Litter Components Research Articles

Diversity of lignicolous and Ingoldian fungi on woody litter from the River Kali (Western Ghats, India)

Three hundred and sixty woody litter samples naturally deposited in a stream and dammed section of the River Kali in southwest India were assessed for the diversity of lignicolous fungi (ascomycetes and anamorphic fungi) via damp chamber incubation and aquatic hyphomycetes (Ingoldian fungi) via bubble chamber incubation. Fifty-six fungal taxa were recorded with the highest of 47 taxa in the stream and 34 taxa in the dam. Twenty-five taxa were common to both sites. The core group (≥10%) comprised one ascomycete (Massarina australiensis), two anamorphic taxa (Acrogenospora sphaerocephala and Sporoschisma saccardoi) and 11 Ingoldian fungi (Anguillospora crassa, A. longissima, Clavariana aquatica, Cylindrocarpon sp., Flagellospora curvula, F. penicillioides, Lunulospora curvula, L. cymbiformis, Lunulospora sp., Triscelophorus acuminatus, T. monosporus). The species richness, average taxa per wood sample, richness of core group fungi and fungal diversity were higher in the Kaiga stream than in the Kadra dam. Species abundance curves showed higher frequency of occurrence of fungi in the stream than in the dam woody litter. The rarefaction indices of fungal species against number of wood samples revealed similar pattern of ascomycetes in both locations, while the richness of anamorphic and Ingoldian taxa was higher in the stream than in the dam. The anamorph/teleomorph ratio ranged between 2.4:1 (Kadra dam) and 3.3:1 (Kaiga stream), which is higher than the ratios reported from other geographical locations (0.7:1−2:1). This study reconfirmed that the method of incubation influences the assessment of fungal communities in woody litter and that Ingoldian fungi also constitute an important component of woody litter.

Carbon and nitrogen inputs by litter fall in fertilized and unfertilized larch plantations

This study was carried out to evaluate the effects of fertilization on carbon and nitrogen dynamics by litter fall of a 36-year-old larch (Larix leptolepis) plantation in the Sambong Exhibition Forests, Gyeongsangnam-do, Korea. Litter was collected monthly between April 2003 and May 2006. Seasonal inputs of litter fall components such as needle, broad leaf, branch, bark and total litter inputs followed a similar pattern between fertilized and unfertilized plots. The annual amounts of the litter components were not significantly different (P > 0.05) between fertilized and unfertilized plots. Mean needle litter fall was similar between the fertilized (2564 kg ha−1 yr−1) and unfertilized plots (2501 kg ha−1 yr−1) and total annual litter fall averaged 3552 kg ha−1 yr−1 in the fertilized and 3541 kg ha−1 yr−1 in the unfertilized plots during the sampling period. Proportion of needle litter fall was slightly higher in the fertilized (72.2%) than in the unfertilized (70.8%) plots. Carbon concentrations of needle litter were not significantly affected by fertilization (P > 0.05), while there was a significant fertilization effect on nitrogen concentrations with high nitrogen concentrations of needle litter in the fertilized (7.7 g kg−1) compared with the unfertilized (6.8 g kg−1) plots. There was no significant difference (P > 0.05) in the organic carbon inputs by needle litter between the fertilized and unfertilized plots, whereas annual nitrogen inputs were significantly higher in the fertilized (17.7 kg N ha−1 yr−1) than in the unfertilized (15.6 kg N ha−1 yr−1) plots. The results indicated that nitrogen dynamics by litter fall could be affected by fertilization, but a minimal impact to carbon dynamics by litter fall in the larch plantation.

Long-term forest-floor litter dynamics in Canada's boreal forest: Comparison of two model formulations

