Article

Biomass and litter dynamics in a Melaleuca forest on a seasonally inundated floodplain in tropical, Northern Australia

Authors:
  • Northern Territory Herbarium, Australia, Palmerston
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Abstract

Litterfall from a Melaleuca forest was investigated as part of chemical cycling studies on the Magela Creek floodplain in tropical, northern Australia. The forest contained two species of tree, Melaleuca cajaputi and Melaleuca viridiflora, with a combined average density of 294 trees ha–1. The M. viridiflora trees had diameter breast height measurements ranging from 11.8 to 62.0 cm, median class 25.1–30.0cm and a mean value of 29.21.0 cm, compared to 13.0 to 66.3 cm, 30.1–35.0cm and 33.51.0cm for M. cajaputi trees. A regression model between tree height, diameter breast height and fresh weight was determined and used to calculate average tree weights of 7751.6kg for M. viridiflora and 10091.6kg for M. cajaputi, and a total above-ground fresh weight of 2630.3t ha–1. The weight of litter recorded each month on the ground beneath the tree canopy ranged from 582103 to 2176376 g m–2 with a monthly mean value of 110551 g m–2. The coefficient of variation of 52% on this mean indicates the large spatial and temporal variability in litter distribution over the study site. This variability was greatly affected by the pattern of water flow and litter transport during the Wet season. Litterfall from the trees was evaluated using two techniques - nets and trays. The results from these techniques were not significantly different with annual litterfall collected in the nets being 705 25 g m–2 and in the trays 71649 g m–2. The maximum monthly amount of litterfall, 108 55g m–2, occurred during the Dry season months of June–July. Leaf material comprised 70% of the total annual weight of litter, 48029 g m–2 in the nets and 495 21 g m–2 in the trays. The tree density and weight of litter suggest that the Melaleuca forests are highly productive and contribute a large amount of material to the detrital/debris turnover cycle on the floodplain.

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... The high productivity within floodplains supports various ecosystem services such as flood regulation, water depuration, and provision of habitat for many commercially important species (Costanza et al. 1997). The productivity of floodplains has long been associated with trees and fast-growing aquatic macrophytes, which by far have the highest biomass contribution of all primary producers (Finlayson et al. 1993, Junk & Piedade 1997, Silva et al. 2009). However, epiphyton-algae and bacteria attached to the submerged portion of aquatic macrophytes-is highly nutritious, with low carbon to nitrogen molar ratios (C:N) and high protein content (Becker 2007), making it an important food source for primary consumers. ...
... We measured diel DO variations to calculate areal productivity and the relative contribution of epiphyton to floodplain aquatic productivity. We also compared aquatic productivity with published values of litterfall NPP (net primary production) of Melaleuca forests-probably the second most important source of decomposable carbon in wetlands of tropical Australia (Finlayson 1993). Our predictions were that epiphyton would contribute significantly to floodplain production and that the potential productivity per biomass of epiphyton would be similar among macrophyte structures. ...
... There is likely additional primary productivity by microalgal mats from the sediment, however, due to light limitations, it is likely to be minor . Additionally, we compared our aquatic productivity estimates with published values of Melaleuca forest litterfall NPP, which included leaves, twigs, bark, fruit, floral bracts, flower parts and woody material <2.5 cm diameter (Finlayson et al. 1993). We used the litterfall production of Melaleuca forests at the end of the wet season (April to July), coincident with the highest productivity of the year (Finlayson et al. 1993). ...
... Generally, the aboveground biomass of Melaleuca forests can be considered to have a moderate level of carbon storage. In natural conditions, the above-ground biomass of Melaleuca forests in Northern Australia has been estimated at 132 t/ha (Finlayson et al., 1993), but had a considerable range from 54 t/ha to 184 t/ha (converted from data ofFranklin et al., 2007). This indicates that the earlier estimate of the Australian Government [about 16 tC/ha in the above ground biomass (MIG, 2008)]is likely to have been a gross underestimation. ...
... The amount of Melaleuca forest litter fall have been found to be quite high; from 7.00 to 7.67 t/ha/year in Australia (Finlayson et al., 1993;Greenway, 1994); and from 8.30 to 8.91 t/ha/year in Florida, USA (Van et al., 2002;Rayamajhi et al., 2006) (Table 3.2). Compared with other USA wetland forests, the mass of Melaleuca litter fall was much higher than in Cypress swamps in ...
... in the understorey and deadwood components of Melaleuca forests in Australia, so these two IPCC categories were not included in the estimates. The amount of carbon inOnly one publication has to date presented an estimate of the amount of tree biomass in Melaleuca forest ecosystems in Australia based on forest inventory data collected in the field.Finlayson et al. (1993)estimated that the average above ground dry biomass in Melaleuca forests is approximately 132 t/ha [the value was converted from the original fresh biomass value byVanCreek/Logan River floodplain, South East Queensland (Greenway, 1994). Greenway (1994) also reported various indicators of high carbon content in the forest litter component ...
Thesis
The genus Melaleuca consists of around 260 species. The genus dominates forests that cover more than six million hectares of land globally. Most of that forest occurs in Australia, but there are also smaller areas in countries in South-East Asia and the Caribbean region, and the southern United States of America. Melaleuca forests predominantly occur in wetland and coastal ecosystems and as a result are substantially exposed to the influences of climate change and human development, particularly in regards to impacts on hydrological and soil systems. Like other wetland forest ecosystems, a large amount of carbon is stored in the biomass and soil components of Melaleuca forests. However, up until now very little research has been published on the extent and nature of those carbon stocks. This thesis addresses this gap in the research literature and presents the results of a study that involved collecting data on the carbon stocks of various Melaleuca forests in Australia and Vietnam. A variety of widely recognised data collection methods were used to collect data on the carbon stocks of Melaleuca forests at field sites in Southern Vietnam and South East Queensland, Australia. Data was collected from five ‘typical’ Melaleuca forest stand-types in Vietnam including: primary Melaleuca forests on sandy soil (denoted VS1); regenerating Melaleuca forests on sandy soil (VS2); degraded secondary Melaleuca forests on clay soil with peat (VS3); regenerating Melaleuca forests on clay soil with peat (VS4); and regenerating Melaleuca forests on clay soil without peat (VS5). Data was also collected from four ‘typical’ Melaleuca forest stand-types in Australia including: primary Melaleuca forests under continuous water inundation (A1); primary Melaleuca forests not inundated by water (A2); degraded Melaleuca forests under continuous water inundation (A3); and regenerating Melaleuca forests under continuous water inundation (A4). Carbon stock densities of VS1, VS2, VS3, VS4, and VS5 were found to be 275.98 tC/ha, 159.36 tC/ha, 784.68 tC/ha, 544.28 tC/ha, and 246.96 tC/ha, respectively. Carbon stock densities of A1, A2, A3, and A4 were found to be 381.59 tC/ha, 278.40 tC/ha, 210.36 tC/ha, and 241.72 tC/ha, respectively. In Australia, carbon accumulation in forest litter in wet conditions (A1) was likely to be 6.5 times higher than those in drained and drier conditions (A2). The total carbon stock densities in Melaleuca forests in the wildfire conditions were found to be lost around 45 % of those in primary forests under wetter conditions. Furthermore, the exchangeable sodium percentage of Melaleuca forests in Vietnam on sandy soil (VS1 and VS2) showed high sodicity, while those on clay soils (VS3, VS4, and VS5) varied from low to moderate sodicity. The results of this thesis also show that: (1) the carbon stock densities of Melaleuca forests in Australia are much greater than previously thought and substantially higher than current estimates used in Australia’s national carbon accounting systems; (2) the carbon stock densities of Melaleuca forests on peat lands in Vietnam are large compared to many other forest types around the world; (3) and that Melaleuca forests on sandy soils in Vietnam are tolerant of highly sodic conditions, an important feature considering how climate change and human development in the region is impacting on local hydrological and soil systems. In these regards, the results of this thesis provide important information for the future sustainable management of Melaleuca forests in both Australia and Vietnam, particularly in regards to emerging forest carbon conservation and management initiatives.
... Comparative studies on litterfall in Melaleuca forests are limited. Finlayson et al. (1993) investigated litterfall and litter accumulation in a seasonally inundated Melaleuca forest (M. cajaputi Powell and M. viridiflora Sol. ...
... These results are comparable with those at Carbrook despite differences in tree density, and they suggest similar tree canopy cover at the two geographical locations. Maximum litterfall (mostly leaf litter), however, occurred during the winter dry season (June-August), which Finlayson et al. (1993) suggested was due to windy conditions or the physiological conditions of the trees. ...
... The presence of antibacterial phenolics in the Melaleuca leaves would also inhibit microbial decomposition. Finlayson et al. (1993) noted that monthly litter accumulation on the forest floor of the Magela Creek floodplain displayed high variability from 582 103 g m-2 to 2176 * 376 g m-2 and was affected by water flow and litter transport during the wet season when the site was flooded. In the present study, litter accumulation was determined only once a year, and although there was high variability within each site, there was no significant difference between years. ...
Article
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Litterfall and litter accumulation were investigated over two years in a Melaleuca quinquenewia wetland in south-eastern Queensland. In 1992, a seasonally wet year, litterfall was 809 ± 135 g m⁻² yr⁻¹ at the floodplain site and 764 ±192 g m⁻² yr⁻¹ at the riparian site, of which Melaleuca leaf litter made up 65% and 56% respectively. Litterfall was significantly lower and more variable in 1993, a drought year, being 725±106 g m⁻² and 675 ± 216 g m⁻² year⁻¹. There was a distinct seasonal pattern, with peak leaf litterfall occurring in spring in 1992 but extending into summer in 1993. Melaleuca leaf fall was significantly lower in 1993, possibly because drought conditions caused greater leaf longevity. Litter accumulation on the forest floor was 3457 g m⁻² at the floodplain site and 2320 g m⁻² at the riparian site; there was no significant difference between years, although the organic matter content of the litter was lower in 1992, possibly as a result of leaching during flooding. Carbon content decreased with decreasing particle size of the litter, whereas nitrogen and phosphorus increased. There was no evidence to suggest leaching of nitrogen or phosphorus, and the high C: N: P ratios indicate slow rates of litter decay. The high accumulation of litter mass suggests that these woody wetlands may function as nutrient sinks.
... In floodplain rivers, a large proportion of the primary productivity that subsequently supports consumers occurs outside the main channel (Junk et al., 1989;Tockner et al., 2000). This typifies many floodplain rivers in the tropics, where seasonal changes in water levels are associated with a dramatic increase in aquatic primary productivity and a corresponding shift in the nature of the dominant primary producers, from algae largely confined to the river channel and isolated water bodies in the dry season, to emergent aquatic macrophytes during floodplain inundation in the wet season (Finlayson, Cowie & Bailey, 1990a;Finlayson, Cowie & Bailey, 1993;Douglas, Bunn & Davies, 2005). ...
... Common vegetation includes paperbark (Melaleuca spp.) forests, open perennial and annual swamps, billabongs and grass ⁄ sedge herbfields (Williams, 1979). The widespread aquatic grassland communities occupy around 40% of the floodplains (Finlayson et al., 1993), with Melaleuca spp. forests or woodlands covering around 30-40% (Finlayson, Bailey & Cowie, 1989). ...
... Estimates of the productivity of the major grass species growing on the Magela Creek floodplain were made from biomass samples taken at 4-weekly intervals from October 1983 to February 1985 (Finlayson, 1991) and also from biomass samples of these grasses measured in the dry season 1999 (Douglas & O'Connor, 2004). The proportions of the floodplain occupied by these major grass species are as follows: 15% for Hymenachne acutigluma, 14% for Pseudoraphis spinescens and 12% for Oryza meridionalis (Finlayson et al., 1993). ...
Article
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1. Globally, tropical floodplains are highly productive ecosystems. This is largely because of predictable seasonal rains providing replenishing floodwaters that stimulate nutrient turnover which, in turn, substantially boosts both primary and secondary productivity. This is associated with concomitant shifts in the types of primary producers and associated food webs. 2. The Magela Creek floodplain on Kakadu National Park in northern Australia is one of the most studied tropical freshwater ecosystems in Australia and provides an opportunity to collate and examine information on organic carbon sources and pathways through food webs to gain a fundamental understanding of how these systems may function. 3. We reviewed biophysical information published since the early 1980s to construct an assessment of the carbon resources for the channel and floodplain. 4. We conclude that macrophytes, largely in the form of grasses and aquatic plants, produce the greatest above-ground biomass on the Magela Creek floodplain. Although macrophytes provide suitable substrata for the attachment of epiphytes, they do not appear to be an important carbon source for aquatic consumers themselves. Nevertheless, macrophytes do provide critical seasonal food and habitat structure for other producers and consumers on the floodplain, such as the abundant magpie geese. 5. We developed a generalised conceptual food web and carbon budget contrasting the ‘wet’ and ‘dry’ seasons for the Magela Creek system, as a representative of tropical seasonal floodplain systems. 6. Our conceptual model of tropical floodplains indicates that knowledge of the seasonal and spatial links and exchanges between the floodplain and the river is critical in understanding ecosystem function.
