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This study examined foliar herbivory on 1 year-old tree saplings planted in previously abandoned fields in central Panama. Plots (15 × 15 trees) of Anacardium excelsum (Anacardiaceae), Dalbergia retusa (Fabaceae), Pachira quinata (Malvaceae), Tabebuia rosea (Bignoniaceae), and Terminalia amazonia (Combretaceae) were tested for herbivory using leaf counts and digital image analysis. Values of foliar carbon, foliar nitrogen, specific leaf area (SLA), and leaf toughness were analyzed to describe mechanical defenses and leaf nutrients on young and mature leaves of each of these species. For all five species, less than 10% of total leaf area was found to be damaged by arthropods. Significant (P-value < 0.001) differences in herbivory were found among both the tree species and the insect feeding guilds considered: chewing, skeletonizing, mining, and leaf-rolling. On mature leaves, Anacardium excelsum had the highest amount of leaf damage (3.53%) while Dalbergia retusa exhibited the lowest herbivore damage (1.72%). Tabebuia rosea had statistically significantly higher damage than other species for young leaves caused by leaf-rolling insects (4.21% rolling of 5.55% total damage). Leaf toughness was negatively correlated with SLA and foliar N. Linear regressions showed that herbivory was positively correlated with foliar N for young leaves and negatively correlated with foliar N for mature leaves. No statistically significant relationships were found between herbivory and the mechanical properties of toughness and SLA. Overall, results from this study indicate that, as young saplings, the species evaluated did not suffer high amounts of foliar herbivory in the plantation environment.
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... Plant functional traits may be one of the important factors determining variation in leaf consumption by insect herbivores. Structural traits can provide physical resistance to herbivory through leaf thickness, water content, or simply due to leaf size (Schuldt et al., 2012;Cárdenas et al., 2014;Muiruri et al., 2019), while reduced leaf nutrient content can deter herbivores by providing low nutritional reward (Paul et al., 2012). Plant traits are strongly dependent on the abiotic environment and resource availability, and the same species might therefore exhibit different trait values when growing in different environments (Auger and Shipley, 2013;Weemstra et al., 2021). ...
... While the effects are likely to be related to the species studied and the herbivores feeding on them, our results are important because they bring additional evidence of the influence of physical traits on insect herbivore feeding guilds. We did not have data on leaf nutrients or secondary chemical metabolites, which are also key defensive strategies that deter herbivores (Carmona et al., 2011;Salminen and Karonen, 2011;Paul et al., 2012;Cosmo et al., 2021) and have been reported to influence the contribution of different guilds (Rossetti et al., 2014). Despite this limitation, our results show that leaf physical traits are important sources of diversification in terms of damage type. ...
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Conversion from natural forest to timber plantation is an important cause of pristine forests loss. These changes alter community structure and cause a decrease in the diversity of plant communities. Leaf functional traits, which are an important defensive strategy, might also be influenced by such alterations. Altogether, shifts from natural forest to timber plantation may lead to profound changes in plant-plant and plant-animal interactions, including herbivory and the relative abundance of different feeding guilds, an important aspect of forest ecosystem function and community dynamics. In this study, we assessed insect herbivore damage in saplings of four native tree species in the understory of natural forests and two types of ca. 80-year-old timber plantations. We measured leaf damage by the most common feeding guilds in over 9000 leaves from 200 saplings. We first compared herbivory between natural forest and plantations, and we then analyzed the drivers of herbivory and of the two most common guilds-chewers and miners-using several indices of forest structure and leaf traits as predictors. Total herbivory did not change among forest types, but it showed some variation in two of the four species. Herbivory decreased with increasing species richness and increased with increasing basal area of conspecific and heterospecific trees. Leaf damage caused by chewers increased with leaf thickness, while damage caused by miners showed the opposite relationship. On an ecological level, our findings support expectations from the resource concentration hypothesis and on the role of leaf traits in mediating the impact of insect feeding guilds on leaf herbivory. On an applied level, these results suggest that timber plantations can support similar levels of ecosystem processes than natural forests decades after their establishment. Allowing the regeneration of a diverse understory in plantation forests should be implemented to favor ecosystem dynamics close to those of the original forests.
