of mahogany to compensate for large differences in soil texture and nutrient availability. pela δ 13 C foram insignificantes, 1 Recebido em 15.03.2013 aceito para publicação em 14.04.2014. MEDINA, E. et al.
... The tree's density ranges from dense stands of very old trees "to stands of small-diameter trees scattered among taller vegetation" (Lugo 2003, v-vi.). The species has been classified as a pioneer species or a light-demanding climax species (Brown et al. 2003). ...
... Recruitment may occur after "multiple, small-scale disturbances" (Brown et al. 2003). ...
... Mahogany seeds dispersed at the end of the dry season may remain on the forest floor until rainfall prompts germination (Brown et al. 2003). Insufficient soil moisture due to large gaps may delay mahogany germination (Brown et al. 2003). ...
... Árbol hasta de 50 metros de altura y hasta 3 m de diámetro (Brown et al. 2003). De copa amplia y abierta con ramas insertas en la parte alta del fuste, el cual es recto, cilíndrico y desarrolla aletones (Figura 17). ...
... Su fibra es recta aunque en algunos casos es ligeramente ondulada, con grano medio a fino. Es una madera de alta durabilidad natural, fácil trabajabilidad y alta estabilidad dimensional (Brown et al. 2003). Su brillo de mediano a alto, veteado suave, no presenta olor característico y su sabor es ligeramente amargo (Mendieta et al. 1999). ...
... La Caoba es una especie demandante de luz, que regenera bien en claros recién abiertos (Snook et al. 2005, Van Rheenen et al. 2004; algunos estudios sugieren que la regeneración natural es episódica y asociada a grandes disturbios (Whitmore 1973, García et al. 1993, Snook 1996, Grogan et al 2002. En la región de Pará, Brasil, se encontró que la regeneración en bosques semi-deciduos es muy prolífera comparada con la de los bosques siempre verdes; en este caso se evidencia que el factor luz define en gran medida su éxito (Brown et al. 2003). Un estudio realizado por Brown et al. (2003) muestra que la regeneración es similar entre bosques aprovechados y bosques no aprovechados y el factor determinante del éxito de su regeneración parece estar asociado más al tipo de bosque. ...
Book
Full-text available
1. Cariniana pyriformis 2. Swietenia macrophylla 3. Cedrela odorata 4. Aniba rosaeodora 5. Ocotea quixos 6. PLANES DE MANEJO PARA LA CONSERVACIÓN 7. ESPECIES AMENAZADAS 8. MADERABLES 9. ABARCO. 10. CAOBA 11. CEDRO 12. PALOROSA 13. CANELO DE LOS ANDAQUÍES. 14. COLOMBIA.
... The species Swietenia macrophylla King, Meliaceae, was selected as a promising lead after the bioassayscreening of several ethanolic plant extracts, because of its significant neutralizing activity against Bothrops asper venom and PLA 2 isolated from the this venom . Swietenia species are found in neotropics regions (Brown et al., 2003;Gullison et al., 1996). The tree can grow up to a height of 40-60 m and is native to tropical America, Mexico, South America, and India (Brown et al., 2003). ...
... Swietenia species are found in neotropics regions (Brown et al., 2003;Gullison et al., 1996). The tree can grow up to a height of 40-60 m and is native to tropical America, Mexico, South America, and India (Brown et al., 2003). Organic and aqueous extracts of S. macrophylla seeds possess a wide array of biological properties such as anti-diabetic (Maiti et al., 2007a), anti-diarrhoeal (Maiti et al., 2007b), anti-inflammatory, anti-mutagenic, antitumor-promoting (Amelia et al., 1996, antimicrobial, and antimalaric (Maiti et al., 2007c;Soediro et al., 1990). ...
Article
Full-text available
Activity-guided fractionation of an ethanol-soluble extract of the leaves of Swietenia macrophylla King, Meliaceae, led to several fractions. As a result, sample Sm13-16, 23 had the most promising activity against phospholipases A2 (PLA2), Asp49 and Lys49 types. This fraction inhibited PLA2 activity of the Asp49 PLA2, when aggregated substrate was used. On the other hand, this activity was weakly neutralized when monodispersed substrate was used. In addition, Sm13-16, 23 inhibited, in a dose dependent manner, the cytotoxicity, myotoxicity and edema induced by PLA2s, as well as the anticoagulant activity of Asp49 PLA2. Overall, this fraction exhibited a better inhibition of the toxic activities induced by the Lys49 PLA2 than those caused by the Asp49 PLA2. The spectral data of Sm13-16, 23 suggested the presence of aromatic compounds (UV λ max (nm) 655, 266, and 219; IR λ max KBr (cm-1): ~ 3600-3000 (OH), 2923.07 and 1438.90 (C-H), 1656.69 (C = O), 1618.63 and 1607.67 (C-O), 1285.47- 772.60). We suggest that phenolic compounds could interact and inhibit the toxins by several mechanisms. Further analysis of the compounds present in the active fraction could be a relevant contribution in the treatment of accidents caused by snake envenomation.
... The species Swietenia macrophylla King, Meliaceae, was selected as a promising lead after the bioassayscreening of several ethanolic plant extracts, because of its significant neutralizing activity against Bothrops asper venom and PLA 2 isolated from the this venom . Swietenia species are found in neotropics regions (Brown et al., 2003;Gullison et al., 1996). The tree can grow up to a height of 40-60 m and is native to tropical America, Mexico, South America, and India (Brown et al., 2003). ...
... Swietenia species are found in neotropics regions (Brown et al., 2003;Gullison et al., 1996). The tree can grow up to a height of 40-60 m and is native to tropical America, Mexico, South America, and India (Brown et al., 2003). Organic and aqueous extracts of S. macrophylla seeds possess a wide array of biological properties such as anti-diabetic (Maiti et al., 2007a), anti-diarrhoeal (Maiti et al., 2007b), anti-inflammatory, anti-mutagenic, antitumor-promoting (Amelia et al., 1996, antimicrobial, and antimalaric (Maiti et al., 2007c;Soediro et al., 1990). ...
Article
Full-text available
Activity-guided fractionation of an ethanol-soluble extract of the leaves of Swietenia macrophylla King, Meliaceae, led to several fractions. As a result, sample Sm13-16, 23 had the most promising activity against phospholipases A2 (PLA2), Asp49 and Lys49 types. This fraction inhibited PLA2 activity of the Asp49 PLA2, when aggregated substrate was used. On the other hand, this activity was weakly neutralized when monodispersed substrate was used. In addition, Sm13-16, 23 inhibited, in a dose dependent manner, the cytotoxicity, myotoxicity and edema induced by PLA2s, as well as the anticoagulant activity of Asp49 PLA2. Overall, this fraction exhibited a better inhibition of the toxic activities induced by the Lys49 PLA2 than those caused by the Asp49 PLA2. The spectral data of Sm13-16, 23 suggested the presence of aromatic compounds (UV λ max (nm) 655, 266, and 219; IR λ max KBr (cm−1): ~ 3600-3000 (OH), 2923.07 and 1438.90 (C-H), 1656.69 (C = O), 1618.63 and 1607.67 (C-O), 1285.47-772.60). We suggest that phenolic compounds could interact and inhibit the toxins by several mechanisms. Further analysis of the compounds present in the active fraction could be a relevant contribution in the treatment of accidents caused by snake envenomation.
... La mara (Swietenia macrophylla) es una especie nativa de América del sur, distribuida principalmente en diferentes bosques del Neotrópico (Brown et al. 2003), siendo Bolivia probablemente el límite sur de la distribución de la mara. En muchos lugares de Bolivia esta especie era común en el pasado y ahora prácticamente ha desaparecido, siendo las principales razones la sobreexplotación, tala ilegal y la deforestación. ...
... La mara (Swietenia macrophylla King) es una especie nativa de América del sur, distribuida principalmente en diferentes bosques del Neotrópico (Brown et al. 2003). Bolivia probablemente es el límite sur de la distribución de la mara en Latinoamérica. ...
... Swietenia macrophylla, commonly known as mahogany, belongs to the Meliaceae family and is distributed naturally from southern Mexico throughout Central and Tropical South America to Bolivia and Brazil, including large portions of the Amazon Basin [7,8]. It is one of the most valuable plants on the international market and because of its beauty and durability its wood is used to make products such as fine furniture and cabinetry, interior trim, paneling, fancy veneers, musical instruments, boat building, pattern making, turnery and carving [9]. ...
Research
Full-text available
Swietenia macrophylla (mahogany) is a highly valued timber species, whereas the leaves are considered to be waste product. A total of 27 phenolic compounds were identified in aqueous extracts from mahogany leaves by comparing retention times and mass spectra data with those of authentic standards using LC-ESI-MS/MS. Polyphenols play an important role in plants as defense mechanisms against pests and pathogens and have potent antioxidant properties. In terms of health applications, interest has increased considerably in naturally occurring antioxidant sources, since they can retard the progress of many important neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. The antioxidant capacities of two aqueous extracts, M1 (decoction) and M2 (infusion), were measured using TEAC and Folin-Ciocalteau methods. Additionally, M1 was used in order to investigate its potential cytoprotective effects on an in vitro model of neurodegeneration, by using primary cerebellar cultures exposed to methyl mercury (MeHg). Under experimental sub-chronic conditions (72 h), concomitant exposure of the same cultures to MeHg and M1 extract resulted in a statistically significant increase in cell viability in all three concentrations tested (10, 50 and 100 μg/mL), strongly suggesting that due to its high content of antioxidant compounds, the M1 extract provides significant cytoprotection against the MeHg-induced in vitro neurotoxicity.
... Questions remain regarding requirements for establishment and vigorous early seedling growth of these timber species. For example, does Swietenia macrophylla (big-leaf mahogany) require large tracts of land opened by catastrophic disturbance for successful recruitment into the forest canopy (Gullison et al., 1996;Snook, 2003), or can it establish and grow to canopy dominance in much smaller single-or multiple-tree forest gaps (Brown et al., 2003;Grogan et al., 2003)? Grogan et al. (2008) indicate that size-class distributions in Brazil belie the catastrophic disturbance hypothesis of regeneration and recruitment. ...
... There is an enormous amount of habitat available between the protected areas in the north east (e.g., Yum Balam), east (Sian Ka'an) and south (Calakmul) that probably contains a population of around 1,000 jaguars. Forest conversion to agriculture is the greatest threat to the region (Brown et al., 2003;Zarza et al., this volume). All these forests must be protected to conserve jaguars, biological diversity and productive activities. ...
... Questions remain regarding requirements for establishment and vigorous early seedling growth of these timber species. For example, does Swietenia macrophylla (big-leaf mahogany) require large tracts of land opened by catastrophic disturbance for successful recruitment into the forest canopy (Gullison et al., 1996;Snook, 2003), or can it establish and grow to canopy dominance in much smaller single-or multiple-tree forest gaps (Brown et al., 2003;Grogan et al., 2003)? Grogan et al. (2008) indicate that size-class distributions in Brazil belie the catastrophic disturbance hypothesis of regeneration and recruitment. ...
Article
This special issue of Forest Ecology and Management addresses management issues for the tropical timber species of the Meliaceae. The concept for this issue originated from a technical session entitled “Sustainable management of highvalue timber species of the Meliaceae: a global perspective”, held at the 2005 World Congress of the International Union of Forest Research Organizations in Brisbane, Australia. With the goal of helping to maintain the world-wide supply of these woods, the papers presented here cover topics that globally affect these species: natural forest management (Grogan et al., 2008; Hall, 2008; Lopes et al., 2008; Negreros-Castillo and Mize, 2008; Norghauer et al., 2008), plantations (Opuni-Frimpong et al., 2008a; Opuni-Frimpong et al., 2008b; Pérez- Salicrup and Esquivel, 2008; Wadsworth and González, 2008); and the conservation and use of genetic resources (André et al., 2008; de la Torre et al., 2008; Ward et al., 2008; Wightman et al., 2008). The tropical timber species of the subfamily Swietenioideae (the true mahoganies) of the Meliaceae include some of the finest cabinet woods in the world, based on generally shared characteristics such as dimensional stability and workability. The wood of these species is prized for cabinetry, veneers, interiors, and artisan uses. The Swietenioideae includes Cedrela and Swietenia in the Neotropics, Entandrophragma, Khaya and Lovoa in Africa, and Chukrasia and Toona in Australia. Genera discussed in this issue include Swietenia, Cedrela, Khaya, and Entandrophragma. In this introduction, we provide a brief overview of the general status of these genera and of the papers in this special issue.
... Existe una enorme extensión de hábitat disponible entre las áreas naturales protegidas del noreste (e.g., Yum Balam), este (Sian Ka'an) y el sur (Calakmul) que mantiene una población adicional probable de cerca de 1 000 jaguares. La conversión de selva con fines agropecuarios es la mayor amenaza para esa región (Brown et al., 2003;Zarza et al., este volumen). Es necesario proteger todas esas selvas para mantener el jaguar, la diversidad biológica y las actividades productivas. ...
... Four of the investigated species (A. graveolens, H. courbaril, S. saman and S. macrophylla) showed non-deciduous characteristics and kept their foliage until the end of the dry season, despite being characterized in the literature as deciduous or semi-deciduous (Brodribb et al., 2003;Brown et al., 2003;Schwarcz et al., 2010). The other four species shed their leaves at the beginning of the dry season (Table 2), while only three are classified by other authors as being strictly deciduous (B. ...