... of the fl oodplain vegetation on the Magela fl ood plain has been investigated, covering seasonal changes in the dry weight of aquatic grasses and litterfall from Melaleuca trees (Finlayson, 1988Finlayson, , 1991 Finlayson et al., 1993b). Changes in theFig. ...
... The annual dry weight production for these species was 0.51 kg m –2 for Orzya meridionalis, 1.91 kg m –2 for Pseudoraphis spinescens, and 2.09 kg m –2 for Hymenachne acu- tigluma. Dry weight production of the widespread Melaleuca woodlands and forests on the Magela fl ood plain were estimated through an analysis of litterfall data (Finlayson, 1988; Finlayson et al., 1993b ). In an intensively sampled forest the total litterfall was approximately 0.7 kg m –2 y –1 compared to 1.5 kg m –2 y –1 at a less intensively sampled site (Finlayson, 1988). ...
... The value of 0.7 to 1.5 kg m –2 y –1 is within the range recorded for other forests at the same latitude (Lonsdale, 1988 ). The above ground biomass of Melaleuca species on the Magela fl ood plain was also calculated using an algorithm relating diameter at breast height to tree height and fresh weight (Finlayson et al., 1993b). This resulted in a calculated tree weight of 260 ± 0.3 t ha-1 based on a tree density of 294 trees ha –1 ; elsewhere on the fl oodplain tree densities were much higher, although an analysis of density across the entire fl oodplain was not undertaken. ...
Article
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The biodiversity values of the wetlands in the Kakadu Region of northern Australia have been recognised as being of national and international significance, as demonstrated through their listing by the Ramsar Convention on Wetlands. Analyses of the wetland biodiversity have resulted in the production of species list for many taxa, and some population and community-level analyses of biomass and abundance, and the mapping of habitats at multiple scales. Wetland habitats include inter-tidal mud-flats, mangroves, hyper-saline flats, freshwater flood plains and streams. The tidal influence on the saline wetlands is pronounced, as is the influence of the annual wet-dry cycle of the monsoonal climate on the flood plains and streams. The vegetation is diverse and highly dynamic with rapid turnover of organic material and nutrients. The fauna is abundant with endemism being high in some habitats. Most fauna analyses have focussed on vertebrates with a large amount of information on waterbirds and fish in particular. However, despite extensive effort over the past two decades much is still unknown about the biota. While the invertebrate fauna in the streams has received some attention, a large taxonomic classification effort is required. The functional inter-relationships between habitats and species have largely not been assessed. Further, the ecology of many species is only cursorily known. At the same time there has been increased attention to pressures on the wetlands, such as weeds and feral animals, water pollution, and the potential impact of climate change and salinisation of freshwater habitats. Importantly, given the social context of the region, increased attention is being directed towards traditional use and management of the wetlands.
... No information is available on litterfall or turnover of melaleuca forests in South Florida. Measurements in its native range in Australia (Finlayson et al. 1993, Greenway 1994) however, have indicated that annual litterfall in melaleuca forests was the highest recorded among other Australian temperate/subtropical forest types, suggesting that these woody wetlands form highly productive ecosystems . This paper presents data on litterfall biomass from six sites representing different hydrological conditions within melaleuca forested wetlands in South Florida. ...
... Greenway (1994) observed that melaleuca wetlands produced higher levels of litterfall than many other forest types of the same area, e.g., eucalypt forest (Rogers and Westman 1977), rainforest (Webb et al. 1969), and mangrove forest (Davie 1983) communities in subtropical eastern Australia. Similarly, Finlayson et al. (1993) indicate litterfall from a melaleuca forest in tropical northern Australia is either equivalent to or higher than that in many forests elsewhere in Australia, suggesting that the forest is comparatively highly productive. In a more temperate climate, however, a much lower rate of litterfall (4.3 t ha -1 yr ...
Article
We monitored litterfall biomass at six different sites of melaleuca (Melaleuca quinquenervia (Cay.) S.T. Blake) forested wetlands in South Florida from July 1997 to June 1999. Annual litterfall of melaleuca varied between sites from 6.5 to 9.9 t dry wt ha-1 yr-1 over the two-year period. Litterfall was significantly higher (P < 0.001) in seasonally flooded habitats (9.3 t ha-1 yr-1) than in non-flooded (7.5 t ha-1 yr-1) and permanently flooded habitats (8.0 t ha-1 yr-1). Leaf fall was the major component forming 70% of the total litter, woody material 16%, and reproductive material 11%. Phenology of flowering and leaf flush was investigated by examination of the timing and duration of the fall of different plant parts in the litter traps, coupled with monthly field observations during the two-year study. In both years, flowering began in October and November, with peak flower production around December, and was essentially completed by February and March. New shoot growth began in mid winter after peak flowering, and extended into the spring. Very little new growth was observed in melaleuca forests during the summer months, from May to August, in South Florida. In contrast, the fall of leaves and small wood was recorded in every month of the year, but generally increased during the dry season with higher levels observed from February to April. Also, no seasonality was recorded in the fall of seed capsules, which apparently resulted from the continual self-thinning of small branches and twigs inside the forest stand. In planning management for perennial weeds, it is important to determine the period during its annual growth cycle when the plant is most susceptible to control measures. These phenological data suggest that the appropriate time for melaleuca control in South Florida might be during late winter and early spring, when the plant is most active.
... biflora (Brown et al., 1984), in the coastal Gulf of Mexico Pachira aquatica and Annona glabra (Lot and Novelo, 1990), in the Yucatan Peninsula Bucida spinosa and Haematoxylum campechianum dominate (Olmsted and Durán, 1986), in the Guyanas and Caribbean region, including Puerto Rico the most conspicuous species are Pterocarpus officinalis and Symphonia globulifera (Alvarez-Lopez, 1990;Migeot and Imbert, 2011), in the Pacific Islands one can find Terminalia carolinensis, Campnosperma brevipetiolatum, Calophyllum vexans (Allen et al., 2005;Ellison, 2009) and in the southern part of Australia Melaleuca spp. (Finlayson et al., 1993;Zoete, 2001). The description of the structure of these forests and their relationship with environmental parameters such as soils, hydrology and geomorphology has established the characteristics of the main types of forested wetlands and their functions (Chimner and Ewel, 2005;Hupp et al., 2009;Klimas et al., 2009;Middleton, 2009), but there are still few examples in the tropical and subtropical regions. ...
... Nevertheless, it is important to note the differences in soils between the flooded forests and the possible causes of variation that occurred between seasons. Finlayson et al. (1993) Regarding seasonal variations, the concentration of P in the soil was consistently higher in all of the forests during the rainy season due to P inputs from runoff (Howard-Williams, 1985). In the forests adjacent to agricultural fields (Cienaga, Chica and Salado), fertilizer use may be an important source of P. Other causes of increasing P include its release in situ because it is found forming complexes with Fe, Al, Ca and Mg and is released by the reduction of these compounds when redox potential decreases (Manahan, 2000). ...
Research
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We studied the influence of geomorphological setting and soil properties on the vegetation structure, composition and diversity of five forested coastal wetlands in Veracruz on the Gulf of Mexico. These swamps are located on floodplains and in dune depressions. We recorded 109 woody and herbaceous species. The most frequent species were the trees Pachira aquatica, Annona glabra, Diospyros digyna and Ficus insipida subsp. insipida, the lianas Dalbergia brownei and Hippocratea celastroides and the hemi-epiphyte Syngonium podophyllum. The Shannon-H diversity index varied from 2.659 to 3.373, density from 1750 to 2289 stems ha�1 and basal area from 32.7 to 76.42 m2 ha�1. The classification analysis defined two groups: one corresponded to forested wetlands along the floodplain (Apompal, Cienaga, Chica) and the other included Mancha and Salado, in dune depressions. PCA ordination of soil parameters during the rainy season explained 67.0% and during the dry season 69.1% of the total variance. In the rainy season Mancha and Salado samples remain close together because they have lower Mg, Na, K, % Total C and % Total N values. Apompal and Chica samples remain close to each other because of their high levels of % Total C, % Total N, Mg, Na and high soil water content. Cienaga samples are separated from the others because of high values of P, Ca and Eh as well as high water levels. In general, soil parameter ordination during the dry season showed that redox potential, P, water level and water content decreased in the forested wetlands and Na values increased in Chica. The soil textures identified were clay, sandy clay loam, sandy loam and clay loam; clay texture dominated alluvial processes in the floodplain (e.g., Cienaga). The forested wetlands in the floodplains had similar vegetation and the same happened in the dune depressions but soil characteristics were more variable in both cases. Plant diversity in floodplains tends to be relatively high, and the presence of adjacent tropical forests probably increases its richness, except in cases in which there are stressing factors, such as salinity. The forested wetlands studied showed dominant floristic elements, which extend north into Florida such as A. glabra and Ficus aurea. Other dominant elements such as P. aquatica are also found in Central and South America. The forested wetlands studied are subjected to continuous deforestation to transform the land into farming or ranching activities, this being a common practice throughout the distribution range of these forests. � 2011 Elsevier B.V. All rights reserved.
... type (at the expense of native grasslands) corresponded to changes in fire regimes as a result of the cessation of Aboriginal burning, a finding supported by Stanton (1992). In both regions, a lack of an understanding of regenerative processes following disturbance in Melaleuca communities is a management concern (Dr J. Russell-Smith, pers. comm.). Finlayson et al. (1993) have published details of the structure of a mixed Melaleuca cajaputi Powell/ Melaleuca viridiflora community on the Magela floodplain near Jabiru in the Northern Territory. The community exhibited a bell-shaped distribution curve across DBH size classes. Importantly, the site has remained unburnt for at least the past 20 years (Dr M. F ...
... Sites 1, 3, 6 and to a lesser extent Sites 13 and 16). The only other published data on the structure of similar Melaleuca communities also recorded a bell-shaped curve and, importantly, the community had remained unburnt for at least 20 years (Finlayson et al. 1993). The structure of frequently burnt communities suggests that recruitment of a midstorey, and, in the long-term, canopy is being prevented. ...
Article
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Tropical lowland plant communities in north-eastern Queensland remain under pressure from continuing clearing, fragmentation, exotic species invasion, inappropriate fire regimes, and altered hydrological patterns. Comparatively little scientific research has been conducted on the highly diverse and ecologically significant range of remnant vegetation types. Additionally, most plant communities remain very poorly represented in the existing conservation reserve system. Melaleuca viridiflora Sol. ex Gaertn. open woodlands were selected for investigation based on their relatively simple structure, compared to other lowland communities, and the large extent to which they have been affected by past clearing patterns. A detailed analysis of community structure and composition was conducted at 24 sites throughout the wet-tropics coastal region between Townsville and Cooktown. Surprisingly, a high diversity of structural and floristic types was recorded, with a total of 127 species documented across the 24 sites. Classification analyses of species composition data produced seven or eight main groups of sites (dependent on the statistical technique used), essentially related to a gradient of latitude and rainfall. These floristic groups were not well explained by either species richness, past fire frequencies or soil types. Structural classification analyses based upon DBH data identified six or seven main groups, the singularly most striking of which were sites with annual fire histories. Ordinations based on both the DBH and species composition data produced groupings that supported those detected by the classification techniques. On closer examination of sites with similar fire histories, soil moisture and soil type were both found to have significant effects on community structure and composition. Many of the woodland types recorded are not adequately included (some not at all) in the existing conservation reserve system.
... biflora (Brown et al., 1984), in the coastal Gulf of Mexico Pachira aquatica and Annona glabra (Lot and Novelo, 1990), in the Yucatan Peninsula Bucida spinosa and Haematoxylum campechianum dominate (Olmsted and Durán, 1986), in the Guyanas and Caribbean region, including Puerto Rico the most conspicuous species are Pterocarpus officinalis and Symphonia globulifera (Alvarez-Lopez, 1990;Migeot and Imbert, 2011), in the Pacific Islands one can find Terminalia carolinensis, Campnosperma brevipetiolatum, Calophyllum vexans (Allen et al., 2005;Ellison, 2009) and in the southern part of Australia Melaleuca spp. (Finlayson et al., 1993;Zoete, 2001). The description of the structure of these forests and their relationship with environmental parameters such as soils, hydrology and geomorphology has established the characteristics of the main types of forested wetlands and their functions (Chimner and Ewel, 2005;Hupp et al., 2009;Klimas et al., 2009;Middleton, 2009), but there are still few examples in the tropical and subtropical regions. ...
... Nevertheless, it is important to note the differences in soils between the flooded forests and the possible causes of variation that occurred between seasons. Finlayson et al. (1993) Regarding seasonal variations, the concentration of P in the soil was consistently higher in all of the forests during the rainy season due to P inputs from runoff (Howard-Williams, 1985). In the forests adjacent to agricultural fields (Cienaga, Chica and Salado), fertilizer use may be an important source of P. Other causes of increasing P include its release in situ because it is found forming complexes with Fe, Al, Ca and Mg and is released by the reduction of these compounds when redox potential decreases (Manahan, 2000). ...
