Nutrient dynamics in decomposing forest leaf litter: A comparison of field and laboratory microcosm approach

The effect of incubation setting (greenhouse: GM and field: FM microcosms) on nutrient element dynamics during decomposition of Japanese Konara Oak (Quercus serrata Murray) and Japanese Red Pine (Pinus densiflora Sieb et. Zucc.) litter was studied. Results show a disparity in relative concentrations and amounts of the same type of litter when incubated in different settings. The nutrient mobility, however, showed similar trend. The order of elemental mobility after 12 months forQuercus in FM was: P>K>Mg>C>Mn>Ca>N>Al>Cu>Zn>Fe; for GM it was: P>K>Mn>Mg>C>Ca>N>Al>Cu>Zn>Fe. ForPinus, elemental mobility in FM was: K>Mg>C>Mn>N>P>Cu>Zn>Al>Fe; while for GM was: K>C>Mn>N>Ca>Mg>Cu>Al>P>Zn>Fe. The elements inQuercus that lost their mass were P, K, Mg, Ca, Mn and C while those that increased were N, Cu, Al, Fe and Zn. ForPinus, K and Mg lost their nutrient mass while the other elements had increased or fluctuated but tended to increase. Three patterns of nutrient mobility were observed: first, the concentration increased while the nutrient mass (absolute amount) decreased; second, both concentration and nutrient mass increased; third, the concentration and nutrient mass decreased. On tracing nutrient mobility over time, the linear regression of nutrient element mass and litter element mass was preferred over the carbon to element ratios because the former gave a clearer picture of the relationship. On the over-all, the pattern of nutrient changes in greenhouse microcosms were different from those observed in the field, hence nutrient cycling studies using greenhouse-microcosm approach alone may give inaccurate results. This study was conducted while the senior author holds a Japanese government scholarship (MONBUSHO Grant No. 920205).     

Comparison of organic matter dynamics in soil between Japanese cedar (Cryptomeria japonica) forest and adjacent Japanese red pine (Pinus densiflora) forest established on flatland

In order to clarify the effects of tree species on organic matter dynamics in soil, we investigated the amount of forest floor material, leaf litter decomposition rate, soil chemical characteristics, soil respiration rate and cellulose decomposition rate in a Japanese cedar forest (cedar plot) and an adjacent Japanese red pine forest (pine plot) established on a flatland. The amount of forest floor material in the cedar plot was 34.5 Mg ha⁻¹ which was greater than that in the pine plot. Because the leaf litter decomposition rate was higher in the pine plot than in the cedar plot, it is likely that the difference in the amount of forest floor material between the plots is caused by the difference in the leaf litter decomposition rate. The C concentrations of soil in the cedar plot were 1.2–2.1 times higher than those in the pine plot. Soil pH(H₂O)s in the cedar plot were significantly higher than those in the pine plot. The soil respiration rates and the rates of mineralized C in the cedar plot byin vitro incubation were higher than those in the pine plot. From this result, it is assumed that soil organic matter in the cedar plot was decomposed relatively faster compared with the pine plot. Furthermore, microbial activities, which were reflected as cellulose decomposition rates in the cedar plot, were higher than those in the pine plot. A part of this paper was presented at the 109th Annual Meeting of the Japanese Forestry Society (1998).     

Leaf litter decomposition of dominant tree species of Namdapha National Park,Arunachal Pradesh,northeast India

Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species (Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea, Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight loss day⁻¹), followed by a rapid decay phase (0.494% weight loss day⁻¹) and a final slow decay phase (0.136% weight loss day⁻¹). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content, lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature, and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling.     

Leaf and twig litter decomposition of main species in different forests along the north slope of Changbai Mountain, northeast China