... This has led to the degradation of the forest, impoverishment of the soil and reduction in volume yield. Regardless of how long trees were clear-cut or selectively removed, logging decreased species diversity (Brown et al. 2003) and reduced the number of economic trees. The severe impacts of uncontrolled logging and several other human activities in tropical rainforest ecosystems on biodiversity conservation, soil properties, residual trees and seedlings and the environment were reported by Makana and Thomas (2006), and . ...
Article
Full-text available
The contributions of a silvicultural practice (enrichment planting technique) to ecosystem restoration, management and biodiversity conservation were assessed. Data were collected from eight 25 × 25 m plots located in the three forest types (Degraded Forest, Strict Nature Reserve and Enrichment Planting Forest) in Akure Forest Reserve, Nigeria, using a systematic line transect. Soil samples were also collected in each plot at three depths. The results indicated that there were 51 tropical hardwood species distributed into 24 families in the forest ecosystem. The Shannon–Weiner indices varied from 3.25 to 2.74. Enrichment Planting Forest was discovered to have the highest number of species, genera and families when compared to the other forest types. Also, highest biodiversity indices were obtained for it. All the variables were significantly higher (p Keywords: enrichment planting; forest reserves; phytosociological; silviculture; soil nutrients Document Type: Research Article DOI: http://dx.doi.org/10.1080/21513732.2013.823464 Affiliations: Department of Forestry and Wood Technology, Federal University of Technology, Akure, Ondo State, Nigeria Publication date: September 1, 2013 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher By this author: Lawal, A. ; Adekunle, V.A. J. GA_googleFillSlot("Horizontal_banner_bottom");
... In the Amazon, mega-El Niño Southern Oscillation (ENSO) events proposed to be responsible for disruptions in the archaeological record at 400-to 500-year intervals over the past two millennia (Meggers 1994) could represent a stochastic mechanism maintaining mahogany populations at observed densities. However, observations of small-gap recruitment in southeastern Amazonia suggest that successful recruitment to the canopy occurs in the absence of large-scale disturbance and that the principal drivers of mahogany population dynamics may vary regionally (Brown, Jennings & Clements 2003;Grogan, Ashton & Galvão 2003). ...
Article
Full-text available
1. The impacts of selective harvesting in tropical forests on population recovery and future timber yields by high-value species remain largely unknown for lack of demographic data spanning all phases of life history, from seed to senescence. In this study, we use an individual-based model parameterized using 15 years of annual census data to simulate population dynamics of big-leaf mahogany Swietenia macrophylla King in southeast Amazonia in response to multiple harvests and in the absence of harvesting. 2. The model is based on regression equations of stem diameter growth, mortality, and fruit production estimated as a function of stem diameter and prior growth; it includes functions for germinating seeds, growing trees from seedling to adult senescence, producing seeds, and creating disturbances at specified spatial scales and return intervals, including logging. We simulate six harvest scenarios by varying the minimum diameter cutting limit (MDCL; 60 cm, 80 cm) and the retention rate requirement (20%, 40%, 60% commercial population retained). 3. Without logging, simulated populations grew over 100 years by 182% from observed densities, indicating that one or more parameters in the model may overestimate long-term demographic rates on this landscape. However, 100-yr densities did not far exceed values reported from forests across this region, and other modelled demographic parameters resembled observed behaviours. 4. Under current harvest regulations for mahogany in Brazil (60 cm MDCL, 20% commercial-sized tree retention rate, minimum 5 commercial-sized trees 100 ha−1 retained after harvest, 30-yr cutting cycle), commercial densities at the study site would decline from 39.7 to 11.3 trees 100 ha−1 before the fourth harvest in year 90, yielding an estimated 16.4% of the initial harvest volume during the fourth harvest. Increasing retention rates caused first-cut harvest volumes to decline but improved population recovery rates between harvests. Under both MDCL scenarios, increasing retention rates led to more robust population recovery compared to the current 20% rate, and higher subsequent harvest yields relative to initial (first-cut) values. 5. Synthesis and applications. These results indicate that current harvest regulations in Brazil for mahogany and other high-value timber species with similar life histories will lead to commercial depletion after 2–3 cutting cycles. Increasing commercial-sized tree retention rates improved population recovery at the cost of reduced initial harvest volume yields. Sustainable harvests will require, in combination, a moderate increase in the retention rate, investment in artificial regeneration to boost population recovery, and implementation of silvicultural practices designed to increase growth rates by future crop trees. This article is protected by copyright. All rights reserved.
... One strategy for enhancing the value of forests is to increase the concentration of economically important, indigenous tree species by planting seeds or seedlings for future harvest ( Brown et al., 2003;Dawkins, 1961;Dawkins and Philips, 1998;Montagnini and Jordan, 2005;Salleh, 1997). This can be accomplished with enrichment planting (EP), and it may help make forest management financially attractive to landholders and thereby reduce forest conversion to other uses. ...
Article
Full-text available
A strategy for enhancing natural forests' economic value is to increase their concentration of economically important, indigenous tree species by planting seeds or seedlings for future harvest, which can be accomplished with enrichment planting (EP). EP may help make forest management financially attractive and thereby reduce forest conversion to other uses but many factors deter landholders from EP, including a lack of reliable information about its costs and benefits. A financial appraisal of an eastern Amazon EP case study is presented with 7 alternate scenarios: high and low financial costs, low timber yield, carbon sequestration payments, higher timber prices, free seedlings, and reduced discount rates. A sensitivity analysis of carbon payment amounts, timber prices, and discount rates is explored. The net present value (NPV), internal rate of return (IRR), and benefit cost ratio (BCR) are reported for each scenario. Results showed that start-up costs must be kept low, and site maintenance must not only be sustained but also kept minimal to prevent costs from exceeding financial benefits of EP. Scenarios with the best NPV and BCR were those with carbon sequestration sales, higher timber prices, and a low discount rate. Carbon sequestration and high timber sale prices resulted in the best IRRs.
... Rather, the financial return from converting tropical forest land to agriculture or ranching often dwarfs that of maintaining forest cover (Cardille and Foley, 2003; Geist and Lambin, 2002; Kaimowitz and Angelsen, 1998; Lambin and Geist, 2003; Perz and Skole, 2003). One strategy for enhancing the value of forests is to increase the concentration of economically important, indigenous tree species by planting seeds or seedlings for future harvest (Brown et al. 2003; Dawkins, 1961; Dawkins and Philips, 1998; Montagnini and Jordan, 2005; Salleh, 1997). This can be accomplished with enrichment planting (EP), and it may help make forest management financially attractive to landholders and thereby reduce forest conversion to other uses. ...
Thesis
Full-text available
Enrichment planting (EP) is a silvicultural tool capable of adding long-term value to forests. Here EP case studies and experimental trials are assessed at two scales: large industrial and family farm planting. Tree growth responses to treatments are reported. Financial cost-benefit analysis (CBA) and Ethnographic Linear Programming (ELP) are used to determine sensitivity to short- and long-term costs and benefits. The goal is to define factors that promote or hinder EP in order to help inform landholders and policy makers of effective use of EP. A case study in the Brazilian Amazon revealed that EP produces multiple timber harvests but may be expensive without short-term financial benefits. Sensitivity analysis of costs and benefits showed that revenue from activities additional to EP, such as carbon sequestration payments, can make EP profitable. A social appraisal of EP may reveal social benefits that would justify governmental, financial, and policy support. Fertilization and site preparation experiments showed that they produce little benefit in growth and survival and therefore may incur unnecessary expenses in these settings. Considering the finding of the CBA results and the treatment experiments, it is suggested that early costs be kept low and therefore planting treatments kept to a minimum. The particular minimum treatment depends on species and site conditions. Relative abundance of EP by smallholders is intriguing given difficulties some large companies experience when implementing EP. ELP was used to assess planting conducted by Amazon smallholders. Diverse short-term benefits, multitasking, low opportunity costs, low start-up costs, reliable tree survivorship and ability to care for planted trees promoted EP among smallholders. As for industrial foresters, monetary payments for EP are also an effective incentive. Both industrial planters and smallholders need short-term benefits and minimal costs but there are differences between the scales. Industrial planters perceive financial benefits; biodiversity conservation or local economy stability are external. To make them internal, and thereby make EP more feasible, external benefits need to be translated into shorter-term financial gains for the companies. Smallholders respond well to payments and other non-financial benefits. Differences between scales should be considered when developing policies or programs to encourage EP. (Permanent online location of dissertation: http://ufdc.ufl.edu/UFE0021994/00001)
... However, there were years (2004 and 2005) in which the smaller individuals of six species were more frequent and it is therefore unlikely that smaller plants were systematically overlooked. The size class distribution of the various species could be the result of logging disturbance or differential rates of growth in each size class (Brown et al., 2003). The low number of seedlings and saplings registered in 2006 (in comparison to 1996, 2004 and 2005) could be due to the short period of time which had elapsed following harvesting (less than one year) and therefore seedlings and saplings in the resulting disturbance conditions were not yet established. ...
Article
One of the main threats to the sustainability of community forestry in the Selva Maya is insufficient regeneration of commercial tree species. We evaluated the regeneration status of 22 commercial tree species in a managed semideciduous tropical rain forest in Southern Mexico. The study was carried out in six harvesting areas along a 16-year chronosequence. In each area, 10 transects (1000 m2) were established and all trees >50 cm height and <10 cm diameter were recorded. We evaluated the relationships between seedling and sapling abundance, and canopy cover and disturbance condition (closed forest, canopy gap, log landing, skid road, primary road and secondary road). The area occupied by closed forest canopy increased with age of harvesting area (65-91% of sampled area), while the area occupied by canopy gaps decreased (22-9%). Log landings occupied less than 1% of the sampled area. The predominant canopy cover was 75-80% in all harvesting areas, even in the most recently harvested areas. The highest densities of seedlings and saplings, of both shade tolerant and intolerant species, were found in log landing and skid trails, followed by secondary roads. Even Simarouba glauca, a shade tolerant species, displayed higher densities in sites with ≤65% of canopy cover. Our results support previous findings and indicate that the levels of disturbance caused by existing harvesting procedures may be inadequate to promote sufficient regeneration of not only light demanding desirable species but also for some of the evaluated shade tolerant species of commercial interest. Seedling and sapling densities exhibited by Swietenia macrophylla, for example, are insufficient to support current harvesting rates. The application of a spatial mixed system with patch-cuts of different sizes, a consequence of group felling, could be applied to provide the necessary conditions for the regeneration of the main commercial species.
... Swietenia macrophylla, commonly known as mahogany, belongs to the Meliaceae family and is distributed naturally from southern Mexico throughout Central and Tropical South America to Bolivia and Brazil, including large portions of the Amazon Basin [7,8]. It is one of the most valuable plants on the international market and because of its beauty and durability its wood is used to make products such as fine furniture and cabinetry, interior trim, paneling, fancy veneers, musical instruments, boat building, pattern making, turnery and carving [9]. ...
Article
Full-text available
Swietenia macrophylla (mahogany) is a highly valued timber species, whereas the leaves are considered to be waste product. A total of 27 phenolic compounds were identified in aqueous extracts from mahogany leaves by comparing retention times and mass spectra data with those of authentic standards using LC-ESI-MS/MS. Polyphenols play an important role in plants as defense mechanisms against pests and pathogens and have potent antioxidant properties. In terms of health applications, interest has increased considerably in naturally occurring antioxidant sources, since they can retard the progress of many important neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. The antioxidant capacities of two aqueous extracts, M1 (decoction) and M2 (infusion), were measured using TEAC and Folin-Ciocalteau methods. Additionally, M1 was used in order to investigate its potential cytoprotective effects on an in vitro model of neurodegeneration, by using primary cerebellar cultures exposed to methyl mercury (MeHg). Under experimental sub-chronic conditions (72 h), concomitant exposure of the same cultures to MeHg and M1 extract resulted in a statistically significant increase in cell viability in all three concentrations tested (10, 50 and 100 μg/mL), strongly suggesting that due to its high content of antioxidant compounds, the M1 extract provides significant cytoprotection against the MeHg-induced in vitro neurotoxicity.
... In this region of Mexico, mahogany mainly grows in low elevation, flat terrain, and in a variety of soils Synnott, 2009). Abundance and tree size of mahogany trees in the forest varies according to soils, topography, and history of disturbances (Brown, Jennings, & Clements, 2003;Grogan et al., 2002;Gullison et al., 1996;Naranjo et al., 2009;Snook, 1996Snook, , 1998Snook, , 2003Synnott 2009;Vester & Navarro-Martı´nez, 2005). On the Yucatan Peninsula, it is frequent to find mahogany forming groups of between two and eight individuals larger than 10 cm diameter at breast height (DBH) per hectare, which has been attributed to the presence of episodic disturbances from hurricanes and fires that have favored its regeneration (Gullison et al., 1996;Snook, 1993Snook, , 1996Snook, , 1998. ...