... Supratidal forests exhibit an enhanced capacity for maintaining substrate elevations due to their tendency to store proportionally more root volume than mass, with the complex size distribution of their root architecture providing a basis for volume additions as the forest matures. Litterfall, which can be particularly high in Melaleuca forests (Congdon 1979;Finlayson et al. 1993) and tidal freshwater forests (Cormier et al. 2012), may also contribute to substrate volume (McKee 2011), although was not directly assessed in this study. As sea levels rise, it will become increasingly important that saltmarshes and supratidal forests continue to produce root volume material to maintain substrate elevations given negligible mineral sediment supply. ...
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Background and aims: Additions of organic matter in coastal wetlands contributes to blue carbon sequestration and adjustment to sea-level rise through vertical growth of substrates. To improve models of carbon sequestration and adaptation to sea-level rise, data of root mass and volume additions across tidal gradients are required. This study aims to characterise the influence of vegetation zonation and tidal position on root mass and volume dynamics within substrates. Methods: The root ingrowth technique was coupled with sediment cores to quantify below-ground root mass and volume production, standing stocks and turnover across two years to 90 cm depth at Kooweerup, Victoria, Australia. Measurements of vertical accretion quantified mineral sediment additions at the surface. Results: The results indicate a complex non-linear relationship between root production and tidal position, which is driven by variation in vegetation structure across mangrove (442–3427 g fine root mass m ⁻² yr ⁻¹ ), saltmarsh (540–860 g m ⁻² yr ⁻¹ ) and supratidal forest (599 g m ⁻² yr ⁻¹ ) zones. Fine root volume additions ranged from 274 to 4055 cm ³ m ⁻² yr ⁻¹ across sampling locations. Root production was greatest for older mangroves and tidally defined optimal zones of production were evident for mangrove and saltmarsh. The live rooting zone extended beyond depths typically measured in studies, and for forested sampling locations, live roots were found as deep as 1.0 m. Conclusion: These data can be used to improve highly parameterised models accounting for carbon sequestration and substrate vertical adjustment across an intertidal gradient by quantifying both root mass and volume additions across the live rooting zone.
... Southern Florida has a subtropical climate, such that litter decomposition is usually rapid, and the accumulation of litter under local hardwood hammock is generally relatively small (Sampaio et al. 1993). However, melaleuca's leaf litter turnover rate of around 60% yearly (Finlayson et al. 1993), though faster than native pine leaf litter, is significantly slower than sawgrass marsh and native broadleaf tree litter. Thus litter accumulation of melaleuca on sites in southern Florida is greater than that of other tropical species (Gholz et al. 2000, Rayamajhi et al. 2010. ...
Article
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Many introduced plants pose invasion risks globally and threaten the biodiversity of native ecosystems. Such non-native plants can become invasive when they have advantages over native plants, such as having fewer natural enemies. Invasive plants often have the ability to alter ecosystem properties after they have become established, which can make it difficult to eliminate the invasive. In principle, this can cause a regime shift that may not be reversed through intense control efforts that increase mortality and reduce growth of the invasive species. Here we use spatially explicit agent-based modeling to simulate the invasion of an introduced tree species into a habitat occupied by a native species. The model describes an invasive tree with fast growth and high seed production and, in addition, produces litter that has a suppressive effect on native seedlings. These are properties, for example, shared by the invasive Melaleuca quinquenervia in southern Florida habitats. We use simulation modeling to test the following logical hypotheses: Partial suppression of native tree seedlings by the invasive tree's litter (1) will accelerate the spread of the invasive tree into native vegetation, (2) will impede efforts to control invasive spread through biocontrol, and (3) can cause a regime shift that is not reversed even if the biocontrol lowers invasive growth and reproduction to levels substantially lower than those of the native species. Additionally, (4) the earlier in the invasion biocontrol is introduced, the more effective it will be in reversing the invasion. The simulations support all four hypotheses. While these results highlight the potential for biocontrol of invasive tree species, our findings also suggest that successful elimination of positive litter feedbacks and invasive spread may critically depend on the timing of control efforts within the invasion process.
... Early research associated with the carbon cycling of Melaleuca forests demonstrated high productivity, biomass, and litter production (Finlayson et al., 1993;Greenway, 1994). More recently, investigation of tropical Melaleuca forests has shown high ecosystem carbon stocks in aboveground biomass and surface soils (Tran et al. 2013(Tran et al. , 2015, and sequestration potential within the range of other blue carbon ecosystems (Adame et al., 2019b). ...
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Coastal Swamp Oak Forests (CSOF) dominated by the species Casuarina glauca are an Endangered Ecological Community under state and Commonwealth legislation in Australia. These forests have suffered significant historic declines due to changes in land use and hydrological modification. Although they have a limited contemporary extent (~320 to over 500 km 2 ) along the east coast of Australia, CSOF represent part of a much larger range of supratidal forested wetlands in Australia, which include wetlands vegetated by the more broadly distributed genus Melaleuca . For the first time, in this chapter we estimated aboveground and 1 m‐depth belowground organic carbon (C org ) stocks in CSOF (mean ± SD: 143 ± 61 Mg C org /ha and 241 ± 136 Mg C org /ha, respectively) across six study sites in temperate and subtropical Australia. Variations in aboveground C org stock are explained by differences in the stature and structure of forests, while belowground C org stocks appear more reflective of within‐ and among‐estuary variations in geomorphic evolution. These early findings show that C org stocks in CSOF are within the range of values reported for mangrove, saltmarsh and seagrass ecosystems. Our data provide a foundation for future research efforts to determine the carbon sequestration potential of CSOF, and their amenability to management interventions which seek to reverse past losses and contribute to climate change mitigation.
... Additionally, the high productivity of palustrine wetlands can result in short or medium-term accumulation of N in the trunks of trees and shortterm accumulation in the dense understory shrub and grass community ; Table 2). The high primary productivity of these wetlands could also cause sporadic exports of N as litter, NH 4 + or DON during floods (Adame et al., 2019b;Finlayson et al., 1993; Table 5). ...
Article
Nitrogen (N) from anthropogenic sources has been identified as a major pollutant of the Great Barrier Reef (GBR), Australia. We developed a conceptual framework to synthesise and visualise the fate and transport of N from the catchments to the sea from a literature review. The framework was created to fit managers and policymakers' requirements to reduce N in the GBR catchments. We used this framework to determine the N stocks and transformations (input, sources, and outputs) for ecosystems commonly found in the GBR: rainforests, palustrine wetlands, lakes, rivers (in-stream), mangroves and seagrasses. We included transformations of N such as nitrogen fixation, nitrification, denitrification, mineralisation, anammox, sedimentation, plant uptake, and food web transfers. This model can be applied to other ecosystems to understand the transport and fate of N within and between catchments. Importantly, this approach can guide management actions that attenuate N at different scales and locations within the GBR ecosystems. Finally, when combined with local hydrological modelling, this framework can be used to predict outcomes of management activities.
... Leaf biomass typically represents only a small proportion of total standing biomass (b15% for melaleucas; Rayachhetry et al. (2001) and b10% for eucalypts; Epron et al., 2013), yet the litter production of melaleucas is known to influence soil properties through their relatively large deposition of leaf litter and woody debris (Finlayson et al., 1993). Litter decomposition rates of melaleuca leaves tend to be slow, and the accumulation of leaf litter on the surface in mature melaleuca stands can suppress the establishment of an understory layer below the melaleuca canopy (Rayamajhi et al., 2010(Rayamajhi et al., , 2006White, 1994). ...
Article
The critically endangered Cumberland Plain woodland within the greater Sydney metropolitan area hosts a dwindling refuge for melaleuca trees, an integral part of Australia's native vegetation. Despite their high carbon stocks, melaleucas have not explicitly been targeted for studies assessing their carbon sequestration potential, and especially little is known about their energy cycling or their response to increasing climate stress, precluding a holistic assessment of the resilience of Australia's forests to climate change. To improve our understanding of the role of melaleuca forest responses to climate stress, we combined forest inventory and airborne LiDAR data to identify species distribution and associated variations in forest structure, and deployed flux towers in a melaleuca-dominated (AU-Mel) and in a eucalypt-dominated (AU-Cum) stand to simultaneously monitor carbon and energy fluxes under typical growing conditions, as well as during periods with high atmospheric demand and low soil water content. We discovered that the species distribution at our study site affected the vertical vegetation structure, leading to differences in canopy coverage (75% at AU-Cum vs. 84% at AU-Mel) and plant area index (2.1 m2 m-2 at AU-Cum vs. 2.6 m2 m-2 at AU-Mel) that resulted in a heterogeneous forest landscape. Furthermore, we identified that both stands had comparable net daytime carbon exchange and sensible heat flux, whereas daytime latent heat flux (115.8 W m-2 at AU-Cum vs 119.4 W m-2 at AU-Mel, respectively) was higher at the melaleuca stand, contributing to a 0.3 °C decrease in air temperature and reduced vapor pressure deficit above the melaleuca canopy. However, increased canopy conductance and higher latent heat flux during moderate VPD or when soil moisture was low indicated a lack of water preservation at the melaleuca stand, highlighting the potential for increased vulnerability of melaleucas to projected hotter and drier future climates.
... Aboveground biomass was estimated from the allometric equations derived for Melaleuca viridiflora (Eqn 1) and Melaleuca sp. (Eqn 2) in northern Australia (Finlayson et al. 1993), as follows: ...
Article
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Excess nitrogen (N) leading to the eutrophication of water and impacts on ecosystems is a serious environmental challenge. Wetlands can remove significant amounts of N from the water, primarily through the process of denitrification. Most of our knowledge on wetland denitrification is from temperate climates; studies in natural tropical wetlands are very scarce. We measured denitrification rates during a dry and a wet season in five floodplain forests dominated by Melaleuca spp., a coastal freshwater wetland of tropical Australia. We hypothesised that the denitrification potential of these wetlands would be high throughout the year and would be limited by N and carbon (C) availability. Mean potential denitrification rates (Dt) were 5.0 ± 1.7 mg m² h–1, and were within the reported ranges for other tropical and temperate wetlands. The rates of Dt were similar between the dry and the wet seasons. From the total unamended denitrification rates (Dw, 3.1 ± 1.7 mg m² h–1), 64% was derived from NO3– of the water column and the rest from coupled nitrification–denitrification. The factor most closely associated with denitrification was background water NO3–-N concentrations. Improved management and protection of wetlands could play an important role in improving water quality in tropical catchments.
... Melaleuca seed (MS) and litterfall events prior to the natural-enemy damage in Florida (Rayamajhi et al. 2006(Rayamajhi et al. , 2017 was relatively higher compared to its native range of Australia (Finlayson et al. 1993;Greenway 1994). Long-term research data, focused on natural enemy-mediated leaf and seed fall, and influence on the composition of non-melaleuca litter in adventive ranges are rare. ...
Article
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The exotic tree Melaleuca quinquenervia (melaleuca) has invaded and formed monotypic forest stands in ecologically sensitive wetlands of Florida. We hypothesized that natural-enemy impact would influence melaleuca’s litter and seed fall dynamics via chronic attacks, and enhance native species diversity, which will be reflected in leaf litter composition. This hypothesis was tested during 1997–2013 by studying melaleuca stands in occasionally inundated habitats infested by its natural enemies. Results from our study showed: (1) an initial increase in the leaf and seed fall during the first-half of the study period, followed by about 70% decline during remainder of the study period, (2) a positive correlation between the amount of leaf and seed fall, (3) a negative correlation between the proportion of natural-enemy damaged melaleuca leaf litter and the quantity of fallen seeds, and (4) a slow but steady increase of the non-melaleuca leaf litter amount by 81% and with a corresponding decrease in melaleuca leaf litter by 15%. Of the 17 non-melaleuca species recovered, we recorded two perennials at the onset of the study, which increased to seven during the second half of the study period, one of which was non-native. Cladium and Myrsine species produced significantly more leaf-litter by the end of the study period. Over 80% of the melaleuca leaf litter manifested natural-enemy damage during the last 7-year of the study period. These results provide evidence of a negative influence of natural enemy attack on melaleuca leaf and seed fall dynamics and a positive influence on native species diversity in the fallen leaf litter.
... Secondly, on the basis of a published value of 7.16 Mg DW ha −1 y −1 for litterfall in a Melaleuca (M. cajuputi and M. viridiflora) forest in Australia (Finlayson et al. 1993), we estimate that the highest likely value of PL′ at Bacho would be 3.58 Mg C ha −1 y −1 . The actual input of carbon as litter would range from this value down to zero, due to the recurring fires that may periodically remove vegetation. ...