From 2001 to 2003, the litter decomposition dynamics of dominant tree species were conducted using a litterbag burying method in the broadleaf-Korean pine forest, spruce-fir forest and Ermans birch forest, which represents three altitudinal belts in Changbai Mountain, northeast China. The spatial and temporal dynamics of litter decomposition and the effects of litter properties were examined. Furthermore, the decomposition trend of different species was simulated by the Olson model, and results showed that annual mass loss rates increased over time, but was not significantly correlated. Leaf decomposition rates increased after decomposing for 638 days (1.75 years), and the order of dry weight remaining rates of leaf litter for different species is: Asian white birch (Betula platyphylla) (24.56%) < Amur linden (Tilia amurensis) (24.81%) < Korean pine (Pinus koraiensis) (38.48%) < spruce (Picea jezoensis var. microsperma) (41.15%) < Ermans birch (Betula ermanii) (41.53%) < fir (Abies nephrolepis) (42.62%). The dry weight remaining rates of twig litter was smaller than that of leaf litter, and followed the order of Amur linden (44.98%) < fir (64.62%) < Korean pine (72.07%) < spruce (73.51%) < Asian white birch (77.37%) < Ermans birch (80.35%). The simulation results by the Olson model showed that, in leaf, the 95%-decomposition rates ranged from 4.5 to 8.0 years, and annual decomposition rate (k) followed the order of Amur linden (0.686) > Asian white birch (0.624) > Korean pine (0.441) > spruce (0.406) > fir (0.397) > Ermans birch (0.385); in twig, it ranged from 7.8 to 29.3 years, and k follows the order: Amur linden (0.391) > fir (0.204) > Korean pine (0.176) > spruce (0.157) > Asian white birch (0.148) > Ermans birch (0.102). In general, the differences of decomposition rate are evident between leaf and twig litter and among species, and were higher in broad-leaved species compared with coniferous species at the same elevation, and decreased with the ascending of elevation. __________ Translated from Acta Ecologica Sinica, 2006, 26(4): 1,037–1,046 [译自: 生态学报]     

Indirect effects of precipitation variation on the decomposition process of Mongolian oak (Quercus mongolica) leaf litter

The effect of precipitation variation on the chemistry of Mongolian oak (Quercus mongolica) leaf litters was examined by analyzing litters of Mongolia oak saplings under four precipitation gradients. The decomposing process of these leaf litters in the Mongolian oak dominated forest was assessed using litter bag method. Compared with the litters of the Mongolian oak saplings from the natural precipitation site (A), litters produced by Mongolian oak from the driest precipitation gradient (A₄₅₀) had significantly higher concentrations of nitrogen (N), phosphorus (P) and potassium (K) while lower acid-insoluble fraction (AIF) concentration. The decomposition study showed that A₄₅₀ exhibited significantly higher decomposition rate, mineralization rates of N, P and K as well as much shorter N and P net immobilization periods. On the contrary, litters produced by seedlings from wettest gradient (A₈₅₀) showed a totally opposite pattern. Litters from saplings that received comparable precipitation (A₆₅₀) to those at the natural site (A) had significantly higher N concentration and faster decomposition rate as well as release rates of N, P and K. The mass loss patterns for the four litter types fitted the exponential model and the decay constant (k) can be well predicted by initial AIF/N. During the decomposition period, N concentration was best related to the percentage of mass remaining of the litters with relatively higher AIF concentrations and lower N concentrations, but the percentage of mass remaining of litters with lower AIF concentrations and higher N concentrations correlates strongly with AIF con centration. Our study proved that changes in precipitation significantly altered the litter quality, and therefore indirectly changed the decay process of leaf litters. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(2): 261–266 [译自: 应用生态学报]     

Nutrient dynamics associated with leaf litter decomposition of three agroforestry tree species (<Emphasis Type="Italic">Azadirachta indica,Dalbergia sissoo</Emphasis>, and <Emphasis Type="Italic">Melia azedarach</Emphasis>) of Bangladesh

Azadirachta indica A. Juss, Dalbergia sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabili- ties from leaf litter decomposition to maintenance of the soil fertility despite their importance in agroforestry practices of Bangladesh. A leaf litter decomposition experiment was conducted using a litterbag tech- nique to assess the nutrient return efficiency of these species. The de- composition rate of leaf litter was highest for M. azedarach and lowest for D. sissoo. Rainfall and temperature of study sites showed a signifi- cant (p<0.05) positive relationship with the rate of leaf litter decomposi- tion. The highest decay constant was observed for M. azedarach (6.67). Nitrogen and Phosphorus concentration in leaf litter showed a decreased trend sharply at the end of the first month, whereas rapid decrease of Potassium concentration was reported within 10 days. Conversely, higher concentration of nutrient was observed at the later stages of decomposi- tion. All three species showed a similar pattern of nutrient release (K > N > P) during the decomposition process of leaf litter. Among the studied species, D. sissoo was best in terms of N and P return and A. indica was best in terms of K return.     