Article
Full-text available
Big-leaf mahogany (Swietenia macrophylla King) is an economically important timber species in the Neotropics. For over three centuries, it has been selectively extracted from tropical forests, threatening its populations. We investigate the actual and potential distribution of big-leaf mahogany and assess its abundance on the Yucatan Peninsula based on the National Forest and Soils Inventory database. Furthermore, we evaluate environmental factors associated with its distribution, abundance, and tree size. The actual and potential distribution models show the presence of mahogany in a wide geographic area covering the southern and eastern portions of the Yucatan Peninsula. Abundance of mahogany in the landscape varies and in general is low. The spatial potential distribution model was best explained by the environmental variables of vegetation cover (medium- and high-stature semievergreen tropical forest) and elevation (upland areas). Results also indicate that mahogany remains relatively abundant and contain larger size classes in localities where the species has been harvested and managed for decades under community forest management. Furthermore, statistical analyses show greater tree density of mahogany mostly associated with low-stature semievergreen tropical forest having deep soils (gleysols and vertisols), while larger tree size (diameter at breast height) was associated with medium-stature semievergreen tropical forests in upland areas with moderately deep or shallow soils (mostly rendzinas or leptosols). Despite deforestation, land-use change and forestry activities on the Yucatan Peninsula, particularly in the past 20 years, the distribution and abundance of mahogany do not appear to be as drastically reduced as described in other neotropical regions.
... S. macrophylla is a species native to Central and South America, and has been introduced and planted for its wood in many tropical countries such as Indonesia (Brown et al. 2003). In Indonesia, this wood has been highly prized in the production of furniture materials due its physical, mechanical, anatomical, and electrical properties (Husein et al. 2014, Anoop et al. 2014). ...
Article
Full-text available
This study investigated the antioxidant activity from the methanol (MeOH) soluble extract of the inner and outer bark of Swietenia macrophylla. The MeOH soluble extracts were fractionated into ethyl acetate (EtOAc) soluble and insoluble. The antioxidant activity was conducted by DPPH (1,1-diphenyl-2-picrylhydrazyl) method and the phenolic compounds were detected by GC-MS. The levels of total phenolic content of soluble and insoluble fraction of EtOAc of outer bark were higher than in inner bark, while total flavonoid content showed opposite results. The crude methanol extract and its EtOAc soluble fraction of outer bark showed a higher level of antioxidant activity. The GC-MS analysis detected higher levels of fatty acids and alcohols of 87.12% than phenolic compounds of 12.17% in the inner bark, while the outer bark showed the opposite pattern with phenolic compounds of 82.65% than fatty acids of 8.43%. A strong correlation was demonstrated between total phenolic content and antioxidant activity.
... In Europe, therefore, tropical woods are highly requested for applications like terrace decking, window scantlings or door construction. Consequently, during the past years the demand for timber with a high natural durability has increased significantly while the supply of traditionally traded timbers from natural tropical forests is getting more and more difficult (Brown et al. 2003;Verwer et al. 2008;Putzel et al. 2011). In this context, plantation-grown timbers are favored as a considerable potential for ensuring a sustainable wood production and for reducing the pressure on timber from natural forests. ...
Thesis
As a consequence of globalized timber markets, overexploitation of primarily tropical tree species and relocation of industrial production facilities, new or unknown wood species, so-called "lesser known species", have been increasingly imported into the European market. Regular evaluations at the Thünen Institute of Wood Research reveal that 20 to 30 "new" timbers (mainly tropical species) are added every year, whereas in many cases their wood and utility properties are largely unknown. As these timbers are often recommended for outdoor use, the determination of the natural durability is of great importance. In this thesis, basic wood anatomical and topochemical analyses (cellular UV-spectroscopy) of lesser known species from Central and South America with special focus on timbers from Mexico and Peru were carried out to study their properties. Natural durability with a quantitative assessment was determined according to the European standard (EN 350-2016); traces of fungal decay were also examined by light and electron microscopy. The anatomical and subcellular characteristics, including a histometric evaluation, of juvenile and adult wood of seven lesser known species (Manilkara zapota, Platymiscium yucatanum, Lonchocarpus castilloi, Roseodendron donnell-smithii, Terminalia buceras, Tabebuia rosea, Lysiloma latisiliquum) from Mexico were studied by light microscopy and X-ray diffraction using the SilviScan®-technique. The purpose was to provide basic data for a detailed differentiation between these two wood tissues. In conclusion, the anatomical examinations allow a clear identification of these timbers to fulfill the due diligence requirements of the European Timber Trade Regulation (EUTR) and are a useful contribution to the assessment of the wood properties of these lesser known species. Content: Publications I. Wood anatomical and topochemical analyses to characterize juvenile and adult wood of lesser-known species from Central America (Mexico) II. Cedrelinga cateniformis (Tornillo, Cedrorana) as substitute for relevant timbers used for window manufacturing and outdoor application. III. Die Europäische Holzhandelsverordnung (EUTR) - Anforderungen an die Holzartenbestimmung in der Praxis. IV. Fasern im Fokus: Holzartenbestimmung von Faserplatten - Erfahrungen aus den Prüfungen im Kontext der EUTR. V. Womit grillen wir da eigentlich? Wissenschaftliche Untersuchungen zeigen, dass viele Chargen zumindest fehlerhaft deklariert sind. VI. Viele Anfragen zu Bubinga und Palisander: Auswirkungen der neuenCITES-Listungen wichtiger Wirtschaftsbaumarten für die Holzverwendung und den Holzhandel.
... However, four of them have been introduced into numerous geographic regions of the intertropical zone [Castañeda-Posadas and Cevallos-Ferriz 2007 (Fig. 3)]. Swietenia aubrevilleana is the result of a hybridisation between macrophylla and mahagoni and is present mainly in certain islands of the archipelago of the Antilles (Brown, Jennings and Clements 2003;Gleason and Panshin 1936;Mabberley 1982). Swietenia mahagoni, macrophylla and aubrevilleana are the only species that are present in Martinique (Fig. 4). ...
Preprint
Full-text available
Background In many geographic areas influenced by tropical and temperate climates, natural forest ecosystems have been destroyed in favour of plantations of allochthonous trees which are economically profitable for different aspects of the timber industry. Some of these mature plantations degrade the soils and inhibit the regenerations of local flora species; others, due to the physical constraints which they impose, can contribute to the installation and the morphogenetic development of autochthonous taxa. The plantations of Swietenia macrophylla and Swietenia aubrevilleana (Mahoganys) in the Lesser Antilles are part of these processes. Methods To study the regeneration methods of forest plant species native to Martinique under plantations of Mahoganys, we carried out surveys in thirteen transects (stations) influenced by humid and subhumid bioclimates. Results The results showed that affine natural flora species from various stages of the plant succession colonise the plots of mature Mahoganys. Conclusions This study shows that mature plantations of not very competitive introduced forest species can greatly accelerate phytocenotic succession and increase specific richness. It is therefore possible to use these introduced species (Swietenia macrophylla and Swietenia aubrevilleana) in reforestation processes of Lesser Antilles biotopes of sylvan potentiality degraded by anthropisation.
... Swietenia macrophylla King, commonly known as mahogany, belongs to the Meliaceae family and is distributed in Western India, southern China, Malaysia, Mexico, Central and Tropical South America to Bolivia, Venezuela and Brazil, including large portions of the Amazon Basin [1,2]. S. macrophylla is in the critically endangered conservation category according to the study of the conservation status of plants in Costa Rica, and is listed in Appendix II of CITES [3,4]. ...
Preprint
Full-text available
The development of pharmaceutical products requires an exhaustive research of traditional medicinal plants with a long history of use in ethnomedicine for the treatment of various chronic and infectious pathologies. In the present study, which has no antecedents in Venezuela, we proposed to determine the concentration of total phenolic compounds and to evaluate the antioxidant activity by three chemical methods of the aqueous extract of seeds of the species Swietenia macrophylla King, thus expanding the knowledge reported worldwide. A higher content of phenolic compounds and antioxidant activity was observed in the leaf acuso extract, with statistical significance. Although the starting point of other investigations in relation to the extract of the leaves and seeds of S. macrophylla, has had interest in determining its hypoglycemic and antidiabetic effect, we consider relevant the investigation of the reducing and antioxidant properties of the aqueous extract, which is the way they are consumed by the indigenous and rural population of many countries of Asia and South America.
... al. [41] is the capacity of the natural process and components to provide goods and services that satisfy human needs, directly or indirectly. is simply implies that the higher the biodiversity, the more efficient the functioning of the ecosystem. Logging decreased the species diversity [42,43]; since logging was not allowed in both west bank forest and block A forest, species diversity was expected to be high. However, the results from the two forests showed a high diversity of plant species despite the disturbance that had occurred in the areas such as illegal hunting, land clearing for experiment, construction of physical structure, and firewood, poles, and stake collection [24,44]. ...
Article
Full-text available
Comparative analyses of diversity and similarity indices of west bank and block A forest of the International Institute of Tropical Agriculture (IITA) were carried out by the vegetation survey using transects and plot sampling techniques. Six transects {A (270°W), B (90°E), C (180°S), D, E (0°N), and F (180°W)} were constructed with the aid of prismatic compass in west bank forest and block A forest. 10 sampling plots of 10 m × 10 m were demarcated along each transect making 30 plots in each forest, and a total number of 60 plots were used for the study. Complete enumeration and identification of plants were carried out in each plot. The results showed that block A forest had 167 plant species from 58 families while west bank forest had 146 plant species from 56 families. A total number of 219 plant species from 70 families and 5804 individual plants were recorded in the two forests. West bank forest had higher values of all the diversity indices and Gamma diversity except Margalef’s community diversity index and alpha diversity index which were high in block A forest. Sorensen’s and Jaccard similarity indices of plants between west bank forest and block A forest were 59.42% and 42.66%, while the dissimilarity index of 40.58% was recorded. Thus, the two forests are richer and diverse in plant species; adequate protection of the two forests should be a priority to prevent loss of diversity of plants. Cutting of poles from the forests should be stopped.
... cupressoides, W. cedarbergensis, and D. cinnabari) are represented as points for the sake of clarity. Distribution ranges were taken from Urrutia-Jalabert, Rossi, Deslauriers, Malhi, and Lara (2015) for F. cupressoides, Little (1976) Barnes, Fagg, and Milton (1997) for V. erioloba, Jack, Hoffman, Rohde, and Durbach (2016) for A. dichotomum, Manders (1986) for W. cedarbergensis, Phys.org (2007) for C. pentandra and Martinez, Blundell, Gullison, and Grogan (2008) in natural range, timber production in South-East Asia (Brown, Jennings, & Clements, 2003;Gullison et al., 1996) Kapok (Lara et al., 1999;Lara & Villalba, 1993) TA B L E 1 Continued demographic feature is also reported to be relevant for species inhabiting environments that are not limited by water, such as tropical and temperate forests. In these regions adverse environmental conditions will be mainly biotically induced by competition with other species (e.g., competition for light) but environmental conditions can become sporadically favorable for recruitment when competition is removed (e.g., by disturbance-induced forest gaps increasing light availability for juvenile plants). ...
Article
Full-text available
Long‐lived, iconic plant species like the baobab, welwitschia, the saguaro cactus or the dragon's blood tree are perceived to be everlasting landscape features due to their pronounced longevity. However, these species are exceptional because new reproductive generations of these plants are infrequently incorporated into existing populations. A strong mismatch exists between the timescale at which these species provide services to society and ecosystems, and the timescale at which their reproductive stages and population development occurs. Here, we draw attention to these mismatches and their relevance for nature conservation and restoration. We argue that more dynamic management programs are necessary to preserve these iconic species for future generations. Summary Plants inhabiting variable environments have to adapt their physiology or demography to maintain fitness and, thus, long‐term population viability. Demographic storage through long‐lived seeds, juveniles, or adults help to overcome periods where unfavorable environmental conditions preclude successful recruitment into reproductive stages. Such storage components can foster long‐term population viability of sporadic recruiters, defined here as species with infrequent recruitment caused by a sporadic release from otherwise prevailing resource limitation. However, the beneficial effect of environmental variation reaches a limit when the species' physiological limits are exceeded or the demographic storage components are not sufficient to overcome periods of unfavorable environmental conditions. This can threaten species' long‐term population viability in an increasingly variable, human‐dominated world. At the same time, long‐lived, sporadically recruiting species provide numerous cultural, socio‐economic, and ecological services by being part of local myths and beliefs, or by providing habitat, food, wood, fiber, cosmetic, or medical products. In this contribution, we seek to raise awareness of what we call the ‘syndrome of long‐lived sporadic recruiters’ and the relevance of this syndrome for nature conservation and restoration. We outline key demographic features and highlight the main environmental threats for these plants, exemplified for a set of globally distributed charismatic plant species. We propose that fostering the long‐term population viability of long‐lived, sporadically recruiting plants will require the adaptive implementation of a dynamic management scheme where management actions, monitoring objectives, public outreach and research on the key demographic features of the species are coordinated. Long‐lived, iconic plant species like the baobab, welwitschia, the saguaro cactus or the dragon's blood tree are perceived to be everlasting landscape features due to their pronounced longevity. However, these species are exceptional because new reproductive generations of these plants are infrequently incorporated into existing populations. A strong mismatch exists between the timescale at which these species provide services to society and ecosystems, and the timescale at which their reproductive stages and population development occurs. Here, we draw attention to these mismatches and their relevance for nature conservation and restoration. We argue that more dynamic management programs are necessary to preserve these iconic plant species for future generations.