... Additionally, in a mixed plantation, different plant species might be differently preferred by herbivores because of their foliar traits (i.e. nitrogen content, toughness, C/N balance, etc.), their provenance (degree of association between local herbivores to trees from different areas of the region), their distribution, since plant species with wider distributions might be attacked at a higher rate by herbivores than more geographically restricted species (Paul et al., 2012;Forister et al., 2014, Kozlov et al., 2015a, 2015b, as well as due to the degree of specialization of the herbivoreś community (Novotny et al., 2010). Moreover, the effects of management intensity on the herbivory of planted trees might be affected by abiotic conditions, plant neighbours, or connectivity changes, which in turn might vary combined with unique features of the tree species (Paul et al., 2012;Underwood et al., 2014;Schuman & Baldwin, 2016). ...
... nitrogen content, toughness, C/N balance, etc.), their provenance (degree of association between local herbivores to trees from different areas of the region), their distribution, since plant species with wider distributions might be attacked at a higher rate by herbivores than more geographically restricted species (Paul et al., 2012;Forister et al., 2014, Kozlov et al., 2015a, 2015b, as well as due to the degree of specialization of the herbivoreś community (Novotny et al., 2010). Moreover, the effects of management intensity on the herbivory of planted trees might be affected by abiotic conditions, plant neighbours, or connectivity changes, which in turn might vary combined with unique features of the tree species (Paul et al., 2012;Underwood et al., 2014;Schuman & Baldwin, 2016). Yet, for Patagonian woodlands, as it happens in most forested ecosystems, it remains unknown how different tree species and their associated herbivores respond to a gradient of woodland extraction, and whether an optimum harvesting level exists that maximises both, plant performance and herbivore guild diversity. ...
Article
Sustainable forest management should optimise the balance between tree productivity and biodiversity conservation. One strategy to achieve both is the use of native plantations in biomass extraction systems. However, it is unknown how different native tree species and their herbivores respond to a gradient of biomass extraction. In a Patagonian woodland, we planted six native tree species of high wood value and contrasting physiological traits, in plots with increasing harvesting intensities (HI: 0, 30, 50 or 70% of basal area removal), and measured herbivory rates, herbivore guild diversity, and sapling survival and growth. To understand whether herbivore diversity in non-planted wild species was affected by harvesting intensity, we performed the same herbivore measures in six wild woodland plant species. Herbivory rates and herbivore guild diversity showed similar responses to HI, being highest on saplings growing at 30% (N. dombeyi, N. antarctica, N. pumilio and N. alpina) or 30% and 50% (N. obliqua) HI. Deciduous tree species were consumed at a higher rate and held more diverse guilds, whereas evergreen species were consumed at a lower rate or barely damaged. Differences among species seem to be mostly driven by leaf habit and nitrogen content. In turn, higher HI increased the heterogeneity of arthropod guild composition, being N. alpina and N. pumilio the species with most variation in guild composition across HI. Contrariwise, regarding the non-planted wild woodland species, there was no effect of HI on herbivory rates or guild diversity. Finally, planted tree species survived and grew more at 30% and 50% HI despite supporting higher leaf damage, except for N. antarctica which showed a similar survival rate across all HI. Species with highest performance were A. chilensis and N. obliqua; but differences regarding plant performance among species were not explained by their physiological traits. Approximately one-third to mid harvesting intensities in this Patagonian woodland were optimal for enhancing native tree plantation performance and sustaining her-bivore guild diversity. Additionally, harvesting intensities did not affect guild diversity on woodland plants. Hence, both lines of evidence suggest an enhancement of both native-wood production and biodiversity conservation. Our study constitutes one step forward in the development of novel sustainable woodland management practices, applicable to other regions worldwide.
... In addition to its cultural and economic importance, D. retusa is ecologically valuable as a leguminous tree species and exceptionally strong nitrogen fixer through associations with rhizobia bacteria (Batterman et al., 2018). High-nutrient leaf litter can enhance soil fertility in the surrounding forest floor (Paul et al., 2012;Gei and Powers, 2013; but see also Quesada-Ávila et al., 2021). D. retusa is also very drought tolerant (Sinacore et al., 2019); the species has high water use efficiency (Cernusak et al., 2007) and avoids drought by losing its leaves during the dry season (Sinacore et al., 2019). ...