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At the Bacho peatland in southern Thailand, peat subsidence was measured at four locations on abandoned agricultural land (degraded peat swamp forest) and at one location in a conservation zone, at monthly intervals over a period of more than 20 years. Average peat subsidence rates during the observation period were 3.1-5.2 cm y(-1) on the degraded peatland, reducing to 1.8-2.6 cm y(-1) when peat loss due to field fires was discounted, and 1.0 cm y(-1) reducing to 0.7 cm y(-1) in the conservation zone. Due to martial law restrictions on access to the Bacho site, measurements of the peat soil respiration rate under various water table conditions were made mostly at other sites in Thailand with similar climate. During these measurements the position of the water table ranged from 0.92 m above the peat surface to more than one metre below it, and daily mean respiration rates ranged from 0.57 to 8.20 mu mol CO2 m(-2) s(-1). The CO2 efflux attributed to peat respiration was 13.7-18.9 Mg ha(-1) y(-1) on the degraded peatland but only 7.5 Mg ha(-1) y(-1) in the conservation zone. To simulate the CO2 efflux resulting from soil respiration at Bacho on the basis of data collected elsewhere, we developed an empirical three-stage model (NAIS Peat Model) that treats the position of the water table as a proxy variable. The observed values of peat subsidence were in good agreement with simulated values of CO2 efflux in two tests. The implications for peatland management are considered.
... Common aquatic habitat types on the floodplain include paperbark (Melaleuca spp.) forests, open perennial and annual swamps, large perennial waterholes (ponds) and grass/sedge herbfields (Williams, 1979). Widespread grassland communities are dominated by: Hymenachne acutigluma (15% of the floodplain), Pseudoraphis spinescens (14%), and Oryza meridionalis (12%) (Finlayson et al., 1993). Invasive para-grass (Urochloa mutica) has replaced large areas of native vegetation occupying ∼35% of the floodplain (Bayliss et al., 2006). ...
Article
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Tropical floodplains are highly productive because of seasonal replenishment of water and nutrients, which substantially boost primary productivity. This study examined how the architecture of aquatic macrophytes affect the light and water quality and consequently the attachment and biomass of epiphytes on a floodplain in northern Australia. Results show that macrophyte structural complexity is not only important for water column light penetration but also for the development of epiphytes on macrophytes. Emergent grasses with simple vertical structure and high plant densities, limit light penetration and consequently the development and biomass of epiphytic algae. In contrast, submerged macrophytes growing just below the water surface, allow greater light penetration. The complex architecture of submerged macrophytes also provides a large surface area for the development of a dense covering of epiphytic algae. Other plant structural forms (e.g., plants with floating leaves) have a simple structure, variable light penetration and low epiphytic algae biomass. The emergent grass Pseudoraphis spinescens (R.Br.) Vickery also had low light penetration but the horizontal alignment of stems across the water surface allow greater exposure to sunlight of the stems and the consequent development of epiphytic algae. We conclude that (1) the complex structure of submerged plants effectively creates a "false bottom" in deeper waters so that they function similarly to the floodplain's littoral zone, and (2) that their extremely large surface area for attachment allows greater production of epiphytic algae than would occur on the sediment surface.
... In this study, M. cajuputi growth was relatively slow possibly due to water stress as this species is known to flourish in swampy areas. In the wild the growth is usually very much faster (Rayamajhi et al., 2006;Finlayson et al., 1993). M. cajuputi forest is a very productive forest and in Florida this tree species is considered as an invasive species (Lopez-Zamora et al., 2004). ...
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Heavy metals are very toxic and soil contaminated with sewage sludge urgently need remediation in order to avoid related health hazards. Phytoremediation is a low cost and reliable technique to remediate heavy metal contamination. However phytoremediation using timber species was rarely reported and its efficiency was questionable. A field study was conducted to examine the efficiency of two timber species namely Acacia mangium and Melaleuca cajuputi in phytoextraction of Zn, Cu and Cd from contaminated soil. Two hundred of A. mangium and M. cajuputi were planted on sewage sludge disposal site and the growth was recorded for 12 months before at the end total biomass of each species was determined. Results show in 12 months, about 72 and 4 t ha-1 of aboveground biomass can be produced by A. mangium and M. cajuputi, respectively. Both species show potential for phytoremediation, however A. mangium is more efficient compared to M. cajuputi where efficiency of A. mangium to remove Zn was 24.4, 6.2 for Cu and 9.5% for Cd. As for M. cajuputi the efficiency was 1.3, 0.3 and 0.14% for Zn, Cu and Cd, respectively. It is projected that A. mangium require 5, 17 and 20 years to remove 79.82 kg ha-1 of Zn, 46.94 kg ha-1 of Cu and 2.33 kg ha-1 of Cd, respectively.
... Melaleuca forests within the Ramsar site are highly productive and contribute a large amount of material to the detrital/debris turnover cycle on the floodplain (Finlayson et al. 1993). Pandanus spp. ...
Technical Report
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An Ecological Character Description describes the ecological character of a wetland at the time of its listing as a Wetland of International Importance. The Ecological Character Description is a fundamental management tool for site managers, forming the basis of management planning and action as well as including guidance on site monitoring requirements to detect changes in the ecological character of the site. The Kakadu National Park Ramsar site is located approximately 200 kilometres east of Darwin in the Northern Territory. The Kakadu National Park Ramsar site was historically two separate Ramsar sites within Kakadu National Park. These were Kakadu National Park (Stage I including wetland components of Stage III) and Kakadu National Park (Stage II). Kakadu National Park Stage I was originally listed as a Ramsar site in 1980 and expanded in 1995 to include wetland components of Stage III, while Stage II was listed in 1989 as a separate Ramsar site. Kakadu National Park comprises of sandstone plateau communities, escarpments, extensive seasonal floodplains, estuaries, tidal flats, offshore islands, seasonal freshwater marshes and permanent freshwater pools. The rivers are tidal in their lower reaches and are associated with extensive tidal flats formed from riverborne mud. The ecological character of a wetland is the sum of all the components, processes and services of that wetland. Ecosystem components are physical, chemical and biological parts of a wetland, from large-scale to very small-scale (e.g. habitat, species and genes). Ecosystem processes are the dynamic forces within an ecosystem. They include all those processes that occur between organisms and within and between populations and communities, including interactions with the non-living environment, that result in existing ecosystems and bring about changes in ecosystems over time. Ecosystem services are the benefits that people receive from ecosystems. This document describes the critical components, processes and services for the Kakadu National Park Ramsar site. Kakadu National Park has 11 critical components: mangroves; Melaleuca forests; palustrine wetlands and billabongs; waterfalls, seeps and waterholes; populations of migratory and resident waterbirds; populations of freshwater fish; populations of freshwater and saltwater crocodiles; populations of threatened sharks; yellow chat populations; pig-nosed turtle populations; and locally endemic invertebrate species. It has four critical processes: fluvial hydrology; fire regimes; breeding of waterbirds; and flatback turtle nesting. It also has three critical services: maintenance of global biodiversity; fisheries resource values; and contemporary living culture. The description also identifies limits of acceptable change which describe the range of variation which key aspects of the ecology of the site can vary without representing a change in the ecological character. Limits of acceptable change for Kakadu National Park have been proposed for all critical components, processes and benefits and services based on existing data. This document also describes the current Ramsar listing criteria met by the site, the key threats and knowledge gaps for Kakadu National Park. Recommended monitoring needs and communication messages are also provided.
... Using these equations, the average biomass was analyzed for five typical Melaleuca stands (VS1, VS2, VS3, VS4, and VS5). To convert from fresh to dry biomass, a moisture rate of 0.5 was applied as suggested by Van et al. [49] for the allometric equation of Finlayson et al. [59]. According to the Global Wood Density Database, the density of M. cajuputi timber ranges from 0.6 to 0.87 g/cm 3 [60], so 0.6 g/cm 3 was applied for the above-ground biomass allometric equation of Chave et al. [61]. ...
Article
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Background In the lower Mekong Basin and coastal zones of Southern Vietnam, forests dominated by the genus Melaleuca have two notable features: most have been substantially disturbed by human activity and can now be considered as degraded forests; and most are subject to acute pressures from climate change, particularly in regards to changes in the hydrological and sodicity properties of forest soil. Results Data was collected and analyzed from five typical Melaleuca stands including: (1) primary Melaleuca forests on sandy soil (VS1); (2) regenerating Melaleuca forests on sandy soil (VS2); (3) degraded secondary Melaleuca forests on clay soil with peat (VS3); (4) regenerating Melaleuca forests on clay soil with peat (VS4); and (5) regenerating Melaleuca forests on clay soil without peat (VS5). Carbon densities of VS1, VS2, VS3, VS4, and VS5 were found to be 275.98, 159.36, 784.68, 544.28, and 246.96 tC/ha, respectively. The exchangeable sodium percentage of Melaleuca forests on sandy soil showed high sodicity, while those on clay soil varied from low to moderate sodicity. Conclusions This paper presents the results of an assessment of the carbon stocks and sodicity tolerance of natural Melaleuca cajuputi communities in Southern Vietnam, in order to gather better information to support the improved management of forests in the region. The results provide important information for the future sustainable management of Melaleuca forests in Vietnam, particularly in regards to forest carbon conservation initiatives and the potential of Melaleuca species for reforestation initiatives on degraded sites with highly sodic soils.
... One possibility is leaf litter. Using data in Table 3 and an assumed annual leaf litter fall rate of 0.7 kg m 2 /year (based on Greenway 1994 andFinlayson et al. (1993) an estimate of the annual contribution of leaf litter to soil solute accumulation can be derived. Using profile 1 to represent open swamp and profile 4 to represent M. quinquenervia forest and assuming an identical initial soil accumulation prior to encroachment and complete loss from the leaves to the soil via leaching, litter accumulation from senescent leaves could theoretically account for 3% and 40% of the differences in soil Cland Al, respectively. ...
... Melaleuca species will poten6ally be lost due to SWI (Finlayson, 1991). The debris of these grasses lej at the end of the wet season and the leaf liOer from the Melaleuca species is rich in nitrogen, phosphorous and potassium and they are important contributors to elemental cycling on the floodplains (Finlayson, 1991; Finlayson et al., 1993). Thus, a loss of these grass and Melaleuca species causes a decrease in available nutrients such as nitrogen. ...
Article
Saltwater intrusion (SWI) can result in the loss of dominant vegetation from freshwater habitats. In northern Australia, sea level is predicted to rise 17–50 cm by 2030–2070. This will exacerbate the impact of SWI, threatening Ramsar-listed habitats. Soil bacteria in these habitats play a significant role in biogeochemical cycling, regulating availability of essential nutrients such as nitrogen to vegetation. However, there is limited understanding as to how SWI will impact these soil bacteria. Floodplain soil samples were collected from the South Alligator River floodplain in Northern Australia from sites with contrasting histories of SWI. A SWI event was simulated over 7 days with treatments of saltwater and freshwater. Bacterial community composition before and after treatment were measured using next generation sequencing of bacterial DNA. Sites with no history of SWI showed no significant changes in community taxonomic composition following treatments, suggesting the community at these sites have broad functional capacity which may be due to their historic conditioning over many years. Sites with a history of SWI showed a significant response to both treatments. Following saltwater treatment, there was an increase in sulfate-reducing bacteria, which are known to have an impact on carbon and nitrogen cycling. We suggest that the impact of SWI causes a shift in the soil bacteria which alters the community to one which is more specialised, with implications for the cycling of essential elements and nutrients.
... and Livistonia eastonii palms can be abundant. Although we are unaware of litterfall estimates for riparian vegetation of the Kimberley, litterfall to fluvial systems in northern Australia, which contains similar climate and vegetation (e.g., Melaleuca spp.) to the Kimberley, can be as high as 375 g/m 2 (Finlayson et al. 1993) and are well known to be sources of DOC and energy to stream food webs (Fellman et al. 2013). ...
Article
The metabolism of dissolved organic carbon (DOC) along fluvial networks determines what fraction of organic matter is exported to the ocean. Although it is thought fresh rather than older DOC is preferred by bacteria, old DOC can also be highly bioavailable to stream bacterial communities. In strongly seasonal and oligotrophic regions, we argue that groundwater inputs of old DOC may increase the bioavailability of stream organic matter. We sampled 22 streams along a gradient of size (wetted widths from 1 to 60 m) and one groundwater spring in the Kimberley region of northwest Australia to determine how the age and bioavailability of streamwater DOC varied with stream size. Our hypothesis was that stream DOC would become more enriched in 14C (younger) and less bioavailable as streams increased in size and depleted 14C-DOC was metabolized by stream microbial communities. We also used fluorescence characterization of DOC, ultraviolet absorbance at 254nm (SUVA254), d13C-DOC and lignin phenol yields to assess how these indicators of DOC character influenced the bioavailability and age of stream DOC. Stream evaporation/inflow ratios (E/I, used as a proxy for catchment water residence time), determined from changes in stream d18O along the gradient of stream size, were positively related to DOC concentration and carbon-normalized lignin yields, while d13C-DOC became more depleted with increasing E/I. Stream D14C-DOC varied from �452.1% (groundwater) to 48.9% and showed progressive enrichment as streams increased in size and accumulated DOC mainly from terrestrial plant material. Older DOC corresponded to higher bioavailability (R2 ¼ 0.67, P <0.01), suggesting that old bioavailable DOC, which has escaped from subterranean food webs utilizing 14C-depleted carbon, is common to one of the oldest landscapes on earth. Therefore, rapid biotic uptake of old bioavailable DOC originating in groundwater springs and the accumulation of modern, terrestrially derived DOC work in opposite directions affecting DOC dynamics along fluvial networks. We suggest the metabolism of old DOC along fluvial networks provides a biogeochemical link between non-contemporary carbon fixation and modern river productivity.