Litter decomposition is a key component in ecosystem material cycling that determines (i) forest soil carbon (C) and nutrient content, (ii) release of carbon dioxide to the atmosphere, and (iii) generation and mass transfer of dissolved organic carbon from terrestrial to aquatic ecosystems. In this study, we provide simulations of long term forest-floor litter dynamics generated with both (i) an existing forest nutrient cycling and biomass growth model (ForNBM) with a single-pool formulation of forest-floor litter decomposition (Zhu et al., 2003. Ecol. Model. 169, 347–360), and (ii) a revised version of the model produced by substituting the single-pool formulation with a three-pool version of the formulation tested against data from litterbag experiments (FLDM; Zhang et al., 2010. Ecol. Model. 221, 1944–1953). This is done to determine the importance of subdividing the litter mass into categories of rates of decay (i.e., fast, slow, and very slow) on model accuracy. Forest-forest litter dynamics simulated with the two models are subsequently compared against field measurements collected at several northern jack pine ( Pinus banksiana) stands along a southwest-northeast oriented transect (climate gradient) associated with the Boreal Forest Transect Case Study in northwest Canada. Initial comparison shows that the single-pool formulation underpredicts residual litter mass when forests are <65 years old, largely due to the improper treatment of the very slow decomposing litter component. This underprediction is resolved when the three-pool formulation is used. From a ecosystems-response point of view, the revised ForNBM (with the three-pool formulation) demonstrates that (i) forest-floor litter initially increases with forest growth and reaches a plateau once the forest matures; (ii) the forest floor stores more litter and C at the southern and warmer sites than at the northern sites; and (iii) in a similar climate regime, the forest floor stores more litter and C at productive than at nutrient-poor sites.

Methyl bromide and methyl chloride fluxes from temperate forest litter

Methyl halide fluxes were measured from fine (nonwoody) litter samples at a temperate deciduous forest site in Scotland on 16 occasions over more than a year and at a coniferous forest site. The resulting mean (±1 sd) CH 3 Br and CH 3 Cl fluxes were 4.1 ± 3.7 ng kg −1 h −1 and 0.98 ± 0.62 μg kg −1 h −1 , respectively, for dry mass leaf litter and 5.7 ± 6.3 ng kg −1 h −1 and 0.47 ± 0.14 μg kg −1 h −1 for dry mass needle litter. Temporal variations of net fluxes from leaf litter were significantly greater than spatial variations suggesting seasonality in the fluxes. The mean CH 3 Cl/CH 3 Br mass ratio of fluxes was ∼200 (to 1 sig. fig.), an order of magnitude larger than the ratio of their estimated global turnovers. Temperate forest litter may be a moderate net source of CH 3 Cl globally but a negligible source of CH 3 Br. These statements refer to the nonwoody litter component only. ► Methyl halide fluxes were measured from forest non-woody litter samples in Scotland. ► At a single site, temporal variations in fluxes were significantly greater than spatial variations. ► Findings indicate temperate forest litter may be moderate source for CH 3 Cl globally but negligible for CH 3 Br.

Transformation of Quercus petraea litter: successive changes in litter chemistry are reflected in differential enzyme activity and changes in the microbial community composition

The links among the changes in litter chemistry, the activity of extracellular enzymes and the microbial community composition were observed in Quercus petraea litter. Three phases of decomposition could be distinguished. In the early 4-month stage, with high activities of β-glucosidase, β-xylosidase and cellobiohydrolase, 16.4% of litter was decomposed. Hemicelluloses were rapidly removed while cellulose and lignin degradation was slow. In months 4-12, with high endocellulase and endoxylanase activities, decomposition of cellulose prevailed and 31.8% of litter mass was lost. After the third phase of decomposition until month 24 with high activity of ligninolytic enzymes, the litter mass loss reached 67.9%. After 2 years of decay, cellulose decomposition was almost complete and most of the remaining polysaccharides were in the form of hemicelluloses. Fungi largely dominated over bacteria as leaf endophytes and also in the litter immediately before contact with soil, and this fungal dominance lasted until month 4. Bacterial biomass (measured as phospholipid fatty acid content) in litter increased with time but also changed qualitatively, showing an increasing number of Actinobacteria. This paper shows that the dynamics of decomposition of individual litter components changes with time in accordance with the changes in the microbial community composition and its production of extracellular enzymes.