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Large areas of the Panama Canal Watershed have been converted to monocultures of teak ( Tectona grandis ), a non-native timber species that is generally not providing hoped-for economic and ecological benefits of Forest Landscape Restoration. Enrichment planting offers a potential strategy for revitalizing these underperforming plantations through the addition of high-value, native species to the understory, but more information is needed to guide implementation and management in this region and other tropical areas. We assessed the performance of six promising native species ( Byrsonima crassifolia, Dalbergia retusa, Dipteryx oleifera, Hyeronima alchorneoides, Platymiscium pinnatum, Terminalia amazonia ) as an enrichment planting in teak plantations, and specifically considered how light availability, crowding pressure and annual fertilization affected seedling performance, we measured survival and growth for the first 30 months post-planting for ∼3,000 seedlings; half received annual fertilization and half did not. We found that growth rate did not significantly affect survival among- or within-species, except for a positive relationship for D. oleifera. Overall seedling survival was high (83%), and, while species varied widely, there was not a strong effect of light, crowding or fertilization on survival. In contrast, overall growth of species was significantly affected by these factors. Across all species growth was negatively related to crowding and positively related to light availability and fertilization. There were among-species differences; while all but one species ( D. oleifera ) were negatively affected by crowding, only half responded positively to light availability ( D. retusa, P. pinnatum , and B. crassifolia ) and fertilization ( D. retusa, P. pinnatum , and T. amazonia ). Our findings suggest that all study species except for B. crassifolia , which suffered unacceptably high mortality, have high potential for use in enrichment planting in Panama teak plantations. Among-species differences in response to fertilization and growing environment highlight the need for continued studies to establish specific silvicultural guidelines for species in the enrichment planting context.
... While D. retusa clearly outcompetes any other species in this study financially and is the least risky option from a financial perspective, this study does not attempt to evaluate the many unknowns associated with plantation forestry, including a potentially positive (though likely modest) effect of nutrient addition. For any selected species, there is always the risk that drought might negatively impact a species that is particularly vulnerable to drought (Gavinet et al. 2019) or that the species is susceptible to pest damage (Paul et al. 2012). Yet recent tree physiology studies at our site found D. retusa well equiped to respond to one of the worst droughts recorded in 100 years in Central Panama (Sinacore et al. 2019;. ...
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Finding suitable tree species that not only grow well on nutrient poor soils but are also safe financial investments is one of the major obstacles to successful reforestation efforts in the tropics. Our study compared the financial viability and growth of valuable timber species in monocultures and mixtures on infertile soils. Our work shows the extraordinary growth in volume and value of Dalbergia retusa and Terminalia amazonia while underscoring the poor financial viability of Tectona grandis and Pachira quinata , all commonly planted timber species in Panama and much of Central and South America. Using Bayesian statistics, our predictions show that T. amazonia monocultures could reach nearly 200 m ³ ha ⁻¹ of merchantable volume after 30 years compared to the ~ 40 m ³ ha ⁻¹ that T. grandis could accumulate in the same time frame. While D. retusa monocultures did not have the highest predicted merchantable volumes of all the species, it did have the highest predicted net present value (NPV), with a predicted mean NPV of > US$97,000 ha ⁻¹ , quadrupling the species with the next highest monoculture’s NPV, T. amazonia monocultures (~ US$20,000 ha ⁻¹ ). Our work emphasizes that reforestation can be financially viable on low nutrient soils, even in the absence of fertilization or other silvicultural manipulations, if species selection and site are carefully considered and matched.
... Leaves are important for gas and heat exchange and carbon gain (Liu et al., 2017). Leaf traits such as specific leaf area (SLA), leaf thickness, chlorophyll concentration, etc., collectively reflect the plants survival and adaptation strategies under shading and defoliation conditions (Houter and Pons, 2012;Paul et al., 2012). Numerous studies indicate that plants grown under low light environment have thinner leaves and lower leaf mass per area (LMA), which goes on the expense of photosynthetic capacity per unit leaf area (Ellsworth and Peter, 1992;Poorter and Bongers, 2006). ...