... In a previous study of mahogany seeds sown into slash and burn fields one year after abandonment in Quintana Roo, seedlings averaged 65 cm in height at 49 months while in this study seedling height averaged 170 cm at 45 months. Shorter height for the other study could be due to differences in site quality and/or weather, but the impact of seed being sown a year and a half later relative to the time the field was abandoned should be substantial (Brown et al., 2003). This would likely result in considerably more competition and less growth for those seedlings than seedlings in this study, in which seeds were sown 20 days after corn was sown during the last cropping year. ...
Article
Full-text available
This paper reports results of direct seeding of mahogany in three slash and burn fields during the last crop year in Betania, Quintana Roo, Mexico. A key issue in managing for timber production is ensuring regeneration of commercially valuable species, which requires considerable knowledge of the species being managed, such as Swietenia macrophylla King (mahogany). This paper reports results of direct seeding of mahogany in three slash and burn fields during the last crop year in Betania, Quintana Roo, Mexico. In each field 121 planting sites were located in a 0.25 ha plot, and five seeds were sown at each planting site. Height, diameter and indications of damage by Hypsipyla grandella of all sprouted seeds were recorded at 2, 11, 23, 38, 45, and 58 months after sowing. Soil color and shading were noted. At 11 months, mortality of seedlings alive at 2 months varied among fields but not among shade levels or between soil colors. Comparing seedlings alive at 58 months to seedlings alive at 2 months but dead by 58 months, percentage survival varied among fields and among shade levels, and did not vary between soil colors. For seedlings, alive at 58 months average diameter was influenced by field and did not vary between soil colors or among shade levels, and average height varied among fields, probably varied between soil colors, and there was no influence of shade level. Two months after sowing 20% of planting sites had at least one seedling. Five years later 63% of seedlings had died, leaving 7.4% of the planting sites occupied by a seedling, and seedling height varied from 0.3 to 8 m. Remarkably, none of 212 seedlings showed indications of damage by H. grandella. Milpa fields in their last cropping year seem to be promising site for regenerating mahogany from seed in a mixed species tropical forest context.
... Adult trees can achieve dimensions of approximately 70 m high, with a diameter at breast height (DBH) of 3.5 m. The species occurs naturally in Belize, Bolivia, Colombia, Costa Rica, Guatemala, French Guiana, Honduras, Mexico, Nicaragua, Panama, Peru, Venezuela, and in the Amazon Basin of Brazil (Brown et al. 2003;Carvalho 2007;da Silva Jr. et al. 2014;Degen et al. 2013;Grogan et al. 2002;Veríssimo et al. 1996). ...
Article
Full-text available
The mahogany tree (Swietenia macrophylla King) is a species of conservation concern, mostly due to illegal and destructive harvesting practices. It has been planted in several agroforestry systems in the Brazilian Amazon to preserve the species and provide a sustainable source of this valuable timber. This study analyzed the growth and yield of the mahogany wood from plants used as shading in cocoa-based agroforestry systems with nitisols and red–yellow acrisols, located in the State of Pará, in the Brazilian Amazon, because these two types of soils are the most recommended for implanting cocoa-based agroforestry systems in the region due to their natural fertility. The installed experiment was a randomized 2 × 6 factorial experiment, with two types of soil and six different tree ages. The results indicate that soil type and plant age both affected the increments in diameter at breast height. Trees from the red–yellow acrisol had statistically higher diameter at breast height values (P < 0.05) than trees from the nitisol (40.05 and 33.57 cm, respectively). There was also a significant interaction between soil type and tree age (P < 0.01). The average stem height differed markedly between the soil types from plants aged 19 and 22 years (P < 0.05), whereas average stem height differed significantly among the 16-, 19-, and 22-year-old plants (P < 0.05). The average wood volume was 1.41 m³ tree⁻¹, and the highest yield (1.75 m³ tree⁻¹) was achieved in the red–yellow acrisol site, for 33-year-old trees. These results demonstrate how the cocoa and mahogany-based agroforestry systems can produce these products in a sustainable manner in the Brazilian Amazon.
... These logging practices are more likely to take place in forest types that include tree species with high commercial value such as mahogany and cedar (Kometter et al., 2004). Yet, valuable tree species may exist in different forest ecosystems (Brown, Jennings, & Clements, 2003;Dauber, Fredericksen, & Peña, 2005), which could explain why selective logging may not be restricted to a particular forest type. Bamboo species for instance, which have traditionally been used as construction material in Peru (Escamilla & Habert, 2014), preponderate in five different forest types as classified by Peru's Ministry of the Environment (MINAM, 2015). ...
Article
The spatial patterns of deforestation are usually non-randomly distributed across the landscape. While anthropogenically driven processes are often addressed in land-use regulation policies and deforestation research, less attention is given to the environmental factors that influence tropical deforestation. This study investigates to what extent climate conditions (temperature and precipitation) and biophysical landscape characteristics (elevation, slope, soil type, forest type, and distance to rivers) facilitate or mitigate deforestation processes in Peru's tropical Andes. A Random Forest regression model was constructed for the entire Peruvian tropical Andes, and separate models were developed for some of the known direct deforestation drivers in the region (coca production, gold mining, and land-use by indigenous and non-indigenous communities). Soil type and precipitation were identified as the most important deforestation predictors when the entire Peruvian tropical Andes was considered, whereas distance to rivers was associated with deforestation by mining activities, and elevation and temperature with coca cultivation areas. Using the regression results, a Random Forest classification model was constructed to locate areas where the composition of environmental factors could either facilitate or mitigate deforestation processes. It was found that almost 85% of the forests classified as having high to very high probability to deforestation were located outside current protected areas. In order to increase conservation impacts, the results suggest that greater consideration should be given to the distribution of environmental factors when designing land-use regulation policies and establishing protected areas.
... The Mahogany tree (Swietenia macrophylla King), which can usually reach 40 to 60 meters, belongs to the Meliaceae family and has a tropical distribution found in Central and South America, in Western India, in Malaysia and in the central and southern China (1,2). This plant is used in Asia for the treatment of various diseases based on their antimicrobial effects, anti-inflammatory, antioxidant, anti-mutagenic, anti-cancer, anti-tumor and anti-diabetic activities (2). ...
Article
Full-text available
Background: The mahogany tree (Swietenia macrophylla King) is widely used in traditional medicine, especially its seeds, which are used in Malaysia, Indonesia and some countries of South America. Recently an active fraction of the leaf ethanolic extract (labelled “Sm13-16, 23”), showed promising results against some toxins of South American pit vipers. Objectives: In this study the aim was to evaluate the acute oral toxicity of fraction Sm13-16, 23 from the leaf ethanolic extract, using Swiss Webster mice. Methods: Fraction Sm13-16, 23 was administered orally in a single dose to 2000 mg/kg and 300 mg/kg, clinical follow-up for 14 days was performed and then euthanasia, necropsy and histopathology of organs were performed. Results: Overall, there were not deaths recorded during the study period. Further not signs of toxicity in doses of 300mg/Kg were observed, but at doses of 2000 mg/kg, histopathological lesions in the liver, as karyomegaly and the binucleation were observed. Conclusions: Fraction Sm13-16, 23 does not produce toxicity lesion at doses of 300mg/kg, indicating that the acute oral toxicity risk is low.
... Mahogany seedlings require high light levels and are intolerant of competition for light from other plants . Within its geographic range many types of natural disturbances create appropriate conditions for mahogany to regenerate (Brown et al., 2003). In Quintana Roo (the state on the eastern side of the Yucatan Peninsula), Mexico, Snook (1993) argued that mahogany regenerates after hurricanes that strike the Peninsula. ...
Article
Full-text available
In tropical America, regeneration of big- leaf mahogany, Swietenia macrophylla King, the most important commercial tree species, is problematic because of its fruiting and dispersal characteristics, very low tolerance of shade and response to logging. In Quintana Roo, Mexico, abandoned slash-and-burn crop elds are excellent candidates for seedling esta- blishment, but an ef cient way to esta- blish mahogany seedlings has not been identi ed. This study assessed the proba- bility of predation on directly sown maho- gany seeds, examining the effects of three treatments (four types of seed protection, two sowing methods, two times of day for sowing). The mean percentage of seeds either partially consumed or removed during a 12-hour period varied from 1.1 to 7.7% among the four seed protection treatments and did not differ between the two sowing methods. Precipitation had an important positive effect on survi- val, and minimum daily temperature had a marginal negative effect on survival. The Julian calendar date had a positive effect on seed survival. Seed predation did not differ among the seed protec- tion treatments that allowed access only to rodents, only to insects, and to both types of seed predators, and predation was greater with these three treatments than with the no-access treatment. Seed predation was not in uenced by the time of day of sowing. Direct sowing offers a good option for regenerating mahogany, especially if the mahogany seeds are soaked for at least 2 weeks before sowing to reduce predation risks and increase prospects for seed survival and seedling establishment.
... Mahogany seedlings require high light levels and are intolerant of competition for light from other plants . Within its geographic range many types of natural disturbances create appropriate conditions for mahogany to regenerate (Brown et al., 2003). In Quintana Roo (the state on the eastern side of the Yucatan Peninsula), Mexico, Snook (1993) argued that mahogany regenerates after hurricanes that strike the Peninsula. ...
Article
Full-text available
In tropical America, regeneration of big leaf mahogany, Swietenia macrophylla King, the most important commercial tree species, is problematic because of its fruiting and dispersal characteristics, very low tolerance of shade and response to logging. In Quintana Roo, Mexico, abandoned slash-and-burn cropfields are excellent candidates for seedling establishment, but an efficient way to establish mahogany seedlings has not been identified. This study assessed the probability of predation on directly sown mahogany seeds, examining the effects ofthree treatments (four types of seed protection, two sowing methods, two times of day for sowing). The mean percentage of seeds either partially consumed or removed during a 12-hour period varied from 1.1 to 7.7% among the four seed protection treatments and did not differ between the two sowing methods. Precipitation had an important positive effect on survival, and minimum daily temperature had a marginal negative effect on survival. The Julian calendar date had a positive effect on seed survival. Seed predation did not differ among the seed protection treatments that allowed access only to rodents, only to insects, and to both types of seed predators, and predation was greater with these three treatments than with the no-access treatment. Seed predation was not influenced by the time of day of sowing. Direct sowing offers a good option for regenerating mahogany, especially if the mahogany seeds are soaked for at least 2 weeks before sowing to reduce predation risks and increase prospects for seed survival and seedling establishment.
Article
While acknowledging the critical importance of maintaining large, core areas of tropical forests as free as possible from human interference, this chapter addresses the need for tropical forest conservation efforts in the wider tropical landscape, beyond the boundaries of strictly protected areas. It highlights the need to understand the resilience of tropical forests to anthropogenic perturbations, focusing on ecosystem-level processes, particularly food web changes, ecological cascades, and alterations to ecosystem functions. Next, it reviews empirical evidence for the resilience of tropical forests to different anthropogenic drivers, considers what humans can do to maximize resilience at various scales, and suggests that it may be possible to maintain tropical forest biodiversity by working within the bounds of 'natural' disturbances. Further, it suggests that conservation efforts in the wider tropical landscape may increasingly need to retain functioning and resilient ecosystems, rather than biodiversity per se.
Article
SUMMARY Like most other species, sustainable management of mahogany in natural forests ultimately relies on continued seed production by the population. Because larger trees produce more fruit, previous authors have emphasised the importance of retaining large trees. In this paper, we investigate levels of fruit production of mahogany in two ecologically distinct forests. Fecundity was related to tree size in some years, but this relationship was neither consistent nor strong. The contribution of any given size class to population-level fruit production depended on both its fecundity and its relative abundance and this differed between forests. The fecundity of small and medium-sized trees was also significantly different between forests and this was consistent with patterns of increased crown exposure caused by differences in forest structure. From a forest management perspective, these results suggest that size-fecundity relationships are insufficient to guide forest management prescriptions without also quantifying the size structure of the population.
Preprint
Full-text available
Background: Mixed-species systems are well-suited to smallholder and community forestry, but reliable evidence regarding and procedures to assess species performance in such systems is scarce. This study concern a field trial with a pair of clinal plots varying spacing and species composition that offered insights into competition between four species proposed for mixed-species plantings by smallholders for landscape rehabilitation in the Philippines. Results: Use of a size-distance competition index allowed an assessment of the competitive and collaborative influences between four tree species. Within the expected general trend for growth to decline with increasing competition, there were indications that Shorea palosapis is a benign competitor that may stimulate the growth of neighbouring individuals. Paraserianthes falcataria is a strong competitor that is also strongly impacted by competition, especially through antagonistic intraspecific competition. Paraserianthes falcataria appears well suited as a solitary tree in a field or village, whereas Shorea palosapis seems ideal for plantations, in both monoculture and mixed plantings. Conclusion: Pterocarpus indicus exbibits strong intraspecific, but low inter-specific competition, so appears well-suited for polyculture plantings. Of the four species, Swietenia macrophylla appears to be best-suited as a monoculture species as it exhibits the lowest intraspecific competition.