Effects of vegetation type and fire regime on flammability of undisturbed litter in Southeastern France

To assess the effect of vegetation types and of fire regime on the flammability of dead fuels, samples of litter were collected undisturbed (i.e. keeping the structure of litter layers) in 29 study sites spread over the limestone-derived soils of Provence. The sampling plan comprised the most representative ecosystems of the study area: pure Pinus halepensis stands, mixed pine-oak stands and shrublands. Three classes of litter depth were studied (low, medium and high) to account for the variability existing in the field. Sampling also included the number of fires in each site since 1960 (no fire, 1 or 2 fires and ≥3 fires) and the time interval since the last fire (≤15 years, 15–45 years and >45 years). Flammability experiments were carried out in laboratory using a glowing firebrand and a 10 km h −1 wind. The main variables recorded were: ignition frequency, time-to-ignition, flaming duration, flame rate of spread, flame propagation, mean flame temperature, maximum flame height and rate of consumption. Results showed that the ignition frequency was higher in mixed stands than in pure pine stands whereas the time-to ignition, flaming duration and rate of consumption were the highest in pure pine stands. The maximum flame height and the flame propagation decreased with the increase of the number of fires and the time-to-ignition was the highest when the interval since the last fire was the shortest. Increases in litter depth resulted in increased mean flame temperature, maximum flame height and flame propagation. These results can be explained, in part, by the proportions of the different litter components.

Organic matter inputs into headwater streams of southwestern British Columbia as a function of riparian reserves and time since harvesting

Riparian vegetation strongly influences the structure and function of terrestrial and aquatic ecosystems; therefore, harvest of riparian trees can profoundly impact these habitats. Riparian reserves (no harvest zones) are used world-wide to reduce these impacts, including effects on organic matter dynamics. There are, however, few experimental evaluations of their efficacy. Particulate organic matter delivery from riparian vegetation to streams, a critical ecosystem process, was measured over an eight year period after logging in southwestern British Columbia, Canada to quantify the relationship between these litter fluxes and riparian reserves (unlogged controls, 30 and 10-m wide uncut reserves, and clear-cuts). We hypothesized that the timing, composition and quantity of organic matter entering these streams would vary as a function of reserve width, but that these differences would decline with time since logging. We also hypothesized that inter-annual variation in precipitation patterns would partially contribute to litter dynamics. Riparian treatment significantly affected the quantity and composition of litter flux: inputs of needles and twigs were significantly lower and proportion of deciduous litter higher in clear-cut streams compared to other treatments. ANOVA models indicated that treatment differences in litter flux persisted through year 7 for some components of litter, while regression models indicated positive trends between reserve width and litter flux through year 8. This positive slope indicates the clear-cut treatment had yet to recover from logging. Variation in snowfall and plant succession contributed to temporal variation in litter flux; in some cases, litter inputs increased with annual snowfall. Another key finding from this study was that riparian reserves provided total litter inputs to streams that were similar to fully forested controls.

Litter decomposition rates in relation to litter stocks in boreal coniferous forests along climatic and soil fertility gradients

The contribution of trees, understorey dwarf shrubs, and mosses in the soil organic matter accumulation in boreal forest soils is still poorly understood. To determine the relationship between litter decomposition and accumulation, we conducted litter decomposition trials and quantified the litter components accumulated on the forest floor in south and north boreal forests at two site types, sub-xeric and mesic forests. Litter used in the litter decomposition trial and the accumulated litter were also chemically characterized. The decomposition rates of bilberry, needle and the moss litter analyzed as accumulated dry weight and C loss did not differ along the climatic and fertility gradients. While the chemical quality of the tree, dwarf shrub, and moss litter differed only slightly by location in the north or the south, there were major differences in the accumulated litter stocks on the forest floor. Litter produced by the trees constituted the most important litter C stock in the south boreal forests, whereas the litter produced by mosses in the north formed as large or an even larger stock than the litter produced by trees. Also the quantity of accumulated dwarf shrub litter was higher in the north than south. According to our results, the differences in the quality and quantity of soil OM stocks between the south and north boreal forests is largely a result of quantitative difference in the litter input by trees vs. mosses and dwarf shrubs, rather than differences in the litter quality or decomposition rates between the north and the south.

Relationships among plant litter, fine roots, and soil organic C and N across an aridity gradient in northern Patagonia, Argentina