... It is assumed that the clearing of wetland vegetation results in the emission of any C stored in biomass to the atmosphere, and that native vegetation will be replaced with a non-woody agricultural species with total above-and below-ground biomass of 7.5 t C/ha. For melaleuca forests and woodlands, it is assumed that the native vegetation in these areas contains 130 t C/ha, based on estimates of above-and below-ground biomass made by Finlayson et al. (1993), Van et al. (2000), and Snowdon et al. (2000). Mangroves are also assumed to contaiñ 130 t C/ha, based on estimates of above-and below-ground biomass made by Twilley et al. (1992) and Snowdon et al. (2000). ...
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Greenhouse gas (GHG) flux from wetland systems, both in their natural state and following drainage, has not been well accounted for in the carbon accounting process. We review GHG production from both natural and drained wetlands, and estimate the likely GHG emissions from these systems in Australia. Only a small number of studies have quantified GHG emissions from undisturbed Australian wetland environments. Consequently, in order to estimate GHG flux for Australia, it was necessary to collate data collected overseas from similar climatic zones. Using this approach, it appears that undisturbed, vegetated wetlands in Australia are likely to be net GHG sinks, with the greatest rates of sequestration occurring in mangrove ecosystems (–2669 g CO2-e/m².year) where biomass production is high but CH4 emissions are limited by salinity. The uncertainty surrounding these values is high, however, due to (a) the low number of measurements from Australia, (b) the low number of measurements for CO2 flux, and (c) the low number of studies where all GHGs have been measured concurrently. It was estimated that the drainage of melaleuca and mangrove forest wetlands in Australia would turn them from carbon sinks into carbon sources, and that in the first 50 years since drainage, this has increased global warming potential by 1149 Tg CO2-e or 23 Tg CO2-e/year. This is significant given that GHG emissions due to land-use change in 2007 totalled 77.1 Tg CO2-e. However, data surrounding the area of wetlands drained, carbon stocks in drained wetlands, and the effect of drainage on CH4 and N2O flux are limited, making the uncertainty surrounding these estimates high. Further study is clearly required if Australia wishes to accurately incorporate wetland systems into national carbon and greenhouse gas accounting budgets.
... Guiding principles  Natural wetlands including riparian vegetation can play a role in water quality improvement by nutrient reduction/assimilation, removal of solids, changing chemical parameters such as biological oxygen demand, and contaminant removal (Daniel and Greenway, 1995;Faithful, 1997;Finlayson, et al. 1993;Fisher and Acreman, 2004;Greenway and Daniel, 1997;Lukacs, 1998;Millennium Ecosystems Assessment, 2005;Reedy and Gale, 1994;WetlandCare Australia, 2008;Lizotte et.al. 2012). ...
... Comparable biomass values of 122 and 170 dry mt/ha were previously reported by Conde et al. (1981) for M. quinquenervia based on destructive sampling of 42 trees in two small plots. Finlayson et al. (1993) used similar regression techniques and determined a total aboveground of 263 mt/ha fresh weight (approximately 132 mt/ ha dry weight) in a Melaleuca forest on a seasonally inundated floodplain in tropical northern Australia. These biomass values approach levels similar to those reported for tropical rainforests (Yamakura et al. 1986). ...
Article
One hundred and thirty-eight Melaleuca quinquenervia (Cav.) S. T. Blake (broad-leaved paperbark) trees were har- vested from six sites in South Florida to formulate regression equations for estimating tree above-ground dry weight. Sam- ple trees were felled, cut, weighed, and sub-samples dried to a constant weight. Diameters of trees ranged from 0.5 to 38.6 cm, total heights from 1.3 to 25.4 m, and dry weights from 0.2 to 309.4 kg. A number of site-specific biomass equations were developed from these parameters and tested statistical- ly. Non-linear models based on stem diameter (diameter in- side bark, DIB, cm) alone explained more than 97% of the biomass (W, kg) variance, with best results obtained after two-sided logarithmic transformations. Strong site-indepen- dent correlations were observed, and a single predictive equation: Log e (W) = -1.06 + 1.99*Log e (DIB) (R 2 = 0.973) was statistically valid for a wide range of conditions. This equa- tion was based on inside-bark diameter to account for differ- ences in bark thickness which varies widely among different sites. Standing biomass of M. quinquenervia was estimated to vary from 129 to 263 dry mt/ha at six sites in South Florida; however, no trend seems evident among the sites in dry, sea- sonally wet, and permanently wet habitats. The equation de- scribed is useful in field evaluation of impacts of biological control agents, by allowing estimation of plant biomass from DIB measurements in permanent study sites where destruc- tive sampling is not possible.
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Background and aims Organic matter additions in coastal wetlands contribute to blue carbon sequestration and adjustment to sea-level rise through vertical substrate growth, with accurate modelling of these dynamics requiring information of root mass and volume additions across tidal gradients. This study aims to characterise the influence of vegetation zonation and tidal position on root mass and volume dynamics within substrates. Methods The root ingrowth technique was coupled with sediment cores to quantify below-ground root mass and volume production, standing stocks and turnover across two years to 90 cm depth at Kooweerup, Victoria, Australia. Results We indicate a complex non-linear relationship between fine root mass production and tidal position, influenced by variable vegetation structures across mangrove (442–3427 g m⁻² yr⁻¹), saltmarsh (540–860 g m⁻² yr⁻¹) and supratidal forest (599 g m⁻² yr⁻¹) zones. Fine root volume additions ranged from 274 to 4055 cm³ m⁻² yr⁻¹ across sampling locations. Root production was greatest for older mangroves and tidally defined optimal zones of production were evident for mangrove and saltmarsh. Live roots extended deeper than typically studied, reaching depths of 1.0 m in forested zones. Conclusion This information of root mass and volume additions across wetland live rooting zones can be used to improve highly parameterised models accounting for carbon sequestration and substrate vertical adjustment along intertidal gradients. We recommend that future studies measure root production across the entire active rooting zone or to 1 m depth to align with standard carbon accounting measurement depths.
Chapter
This study investigates the biomass of Melaleuca cajuputi tree at the Tra Su Melaleuca Forest Landscape Protection Area, located in An Giang province, Vietnam. Tra Su Forest is a managed territory under the An Giang Forest Protection Department. Established as a landscape protection area since 2005, the area has been designated for sustainable development, ecological preservation, educational endeavors, and nature conservation. By quantifying individual tree volumes and the overall population’s productivity, this study calculates the volume and production of Melaleuca tree and identifies the sylviculture characteristics within the Melaleuca population of the forest. Methodologies used include the establishment of standard plots for measurement, analysis of tree biomass through field and laboratory techniques, and statistical processing to build correlation equations between various factors. The findings highlight the statistical characteristics of the surveyed area, providing correlations between tree diameters, heights, and their corresponding volumes. Equations derived from these correlations point out the estimation of individual tree volumes which are crucial for forest management and productivity assessment. The study reveals distinct biomass structures within different age groups, emphasizing the significance of forest age in biomass accumulation, distribution, and shaping the ecosystem’s sustainability. The results of this study serve as a foundational resource for forestry management, ecosystem preservation, and decision-making reference for sustainable resource utilization within the Tra Su Forest.
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Managing coastal wetlands is one of the most promising activities to reduce atmospheric greenhouse gases, and it also contributes to meeting the United Nations Sustainable Development Goals. One of the options is through blue carbon projects, in which mangroves, saltmarshes, and seagrass are managed to increase carbon sequestration and reduce greenhouse gas emissions. However, other tidal wetlands align with the characteristics of blue carbon. These wetlands are called tidal freshwater wetlands in the United States, supratidal wetlands in Australia, transitional forests in Southeast Asia, and estuarine forests in South Africa. They have similar or larger potential for atmospheric carbon sequestration and emission reductions than the currently considered blue carbon ecosystems and have been highly exploited. In the present article, we suggest that all wetlands directly or indirectly influenced by tides should be considered blue carbon. Their protection and restoration through carbon offsets could reduce emissions while providing multiple cobenefits, including biodiversity.
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Wetlands are characterised by soils rich in organic matter that accumulate carbon, providing an important pathway for carbon dioxide sequestration. Nevertheless, not all the carbon fixed can be accumulated, and a proportion will decompose through microbial consumption and be partly released into the atmosphere. Rates of organic matter decomposition in tropical wetlands and the factors associated with this process are scarce. We conducted a 2-year field study in three Melaleuca wetlands in tropical and subtropical Australia using standardised tea litter substrates (green-labile and rooibos-recalcitrant) to measure organic matter decomposition and the microbial communities associated with this process. Decomposition rates were 4-fold higher in labile litter, which was low in carbon: nitrogen, compared to recalcitrant litter. The prokaryotic communities associated with the decomposing litter were unique at each site and different from the soil. They contained taxonomic groups adapted to anaerobic, high temperatures, acidic conditions and suggestive of slow anaerobic turnover. Microbial communities changed as decomposition progressed, with the latter characterised by taxa with cellulose-degrading functions. The decomposition of recalcitrant organic matter within Melaleuca soils was relatively slow, with half of the organic matter inputs remaining after two years, supporting long-term carbon sequestration.
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Wetlands can increase resilience to extreme climatic events and have a key role in protection and water quality improvement in coastal ecosystems. Studies in tropical coastal wetlands at a catchment scale are scarce, and most work has been undertaken on small, temperate wetlands. In this study, we tested whether natural coastal wetlands in a tropical catchment (Tully-Murray, Queensland, Australia) could ameliorate nitrogen (N) exported to the Great Barrier Reef during a flood event. We measured denitrification rates in different types of coastal wetlands (mangroves, saltmarshes, waterbodies with macrophytes, and floodplain wetlands dominated by Melaleuca spp.) to assess their potential contribution to N losses during the 6-day duration of a flood in March 2018. Denitrification potential was variable across the landscape, and we identified “hotspots” in sub-catchments with high NO3--N concentrations (0.4–0.6 mg L⁻¹) and large areas of wetlands (>800 ha, >40% of the sub-catchment). These hotspots can denitrify up to 10 t of NO3--N per day during a flood. We used our measured denitrification rates to provide input parameters for a model that includes the main biogeochemical processes affecting N transformations within wetlands (nitrification, denitrification, plant uptake, sedimentation, anammox, and mineralization), and accounts for transport via the duration, depth, and flow of water. Model simulations of a sub-catchment of the Tully-Murray indicate that flood inundation of large areas of natural wetlands (>40% of the sub-catchment area) could potentially remove 70% of the incoming NO3--N load in the first 24 h of the flood. The management and restoration of coastal tropical wetlands could play a critical role in sustaining the health of coastal ecosystems through water quality improvement.
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Wetlands of Melaleuca spp. in Australia form large forests that are highly threatened by deforestation and degradation. In America, Melaleuca has invaded large areas of native wetlands causing extensive damage. Despite their status as an endangered native ecosystem and as a highly invasive one, little is known about their C and N dynamics. In this study, we sampled five Melaleuca wetlands and measured their C and N ecosystem stocks (aboveground biomass and soil), tree accumulation rates, sedimentation rates, and soil stability. Melaleuca wetlands were highly heterogeneous, but most have large ecosystem C [mean ± SE (range); 360 ± 100 (80–670) Mg C ha⁻¹] and N [8100 ± 1900 (1600–13,000) kg N ha⁻¹] stocks. Tree accumulation rates were 5.0 ± 2.1 Mg C y⁻¹ and 26 ± 14 kg N y⁻¹, and surface soil accumulation rates were 0.6 ± 0.2 Mg C ha⁻¹ y⁻¹ and 39 ± 1 kg N y⁻¹. We found evidence of long-term C and N accumulation in the soil, but also of some level of organic decomposition. Overall, we found that Melaleuca wetlands store and accumulate large amounts of C, especially in their trees, and large amounts of N in their soils, suggesting an important role in coastal biogeochemical cycles.
Chapter
Wetlands in the Kakadu region include mangroves, freshwater flood plains, salt flats and small permanent lakes. One of the major environmental changes in the region over the last 6000 years has been the reduction in mangrove swamps as freshwater flood plains were formed. Mangroves are now restricted to a narrow band along the coast and the tidal reaches of the rivers. Zonation within the mangroves is greatly influenced by the high tidal range with some forests extending and others receding. The tall creek-side mangroves are relatively productive compared to mangroves elsewhere with litterfall values of around 1 kg m ⁻² y⁻¹. The freshwater wetlands are found along the major rivers and are greatly influenced by the seasonal hydrological cycle. During the wet season the flood plains are covered with 1–2 m of water and contain a multitude of plants. During the dry, in contrast, the plains are parched and the vegetation is sparsely distributed. The distribution of plants on the flood plains has been well documented over the past decade. Many of the plants on the flood plain are annuals and their relative abundance and distribution varies seasonally. Seasonal changes in the distribution and biomass dominance of the vegetation are greatly affected by the flooding patterns, although feral animals and exotic weeds have also exerted an influence. The widespread grasslands are very productive with dry weight biomass values ranging from 0.5–1.1 kg m⁻² y⁻¹ The Melaleuca forests are similarly productive with litterfall values of 0.7–1.5 kg m⁻² y⁻¹.