Technical Report
Full-text available
In recent decades big-leaf mahogany, Swietenia macrophylla, has been intensively harvested across its natural range in tropical South America. Future timber production from natural forests will depend on protection and stewardship of surviving commercial populations through sustainable management practices. The Big-Leaf Mahogany Growth & Yield Model presented here projects population recovery and timber production from simulated harvests of mahogany in the Brazilian Amazon. The model offers forest managers a computer-based tool for assessing the impact of current management practices on both pre-installed example mahogany populations and on user-entered populations. Although the model was developed based on mahogany population dynamics in Brazil, it can offer useful insights into post-harvest recovery by natural populations throughout South and Central America. The growth & yield model uses the NetLogo 5.0.3 (Wilensky 1999) platform and can be installed on computers using Windows or Mac OS X operating systems. The growth & yield model functions (algorithms) are derived from demographic data collected annually during 1995–2010 for nearly 600 mahogany trees and many thousands of seedlings, saplings and pole-sized trees at multiple field sites in southeast Pará and Acre. Model simulations can be run with or without harvesting. Under logging scenarios, the model harvests (kills) trees at specified intervals. During intervals between harvests, surviving individuals grow, reproduce, and die at rates observed in field studies. Harvest simulations are based on current legal management practices (60 cm minimum diameter cutting limit, 20% commercial-sized tree retention rate, minimum 5 commercial-sized trees / 100 ha retention density, 30-year cutting cycle). Forest managers can input mahogany population data from field inventories in order to project recovery and production outcomes following multiple harvests. Harvest parameters can be changed to view population and timber production outcomes under alternative management scenarios by adjusting one or more of the four management practices. The model interface allows harvest simulations to be set up and run by clicking on a series of buttons as explained in the sections to follow. For a given starting population and harvest scenario, each ‘run’ will yield a different outcome (number of trees and commercial volume harvested, surviving density, etc.). This occurs because the model functions for survival, growth, and reproduction are recalculated each year using a random error term, leading to different long- term outcomes. For this reason, average outcomes from multiple simulations will best represent long-term population recovery and production rates for a given population and harvest scenario. During each time step (year) of model simulation, the following actions occur on the model interface: (1) the time display advances 1 year; (2) trees grow in size on the landscape (trees are sized according to diameter); (3) trees are logged and removed from the landscape at specified harvest intervals; (4) trees die and are removed from the landscape; (5) the landscape experiences disturbance (red circles = disturbance; dark red = zone of recruitment); (6) trees reproduce and new seedlings are added to the landscape; and (7) disturbances are removed from the landscape and the plots and monitors are updated.
Book
Full-text available
Management for timber in the tropical forests of the Yucatan Peninsula is advised to consider the multiple species, products and services that may flow out of these forests. Group selection and small clearcuts are recommended practices for regeneration. Analysis of neighboring trees to select target trees may allow better ground coverage by the residual stock in partial cuts. Slash and burn practices may also be considered an excelent silviculture system. This silviculture guide was sponsored by the North American Forest Commission. Paper copies can be obtained from Comisión Nacional Forestal (Mexico).
Technical Report
Full-text available
En décadas recientes, el árbol de caoba, Swietenia macrophylla, ha sido extensamente cosechado a lo largo de sua áreas de distribución natural en Suramérica tropical. La producción de madera de los bosques naturales dependerá de la implementación de prácticas de manejo sustentable que aseguren la protección y administración de las poblaciones comerciales que aún sobreviven. El Modelo de Crecimiento y Rendimiento de la Caoba que aquí se presenta es capaz de proyectar la recuperación de poblaciones de caoba y su producción maderera en cosechas simuladas dentro de la Amazonia de Brasil. El modelo les ofrece a los manejadores de bosques una herramienta computadorizada para evaluar el impacto de las prácticas de manejo que utilizan actualmente, aplicándolas tanto a poblaciones predefinidas a modo de ejemplo, como a poblaciones creadas por el usuario. A pesar de que el diseño del modelo está basado en las dinámicas poblacionales de la caoba en Brasil, puede ser de gran utilidad para evaluar la recuperación post-cosechas de las poblaciones naturales de esta especie en Sur y Centroamérica. El modelo de crecimiento y rendimiento utiliza la plataforma NetLogo 5.0.3 (Wilensky 1999) y puede ser instalado en computadoras que utilizan los sistemas operativos de Windows o Mac OS X. Las funciones del modelo de crecimiento y rendimiento (algoritmos) son derivadas de datos demográficos recopilados anualmente de 1995–2010 para aproximadamente 600 árboles de caoba y miles de plántulas, árboles jóvenes y árboles de tamaño de poste en diferentes áreas de campo en el sureste de Pará y Acre. Las simulaciones del modelo pueden correr con y sin parámetros de cosecha. Cuando se utilizan escenarios de tala, el modelo cosecha (mata) árboles a intervalos específicos. Durante los intervalos en medio de cosechas, los árboles sobrevivientes crecerán, se reproducirán y morirán de acuerdo a los ritmos observados en estudios de campo. Las simulaciones de cosechas están basadas en prácticas legales de manejo que se utilizan actualmente (un límite mínimo de 60 cm de diámetro para árboles a ser cortados, un índice de retención de 20% para árboles de tamaño comercial, una densidad mínima de retención de 5 árboles de tamaño comercial / 100 hectáreas (ha), un ciclo de tala de 30 años). Los manejadores de bosques pueden entrar datos de la población de caoba obtenidos de inventarios de campo para proyectar los resultados de recuperación y producción de múltiples cosechas. Los parámetros de cosecha pueden alterarse para evaluar resultados de población y producción maderera de acuerdo a diferentes escenarios de manejo, mediante ajustes a una o más de las cuatro prácticas de manejo incluidas. La interfaz permite que las simulaciones de cosecha se establezcan y operen al pulsar una serie de botones, según se explica en las secciones siguientes. Para una población inicial y escenario de cosecha determinados, cada vez que se pulse ‘operar’ se obtendrá un resultado diferente (número de árboles y volumen comercial cosechado, densidad de la población sobreviviente, etc.). Esto se debe a que las funciones del modelo para la supervivencia, el crecimiento y la reproducción de los árboles se vuelven a calcular todos los años utilizando un término de error aleatorio, que produce diferentes resultados a largo plazo. Por ende, un promedio de resultados de diferentes simulaciones proveerá la mejor representación de la recuperación y los ritmos de producción a largo plazo en determinadas poblaciones y escenarios de cosecha. Durante cada etapa de tiempo (año) de simulación del modelo, las siguientes acciones se reflejan en la interfaz: (1) el tiempo avanza un año en el visualizador; (2) los árboles en el sitio de campo crecen en tamaño (el tamaño de los árboles está ajustado al diámetro); (3) los árboles en el sitio de campo son talados y removidos a intervalos determinados de cosecha; (4) árboles mueren y son removidos del sitio de campo; (5) el sitio de campo es impactado por perturbaciones (círculos rojos = perturbación; rojo oscuro = zona de reclutamiento); (6) árboles se reproducen y nuevas plántulas aparecen en el sitio de campo; y (7) se remueven las perturbaciones del sitio de campo y se actualizan los monitores y las gráficas.
Thesis
Full-text available
br>Smallholders in the Amazon are one of the most important actor groups for achieving long-term maintenance of the remaining forests. They manage vast areas of forestlands based on customary rights, and possess significant local knowledge about their resources. Smallholders have been exploited and marginalized throughout centuries within paternalistic societies ruled by economic and political elites. More recently, in response to pressure from emerging societal movements, many national governments, supported by the international community, have recognized the rights and roles of smallholders living in rural, often still forested landscapes. During the 1990s, Sustainable Forest Management (SFM) proliferated throughout the Amazon region as a promising approach to halter deforestation and biodiversity loss, as well as to mitigate climate change. While SFM initially focused on the capacities of professionally working timber companies managing public forests in concessions, soon the need became obvious to consider the smallholders living in and from these forests. This gave rise to the concept of community-based forest management that primarily relates to the management of timber by small local forest owners based on legally authorized management plans grounded in the principles of Reduced Impact Logging (RIL). Accordingly, many different governmental and non-governmental organizations, supported by the international donor community, started initiatives to support this new approach. However, after many years of promotion of community-based forest management, experiences have been rather ambivalent. Despite some impressive success stories of some forest development projects, only very few smallholders adopted the proposed management schemes. This lack of broader success indicated a lack of compatibility between the regulatory and market frameworks for community-based forest management and the capacities and interests of smallholders. This raised the more general question if and to what degree the management of forests for timber under the specific conditions of the Amazon region is a feasible option for smallholders to generate the urgently required income in a sustainable way. Against this backdrop, this study aimed at analysing the effective potential of timber management for smallholders in the Amazon to provide orientation for the formulation of policies to promote community-based forest management for the benefits of smallholders. The study considered two critical impediments to community-based forest management: the locally absent technical skills and financial means needed to act successfully in timber markets; and a low abundance, unsatisfactory regeneration and productivity of marketable species in natural forests. Related to this, it is often argued that smallholders tend to seriously overexploit and damage their forests if not controlled. Accordingly, the study followed four research questions: i) What possibilities do smallholders have to engage in timber markets?; ii) What is the commercial potential of their primary and secondary forest areas?; iii) What are the effects of smallholders’ timber logging on forests?; and, iv) What are the possibilities for long-term management of timber resources?. As part of the EU-financed international research project “Forest management by small farmers in the Amazon - An opportunity to enhance forest ecosystem stability and rural livelihood”, this study addresses these three questions by empirically analysing 21 communities in four forest regions in Bolivia (Riberalta), Ecuador (Macas) and Peru (Pucallpa and Puerto Maldonado) selected for their relevance and representativeness regarding regional contexts in terms of markets characteristics, smallholder’s management strategies, and forest characteristics. The analysis included three studies: i) A market and value-chain analysis to understand the role of smallholders in contemporary timber markets and to identify the barriers and potentials to make forest management an attractive source of income. ii) An analysis of the monetary value of timber in smallholders’ primary and logged areas. iii) An assessment of the effects of smallholder’s logging activities in primary and secondary forests on forest structure and composition through comparisons between primary and logged farm forests. In these studies, farm inventories were carried out in primary, secondary, and logged forests. Semi-structured interviews were conducted with smallholders about timber management practices, generated incomes, production costs, and timber marketing. Secondary information and expert interviews complemented information particularly related to the scientific names and ecological characteristics of the inventoried trees, production chains, and relevant legal aspects. Multivariate and univariate approaches were used to analyse farm forests, and to classify smallholders according to their forest management strategies. In a final step, the findings were used to calculate the financial and ecological potential of community-based timber management under consideration of different area size, logging intensity, and productivity scenarios. The market analysis revealed that the number of species with commercial potential for regional or international markets differed largely between the study areas. Whereas in Riberalta, Bolivia, 15 tree species were regarded as commercial, 22 commercial species were regarded as such in the Pucallpa and Puerto Maldonado regions in Peru, and up to 80 species in the Macas region in Ecuador. Accordingly, the stocking commercial volumes in the analysed forests varied from around 20 m-3 in Riberalta, Pucallpa and Puerto Maldonado, to up to 80 m-3 ha-1 in Macas. The specific numbers strongly varied between the different smallholder forest stands due to previous logging practices and local forest composition. Also, the prices paid by local traders for timber varied strongly. For Cedrelinga cateniformis, a timber tree species found in all the study regions, the price varied from only USD$ 3.7 in Riberalta, to USD$ 6.7 in Pucallpa and Puerto Maldonado, up to USD$ 16 m-3 of round wood in Macas. Accordingly, the monetary value of stocking timber volume for one hectare varied from USD$ 0 in a logged farm forest located near Riberalta, to USD$ 1,324 in a smallholder forest located in the Macas region. The analysed households used this potential to different degrees. It is possible to distinguish five general categories of smallholders: (1) Those not dependent on income from timber; (2) those requiring occasional income from timber; (3) smallholders requiring complementary income; (4) those obtaining their principal income from timber; and (5) smallholders specialized in timber harvesting and trade. Depending on market opportunities, forest conditions and the strategy of the smallholder, incomes from timber varied from USD$ 194 yr-1 in Pucallpa and Puerto Maldonado, to USD$ 216 in Riberalta, up to USD$ 2,589 in Macas. Forests previously logged by smallholders showed significant differences to pristine forests regarding basal area, number of trees and DBH distribution of the principal commercial species. Particularly, a large shift towards smaller size classes was observed. In secondary forests, the commercial timber potential depended in particular on the regeneration and dominance of commercial tree species. In some young secondary forests, dense regeneration of pioneer species with a commercial value in local markets dominated the forest composition. In other cases, only few commercially interesting trees were found. Projections of timber production for the next thirty years resulted in the volumes: between 7.4 m3 ha-1, 12.2 m3 ha-1, and 20.9 m3 ha-1 for Bolivia, Peru, and Ecuador respectively, with large variations depending on previous logging practices. These values translate into Annual Allowable Cuts between 0.05 m3 ha-1 yr-1 in a stand located in Puerto Maldonado, up to 1 m3 ha-1 yr-1 in a still pristine forest in Ecuador. Considering the average forest areas of smallholder farms of 53 ha in Bolivia, 46 ha in Peru, and 31 ha in Ecuador, the yearly harvestable volume per smallholder is around 11.5 m3 yr-1, 12.5 m3 yr-1, and 7.2 m3 yr-1 in Bolivia, Peru, and Ecuador, respectively. These translate into potential annual incomes of around USD$ 45 (Bolivia), USD$ 84 (Peru), and USD$ 115 (Ecuador) for the three countries. The potential annual net income also strongly varied depending on transport distance to the nearest road and the availability of horses and chainsaws. Thus, income prospects of forest that were three hours distant from a road were around USD$ 200 yr-1 compared to USD$ 1,000 yr-1---- for a forest located near a road. These findings suggest that timber management can be financially attractive for smallholders particularly if value is added through the cutting of planks. However, in practice, this potential depends largely on local marketing possibilities and timber prices, the possibility of integrating into value-added chains, as well as the size, composition and state of the forest. In case of vibrant timber markets that absorb large volumes of a wide range of tree species, the financial attractiveness of timber logging is high. Even under less favourable conditions, smallholders tend to develop strategies to take advantage of an eventually existing potential for generating income from the logging of timber in their forests. The identified timber use strategies employed by smallholders in the study regions, although not under control of the forest authorities, so far have only moderately changed the structure and composition of forests at a level comparable with the one documented for sustainable timber management schemes. Timber growth projections for forests that have been logged by smallholders are comparable to those of logged areas under management plans. It can be concluded that the management of forests to produce timber can be attractive for smallholders as a complementary source of urgently required income while contributing in parallel to the long-term conservation of significant forest areas in the Amazon. Against this backdrop, it is highly recommended to more intensively support smallholder forestry in the region, above all by the formal recognition of local management schemes and a substantial improvement of local conditions for the commercialization of timber.