We analyzed the relationship between organic C and N in the upper soil and the quantity (mass) and quality (N, soluble phenolic, and lignin concentrations) of plant aboveground litter and upper fine roots at contrasting microsites (plant patch and bare soil) in 15 study sites across an aridity gradient in Patagonia. At each site, we estimated the total, grass, and shrub cover and randomly selected 10 plant patches of modal size (height and crown diameter) and species composition. We extracted an upper soil core (0–10 cm depth) and collected the aboveground litter underneath each plant patch canopy and at the contiguous bare soil. We separated the fine roots (< 2 mm in diameter) from the soil and assessed the biomass and the concentrations of organic C and N in soil and the lignin, soluble phenolic, and N in shrub and grass components of aboveground litter and in fine roots. Total plant and grass cover decreased with increasing aridity. Total litter mass did not vary across the aridity gradient, but the proportion of shrub components in litter increased and litter quality decreased with increasing aridity. The mass of fine roots was positively correlated to soil organic C and N and decreased with increasing aridity. All these trends were consistent at plant patch and bare soil microsites. We conclude that the decrease in soil organic C and N across the aridity gradient was the outcome of different above- and belowground controls resulting from the replacement of grasses by shrubs. Accordingly, the main controls of soil organic C and N could be the quality of aboveground litter and the quantity of the organic matter input to soil through fine-root turnover from belowground.

Litterfall dynamics and nutrient decomposition of arid mangroves in the Gulf of California: Their role sustaining ecosystem heterotrophy

This study shows results on litterfall dynamics and decay in mangrove stands of Avicennia germinans distributed along a latitudinal gradient (three forest sites) in the Gulf of California, in order to assess whether internal sources could support the observed mangrove ecosystem organic deficit in this arid tropic. Total mean annual litterfall production increased southward (712.6 ± 53.3, 1501.3 ± 145.1 and 1506.2 ± 280.5 g DW m −2 y −1, in the Yaqui, Mayo and Fuerte areas respectively), leaves being the main component of litter in all locations during the entire year, followed by fruits. The wet season (June–September) showed the highest litterfall rates through fruits. The temporal trend of litterfall production was significantly explained through mean air temperature ( R 2 = 68%) whilst total annual litter production in the entire region showed a statistically significant relationship with total soil phosphorus, salinity, total nitrogen, organic matter and tree height ( R 2 = 0.67). Throughout 117 days of the decomposition experiment, the litter lost 50% of its original dry weight in 5.8 days (average decay rate of 0.032 ± 0.04 g DW d −1) and there were not significant differences in the remaining mass after 6 days. The percentage of both C and P released from the litter correlated significantly with the ratio of tidal inundated days to total experiment days ( R 2 = 0.62, p = 0.03 and R 2 = 0.67, p = 0.02, respectively); however, the frequency of tidal inundation only showed a significant increase in C release from Avicennia litter after 6 and above 48 days of decomposition. Whereas the total C content of litter bags decreased linearly over the decomposition to (% Total C = 5.52 − 0.46 days, R 2 = 0.81, p = 0.0005), N content displayed an irregular pattern with a significant increase of decay between 48 and 76 days from the beginning of the experiment. The pattern for relative P content of litter revealed reductions of up to 99% of the original (%tot- P = −9.77 to 1.004 days, R 2 = 0.72, p = 0.01) although most of the P reduction occurred between 17 and 34 days after the experiment started. Soil N and P contents, which exhibited significant differences in the course of the decomposition experiment, appeared to show significant differences between sampling sites, although they were not related to tidal influence, nor by leaf and nutrient leaching. In a global basis, C/ N litter ratios decreased linearly ( C/ N = 32.86 − 0.1006 days, R 2 = 0.62, p = 0.02), showing a strong and significant correlation with meteorological variables ( R 2 = 0.99, p = 0.01). C/ P ratios of litter increased through an exponential function ( C/ P = 119.35e 0.04 day, R 2 = 0.89, p < 0.001). Changes in the remaining percentage of litter mass during the experiment were significantly correlated with soil C/ N ratio ( R 2 = 0.56, p = 0.03) as well as with the soil C/ P ratio ( R 2 = 0.98, p < 0.001). Our results of litter decomposition dynamics in this mangrove support the fact of null net primary productivity of the arid mangrove wetlands: fast litter decomposition compensates the ecosystem organic deficit in order to sustain the mangrove productivity. Litter decomposition plays a key role in the ecosystem metabolism in mangroves of arid tropics.