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Seedlings in regenerating layer are frequently attacked by herbivorous insects, while the combined effects of defoliation and shading are not fully understood. In the present study, two Leguminosae species ( Robinia pseudoacacia and Amorpha fruticosa ) were selected to study their responses to combined light and defoliation treatments. In a greenhouse experiment, light treatments (L+, 88% vs L−, 8% full sunlight) and defoliation treatments (CK, without defoliation vs DE, defoliation 50% of the upper crown) were applied at the same time. The seedlings’ physiological and growth traits were determined at 1, 10, 30, and 70 days after the combined treatment. Our results showed that the effects of defoliation on growth and carbon allocation under high light treatments in both species were mainly concentrated in the early stage (days 1–10). R. pseudoacacia can achieve growth recovery within 10 days after defoliation, while A. fruticosa needs 30 days. Seedlings increased SLA and total chlorophyll concentration to improve light capture efficiency under low light treatments in both species, at the expense of reduced leaf thickness and leaf lignin concentration. The negative effects of defoliation treatment on plant growth and non-structural carbohydrates (NSCs) concentration in low light treatment were significantly higher than that in high light treatment after recovery for 70 days in R. pseudoacacia , suggesting sufficient production of carbohydrate would be crucial for seedling growth after defoliation. Plant growth was more sensitive to defoliation and low light stress than photosynthesis, resulting in NSCs accumulating during the early period of treatment. These results illustrated that although seedlings could adjust their resource allocation strategy and carbon dynamics in response to combined defoliation and light treatments, individuals grown in low light conditions will be more suppressed by defoliation. Our results indicate that we should pay more attention to understory seedlings’ regeneration under the pressure of herbivorous insects.
... Greater C ratio can lead to a decrease in litter layer decomposition rates due to nutrient immobilization by a limited N soil microbial community (Gei & Powers, 2013). Paul et al. (2012) reported that the T. amazonia had one of the greatest leaf level C:N ratio among the species of the Agua Salud Project mixtures at an early age (also see Kerdraon et al., 2019). The even and low ammonium and nitrate concentrations found between the Dalbergia and Terminalia trees in our study plantations could be explained by this phenomenon, due to the soil nutrient deficiency of the area (Mayoral et al., 2017). ...
Article
The use of native species for timber plantations in the tropics has lately gained interest. Recent studies have shown that native tree plantations can have greater economic, and ecological benefits than non-native plantations. Facilitative nutritional interactions with nitrogen-fixing trees are a common practice used in hopes of enhancing nitrogen input. Dalbergia retusa and Terminalia amazonia are two neotropical species frequently used for timber extraction. In order to understand these species belowground interactions, we worked on 33 plots of the T. amazonia and D. retusa mixtures in the Agua Salud Project Native Species plantations in Panama. The objective of this study was to assess if soil biochemical properties under T. amazonia trees might be influenced by D. retusa in these mixtures. For this, soil samples were collected and analyzed for nitrogen pools, extractable cations and selected phosphorus constituents. Our results showed that nutrient concentrations were not significantly different below D. restusa and T. amazonia trees. Nonetheless, temporal and physicochemical characteristics of the plantation might be influencing the tree performance and should be considered for a better understanding of the nutrient dynamics in native tree plantations.
... In this context, the resources provided by seeds can also contribute to seedlings' defense (Kraft et al., 2015). Leaf area and width, specific leaf area (SLA), dry weight per unit area, and chlorophyll content are traits directly related to the growth and nutritional quality of leaves, and indirectly related to seedlings' defense (Cornelissen et al., 2003;Paul et al., 2012). ...