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Flow regimes are fundamental to sustaining ecological characteristics of rivers worldwide, including their associated floodplains. Recent advances in understanding tropical river?floodplain ecosystems suggest that a small set of basic ecological concepts underpins their biophysical characteristics, especially the high levels of productivity, biodiversity and natural resilience. The concepts relate to (1) river-specific flow patterns, (2) processes ?fuelled? by a complex of locally generated carbon and nutrients seasonally mixed with carbon and nutrients from floodplains and catchments, (3) seasonal movements of biota facilitated by flood regimes, (4) food webs and overall productivity sustained by hydrological connectivity, (5) fires in the wet/dry tropical floodplains and riparian zones being major consumers of carbon and a key factor in the subsequent redistribution of nutrients, and (6) river?floodplains having inherent resilience to natural variability but only limited resilience to artificial modifications. Understanding these concepts is particularly timely in anticipating the effects of impending development that may affect tropical river?floodplains at the global scale. Australia, a region encompassing some of the last relatively undisturbed tropical riverine landscapes in the world, provides a valuable case study for understanding the productivity, diversity and resilience of tropical river?floodplain systems. However, significant knowledge gaps remain. Despite substantial recent advances in understanding, present knowledge of these highly complex tropical rivers is insufficient to predict many ecological responses to either human-generated or climate-related changes. The major research challenges identified herein (for example, those related to food web structure, nutrient transfers, productivity, connectivity and resilience), if accomplished in the next decade, will offer substantial insights toward assessing and managing ecological changes associated with human alterations to rivers and their catchments.
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After soil horizons and living matter were considered as factors affecting the quality of surface water in the Melaleuca forest (M. cajuputi) on acid sulphate soil in the Mekong Delta of Vietnam, litter decomposition could be another factor affecting water quality. To investigate , a series of experiments mimicking field conditions was conducted to clarify the effects of decomposition processes. Litters of Melaleuca and Eleocharis (E. dulcis) undergrowth were collected and incubated with water samples of different quality for chemistry analysis under different incubation time, state of samples, and microbial activities. Water with low pH value, high EC value and Fe, Al, SO4 concentration did not affect Melaleuca and Eleocharis litter decomposition. High levels of water and nutrient contents in the litter increased decomposition rates. Eleocharis litter decomposed faster than Melaleuca litter. With 50% of the dry matter of Eleocharis lost within two months decomposition, but that values on Melaleuca litters need more than five months. Litter decomposition strongly affected water quality. Fresh litter has more effect than dry, old, decomposed litter. Eleocharis litter decomposition at early stage slightly increased sulphate concentration, but also improved water quality nearly as well as Melaleuca litter. Both produce a pH increase and decrease of Fe, Al and SO4 concentration in the acid water. pH increase and Al decrease were chemical reactions control, whilst Fe decrease was microbial effects only. Sulphate is different, chemical reactions tended to release more SO4 but microbial activity reduced them. After one week of decomposition, both Melaleuca and Eleocharis increased about one pH unit of the solutions, decreased about 80% Fe within two weeks and 50% Al within 8 weeks. Without microbial activities, sulphate increased about 23% after four weeks, but it decreased very little (<10%) in the present of microbial activities. Estimation every year a hectare of the Melaleuca forest can reduced 7.4 Kg Al, 4.6 Kg Fe, and 48.2 Kg SO4 in the surface water by its litter decomposition. 2
Chapter
The Kakadu region in northern Australia has become well known for its spectacular wilderness and nature conservation values. These values are enshrined in the management regime for the 20 000 km² Kakadu National Park which comprises a large proportion of the region. The remainder of the region takes in part of the vast area of Aboriginal land known as Arnhem Land. The landscape is spectacular and is visibly dominated by a sandstone escarpment and plateau, extensive lowlands and seasonally flooding plains along the major rivers. The climate is highly seasonal with a hot, humid wet season and a mild to warm dry season. The soils are generally low in nutrients and organic material but they do support a highly diverse vegetation comprised of large tracts of savanna woodlands and forests, restricted monsoonal forests and extensive wetlands. The vegetation has been greatly influenced by the frequency and intensity of fires, and the occurrence of alien weeds and feral animals, especially the Asian water buffalo. Whilst the numbers of buffaloes have been severely reduced in recent years weed species are still a major problem. The vegetation patterns are also greatly influenced by interactions with native animals such as termites and ants.
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The project “Strengthening Biodiversity Conservation and Improving Dependent Local Livelihoods Through Community Based Natural Resource Use and Management in Tram Chim National Park” is implemented under the collaboration between WWF -Vietnam and Tram Chim National Park (TCNP) and sponsored by the Coca-Cola Company. The objective of the project is to enhance biodiversity conservation through proper water management and improved local livelihoods by engaging the communities in ecotourism activities that combine the biodiversity, landscape beauty and local culture with natural resource management. In order to achieve the above objective, consultants were hired to conduct a review on the existing water – fire management strategy, which was developed during Tram Chim project–phase 1, funded by WWF-Coke Global Water Partnership, in considering climate change issues, biodiversity conservation and irregular Mekong floods that have negatively affected the hydrological regime in the TCNP. The outputs of this activity are to produce a new water-fire management strategy, including the water control levels at different zones and quick response to changing climate parameters and floods. This task will require collection of available data from different sectors and sources and predicting changing climate parameters and floods in the larger delta area.
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Tropical wetlands are not included in Earth system models, despite being an important source of methane (CH4) and contributing a large fraction of carbon dioxide (CO2) emissions from land use, land use change and forestry in the tropics. This review identifies a remarkable lack of data on the carbon balance and gas fluxes from undisturbed tropical wetlands, which limits the ability of global change models to make accurate predictions about future climate. We show that the available data on in situ carbon gas fluxes in undisturbed forested tropical wetlands indicate marked spatial and temporal variability in CO2 and CH4 emissions, with exceptionally large fluxes in Southeast Asia and the Neotropics. By up-scaling short term measurements, we calculate that c. 90 ± 77 Tg CH4 yr-1 and 4540 ± 1480 Tg CO2 yr-1 are released from tropical wetlands globally. CH4 fluxes are greater from mineral than organic soils, whereas CO2 fluxes do not differ between soil types. The high CO2 and CH4 emissions are mirrored by high rates of net primary productivity and litter decay. Net ecosystem productivity was estimated to be greater in peat-forming wetlands than on mineral soils, but the available data are insufficient to construct reliable carbon balances or estimate gas fluxes at regional scales. We conclude that there is an urgent need for systematic data on carbon dynamics in tropical wetlands to provide a robust understanding of how they differ from well-studied northern wetlands and allow incorporation of tropical wetlands into global climate change models.
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Litterfall was measured over 3 years at two sites in coastal wetland forests dominated by Casuarina glauca Sieb. ex Spreng. in New South Wales. One site was in an incised river valley adjacent to the Hawkesbury River estuary, and the other site was in an open embayment adjacent to Botany Bay. Branchlets were the major litter component, followed by stems and infructescences. Significant year to year variation in branchlet fall correlated with storm events in one year. Overall, no significant differences in annual total litterfall were detected among sites and, averaged over all sites and years, the mean annual litterfall was 848 g m-2. This suggests that coastal wetland forests dominated by C. glauca have some of the highest recorded annual litterfall rates for Australian temperate and subtropical forests. A flood event in the river valley site removed about 75% of the standing litter accumulated on the forest floor prior to flooding (1244 g m-2). This suggests that accumulated organic matter and nutrients can be directly transported to estuarine ecosystems. Under non-flood conditions, however, these forests appear to act as organic matter and nutrient sinks.
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Thee tree species from the genus Melaleuca are being examined for use in constructed wetlands in subtropical SE Queensland, Australia. Growth responses of Melaleuca to secondary treated effluent (100% - approximately 5mgPL−1 and 8mgNL−1), half strength (50%), P enriched (+P) and N enriched (+N) secondary treated effluents were monitored in a 2 year pot trial. A growth index was derived from measurements of height, girth diameter, branch number and new leaf number. Highest rates of growth were achieved in the +N and 100% treatments, and lowest rates in the +P and 50% treatments. Seasonal growth trends were evident. Continuously waterlogged trees had slightly higher growth rates than those subjected to aeration cycles, demonstrating their suitability to wetland environments. An aerated network through the bark extending to the roots may provide a mechanism of root aeration. Biomass and nutrient partitioning were measured in an experimental constructed Melaleuca wetlands receiving pure effluent. Biomass nutrient accumulation rates were comparable to studies of other macrophytes. M. alternifolia stored approximately three times more N and P than M. quinquenervia. However, M. quinquenervia had higher rates of litter fall induced by severe insect damage, increasing the rate of transfer of nutrients to the long term sediment sink. P concentrations in the senescent leaves were highly responsive to external concentrations, and may be used as an indicator of P loading rates in constructed wetlands. Since senescent leaves provide a major pathway of biomass nutrients into the sediment sink, this provides a self regulating P storage mechanism.
Article
Seasonally flooded evergreen forests and non-flooded deciduous and semi-deciduous forests of the Pantanal of Mato Grosso, Brazil, were studied to compare their structure and floristic composition, their production of small litterfall and its seasonal variation, as well as the nutrient input into the soil by fallen litter. The litterfall data were used to test the hypothesis that seasonally flooded forests of the Pantanal are more productive than non-flooded forests. Eight permanent plots of 0.25ha each were established in three forest types. The clayey forest soils had low N and P concentrations, a CEC from 20 to 190μmolg−1 and a pH from 5.1 to 6.6. All trees of ≥5cm DBH were identified and their diameters measured. Tree density and stand basal area ranged, respectively, from 368 to 1700ha−1 and 15.5 to 25.3m2ha−1 in non-flooded and from 725 to 2005ha−1 and 22.1 to 32.6m2ha−1 in seasonally flooded forests. There were no significant differences in stem density and basal area between non-flooded and seasonally flooded forest. Species richness ranged from 4 to 17 per plot. Small litterfall (leaves, wood≤2cm, reproductive parts, trash
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Essential oils of paperbarks, Melaleuca spp., have been shown in laboratory studies to inhibit bacterial activity and slow the rate of cellulose decay. Field (Gippsland Lakes, south-eastern Victoria, Australia) and glasshouse experiments were conducted to test the hypothesis that leaves of Melaleuca ericifolia Sm. (the swamp paper-bark) suppressed the decay of leaf litter under conditions existing or mimicking those in natural wetlands. Under field conditions, neither brown nor green M. ericifolia leaves, at loadings that would normally occur in a typical paperbark wetland and over a range of leaf-mass ratios, significantly affected the decay rate of two common freshwater macrophytes, Triglochin procerum (water ribbon) and Phragmites australis (common reed). In contrast, glasshouse experiments showed that Melaleuca ericifolia leaves (both intact and ground, and both brown and green) suppressed decay of T. procerum when placed in moist conditions on the sediment surface. However, no inhibitory effect was observed when leaves were flooded. Purified, commercially available Melaleuca essential oil (extracted from Melaleuca alternifolia leaves) decreased the rate at which T. procerum leaves decayed under glasshouse conditions by as much as 43 %. As with entire leaves, the inhibitory effect of purified Melaleuca essential oil was greatest when the leaves were placed in moist, but not submerged, conditions. Experiments designed to test the possibility that the inhibition was due to a simple, physical (coating) effect rather than metabolic inhibition of microbes showed clearly that the effect was not due simply to the hydrophobic nature of essential oils. This study indicates that M. ericifolia leaf litter in freshwater wetlands probably exerts only a small effect on the rate at which leaves from other wetland plant species decay. Any inhibitory effect is likely to be greater after water levels drop (e.g., seasonally in a Mediterranean climate) and remaining leaf material is left moist on the surface of water logged sediments than when material is totally submerged, as during the wetland's high water phase.
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Abstract Coarse woody debris (CWD) is the standing and fallen dead wood in a forest and serves an important role in ecosystem functioning. There have been several studies that include estimates of CWD in Australian forests but little synthesis of these results. This paper presents findings from a literature review of CWD and fine litter quantities. Estimates of forest-floor CWD, snags and litter from the literature are presented for woodland, rainforest, open forest and tall open forest, pine plantation and native hardwood plantation. Mean mass of forest floor CWD in Australian native forests ranged from 19 t ha−1 in woodland to 134 t ha−1 in tall open forest. These values were generally within the range of those observed for similar ecosystems in other parts of the world. Quantities in tall open forests were found to be considerably higher than those observed for hardwood forests in North America, and more similar to the amounts reported for coniferous forests with large sized trees on the west coast of the USA and Canada. Mean proportion of total above-ground biomass as forest floor CWD was approximately 18% in open forests, 16% in tall open forests, 13% in rainforests, and 4% in eucalypt plantations. CWD can be high in exotic pine plantations when there are considerable quantities of residue from previous native forest stands. Mean snag biomass in Australian forests was generally lower than the US mean for snags in conifer forests and higher than hardwood forest. These results are of value for studies of carbon and nutrient stocks and dynamics, habitat values and fire hazards.