Variation in litter under individual tree crowns: Implications for scattered tree ecosystems

AbstractIn forest ecosystems litter is usually assessed in terms of the average amount produced by the canopy. In scattered tree ecosystems this approach is problematic because the canopy is discontinuous and the spatial arrangement of litter highly variable. We addressed this problem by quantifying the spatial variation in litter load and litter composition associated with individual trees in a Eucalyptus melliodora – Eucalyptus blakelyi woodland. Litter was sampled under crowns and in grassland adjacent to 10 E. blakelyi and 10 E. melliodora trees ranging in diameter at breast height (dbh) from 14 to 129 cm. A total of 302 L samples were collected from these trees, at distances ranging from 0 to 42 m from main stem. The sampled litter loads ranged from 0.02 to 109.3 t ha−1 and were significantly higher under tree crowns than in grassland for litter and each component of litter (leaves, bark, fine twigs, coarse twigs). In particular, the mean litter load under tree crowns (12.5 t ha−1) was an order of magnitude higher than the mean litter load in grassland (1.27 t ha−1). There was a significant (P = 0.0103) positive relationship between mean litter load under the tree crown and dbh, indicating larger trees produced more litter per unit area of ground than smaller trees. Generalized Linear Modelling produced highly significant (P &lt; 0.0001) models predicting the spatial variation in litter load and litter composition in terms of distance from main stem and dbh. Our models demonstrate gradients in litter load and composition under tree crowns. These gradients were most pronounced for the large trees in our study. The disproportionate input of litter and variety of litter components associated with large trees in our study supports their keystone role in scattered tree ecosystems and highlights the need to maintain these structures in agricultural landscapes.

Litterfall and litter chemistry change over time in an old-growth temperate forest, northeastern China

• Litterfall and litter chemistry are key factors for the assessment of forest floor properties. A long-term study on litterfall, litter chemistry and forest basal areas was carried out in an old-growth temperate forest, northeastern China.• The objective of this study was to test whether forest floor properties in the old-growth forest remain relatively constant.• Litterfall increased significantly over the past 27 y but litterfall of various litter components showed different temporal trends. Changes in proportions of various litter components, combined with the inherent chemistry differences among them, made litter carbon (C): nitrogen (N) and lignin:N ratios increase at an average rate of 0.19 and 0.16 per year, respectively, suggesting a decreasing trend in the forest floor C and N cycling rates. Changes in dominant tree species biomass significantly affected their corresponding foliar litter production and proportions in the total litterfall and therefore played a dominant role in regulating the developing trends of litter chemistry and quantity in this forest floor.• Our study indicated that forest floor properties in the old-growth forest still showed a directional change and this was mainly caused by the intrinsic changes rather than yearly climatic fluctuation.

Monitoring of nutrient removal within integrated constructed wetlands (ICW)

The aim of the project was to assess the nutrient removal within integrated constructed wetlands (ICW). The study was based on twelve free-water surface ICW treating farmyard runoff in Ireland.The principal design criterion leading to adequate effluent water quality (i.e. molybdate reactive phosphate (MRP) less than 1mg/L) from ICW is that the total wetland area needs to be sized by a factor of at least 1.3 times the farmyard area. It is common practice to construct at least four wetland cells in series with individual aspect ratios of less than 1:2 (width to length).Most of the MRP concentrations after ICW treatment were in agreement with Irish urban wastewater standards for discharge to sensitive waters, which can be used as a benchmark to measure ICW performance and which are usually applied to ICW even if it may appear to be too stringent. Furthermore, the number of denitrifying bacteria detected in the benthos of ICW systems is higher than the number of ammonia-oxidising bacteria. Anoxic conditions at the wetland bottom create conditions which are favourable for denitrifying bacteria. It follows that sediment and litter components of the ICW system support denitrification.The outflow water quality was within recommended guidelines. The study suggests that phosphorus exported from an ICW system was similar to the typical background concentrations of phosphorus export rates from land to water.

Litter Decomposition in Semiarid Grassland of Inner Mongolia, China

Long-term overgrazing has significantly changed plant species composition in rangeland ecosystems, and this change may alter ecosystem functioning remarkably. In this study, decomposition rates and nutrient dynamics of pure litter (leaf, stem, or root litter) and 11 litter mixtures (from two to five litter components), including nine aboveground litter mixtures and two root litter mixtures, of five common plant species in degraded semiarid rangelands of northern China were studied for 1 yr. We found that fine root litters generally decomposed faster and had faster nutrient turnover rates than leaf and stem litters. The decomposition rates of leaves and stems were significantly and positively correlated with initial litter nitrogen (P , 0.01) and phosphorus contents (P , 0.05), and the decomposition rates of fine roots were significantly and negatively correlated with initial litter carbon:nitrogen ratios (P , 0.05). Nonadditive effects were found in six out of the nine aboveground litter mixtures (three positive and three negative). There were only additive effects on decay rates and nutrient fluxes in the two root litter mixtures. The occurrence and direction of nonadditive effects were dependent on the properties of component litters and had no obvious correlations with litter diversity. Negative mixing effects on nutrient immobilization can facilitate the release of some important nutrients during litter decomposition processes, and further help to accelerate nutrient cycling in such semiarid rangeland ecosystems. Our results indicate that change of plant species composition by overgrazing may slow down the mass loss rates, but may not necessarily impact the release of some nutrients.