Article
Cedrelinga cateniformis (tornillo) is a timber species of the South American Amazon Basin. In its natural distribution area, the wood has various local uses, such as furniture, art work, door and window frames, and light construction. In order to promote this lesser known species for high valued applications on the international market, wood anatomical, topochemical and physical/mechanical studies were carried out to characterize the wood properties. The topochemical distribution of the lignin and phenolic extractives in the tissue were studied by means of cellular UV microspectrophotometry (UMSP). The results of the structural and topochemical analyses were compared with the interrelation of certain anatomical and subcellular structures as well as the chemical composition with regard to the physical and mechanical properties. The natural durability of the mature heartwood was analyzed according to the European Standards and is resulting in a durability class 1 against basidiomycetes. Based on the findings of the comprehensive investigations concerning physical and biological features, e.g. the dimensional stability and durability, Cedrelinga cateniformis is ideally suited as a substitute for overexploited tropical woods currently used in Europe for wooden window frames and other above ground outdoor applications and thus can contribute to increase the value-added production in Peruvian forests.
Conference Paper
Full-text available
The aim of this study was to investigate the lipophilic extractives in the bark of mahogany (Swietenia macrophylla). The bark was separated into inner and outer bark region. The bark was ground to form powder and then was extracted by n-hexane at 90 o C for 6 hours. Further, n-hexane soluble extract was fractionated to obtain neutral-acidic fraction. The amounts of n-hexane extract of inner and outer bark were 0.63 and 0.54 % , respectively (based on oven dried wood). The extracts of n-hexane extract, neutral, and acidic fractions were identified by gas chromatography-mass spectrometry (GC-MS) to investigate the lipophilic constituents. The lipophilic constituents composed of hydrocarbons, aliphatic alcohols, fatty acids, terpenoids and sterols. After fractionation, sterols and terpenoids, was the most abundant in neutraf fractions whereas fatty acids were the major compounds in acidic fraction, particulary in the outer bark. The high levels of terpenoids and sterols in the barks should be followed by compound isolation and toxicity test in medicinal purposes point of view.
Article
Full-text available
CÁMARA-CABRALES L & KELTY MJ. 2009. Seed dispersal of big-leaf mahogany (Swietenia macrophylla) and its role in natural forest management in the Yucatán Peninsula, Mexico. As part of efforts to design appropriate silvicultural methods for sustainable forest management of big-leaf mahogany (Swietenia macrophylla: Meliaceae) in natural mixed forests of Quintana Roo, Mexico, a study of seed dispersal of 11 mahogany seed trees was undertaken. Both small (50-74 cm diameter at breast height, dbh) and large (75-100 cm dbh) seed trees showed seed distributions that were skewed to the west, generally matching the prevailing easterly trade winds. Total mean seed production of trees in the smaller size class was one-half of that of the large trees. Maximum seed dispersal distance was 50 m in the westerly directions (NW-W-SW) and only 20-30 m in other directions. Total seed dispersal areas were 0.4 and 0.5 ha for the small and large trees respectively. These results are important for designing seed tree or shelterwood regeneration methods for mahogany; they provide guidelines for creating the size and spatial layout of an overstorey felling and site preparation treatment that would match the dispersal area.
Chapter
Big-leaf mahogany is an emergent tree that occurs at low densities in seasonally dry forests from Mexico to Bolivia. Managing natural populations of mahogany for sustainable timber production requires matching harvest levels to population recovery rates. We describe the basic components of mahogany population dynamics observed from field studies – the distribution of stem size classes and ages from seedling to senescent adult, and mortality, growth, and reproductive rates – and silvicultural practices for reducing mortality and enhancing growth. Population structures vary predictably according to annual rainfall totals and dry season length, with important implications for management planning. For mahogany and heavily exploited high-value tropical species like it, silviculture based on thorough understanding of life history offers both management tools for ensuring future harvests and conservation tools for protecting natural populations.
Thesis
Full-text available
Regeneration and growth of mahogany and associated species were documented on 10 essentially even-aged stands of about 40 tree species that became established 2-75 years ago after fire, clearing or hurricane. Stand structure and species mixtures varied with disturbance type. More species and more individuals survived hurricanes than fire. Mahoganies have buttresses and thick bark that enable them to survive both hurricanes and fires better than all other species except chicozapote (Manilkara zapota), source of the chicle latex. As a result, mahoganies continue to grow larger over centuries, through the destruction and replacement of several generations of associated trees. Eight of the most common tree species, including mahogany, regenerated more abundantly after fire or clearing. Seven species, including chicozapote, were favored by hurricane. Thirty or more years after fire, post-disturbance mahoganies occurred at densities of 15-22/ha as compared to 6/ha 34 years after a hurricane. In both cases, diameter distributions of the post-disturbance cohort corresponded to bell-shaped curves characteristic of even-aged aggregations. The highest density of mahoganies (5600 saplings/ha at 4 m tall) was found on disturbed soil on a roadside. Where light fires had stimulated sprouting among other species rather than reducing their site occupation, mahoganies were suppressed and moribund in the seedling layer 15 years later. Measurements of trees on a chronosequence of post-fire stands 15-75 years old revealed how differential growth rates among species resulted in canopy stratification within even-aged cohorts. By age 45, heights ranged from less than 12 m to 20 m. After age 15, when their branches begin to develop, mahoganies grow more rapidly than other species in both height and diameter. By age 45 mahoganies are taller than most other species and by 75 their crowns emerge and begin to expand laterally above the main canopy. Nonetheless, extrapolated growth curves indicate that mahoganies require over 120 years to attend the current commercial diameter limit of 55 cm.
Article
Full-text available
Low rates of natural regeneration of big-leaf mahogany (Swietenia macrophylla King) were found in gaps due to felling and natural treefalls in the Yucatan. This finding is consistent with low post-logging abundances of reproductive-sized trees as well as relatively low growth rates of planted mahogany seedlings in small felling gaps. High growth rates of seedlings in large felling gaps and landings provides optimism that the extensive plantings done in the region will provide timber in the future. The long-term effects of shoot borers, which predominantly attack the fastest growing seedlings, are uncertain.
Technical Report
Full-text available
Neste trabalho, os autores apresentam uma descrição sobre o mogno em toda a sua área de ocorrência natural na América do Sul e América Central, com ênfase em uma pesquisa conduzida no Brasil. O livro apresenta os fatores que influenciam na regeneração do mogno e traz recomendações para o manejo desta espécie.
Article
Full-text available
Mahogany (Swietenia macrophylla King) is the single most important commercial tree species in the forests of the state of Quintana Roo, Mexico. Mahogany regeneration has been associated with natural disturbances that increase understory light levels. A study to analyze the effect of overstory removal on seed germination and early seedling survival and growth of mahogany was conducted. Twenty-five 0.2 ha plots were treated to create different levels of overstory removal and then seeded. Two seeding methods were used, dibbling and dropping. Dropping was used to simulate the way that seeding occurs in nature. Understory light levels were measured after the overstory removal was done. A year after applying the treatments, seed germination and seedling survival were not affected by the understory light levels created by the overstory removal. It is expected that over the next several years seedling survival and growth will be more affected by understory light levels. Seedling establishment by dibbling and dropping gave similar results. There was a high correlation (r = 0.95) between the percent of overstory removal and understory light levels.
Article
Full-text available
In an old-growth longleaf pine population in which all trees of at least 2 cm in dbh were mapped and tagged, the population was of uneven age and size; tree size correlated positively with tree age. Large or old trees were only loosely aggregated, forming a background matrix that filled the forest. Juvenile trees were highly aggregated, located in areas of low adult densities. Recruitment thus occurs primarily within open spaces created by the deaths of large trees. Variable time lags may occur before the colonization of open spaces, however, because of temporal variation in seed production and occurrence of summer ground fires. Recruitment within the mapped plot has occurred frequently for at least the past 250 yr. Temporal variation in adult mortality and recruitment into open spaces, coupled with strong negative interactions between cohorts of different ages, appears likely to produce alternating phases of population growth and decline that are highly variable in length and magnitude. An upper bound to population size occurs when all available space is filled with trees; but no lower bound exists, and extinction probabilities may be increased at very low densities. The population is buffered from declines to very low densities, however, by the tendency for small trees to recruit into openings created by the deaths of adults. Longleaf pine possibly maintains the environment in an open state suitable for its own regeneration by transmuting a localized disturbance (lightning) into a widespread disturbance (ground fires). Fire facilitation results in an extended, but indefinite, increase in the persistence of environmental conditions in which longleaf pine, but no other tree species, can survive and reproduce. -from Authors
Article
Full-text available
Legally recognized Indian reserves of Brazilian Amazonia span over 100 million ha of largely intact forest and are potentially valuable for biodiversity conservation. An important example is provided by the Kayapó territories which span more than 13 million ha in Pará and Mato Grosso, Brazil, and protect a unique and vulnerable Amazonian forest type that is poorly represented in existing nature reserves. The Kayapó of southern Pará have stopped invasion of their lands by the most perverse threats to Amazonian forests, but they have become involved extensively in the sale of illegal logging concessions for the high-value timber species mahogany (Swieteniamacrophylla). In 1992, the non-governmental organization Conservation International do Brasil (CI-Brasil) began a conservation and development project with the Kayapó community of AUkre and CI-Brasil satisfies common pool resource principles, and (3) propose a model for expanding the small-scale conservation results achieved by the CI-Brasil project to all Kayapó territories. Several mammals (Tayassupecari, Pteronurabrasiliensis, Priodontesmaximus, Pantheraonca) and at least one bird species (Anodorhynchushyacinthinus) listed as endangered were regularly encountered within 15 km of A1 within groves and 0.13 stems haUkre to meet criteria of successful common pool resource institutions. The CI-Brasil project resulted in protection of an intact mahogany population in 8000 ha of forest maintained by the community for ecological research purposes and mahogany preservation. Our analysis attributes the success of the conservation alliance with AUkre could be expanded to include the entire Kayapó nation and thereby contribute to conservation of more than 13 000 000 ha of forest and cerrado in the south-eastern Amazon.
Article
Full-text available
Mahogany (Swietenia macrophylla King) regenerates in areas of erosion on high terraces and in forest killed by flooding and deposition of alluvial sediments in the Chimanes Forest, Bolivia. These hydrological disturbances are patchy, and only one of five stands of mahogany that we inventoried was regenerating. Mahogany survives these disturbances significantly better than the common tree species. The long time between disturbances appears to favour late maturation. Mahogany trees allocate little photosynthates to reproduction until they are very large emergents, at least 80 cm in diameter. The episodic nature of the regeneration sites means that mahogany stands are composed of one or a few cohorts, which are vulnerable to overharvesting, particularly with the current use of a minimum cutting diameter to regulate harvest. The delayed onset of fecundity means that the small trees that escape harvest are not very fecund, resulting in minimal seed input to logged forest. Only 7–9% of the gaps created by logging contain natural regeneration after 20 + yr. A successful management plan for mahogany would entail a monocyclic harvest, with a rotation age of 100 + years, the estimated time that it takes for trees to achieve commercial size in natural forest. Since the number of seed trees that will be left is small, they should be concentrated in sites that are likely to be conducive to natural regeneration, such as near rivers and flood damaged forest. Seed production will be maximized for a given basal area (opportunity cost to loggers) if trees c. 110 cm dbh are selected as seed trees. The mahogany stocks in the Chimanes Forest are nearly exhausted, but the findings of this study could be used to help rebuild the mahogany populations, or to design management plans for the commercial species that have similar ecologies to mahogany.