Article
In tropical forests, herbivore damage is one of the main causes of seedling mortality. However, along with seed size, the resources herbivores provide are an important factor in a seedling's response to selection pressure. The objective of this study was to evaluate the role of seed size and artificially-induced herbivory on the functional traits of Ceiba aesculifolia seedlings. To do this, we established four levels of foliar damage: 10%, 25%, 50%, and 75% (n = 270), and a control treatment (no damage; n = 60). Foliar damage treatments were conducted 60 days after germination. These treatments were applied to seedlings developing from seeds of three different sizes. The response variables were growth, some foliar traits, and seedling biomass. Seedlings from small seeds showed higher growth rates in terms of height (0.44 ± 0.02 cm month⁻¹), diameter (0.24 ± 0.01 mm month⁻¹), and foliar production (9.1 ± 0.19 leaves), as well as higher total dry weight (8.5 ± 0.03 g) and larger leaf area (49.3 ± 1.9 cm²) than those from medium and large seeds. Seedlings from large and medium seeds showed higher root:stem ratio values than seedlings from small seeds (p < 0.05). Foliar damage was found to have an effect on dry weight. The total biomass of seedlings with 75% damage was considerably smaller than that of seedlings with 10% damage. Chlorophyll content was found to be related to the interaction between seed size and foliar damage, and it was lower in seedlings from medium seeds and 50% damage than in those from small seeds with the same level of damage and large seeds with 75% damage. In short, seed size had a significant effect on growth traits. Contrary to our expectations, seedlings from small seeds showed the best performance in terms of height, biomass, number of leaves, and foliar area.
... We identified seven phenolic compounds; rosmarinic acid (RA), and six flavonoids [i.e., apigenin-7-sulphate, APS; diosmetin-7-sulphate, DS; luteolin-7-sulphate, LUTS; luteolin-7-O-β-glucoside, LUTG; luteolin-7,3'-disulphate, LUTS2; luteolin-7-O-β-(6''-malonyl) glucoside, LUTMG]. Specific leaf area (SLA = leaf area/ leaf weight; cm 2 /g), which is used to evaluate leaf toughness (with high SLA indicating low toughness; Paul et al., 2012), was quantified in five to ten shoots per plot at the end of the experiment. A detailed methodology for all chemical analyses of plant traits can be found in the Supporting Information (Methodology S1). ...
Article
Aim Studies on latitudinal patterns in plant defence have traditionally overlooked the potential effect that resource availability may have in shaping plant defence. Likewise, latitudinal patterns of tolerance traits have rarely been studied, yet they can be a critical component of plant defence. Therefore, the aim of our study was to examine latitudinal variation in the production of tolerance and resistance traits against herbivory along a latitudinal range and a natural gradient of resource availability from upwelling conditions. Location North America (Canada, USA, Mexico). Time period Summer months of 2015. Major taxa used The seagrass Zostera marina. Methods We conducted experiments simulating macroherbivore (e.g., bird, fish) damage on the seagrass Z. marina at 10 sites across the Eastern Pacific coast (Canada–Mexico) and Quebec and analysed several traits related to resistance and tolerance strategies against herbivory. In addition, we examined the effects of potential seagrass changes in defence strategies by performing a series of feeding experiments with mesoherbivores in a subset of sites. Results We found that eelgrass resistance defences did not follow a linear latitudinal pattern but rather followed a bell‐shaped curve which correlated with bottom‐up control. In sites with higher nutrient availability, plants allocated resources to tolerance strategies and had lower resistance traits. Furthermore, seagrasses did not respond linearly to increased herbivory pressure; while they tolerated moderate levels of herbivory, they underwent a significant reduction in tolerance and resistance under high herbivory levels, which also made them more susceptible to consumers in feeding experiments. Main conclusions Our results highlight the importance that nutrient availability has in shaping latitudinal patterns of plant defence against herbivory and show how these defences may not respond linearly to increased herbivory pressure in seagrasses.