Patterns of litterfall and return of nutrients across anthropogenic disturbance gradients in three subalpine forests of west Himalaya, India

The study was conducted to improve our understanding of the effects of forest disturbance on litterfall and patterns of nutrient return in three subalpine forest ecosystems (i.e. Betula utilis-dominated, Abies pindrow-dominated, and Acer mixed broadleaf) of Indian west Himalaya. Total litterfall (t ha−1 yr−1) ranged between 2.6–3.6 and 2.1–2.6 for pristine and degraded stands, respectively. Whereas total litterfall decrease from pristine to degraded stand was about 25–30% in B. utilis and Acer mixed-broadleaf forests, the level of disturbance did not affect total litterfall in A. pindrow (coniferous) forest. Nutrient (N, P, and K) concentrations in litter components of the forests studied also varied across forest types and disturbance intensities. For pristine stands, among all the forests, return of total nutrients via litterfall was higher. The study revealed that patterns of litterfall and nutrient return in the forests studied were sensitive to intensity of disturbance, although sensitivity varied among forest types and nutrient contents. Increased intensity of disturbance greatly affected the total annual amount of nutrient return in broadleaf forests. Maximum impact was recorded in B. utilis forest with a significant decline in nutrient return from pristine to degraded stands (i.e. 64% for N, 38% for P, and 67% for K). Corresponding values for decline in Acer mixed forest were 17, 13, and 33% for N, P, and K, respectively, whereas in A. Pindrow forest N return was 15% higher and P return was 33% lower. This study indicates that the litterfall and litter nutrient concentrations in these forests are sensitive to the intensity of disturbance, which affects the amount of nutrient return. This will have a strong bearing on forest nutrient cycling.

Saprotrophic cord systems: dispersal mechanisms in space and time

In natural terrestrial environments, nutrients are often patchily and sparsely distributed, and the microclimate is constantly changing both temporally and spatially. To survive, fungi must be able to transfer to a new resource before the nutrient supplies in their current food base are exhausted. While the majority of fungi propagate as spores, some basidiomycetes can grow out of a resource as mycelium in search of new resources. The mycelium of these fungi typically aggregates to form linear organs, termed cords or rhizomorphs, that ramify at the soil–litter interface in forests, interconnecting disparate litter components to form extensive (many square meters or even hectares), long-lived (many years) systems. These mycelial systems form effective dispersal mechanisms in space and time. This article reviews the two main, but not mutually exclusive, mycelial dispersal (resource capture) strategies: (1) a “sit and wait” strategy, whereby a large mycelial network waits for resources to land on it and then actively colonises those resources; and (2) growing and searching actively for new resources. The way in which mycelia balance exploration and nutrient transport, and robustness to damage, against “cost” of production and speed with which an area can be colonised, is explored using techniques borrowed from graph theory and statistical mechanics.

Nutrient Dynamics and Litter Decomposition in &lt;i&gt;Leucaena leucocephala&lt;/i&gt; (Lam.) De Wit plantation in the Nigerian Derived Savanna