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The exotic tree Melaleuca quinquenervia (melaleuca) forms dense forests usually characterized by low plant diversities and dense litter biomass accumulations on forest floors of ecologically sensitive ecosystems, including portions of the Florida Everglades. We quantified litter accumulation in mature melaleuca stands and compared decomposition rates of melaleuca leaves with a sympatric native plant, either Cladium jamaicense (sawgrass) in sawgrass marshes or Pinus elliottii (slash pine) in pine flatwoods habitats that varied in soil types. Total litter accumulation in mature melaleuca forests prior to June 1997 ranged from 12.27 to 25.63 Mg ha−1. Overall, melaleuca leaves decomposed faster in organically rich versus arenaceous soils. Decomposition rates were lower for melaleuca leaves than for sawgrass in both melaleuca-invaded and uninvaded sawgrass marshes. In arenaceous soils of pine flatwoods, melaleuca leaf and pine needle decomposition rates were similar. Complete mineralization of sawgrass leaves occurred after 258 weeks, whereas melaleuca leaves had up to 14% and pine foliage had up to 19% of the original biomass remaining after 322 weeks. Total carbon (C) in intact decomposing leaves varied slightly, but total nitrogen (N) steadily increased for all three species; the greatest being a fourfold in sawgrass. Increases in N concentrations caused decreases in the C/N ratios of all species but remained within an optimal range (20–30) in sawgrass resulting in higher decomposition rates compared to melaleuca leaves and pine needles (C/N ratio >30). Slower decomposition of melaleuca leaves results in denser litter layers that may negatively affect recruitment of other plant species and impede their establishment in invaded communities.
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The wetlands of the Alligator Rivers Region of northern Australia have been recognized as having high national and international conservation value. The diversity and productivity of these habitats is, however, under current and future threat from invasive feral animals (Asian water buffalo and pigs) and naturalized alien plants (mimosa, salvinia and para grass) and also from climate change and sea level rise. Some habitats have already been severely degraded and require rehabilitation. In response to this situation feral animal management has centered on eradicating the buffalo population and introducing measures to control pigs. Weed management has focused on control of mimosa and salvinia with an increasing emphasis on integrated control measures. The vulnerability of the freshwater wetlands to climate change and sea level rise is considerable, although the exact nature of environmental change has not been determined. Rehabilitation of the degraded wetlands has centered on controlling the cause of the problem (e.g., the invasive species) and allowing subsequent natural succession to occur. It is recommended that further monitoring and assessment of successional change is undertaken to ascertain if this is sufficient. An integrated monitoring program for detecting the extent and rate of ecological change because of climate change and sea level rise is also proposed. Specific management and research tasks for each of the major broad causes of wetland degradation within the region are made. It is then strongly recommended that all rehabilitation and monitoring activities, including related research, are conducted within a holistic management framework that takes into account the different land jurisdictions within the region and also within the broader landscape context. The utilization of existing management and research structures and processes is stressed as one means of achieving an integrated approach.
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Melaleuca quinquenervia dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive tree. We delineated large-, intermediate-, and small-tree stands in non-flooded, seasonally flooded and permanently flooded areas of Florida in 1997, measured their biological attributes, and then quantified litterfall components for 3–4year periods. Melaleuca wood components and mature seed-capsules comprised the largest and the smallest portions of aboveground biomass, respectively, while leaves, fine stems, mature fruits, bud scales, floral structures, and residues represented decreasingly smaller fractions of the litter during the succeeding year. Dry weight proportion of leaves in litter was greatest (80.9%) in non-flooded and least (69.1%) in permanently flooded habitats. It was also greatest in small (85.6%) and least in large (64.7%) tree stands. Reproductive structures and mature-fruit fractions in litter were highest in large-tree stands whereas the bud-scale fraction showed no relationship to tree size. Seasonally flooded habitats had the most litterfall, wherein small-, intermediate-, and large-tree stands generated 0.662, 0.882, and 1.128kgm−2yr−1, respectively. Dry weight of stems, leaves, bud–scales, floral structures, and mature fruit fractions in litter increased as the predominant size of the trees in the stand increased. Total annual litter production was highest during 1999–2000. Leaf fall occurred year-round with maximal amount during April, July, and October. Highest amounts of bud scales and floral structures fell during October–January, which corresponded with flushes of vegetative growth and major flowering events. Overall, melaleuca alone accounted for nearly 99% of the total litterfall dry weight in all habitats and months sampled. The amount of non-melaleuca litter was greater in small-tree stands than in intermediate- or large-tree stands. Litterfall data of this nature will be helpful in detecting changes occurring in melaleuca canopies in response to biological control impact and in prescribing site-specific management strategies.
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In the context of the 200th anniversary of Charles Darwin's birth in 1809, this study discusses the variation in structure and adaptation associated with survival and reproductive success in the face of environmental stresses in the trees of tropical floodplains. We provide a comparative review on the responses to flooding stress in the trees of freshwater wetlands in tropical environments. The four large wetlands we evaluate are: (i) Central Amazonian floodplains in South America, (ii) the Okavango Delta in Africa, (iii) the Mekong floodplains of Asia and (iv) the floodplains of Northern Australia. They each have a predictable 'flood pulse'. Although flooding height varies between the ecosystems, the annual pulse is a major driving force influencing all living organisms and a source of stress for which specialized adaptations for survival are required. The need for trees to survive an annual flood pulse has given rise to a large variety of adaptations. However, phenological responses to the flood are similar in the four ecosystems. Deciduous and evergreen species respond with leaf shedding, although sap flow remains active for most of the year. Growth depends on adequate carbohydrate supply. Physiological adaptations (anaerobic metabolism, starch accumulation) are also required. Data concerning the ecophysiology and adaptations of trees in floodplain forests worldwide are extremely scarce. For successful floodplain conservation, more information is needed, ideally through a globally co-ordinated study using reproducible comparative methods. In the light of climatic change, with increasing drought, decreased groundwater availability and flooding periodicities, this knowledge is needed ever more urgently to facilitate fast and appropriate management responses to large-scale environmental change.
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This report incorporates all of the raw data from a mangrove litterfall study initiatied and directed by J. Bunt over the period 1975-1978.
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In NE Queensland annual litterfall ranged from 728-1053 g m-2yr-1 over 3 yr at all sites. Litterfall is strongly seasonal, heaviest falls occurred in the latter part of the dry season and the early part of the wet season. Between-year-variation in total litterfall was low and 3-yr coefficients of variation within sites ranged from 4.5-10.0%. The proportions of leaf, fine woody material, and of flowers, fruits and seeds were assessed and related to the characteristics of the forests. Seasonal, annual and between-site variation in the standing crops of litter was marked. Minimum standing crop at the most mesophytic sites was c300 g m-2; the maximum recorded was >1050 g m-2. The relative proportions of leaf, wood and of flowers, fruits and seeds in the standing crop of litter varied seasonally and between sites.-from Author
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Litter fall and leaf decomposition rates were measured in Murrumbidgil Swamp, a river red gum (Eucalyptus camaldulensis) swamp near Booligal, New South Wales. Total litter fall, excluding large branches, was about the same as in other eucalypt and overseas hardwood forests (369-580 g m⁻² year⁻¹), but the proportion of leaf fall (21-29%) was lower. Litter fall was greater after the swamp dried out following a prolonged period of flooding than during the flood period. Ionic concentrations in the leaf litter were higher than in other eucalypts, but accessions were similar because leaf fall was lower in the red gum forest. The order of nutrient input was Ca > N > Mg ≈ Na ≈ K > S > P > Fe. Decomposition of red gum leaves submerged in the swamp was rapid at first (up to 19.2% loss in weight in 24 h) and then slowed down. The half life of the leaves decomposing over 4 months was 80 days. It is suggested that E. camaldulensis litter may provide an important food source for detritivorous invertebrates and hence for waterfowl in red gum swamps.
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A materials budget was estimated for the Magela Creek system during the 1982-83 wet season. This tropical system in northern Australia consists largely of a well-defined creek (Magela Creek contributes approximately 50% of the total inflow to the floodplain) flowing into an extensive wetlands area and then into the East Alligator River. Intensive sampling of creek water, rainfall and water flowing from the system provided the data base for the budget calculations. The annual transport of both dissolved and particulate matter by Magela Creek (area 600 km²) is very low, even when compared with other low-relief tropical systems. The annual load transported during 1982-83 was 1260 t (21 kg ha⁻¹) of dissolved salts and 2330 t (39 kg ha⁻¹) of particulate matter. Rainfall appeared to contribute all the sodium, potassium and chloride, and part of the calcium (c. 30%) and magnesium (25%) transported during the 1982-83 wet season by Magela Creek. Most of the manganese (c. 60%) (and probably iron) was contributed from weathering processes occurring in the catchment. Only small amounts of the trace metals copper, lead, zinc and uranium were transported by the creek. During the 1982-83 wet season, more trace metals were contributed in rainfall than transported from the catchment by the creek. However, this is probably atypical and resulted from dust particles that had entered the atmosphere in greater numbers due to the extended dry season. The vast bulk of the nutrients (total P 93%, NO3⁻ N 86%, NH4⁺ N 98%) added to the catchment by rainfall was removed by the catchment, probably via uptake by the vegetation. Consequently, the creek transported only very small amounts of nutrients to the floodplain. An input-output budget for the Magela floodplain was calculated. The uncertainty in the net amounts deposited or released from the floodplain was estimated using a new quantitative method developed for this purpose. The uncertainties in the net values estimated were high, ranging from around 30% for bicarbonate to 500% for uranium. These data suggest that the Magela floodplain is a net source of the major ions (sodium, potassium, calcium, magnesium, chloride, sulfate and bicarbonate) and also of iron, and a net sink for suspended solids, nutrients (total phosphorus, nitrate and ammonia) and manganese. The floodplain also appears to be a net sink for the trace metals copper, lead, zinc and uranium.
Article
Total litterfall and leaf litterfall were examined for 389 forest sites throughout the world using multiple regression, considering latitude, altitude and precipitation as predictor variables. In its best model, Ig total litterfall was negatively related (r2 = 0.58) to latitude and altitude, while in the best model for lg leaf litterfall there was a negative relationship (r2 = 0.35) with only one variable, latitude. When tropical forests were considered separately however, lg leaf litterfall was positively related to precipitation, and negatively related to altitude (r2 = 0.43). The predictive power of all the regression equations was low, with large percentage values of scatter about the fitted values for all equations. In addition, there was no relationship between the ratio of non-leaf material to leaf material in the litter with any of the predictor variables.
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(1) Litterfall in a plantation of Araucaria cunninghamii and in an adjacent rain forest was compared at two sites in north-eastern Australia over 3 and 4 years respectively, for quantity, temporal distribution, and the content of nitrogen, phosphorus, sodium, potassium, calcium and magnesium. (2) The average litterfall for the four plots was 9.25 t ha -1 per year, a result comparable with values from similar studies on other tropical forests. There were no consistently significant differences in the quantity of litterfall between forest types or sites, or between years for the ran forest plots. (3) Litter from the rain forest plots at both sites had significantly higher concentrations of nitrogen and potassium than litter from the Araucaria plots. Litter from both forest plots at the sites where the soil was more fertile was significantly higher in concentrations of nitrogen, however, the differences between plots in the two forest types were greater than the differences between sites. (4) The calcium content of Araucaria litter during the period of heavy seed production in December-January of the second study year was lower than at all other times. Sodium was the only one of the mineral elements studied to show a regular seasonal pattern of concentration, with lower concentrations in the wet season than during the dry season. (5) In spite of the significant differences in the mineral-element concentrations of litter both between forest types and between sites, there were not significant differences in annual mineral-element accession to the soil. (6) There appears to have been little effect on the annual accession to the soil of litter and the associated mineral elements as a result of the conversion of rain forest to Araucaria plantation at each site; differences between sites in properties such as soil fertility and rainfall also had little effect.
Article
(1) The environment, structure and floristics of four evergreen rainforest sites at 575-800 m altitude in Karnataka, southern India, are described. (2) The mean annual rainfall on the four sites ranges from 5310 to 7670 mm. Most of the rainfall occurs from June to September and there is an intense dry period from December to April. All the sites occur on oxisols overlying hornblendic rocks. (3) The forests at three of the sites are species-rich with an important contribution from the Dipterocarpaceae but one site is unusual and has an almost monospecific dominance by Poeciloneuron indicum (Guttiferae). (4) The total aboveground tree biomass was 420-649 t ha-1. The root fraction was 13.9-20.2 t ha-1. (5) Girth increment data over 35 years were available for one site and these were used with biomass estimates to calculate the approximate mean annual increase of above-ground and root (⩾ 5-cm girth) biomass in the four sites. These were 6.4-11.1 t ha-1 for aboveground material and 0.2-0.4 t ha-1 for roots. (6) For small trees (⩽ 5 cm dbh) and herbs, biomass was estimated by destructive sampling in one plot. The combined above-ground biomass of these fractions was 7.2 t ha-1
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Annual burning is practised over nearly the whole of that part of the Northern Territory which has an annual rainfall of more than thirty-five inches. The remainder of the Territory is burnt at greater intervals.Before the arrival of aboriginals fires would have been lit by natural agencies, especially lightning. The aboriginals used fires extensively for hunting and access clearing. Europeans have adopted a burning regime similar to that established by the aboriginals, for fire has been found to be a cheap and valuable tool in the management of much of the Territory's range lands.The vegetation of the Territory in the area of annual or frequent burning appears well suited to regular burning, and is probably dependent upon fire for its maintenance. The vegetation in arid and semi-arid areas is more fire-sensitive. The interval between fires in these areas may be considerable because unusually heavy rainfalls are required to produce enough grass to carry a fire. Fires rarely occur in the small areas of monsoon forest.