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Although insect herbivorous communities in tropical forests are known to exhibit strong seasonality, few studies have systematically assessed temporal patterns of variation in community structure and plant–herbivore interactions in early successional arboreal communities. We assessed seasonal and interannual variation of the diversity and composition of herbivorous beetles and the tree-herbivore network in a recently established polyculture forest plantation, during the dry and the rainy seasons of 2012 and of 2013. Species richness was similar between years, while the ecological diversity was higher in 2012. Comparing seasons, no differences were found in 2012, whereas in 2013, the species richness and ecological diversity were higher during the dry season. The species composition differed radically across years and seasons. Moreover, a quantitative nested pattern was consistently found across both temporal scales, more influenced by species densities. We found temporal changes in the species strength, whereas connectance and interaction evenness remained stable. Rapid temporal changes in the structural complexity of recently established polyculture plantations and the availability and quality of the trophic resources they offer may act as drivers of beetle diversity patterns, promoting rapid variation in herbivore composition and some interacting attributes. Nonetheless, network structure, connectance, and interaction evenness remained similar, suggesting that reorganizations in the distribution of species may determine the maintenance of the patterns of interaction. Further work assessing long-term temporal dynamics of herbivore beetle assemblages are needed to more robustly relate diversity and interaction patterns to biotic and abiotic factors and their implications in management programs.
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Although commercial forest plantations have experienced a major growth in the tropics over the past decades, little attention has been paid to their role in the conservation of epigeal arthropod communities. We studied diversity patterns of the epigeal beetle community in monoculture and polyculture forest plantations with big-leaf mahogany (Swietenia macrophylla). Likewise, we explored the existence of indicator species of each plantation type. Our findings highlight that each plantation type promotes multiple impacts on diversity patterns. We found that monocultures positively influenced overall beetle species richness and ecological diversity. When broken down by guild, both predator and decomposer species richness were similar between monoculture and polyculture, whereas for beetle diversity we found contrasting responses by guild: decomposer diversity was greater in monoculture whereas predator diversity was higher in polyculture. In addition, species composition differed between monoculture and polyculture, except for the predator guild. Species turnover was the main component explaining beta diversity patterns at all levels, indicating that each plantation type promotes biologically distinct epigeal assemblages. Few superabundant heliophile species dominated the beetle community structure; moreover, monocultures had a composition skewed towards heliophile species whereas polyculture favored umbrophile species. These patterns could be attributed to differences in habitat complexity between plot types, namely differences in tree cover. Additionally, indicator species only were identified in polycultures, reflecting their higher spatial complexity. Monoculture and polyculture plantations with big-leaf mahogany are complementary agroecosystems for preserving diverse epigeal beetle communities and should be considered valuable tools for conservation purposes in the tropics.
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Variability in the extent and patterns of insect herbivory on leaves of Pentagonia donnell-smithii (Rubiaceae) was quantified with respect to leaf age and habitat type (sites) in lowland tropical wet forest in Costa Rica. Rates of herbivory were higher for young than for mature leaves. The common leaf beetle, Phanaeta sp. (prob. ruficollis, Chrysomelidae) preferred young leaves, but another herbivore (the seed bug, Nicuesa speciosa) preferred mature leaves in a choice test. Total rates of herbivory over a 10-day period were higher in a secondary forest site than in successional plots 1-5 yr old. Phanaeta sp. preference for leaves from younger, more open sites was not explained by either leaf toughness or leaf water content. -from Author
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Eighteen species of wind-dispersed trees on Barro Colorado Island, Panama, are compared with respect to germination, survival, and growth of seedlings during 1 yr under sun and shade conditions in a screened enclosure. The species vary in their mean dry weight of seed from 1.9-686 mg. High and synchronous germination occurs in both sun and shade for 16 of the species. Most species have epigeal germination with leafy green cotyledons. Seedlings of 15 species survive better in sun than shade; none survive better in shade than sun. Shade tolerance varies widely and continuously among the species; it correlates with adult wood density, an indicator of growth rate and successional status, but not with the dry weight of seed reserves. The more shade-tolerant species have a lower proportion of seedlings dying from disease in the shade. Seedling height after 1 yr is greater in sun than in shade for all species. In the shade, number and length of leaves show little or no change with time; leaf turnover is negligible. In the sun, leaf number, increases and successively younger leaves mature at larger sizes. Leaf size is greater in the sun than in the shade. Senescence of the leafy cotyledons is more rapid in sun for all species. This study predicts that all species examined benefit from seed dispersal to light-gaps.-from Author