Mixed litter decomposition in a managed Missouri Ozark forest ecosystem

We monitored the decomposition of mixed leaf litter (Quercus spp., Carya spp., and Pinusechinata) in a Missouri Ozark forest eight years after experimental harvest. Leaf litter mass losses and changes in carbon chemistry (extractive, acid soluble, and acid insoluble fractions) were measured over 32 months in field incubations to determine the effects of litter composition and stand manipulation on decomposition and nitrogen (N) concentration in the remaining litter. The decay (k) rate over this period ranged between 0.39 (±0.010) and 0.51 (±0.002) year⁻¹ for oak, oak–hickory, and oak–pine litter. There were significant main effects of stand manipulation (p = 0.03) and litter type (p < 0.01) on decay. Mass losses of oak and oak–hickory litter were 7% (p = 0.02) and 4% (p = 0.04) higher on harvested stands than controls, respectively. Mass loss of oak–hickory litter was 3% faster than oak–pine (p = 0.03) and 6% faster than oak (p = 0.02) litter on control stands, whereas the oak–hickory litter mass loss was 5% higher than oak litter on harvested stands (p = 0.01). The decay (k) rate had a linear relationship with initial leaf litter nitrogen content and lignin-to-N ratio. The nitrogen concentration in remaining litter had a nonlinear relationship to cumulative mass loss suggesting an exogenous source of N. In summary, this study demonstrated significant effects of timber harvest and litter mixtures on decomposition and N dynamics in a managed Missouri Ozark forest.     

UV-B辐射对亚热带森林凋落叶分解的影响

采用分解袋法研究自然和UV-B辐射滤减2种环境下6种亚热带代表性树种(杉木、马尾松、木荷、香樟、青冈和甜槠)凋落叶的分解情况。结果表明:除个别分解阶段外,各树种凋落叶在2种UV-B辐射环境下的干质量剩余率均存在显著差异,且随着分解时间延长,差异逐渐加大;与对照相比,UV-B辐射滤减显著降低了6个树种凋落叶的分解速率(P<0.01),降幅为33.3%～69.6%,对香樟凋落叶分解的影响最小,对杉木凋落叶分解的影响最大;UV-B辐射处理和凋落物类型对凋落叶的分解速率均有极显著影响(P<0.001),以UV-B辐射的影响更强烈;自然和UV-B辐射滤减环境下凋落叶的分解速率均与C∶N呈显著负相关(P<0.05)。     

Decomposition and nutrient release patterns of Phyllostachys bambusoides and Arundinaria racemosa, India

We investigated decomposition and nutrient release patterns of leaf and sheath litter of two important highland bamboo species (viz. Phyllostachys bambusoides Sieb. (Zucc.) and Arundinaria racemosa Munro) by using a litter bag technique. Our objective was to improve understanding of the addition of organic matter and nutrients to soil from the litter of two abundant highland bamboo species, species that support the local population of the region in many ways. N concentration and N/P ratio were significantly higher (p<0.01) in leaf litter of P. bambusoides. Significantly, larger values of lignin concentration, C/N ratio, and lignin/N ratio were found in the sheath litter of A racemosa. Weight loss of both leaf and sheath litter was strongly positively correlated with N and N/P ratio, and significantly negatively correlated (p<0.01) with C/N ratio. Lignin/N had a negative correlation with decay rate. In both species, only lignin concentration of the litter showed strong positive correlation with N release. Litter decomposition and N release patterns were similar for the two bamboo species, whereas, P release rate from leaf litter was higher in P. bambusoides and differed significantly between sheath and leaf litter for both species. The complex pattern of nutrient release through mineralization and immobilization during litter decomposition ensures nutrient availability in both managed and natural bamboo stands subjected to anthropogenic disturbances.     