Article
Full-text available
Plants respond to Pleistocene climatic change as species, not as associations or biomes. This has been demonstrated unequivocally by paleobotanical data for temperate latitudes. In the far richer vegetations of the tropics species populations also #uctuated independently in response to climatic forcing, from their longlasting glacial states to the patterns of brief interglacials like the present and back again. We use pollen data to reconstruct the vegetation of the Amazon basin in oxygen isotope stages 3 and 2 of the last glaciation in order to measure how the plant populations of the Amazon responded to the global warming at the onset of the Holocene. We "nd that plant communities of the neotropics vent copious pollen to lake sediments and that this pollen yields powerful signals for community composition. Three continuous sedimentary records reaching through oxygen isotope stage 2 are available from the Amazon lowlands, those from Carajas, Lake Pata and marine deposits o! the mouth of the Amazon River. All three records yield pollen histories of remarkable constancy and stability. By comparing them with deposits of equal antiquity from the cerrado (savanna) of central Brazil, we show that most of the Amazon lowlands remained under forest throughout a glacial cycle. This forest was never fragmented by open vegetation as postulated by the refugia hypothesis. Instead the intact forest of glacial times included signi"cant populations of plants that are now montane, suggesting that the global warming of the early Holocene resulted in the expulsion of heat intolerant plants from the lowland forest. Pollen data from the Amazonian #ank of the Andes and from Paci"c Panama provide evidence that populations of these heat intolerant plants survive the heat of interglacials in part by maintaining large populations at cooler montane altitudes. Our conclusion that the Amazon lowlands were forested in glacial times speci"cally refutes the hypothesis of Amazonian glacial aridity. Accordingly we examine the geomorphological evidence for glacial aridity and "nd it wanting. Of the three paleodune systems reported for tropical South America, that of NE Brazil was active in the Holocene as well as the Pleistocene. Parts of NE Brazil were actually moister than now in late-glacial times. Paleodunes in the Pantanal have never been seen on the ground, and those in the Orinoco Llanos are undated and may be of any age since the Tertiary. Arkosic sands in the Amazon fan deposits came from the Andean foothills or from down cutting by rivers and cannot be evidence of a former arid land surface. White sands of Amazonia formed as podzols, not by aeolian activity. Such Amazonian stone lines as have received critical scrutiny are concretionary pisolites in stratigraphic formations that are more than ten million years old. Although the Amazon was never arid, modeling cooler glacial tropics gives plausibility to a somewhat drier Amazon in glacial times, a concept given substance by pollen data for the movement of ecotones in Rondonia, by stream histories in the Bolivian Andes, and by evidence for lowered lake levels at Carajas and Lake Pata. But this reduced precipitation was never enough to fragment the forest in the Amazon lowlands themselves. Pleistocene mammals of the Napo river valley in Ecuador were able to live along the river system in a forested landscape. Our data suggest that the Amazon forests have been stable since the start of the Pleistocene, a fact that has contributed to the storage of vast diversity. The coming anthropogenic global warming and CO enrichment will add to the global warming already endured by Amazon biota in the Holocene. We think it possible that the expulsion from the lowland forests of heat intolerant species is already complete and that the forest property of maintaining its own microhabitat will allow the high species richness to survive more global warming, provided large enough tracts of forest are preserved.
Article
Full-text available
Swietenia macrophylla King (big-leaf mahogany) is one of the most economically important tree species that grows in the Yucatan peninsula. While it is well known that exposure to high levels of light and low levels of competition are necessary for big-leaf mahogany establishment, conditions favoring germination have been little studied. The effect of sowing date, shade, and irrigation on germination were investigated in a nursery in Quintana Roo, Mexico. Three levels of shade (0, 63, and 80%) and two levels of irrigation (non-irrigated and irrigated 20 mm per week) were used. In addition, seed were sown on four different dates, spanning the dry season to the middle of the rainy season. Germination increased linearly with increasing shade. Irrigated seed had significantly higher germination than non-irrigated seed across all three levels of shade. Seed sown in April germinated 10 weeks after sowing, and seed sown in May and June germinated 4–5 weeks after sowing. Most seed sown in August did not germinate. Although shade does not favor establishment and growth, it may contribute to maintaining soil moisture and seed viability during germination of big-leaf mahogany.
Article
Full-text available
The impact of logging on the stand structure and spatial pattern of commercial species was studied along a chronosequence of 5–19-year old logged stands in the Forest Reserve of Caparo, Venezuela. For comparison, a mature forest stand was surveyed. A systematic sampling design was applied. On average, 10.2 trees/ha with a bole volume of 66.5 m3/ha were removed. Up to the mid-1980s, covered by this study, only Bombacopsis quinata, Swietenia macrophylla, Cedrela odorata and Cordia apurensis were logged. The 5-, 8- and 19-year old logged stands showed a mean basal area of 17.8, 21.3 and 22.2 m2/ha, respectively, whereas 33.2 m2/ha were measured in the mature forest. The share of undamaged trees in the basal area increased from 30.8% in the 5-year old logged stand to 43.9% in the oldest logged stand. The number of emergent trees (>30 m height) was considerably reduced by logging; even 19 years after logging only 8 stems/ha were found in this height class comparing to 51 stems/ha in the mature forest. B. quinata, the most important timber species in the study area, occurred with only two heavily deformed individuals in the logged stands. Juveniles of B. quinata were rare (<10 stems/ha) in both logged and unlogged stands. A similar situation was found in C. odorata and S. macrophylla. In contrast, C. apurensis was well represented in small size classes in logged and unlogged areas. A second cutting cycle will be based on a variety of medium- and small-sized shade-tolerant and light-demanding species which were regularly distributed in the unlogged and logged area. However, the spatial patterns of seedlings and saplings of these species did not show any clear trend. Nineteen years after logging, only one-third (61.3 m3/ha) of the commercial bole volume of the mature forest (185.3 m3/ha) was attained.
Article
Full-text available
Forest ecologists often evaluate how well the species composition of saplings in the understory matches that of the canopy: absence of juveniles suggests that a tree species is suffering population decline. Here we offer a theoretical and empirical test of this assertion using data from a 50-ha census plot in Panama. Theory indicates that higher rates of population change, lambda, lead to more steeply declining size distributions (more juveniles relative to adults). But other parameters also affect the size distribution: lower growth rate of juveniles and lower survival at any size produce more steeply declining size distributions as well. Empirical evaluation of 216 tree populations showed that juvenile growth was the strongest predictor of size distribution, in the direction predicted by theory. Size distribution did correlate with population growth, but weakly and only in understory species, not canopy species. Size distribution did not correlate with the growth rate of larger individuals nor with survival. Results suggest that static in formation on the size distribution is not a good predictor of future population trends, while demographic information is. Fast-growing species will have fewer juveniles in the understory than slow growing species, even when population growth is equal.
Article
Full-text available
Fully mapped tree census plots of large area, 25 to 52 hectares, have now been completed at six different sites in tropical forests, including dry deciduous to wet evergreen forest on two continents. One of the main goals of these plots has been to evaluate spatial patterns in tropical tree populations. Here the degree of aggregation in the distribution of 1768 tree species is examined based on the average density of conspecific trees in circular neighborhoods around each tree. When all individuals larger than 1 centimeter in stem diameter were included, nearly every species was more aggregated than a random distribution. Considering only larger trees (≥ 10 centimeters in diameter), the pattern persisted, with most species being more aggregated than random. Rare species were more aggregated than common species. All six forests were very similar in all the particulars of these results.
Article
Forest ecologists often evaluate how well the species composition of saplings in the understory matches that of the canopy: absence of juveniles suggests that a tree species is suffering population decline. Here we offer a theoretical and empirical test of this assertion using data from a 50‐ha census plot in Panama. Theory indicates that higher rates of population change, λ, lead to more steeply declining size distributions (more juveniles relative to adults). But other parameters also affect the size distribution: lower growth rate of juveniles and lower survival at any size pro duce more steeply declining size distributions as well. Empirical evaluation of 216 tree populations showed that juvenile growth was the strongest predictor of size distribution, in the direction predicted by theory. Size distribution did correlate with population growth, but weakly and only in understory species, not canopy seecies. Size distribution did not correlate with the growth rate of larger individuals nor with survival. Results suggest that static in formation on the size distribution is not a good predictor of future population trends, while demographic information is. Fast‐growing species will have fewer juveniles in the understory than slow growing species, even when population growth is equal.
Article
Seeds of six species of Meliaceae were tested for germination following desiccation and subsequent hermetic storage for up to 26 months in different environments. Seeds of both Aglaia clarkii and Sandoricum koetjape were very sensitive to desiccation; no seeds survived desiccation to 20% moisture content or below. In contrast, stones of Melia azedarach survived desiccation to 3.5% moisture content and viability was maintained during 26 months' subsequent hermetic storage in 14 of the 15 environments which combined factorially five stone moisture contents between 3.5 and 11.7% with three temperatures between -20 °C and 10 °C, the exception being that environment which provided the highest moisture content and temperature (i.e. 10 °C with 11.7% moisture content) in which loss in viability was considerable. Seeds of Azadirachta indica tolerated desiccation to moisture contents in equilibrium at 20 °C with 30-55% r.h. depending on seed lot, and a considerable proportion of seeds survived further desiccation to moisture contents in equilibrium with 6.5 to 30% r.h. Seeds of Swietenia macrophylla and Khaya senegalensis were more tolerant of desiccation than those of Azadirachta indica, but some loss in viability was detected on desiccation to moisture contents in equilibrium with 17% r.h. Moreover, the longevity of all three species in hermetic air-dry storage was shorter at cooler (-20 °C and 0 °C) than at warmer (10 °C) temperatures. We conclude that Aglaia clarkii and Sandoricum koetjape show recalcitrant seed storage behaviour, while Melia azedarach shows orthodox seed storage behaviour, but that Azadirachta indica, Khaya senegalensis and Swietenia macrophylla show intermediate seed storage behaviour. We illustrate how combining information on four criteria (seed weight, shape, moisture content at maturity, and plant ecology) may provide a guide to likely seed storage behaviour in Meliaceae.
Article
Light is widely considered to be the most important factor limiting the performance of plants on the floors of forests and woodlands, but the roles of nutrient availability and water supply remain poorly defined. We seek to predict the types of forest in which root competition affects seedling performance, and the types of plants that respond most strongly to release from root competition. We then test our predictions by reviewing experiments in which tree seedlings and forest herbs are released from belowground competition, usually by cutting trenches to sever the roots of surrounding trees. First, we provide a worldwide review of changes in canopy form and fine-root mass along gradients of soil fertility and seasonal drought, keeping in mind the stages of forest development. Our review shows that penetration of light is least in forests on moist soils providing large amounts of major nutrients. The changes are far more complex than those considered by allocation models. Dry woodlands typically allow 20 times as much light to penetrate as do wet forests, but there is surprisingly little evidence that they have greater fine-root densities in the topsoil. Tropical rain forests on highly infertile soils have only slightly more open canopies than those on fertile soils, but much greater fine-root densities. Northern temperate forests on highly acidic peats and sandy soils are often dominated by early-successional, open-canopied conifers (generally pines), mostly as a result of recurrent fires, and transmit about five times as much light as surrounding deciduous forests. A review of trenching experiments shows that light alone limits seedling growth in forests on moist, nutrient-rich soils, but competition for belowground resources becomes important on infertile soils and in drier regions. Secondly, we consider how root competition alters species' shade tolerances. Shade-house experiments demonstrate that species differ markedly in the minimum irradiance at which they respond to nutrient addition, but there generally tends to be a sizable response at >5% daylight and little response in <2% daylight. There is some evidence that species that have high potential growth rates and that respond markedly to increased irradiance are also most responsive to nutrient addition in 2-3% daylight. T. Smith and M. Huston have hypothesized that species cannot tolerate both shade and drought; this appears to be the case for species that tolerate shade chiefly by maximizing leaf area. However, many shade-tolerant woody plants in tropical and mediterranean-climate forests have thick, tough, long-lived leaves and a relatively high allocation to roots, and these species are much more drought tolerant. A few studies indicate that root trenching allows species to persist in deeper shade than that in which they are normally found and allows species from mesic sites to invade more xeric sites. Usually, the impact of trenching on growth rate is much greater in gaps than in the understory. Finally, we discuss the ways in which life-form composition and population structure of plant communities are shaped by reduced water supply and reduced nutrient availability, emphasizing the inadequacy of models that consider the impact of 'belowground resource availability' in a generic sense. Competition in a dry climate leads to widely spaced dominants, a lack of interstitial plants, high rates of seedling mortality in the understory, and a restriction of regeneration to patches where established matrix-forming plants have died. In contrast, vegetation on moist, infertile sites is characterized by closely packed, slender dominants, miniaturized interstitial plants, and slow rates of seedling growth in the understory, combined with relatively low rates of seedling mortality. Consequently, there is a continuum of sizes among the individuals of the dominant species, and a lack of reliance on gaps for establishment.