Nutrient contents and rate of litter decomposition were investigated in Leucaena leucocephala plantation in the University of Agriculture, Abeokuta, Ogun State, Nigeria. Litter bag technique was used to study the pattern and rate of litter decomposition and nutrient release of Leucaena leucocephala. Fifty grams of oven-dried leaf litter of the species was weighed into 0.2 mm mesh litter bag, 35 cm × 25 cm in size, these bags were closed at all ends. Eighteen litter bags were used for the studies. The litter bags were numbered and placed on the field (above ground) on 26th April 2005. Three bags were retrieved randomly from the field at 20-day intervals for 120 days. The nutrient concentration in L. leucocephala followed the trend N > P > Mg > Ca > K > Na for leaf litter and seed components. Nutrient concentration in twigs and pods ranked N > Mg > P > Ca > K > Na. Among all the litter components, leaf litter contributed more nutrients, especially nitrogen, than other litter components. High potassium concentration during the dry season was due to lack of rainfall to leach out the element. Lower magnesium content in leaf litter was due to chlorophyll decay. High N-flux reflected the quantity and quality of nitrogen in the soil. Mass loss was significantly correlated with calcium (P < 0.05). At 120 days, 80% of the litter had decomposed; this implies that decomposition rate was at 0.6% per day. A net immobilization of all the nutrient elements at 20 days was due to lack of rainfall to leach out the nutrients. High rate of decomposition at the early stage was due to less moisture content in the soil and high temperature. Litter decomposed more during the wet season than the dry season.West African Journal of Applied Ecology Vol. 13 2008: pp. 96-103

Litterfall from trees in semiarid woodlands of north-east Queensland

The amount and chemical composition (nitrogen, phosphorus and sulfur concentrations) of the components of tree litter were measured in eucalypt woodlands at two sites (Cardigan and Hillgrove) near Charters Towers, Queensland, Australia. Annual litterfall averaged 720 kg ha–1 (Cardigan) and 1270 kg ha–1 (Hillgrove) over 3 years with leaves the major component at both sites. Rate of litterfall was greatest during September–December and lowest during May–July. Nutrient concentrations varied widely but no seasonal patterns were detected. Phosphorus concentrations in the leaf litter at Hillgrove (mean = 0.112%) were much higher than in other studies of eucalypt litter, probably reflecting the high soil phosphorus levels at the study site. Tree litter represents an important proportion of the organic material and nutrients being cycled through these woodlands.

서부 호주 밀 재배지역 내 자연보호구역에 서식하는 흰개미 Drepanotermes tamminensis (Hill) 집에 저장된 식물유체의 영양물질 함량

본 연구는 서부 호주의 Durokoppin 자연 보호 구역에 서식하고 있는 흰개미에 의해 수확되어 개미집에 저장되어 있는 식물유체와 영양물질 함량을 조사하기 위해 수행되었다. 개미집에 저장된 식물유체의 경우 두 조사지역간의 유의적 차이는 없었으며, 개미집에 저장된 식물유체를 분류한 결과 잎과 가지 등 7가지 종류의 식물 유체로 확인되었다. 개미집 내 저장된 식물유체의 영양물질 함량은 유의적 차이는 없었지만 shrubland 보다 Woodland가 높았으며, 영양물질 총량 역시 shrubland보다 Woodland가 많았다. 연구결과를 종합해 보면 흰개미는 조사지역에서 다양한 종류의 식물유체를 수확하여 이용하고 있으며, 조사지역내 토양 유기물 함량이 적은 점을 고려할 때 생태계 영양물질 순환에 있어서 중요한 역할을 하고 있는 것으로 사료된다. This study estimated the mound litter biomass and the nutrient content of mound litter in the two study plots in Durokoppin Nature Reserve, Western Australia between 2004 and 2005. There were no significant differences in biomass of litter in individual mounds between the two study plots. Seven components of litter were found in the mounds. The nutrient concentrations were higher in the woodland than in the shrubland plot, although the differences were not statistically tested, and the total amount of each nutrient measured was generally greater in the woodland than in the shrubland plot. The aforementioned results show that D. tamminensis harvests various plant material according to biomass availability. The role of this termite takes on particular importance in view of the fact that Western Australian soils are notoriously impoverished in nutrients.

Characteristics of the biochemical composition of plant litter at different stages of decomposition (according to thermal analysis data)

The composition of samples of needles, leaves, sheaved cottongrass (Eriophorum vaginatum) tissues, and the L horizon of the forest floor of different degree of decomposition, isolated from the plant litter in southern taiga ecosystems, was studied by thermal analysis. It was established that plant litter decomposition is accompanied by structural changes in celluloses and that the decomposition rates of hemicellulose and structured cellulose vary at different stages of decomposition. The structural specificity and incongruent thermal decomposition of grass lignocellulose were observed in all samples of plant material. The rates at which the content of components of the plant litter decreased depended on the type and stage of decomposition of plant material. The decomposition rate of biochemical components tended to increase in better drained soils.