Article
Ash (Fraxinus excelsior), birch (Betula pubescens and B. pendula), oak (Quercus petraea), sycamore (Acer pseudoplatanus) and lime (Tilia cordata) were felled at four localities in the English Lake District. The trees were growing on both siliceous and calcareous soils of variable depth. Correlations between loge tree dry weight and loge girth were higher (r = 0.9977-0.9871), than with loge height (r = 0· 9547-0.8147). Multiple regression analysis demonstrated that the inclusion of height only marginally improved the tree dry weight estimates. Regression equations, of the form loge y = a + b (loge x), where y = tree dry weight (trunk + branches) and x = tree girth at 1.3 m, were used to predict tree dry weight. The 95% confidence limits of the estimates were generally in the range of ± 10-15%, but in some examples as low as ± 2% and up to ± 20-30%, depending upon the sample number and variance of the particular regression. The regression equations for species from different sites exhibited small but significant differences as tested by analysis of variance. Equations derived from trees of all species provided acceptable estimates, but the most valid predictions of tree dry weight are obtained from species samples felled in the area for which estimates are required. Correlations between stem and branch categories and girth (in loge terms) were lower than for total tree weight and girth.
Article
In New South Wales mean annual litterfall was 6.2 (±0.22), 7.3 (±0.57), and 10.0 (±0.74) t ha-1 for cool temperate (microphyll fern forest, MFF), warm temperate (simple notophyll vine forest, SNVF), and subtropical (complex notophyll vine forest, CNVF) rainforests, respectively, with an average of 7.4 t ha-1. Leaf material averaged 54% over all years and sites, with 35% wood and 11% reproductive parts. MFF exhibited bimodal peaks of leaf-fall in autumn (March-June) and spring (September-October). CNVF canopies showed a summer leaf-fall peak (November-December), and SNVF had an early summer (October-December) leaf-fall peak. Estimates of litterfall were sometimes significantly affected by presence of overhanging subcanopy branches, closeness to tree trunks, and species of canopy tree overhead. Trees exhibited variability in rates of leaf decay, ranging from <6 months for complete leaf decay in Dendrocnide excelsa to ↔3yr for Nothofagus moorei. -from Author
Article
The components and chemical composition of litter fall and the litter layer of two woodlands growing close together near Narrabeen Lagoon, New South Wales, were examined over a 5-year period. Total litter fall peaked in the summer but some tree and shrub species in both communities showed peaks of litter fall in summer and autumn. Litter fall averaged 540 g m-2 year-1 for a hillside Angophora costata-Eucalyptus gummifera-dominated woodland on a gradational sand, and 745 g m-2 year-1 for a E. botryoides-E. robusta-A. floribunda-dominated community on podzolized sand at the slope foot. The accumulated litter masses averaged 2100 and 1900 g m-2, respectively: calculated litter half-lives were 2.7 years and 1.8 years. The higher rates of litter fall and turnover of organic matter and nutrients in the E. botryoides-E. robusta-A. floribunda community, despite its poorer soil nutrient status, are postulated to result from a more reliable water supply and differing microbial activity at the litter-soil interface, leading to more rapid recycling of nutrients.
Article
The litter of Eucalyptus regnans forests forms a mull humus, and leaf material is readily incorporated into the topsoil. The annual litter fall is high by world standards, averaging 7.66 tonneslha. The amount of bark and twig fall and the contribution of the understorey to the total litter are also com- paratively high. The annual leaf fall in even-aged stands is in the order of spar stage > mature > pole stage. The maximum fall at 40-50 years coincides with the culmination of annual growth increment. Leaf fall is at a maximum in summer and early autumn and at a minimum in winter and early spring. The nutrient return by the total litter is fairly high, although bark and wood have low nutrient contents. The understorey of Pomaderris aspera contributes much of the calcium return. Leaf litter decays and disintegrates within 12-18 months, but bark and wood tends to accumulate on the floor. Crustaceans, millipedes and earthworms contribute to the incorporation of leaf material. Their number fluctuates seasonally, locally and between stands. Lyrebirds are important 'cultivators' of the forest floor and litter may be buried once every two years. Rapid nutrient turnover, high rainfall and excellent soil structure are favourable for high growth rates of these forests.
Article
Publisher Summary In this chapter, the litter production in forests of the world is discussed. The study of quantitative aspects of litter–fall is an important part of forest ecology, dealing with a major pathway for both energy and nutrient transfer in ecosystem. This chapter collates the available data on the quantity of litter produced by forests in different parts of the world. It demonstrates the importance of litter–fall in the nutrient cycle of the forest, and the significance in soil development is investigated in the types of forest humus layer. Harvest methods are used to commercially utilize litter. The various sources, selection criteria, arrangement, and presentation of data are provided. The annual production of leaf and total litter by forests of the world are tabulated. The detailed litter separation components, percentage of non–leaf litter in different climates, understory litter, mineral material, and organic material are also described. Major factors affecting litter–fall are evergreen gymnosperms and deciduous angiosperms, and the environment. The proposed treatments for litter–fall are also discussed. The seasonal litter–fall of in forests is graphically represented and the dry weight of standing crops of leaves on an annual production basis is tabulated.
Article
Sites of 1 ha were established in each of 4 contrasting types of primary lowland rain forest: alluvial forest (AF); dipterocarp forest (DF); heath forest (HF) and forest over limestone (LF). The total above-ground forest biomass (t ha-1 dry weight) was calculated as: AF,250; DF,650; HF,470; LF,380. There were at least 223 species ha-1 in the AF; 214 in the DF; 123 in the HF; and 78 in the LF. The AF soil was heterogenous, with gley soils of high base status in the lower, occasionally flooded, part and podzols and peats in the higher part. The DF soil was acid and very low in Ca. It was lower in total exchangeable bases than the very acid podzolic soils of the HF. The LF soils were shallow, highly organic, of high base status, and neutral to mildly acid pH. The species-rich DF occurred on very poor soils but there was no simple relationship between soil nutrient element concentrations and biomass of species richness. The causes of the distinctive sclerophyllous leaves of the heath forest are discussed. Extreme soil acidity in the organic soils may limit N-mineralization and low levels of biologically active nitrogen favour sclerophylly. Features of heat forest which reduce transpiration may be important in reducing the mass flow of soil toxins to the root surfaces.-from Authors English
Article
Annual litter fall, nutrient concentrations in litter components and annual weight of nutrients in litter fall have been estimated for karri forest stands aged 2, 6, 9 and 40 years and in mature forest. The weight of litter falling annually increases with stand age, ranging from 1.13 t/ha in 2‐year‐otd regeneration to 9.45 t/ha in mature forest. This increase is due mainly to greater amounts of twigs, bark and fruit falling in older stands. Leaf fait is relatively independent of stand age once the canopy of regenerating stands closes and the understorey has developed. Concentrations of N, P, K, S and Mn in karri leaf litter differ significantly between sites and the differences appear to be related to stand age. Highest levels of these elements are found in karri leaf litter from the youngest stand and the concentrations decrease with increasing stand age. The amounts of annual litter fall and of nutrients cycling in litter are among the largest reported for Australian forests. In particular cycling of Ca, K and Mg in mature karri forest is greater than has been reported for any other eucalypt forest. Karri forest understorey plays a key rote in nutrient cycling in these ecosystems, contributing 30–70% of the weight of many of the nutrients in the leaf component of titter. Understorey leaf material is particularly important in the cycling of N, S and the micro‐nutrients Cu and Zn.
Article
Paperbark low closed forest, dominated by Melaleuca cuticularis, produced 430 g (dry weight), m−2 of litter over a year, containing some 3.4 g.m−2 of nitrogen and 77 mg.m−2 of phosphorus. Twigs and bark made up more than 50% of the total annual litter fall. The twigs and bark contribute most of the nitrogen (54 %) and phosphorus (56%), compared with leaf fall (37% and 35%) and flower and fruit fall (8% and 9%). The fall of leaves, twigs and bark was primarily related to wind, and flower and fruit fall was greatest after flowering. The litter must make a significant contribution to the accretion of peat. Since the forest covers some 200 ha of the lower Blackwood River estuary, it may contribute some 8001 of litter to the ecosystem each year, containing some 6600 kg of nitrogen and 154 kg of phosphorus.
Article
The effects of high intensity fire on the cycling of nutrients in litter and canopy through fall were studied in pole stand jarrah (E. marginata Bonn ex Sm.) forest near Dwellingup, south-western Australia. In the first year following burning, twice as much litter fell on the burnt site as on an unburnt control site. Concentrations of phosphorus and nitrogen were higher in post-fire litter probably because crown scorch during burning prevented withdrawal of phosphorus and nitrogen into the tree before leaf fall. This, together with the increased weight of litter, resulted in a four-fold increase in the accession of phosphorus and nitrogen to the forest floor in litter one year after the fire on the burnt site. The concentrations of potassium, magnesium, sodium and chlorine in the litter were all significantly lower on the burnt site than on the unburnt site in the first year following burning.During the second year after the fire, significantly less litter fell on the burnt area than on the unburnt control site. Phosphorus concentrations in the litter from the burnt site remained 50% higher than in litter from the control but the other nutrient elements returned to their pre-fire levels.There are indications that more phosphorus and potassium are cycled via canopy leaching immediately after burning. In the second winter following the fire there were no significant differences in the amounts of nutrients in canopy leachate on the burnt and unburnt areas.
Article
Components of litter accession were measured for 2 years in two re growth eucalypt stands, a Nothofagus mixed forest, and a tall shrubland in the temperate forests of southern Tasmania. Total annual litterfall (t ha ‐1 ) ranged from 4.77 to 5.64 in the regrowth eucalypt stands and 4.06 to 4.94 and 1.95 to 2.17 in the Nothofagus mixed forest and tall shrubland, respectively. Significant correlations were found between annual litterfall of individual tree species and their respective basal area measured at 1.3 m height. The seasonal patterns of litterfall were most closely related to mean maximum temperatures. However, fall of non‐leaf material was also related to gale force winds associated with the spring equinox.
Article
Aboveground plant biomass was examined in a tall virgin tropical lowland evergreen rain forest dominated by Dipterocarpaceae in Sebulu, East Kalimantan, Indonesia, with special reference to the gap-, building- and mature phases of the forest growth cycle. From the records of dimensions of sample trees examined by the stratified clip technique and DBH inventory data of trees in a study plot, the biomass of larger trees (DBH 4.5 cm) was estimated by the allometric correlation method. The biomass of smaller plants (DBH < 4.5="" cm)="" was="" estimated="" by="" harvesting="" the="" plants="" in="" small="" quadrat="" plots.="" although="" large="" differences="" were="" found="" between="" aboveground-biomass-estimates="" in="" different="" patches="" of="" different="" growth="" stages,="" the="" aboveground="" biomass="" in="" a="" 1.0="" ha="" plot="" was="" 509="" t/ha,="" and="" the="" one-sided="" lai="" was="" 7.3="" ha/ha.="" these="" values="" seem="" to="" result="" from="" the="" tall="" forest="" architecture="" with="" huge="" emergent="" trees="" (over="" 70="" m="" high)="" and="" a="" moderate="" packing="" of="" plant="" mass="" indicated="" by="" the="" basal="" area="" value="" of="" 38.8="">2/ha for trees with DBH 4.5 cm.
Tropical forest litterfall II. The data set Tropical rainforest: The Leeds Symposium, Leeds Philosophical and Literary Society Ecolog-ical studies in four contrasting lowland forest types in Gunung Mu-lu National Park, Sarawak. I. Forest environment, structure and flo-ristics
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The macrophyte vegetation of Magela Creek floodplain, Alligator Rivers Region
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Finlayson, C.M. 1988. Productivity and nutrient dynamics of seasonally inundated floodplains in the Northern Territory. In: D. Wade-Marshall and P. Loveday (Editors), Northern Australia: Progress and Prospects, Vol. 2. Floodplains Research. ANU Press, Canberra, pp.58-83.
An analysis of litterfall in forests of the world
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Growth, aging and succession
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A revision of Melaleuca L
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Mangrove litter fall data from Hinchbrook Island, north-eastern Australia. Australian Institute of Marine Science Data Report Coastal Studies Series
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Tropical forest litterfall II. The data set
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Forest Trees of Australia
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Williams, A.R. 1984. Changes in Melaleuca forest density on the Magela floodplain, Northern Territory, between 1950 and 1975. Aust. J. Ecol., 9: 199-202.