Chapter
To obtain a better insight into past vegetational, and climatic changes along the Pole-Equator- Pole: Americas transect, 32 late Quaternary pollen records from savanna, forest-savanna transition regions of the South American neotropics, and north and south of the equator, have been compared in this chapter. During pre-full glacial times, environmental changes in savannas were spatially complex. Some records show either stable grassland, where forest exists today, or a repeated alternation between forest, and savanna. During the full glacial period, neotropical savannas, both north and south of the equator, expanded because of markedly drier conditions. In the southern neotropical regions, savanna area was reduced, and replaced by subtropical grassland by cold climatic conditions during glacial periods. During the late glacial period, climate changed to wetter conditions north of equator earlier at 16,000-14,000 14C B.P., in montane regions. Wetter conditions were not recorded in the high plains or lowlands. During the early Holocene, the climate was drier in most of the South American savannas. Early Holocene distribution of savanna was much larger than during the late Holocene. The general synchrony of paleoenvironmental changes since the full glacial period, from neotropical savanna sites north and south of the equator, suggests changes in the latitudinal migration of the Intertropical Convergence Zone (ITCZ) may have played an important role. The movement of the high pressure cell over the South Atlantic, and changes in frequency of the tracks of the Antarctic cold fronts were also important.
Article
The Cambridge Botanical Expedition to Nigeria, 1947-48, studied the pattern of distribution of species, the regeneration, and the stability of Rain Forest, particularly in relation to the theory of `mosaic' structure. The Okomu Forest Reserve, a compartment of which was studied by transects, lies on Benin sands and has a rainfall of 80-100 in.; it has been lightly exploited for at least forty years. On well-drained `plateau' sites `Gully-margin Forest', presumably an edaphic variant, is distinguishable both floristically and physiognomically from the more extensive forest which was mainly studied. The plateau-forest is a patchwork of the following serally-related phases, which are more distinct physiognomically than floristically: (a) `High Forest' with continuous middle and lower storeys and numerous emergents. (b) `Broken High Forest', differing from (a) in being interrupted by slight gaps. (c) and (d) `Tall' and `Low Closed Scrub' with a continuous climber-blanketed canopy at 6-12 m. and 3-6 m. respectively and fewer emergents than in (a). (e) `Open Scrub', as (c) and (d), but interrupted by many open glades containing light-demanding herbs, and much frequented by elephants. Scrub has been greatly extended by tree-felling, but it is also formed by wind and is a normal component of unexploited forest. Of the three storeys, that of the emergents is best characterized floristically; 21 per cent of its stems are species which are very strong light-demanders that are scarcely represented in the two lower storeys, 45 per cent are species which are abundant in the lower storey but scarcely represented in the middle storey, and 32 per cent are species which increase progressively in abundance from the emergent to the lower storey. There are striking variations in the abundance of particular species even over distances of a few kilometres, and within the 200 ha. which were sampled by transects there are some species which are randomly distributed, others which are patchily distributed on a large scale though randomly distributed on a small scale, others which are widely distributed but tend to occur in small patches, etc. In general, emergents are distributed more nearly at random than are members of the two lower storeys and the tendency to aggregation increases with decreasing size; nevertheless, some species of medium or small size appear to be randomly distributed, and others of comparable size and abundance are patchily distributed. Very few pairs of species (only Lovoa klaineana with Khaya ivorensis, Macrolobium macrophyllum with Barteria fistulosa, B. fistulosa with Grewia coriacea, and G. coriacea with Xylopia quintasii) could be shown to tend to associate, as they should if floristically well-defined communities were present. Thus despite the existence of a mosaic of physiognomically distinct phases and despite the patchy distribution of certain species, it was not possible to detect any well-marked mosaic of species. Of the emergent species nearly half are wind-dispersed and an equal number are animal-dispersed; in the lower storeys the proportion of wind-dispersed species is small and that of animal-dispersed species high. Seeds with a short life and rapid germination are frequent, but seeds with prolonged dormancy are not rare, especially amongst the animal-dispersed species, and perhaps amongst the members of the understorey. Seedlings of most of the woody species are probably present in the forest, but many are extremely local in their distribution, tending to occur in small patches, e.g. near mature trees. Broadly speaking, all sizes of the shade-tolerant members of the lower and middle storeys are adequately represented, suggesting that they may be regenerating continuously and maintaining the existing population; nevertheless, dead trees of some of these species (e.g. Anonidium, Trichilia prieuriana) are very rare, and dead trees of other species (e.g. Scottellia, Strombosia spp.) are abundant, suggesting that their regeneration may be discontinuous. In contrast, in most of the emergent species stems of medium size tend to be less abundant than large-sized stems, even when small sizes and seedlings are abundant. Some figures for rate of growth of trees of various sizes suggest that this paucity of middle sizes cannot always be explained by fast growth of the deficient size-classes; the alternative explanation must be that of discontinuous recruitment. Seedlings of even the more shade-tolerant emergents survive only in or near small gaps in the canopy. The number of small individuals of emergent species per unit area increases with the degree of degradation of the forest; in High Forest they are certainly not numerous enough to maintain the existing stocking of mature emergents. In the scrub phases they are about twice as numerous and more species are represented, but even here it is doubtful whether they are numerous enough to reconstitute a forest as rich in emergents as that now existing, assuming that the scrub will revert to High Forest. Some emergent species seem to be represented by a disproportionately large number of standing dead trees; dead individuals of other abundant emergent species were not recorded. The death-rate increases rapidly with increasing size above about 7 ft. girth. There is thus much to suggest that the composition of the forest is tending to change, particularly in respect of the emergents. Fragments of pottery and charcoal in the soil show that the land has been farmed. It is probable that the farming was relatively recent rather than prehistoric, but it cannot have been less than about 200 years ago, and it is in accordance with all the evidence to regard the forest as secondary forest of this age which is now breaking up. There are reasons for suspecting that no matter whether scrub is a normal phase in the progression or not, the forest of the true climatic climax might have few large trees, and perhaps fewer species and a simpler structure.
Article
The natural regeneration of some desirable species under exploitation pressure in Amazon is often very poor or non-existent. The traditional techniques of enrichment planting have presented low performance of the planted seedlings and high costs for its implementation. This study analyzes the first 5 years of growth and survival of five tropical tree species (Bertholletia excelsa, Ceiba pentandra, Torresia acreana, Swietenia macrophylla and Cedrela fissilis) planted in skidding trails and exploitation gaps. The basic planting technique consisted in using the cleared areas after forest harvesting for the establishment of seedlings of species ecologically adapted to the gap environment. The study was carried out in the EMBRAPA-CPAF-ACRE (Agroforestry Research Centre of Acre) in Acre State in West Amazon. The diameter increment varied from 0.30 cm year−1 for Bertholletia to 0.52 cm year−1 for Swietenia and Torresia. After 5 years the height growth was similar for all species around 3.0 m. In the first year Bertholletia presented a high mortality, around 80%, caused by severe predation by rodents. Ceiba also presented a high mortality after the second year of planting probably due the canopy closure. The best survival percentage was presented by Torresia, over 90%. The Meliaceae (Swietenia and Cedrela) species had a similar survival, around 70 to 75%. The Hypsipyla grandella attack was more severe in Cedrela than in Swietenia, but in both cases (9.37 and 31% after 7 and 5 years respectively for Swietenia and Cedrela) was still low when compared with other enrichment plantings.
Article
The social impact of the mahogany trade on the indigenous peoples of Brazil is described. Emphasis is placed on the violence directed against Indians and the consequences of the destruction of their environment which results from the trade. Also mentioned are the judicial issues regarding the illegal extraction of mahogany from protected areas and several of the court cases against logging companies. A moratorium on mahogany logging in Brazil is advocated as is the right of indigenous peoples to control their lands and resources as the way to conserve their environment.
Article
The social impact of the mahogany trade on the indigenous peoples of Brazil is described. Emphasis is placed on the violence directed against Indians and the consequences of the destruction of their environment which results from the trade. Also mentioned are the judicial issues regarding the illegal extraction of mahogany from protected areas and several of the court cases against logging companies. A moratorium on mahogany logging in Brazil is advocated as is the right of indigenous peoples to control their lands and resources as the way to conserve their environment.
Article
Mahogany (Swietenia macrophyllaKing) regenerates in areas of erosion on high terraces and in forest killed by flooding and deposition of alluvial sediments in the Chimanes Forest, Bolivia. These hydrological disturbances are patchy, and only one of five stands of mahogany that we inventoried was regenerating. Mahogany survives these disturbances significantly better than the common tree species. The long time between disturbances appears to favour late maturation. Mahogany trees allocate little photosynthates to reproduction until they are very large emergents, at least 80 cm in diameter. The episodic nature of the regeneration sites means that mahogany stands are composed of one or a few cohorts, which are vulnerable to overharvesting, particularly with the current use of a minimum cutting diameter to regulate harvest. The delayed onset of fecundity means that the small trees that escape harvest are not very fecund, resulting in minimal seed input to logged forest. Only 7–9% of the gaps created by logging contain natural regeneration after 20+ yr. A successful management plan for mahogany would entail a monocyclic harvest, with a rotation age of 100+ years, the estimated time that it takes for trees to achieve commercial size in natural forest. Since the number of seed trees that will be left is small, they should be concentrated in sites that are likely to be conducive to natural regeneration, such as near rivers and flood damaged forest. Seed production will be maximized for a given basal area (opportunity cost to loggers) if treesc. 110 cm dbh are selected as seed trees. The mahogany stocks in the Chimanes Forest are nearly exhausted, but the findings of this study could be used to help rebuild the mahogany populations, or to design management plans for the commercial species that have similar ecologies to mahogany.
Article
Recent debate on whether or not mahogany (Swietenia macrophyllaKing) is threatened by the international timber trade has focused on the breadth of its range and estimates of the remaining stock of mahogany trees. These data are inadequate to reveal the status of mahogany populations, both because they are incomplete in areal extent and because they do not reveal population parameters such as the existence or density of young trees smaller than commercial size. However, there is sufficient information on the regeneration ecology of mahogany to indicate that under natural conditions this species regenerates in essentially even-aged stands after catastrophic disturbances destroy many or most trees, and, in the case of fires and flooding, saplings and seedlings as well. Adult mahoganies tend to survive these events, and regenerate by shedding seed onto the resulting gaps or clearings. This ecological strategy makes mahogany vulnerable to logging, first because juvenile mahoganies are not found in the understorey, and secondly because logging operations shortcircuit mahogany regeneration processes by selectively removing almost all mahogany seed sources while leaving standing competing vegetation of other species. Listing of mahogany in CITES Appendix II could provide both a mechanism to fill in gaps in information and an incentive to change current practices in favour of silvicultural management to provide for regeneration of this valuable timber species in forests subjected to logging.
Article
Genuine or American mahogany is obtained from trees of the genus Swietenia (S. mahagoni, S. macrophylla , and S. humilis ), and is one of the premier timbers of international commerce. The trade in mahogany commenced almost five centuries ago with S. mahagoni from the Caribbean; but following ‘commercial’ extinction of this resource, trade became centred on mahogany populations in South and Central America ( S. macrophylla ). The trade in mahogany is predominantly from primary forests, and has led to population and genetic resource declines — particularly in the Caribbean and Central America. More recently, there have been an increasing number of ‘commercial’ extinctions in South America. As the resource declines, pressures mount to accelerate the illegal extraction of mahogany from National Parks and lands reserved for indigenous (‘Indian’) peoples. Inability to control this trade threatens mahogany populations and genetic resources throughout its range, at the same time adversely affecting the livelihoods of indigenous peoples in the process. Mahogany often regenerates poorly following logging operations that are conducted using current management practices, and further research is required to determine the optimum biological and economic conditions for in situ silviculture. Attempts to cultivate mahogany in plantations have met with little success in the Americas, due mainly to effects of the shoot-borer ( Hypsipyla grandella ), a moth larva that damages terminal shoots, so leading to excessive branching and reduced timber value (Figs 3 and 4). The success of mahogany plantations in the neotropics will require the development of an integrated pest-management system, perhaps involving the incorporation of pestresistant genotypes within agro-forestry or mixed plantation systems. It is vital that appropriate silvicultural and trade practices are adopted to ensure sustainable mahogany extraction, while at the same time conserving an adequate population and genetic resource-base. To this end, effective trade monitoring and resource-regulation measures must be introduced to assist in controlling illegal trade and to encourage a scientifically managed, sustainable, utilization of mahogany. Two of the three mahogany species, S. humilis and S. mahagoni , have been listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). The third and only other recognized species of Swietenia, S. macrophylla , should also be considered for listing in CITES Appendix II, thereby benefiting from the international trade-monitoring and resource regulation requirements consequent upon such listing.
Article
Recent debate on whether or not mahogany (Swietenia macrophylla King) is threatened by the international timber trade has focused on the breadth of its range and estimates of the remaining stock of mahogany trees. These data are inadequate to reveal the status of mahogany populations, both because they are incomplete in areal extent and because they do not reveal population parameters such as the existence or density of young trees smaller than commercial size. However, there is sufficient information on the regeneration ecology of mahogany to indicate that under natural conditions this species regenerates in essentially even-aged stands after catastrophic disturbances destroy many or most trees, and, in the case of fires and flooding, saplings and seedlings as well. Adult mahoganies tend to survive these events, and regenerate by shedding seed onto the resulting gaps or clearings. This ecological strategy makes mahogany vulnerable to logging, first because juvenile mahoganies are not found in the understorey, and secondly because logging operations shortcircuit mahogany regeneration processes by selectively removing almost all mahogany seed sources while leaving standing competing vegetation of other species. Listing of mahogany in CITES Appendix II could provide both a mechanism to fill in gaps in information and an incentive to change current practices in favour of silvicultural management to provide for regeneration of this valuable timber species in forests subjected to logging.