Decay of Rhizophora apiculata(Blume)and Xylocarpus granatum(Koenig)detrital sources in the Sarawak Mangrove,Malaysia

Decaying mangrove detritus plays a significant role in nutrient cycling and fueling in both the forests and aquatic habitats where the detritus stems from estuarine and coastal food webs.Detrital decay rates partly depend on the type of detritus,but most studies have thus far focused on leaf litter decay and decomposition,whereas other detrital sources(except for roots)have largely been ignored.We compare the decay rates of Rhizophora apiculata and Xylocarpus granatum non-leafy detritus(flowers,propagules,stipules,and twigs)with mangrove leaf litter in field studies,using litter bags during the dry and the wet seasons in the tropical mangrove forest of Sibuti,Sarawak,Malaysia.We observed higher microbial decay rates of stipules,flowers,propagules,and twigs for both the R.apiculata and X.granatumduring the wet months.By contrast,leaf decay rates were higher during the dry months.Decay rates depended on the lignin content of the detrital sources of both species,both during dry and wet months.Accordingly,the half-life(T0.5)and 95%lifespan(T0.95)of non-leaf materials(flowers,propagules,stipules and twigs)for both species were remarkably longer than those of leaf litter.Slowly decaying non-leafy detritus may play a significant role in nutrient and carbon cycling over longer time,when leaf litter is either being decomposing rapidly and/or being washed away by tidal flush and river runoff.Hence,non-leafy(flowers,propagules,stipules and twigs)detritus should be taken into account when budgeting organic matter turnover in mangroves.     

西南桦和尾巨桉凋落叶分解及其与土壤性质的相关性

[目的]探讨南亚热带西南桦和尾巨桉人工纯林的凋落叶分解动态及其与土壤化学性质之间的相关关系.[方法]采用原位分解袋法研究凋落叶的分解过程.[结果]表明:西南桦、尾巨桉人工林凋落叶分解系数分别为0.96 a^-1和0.88 a^-1.在为期12个月的分解试验中,2种凋落叶有机C含量在整个分解过程中呈逐渐下降趋势;全K含量和C/N比在分解前期迅速下降,之后趋于平缓;全N含量和全P含量在整个分解过程中呈逐渐上升趋势;2种凋落叶N/P比则呈先升高后下降的趋势.无论是分解前期还是分解后期,凋落叶质量损失与N含量均呈显著正相关(前期R=0.877;后期R=0.855),与C/N均呈显著负相关(前期R=-0.735;后期R=-0.697).与尾巨桉林地土壤性质相比,西南桦凋落叶分解提高了林地0~10、10~20 cm土壤的有机C、全N、全P、全K、N/P,对2030 cm土壤有机C、全K、pH值、C/N、N/P则未产生显著影响.相关分析表明:凋落叶初始有机C含量与土壤有机C、全N、全P、全K、N/P显著相关;凋落叶初始全N含量与土壤全N、pH值、C/N显著相关.[结论]凋落叶的养分含量与土壤养分的关系紧密;与尾巨桉相比,西南桦凋落叶的养分含量明显较高,分解速率更快,释放到土壤中的养分也更多.     

Decomposition Dynamics and Nutrient Release Pattern from Leaf Litters of Five Commonly Occurring Homegarden Tree Species in Mizoram,India

Leaf litter decomposition and nutrient release patterns from five common multipurpose tree species—viz., Artocarpus heterophyllus, Mangifera indica, Areca catechu, Citrus sp., and Tamarindus indica, found in homegardens of Mizoram—were evaluated using a litter bag technique. The result of the study indicates a varying pattern of decomposition and nutrient release (N&P) among the species. Citrus sp. and T. indica were found to be the most labile species with comparatively much higher decay constant and faster nutrient release. Initial nitrogen concentration, lignin content, and lignin/N ratio of foliage litter showed significantly higher (p < .01) correlation with the decay coefficient and were found to be the important determinants in the decay process. The initial slow release and immobilization of N in A. heterophyllus and M. indica leaf litter reflect their potential as a source of nitrogen storage and effective mulching material. While litter from T. indica and Citrus sp. can provide the short-term nutrient need, foliage for the other three species may supply the long-term nutrient requirement for the understory crops in such agroforestry systems.     

Ecological process of leaf litter decomposition in tropical rainforest in Xishuangbanna, southwest China. III. Enzyme dynamics

We tested the dynamics of nine enzymes during leaf litter decomposition in Xishuangbanna tropical rain-forest both in the field and laboratory to explore the response of enzyme dynamics to decomposition under different food-web structures. We used coarse and fine (1 mm and 100 μm mesh size, respectively) litterbags in the field to create different food-web structures during litter decomposition. Most soil macrofauna such as nematodes could access only the coarse mesh litterbags, leaving only microbiota, such as mites, in the fine mesh litterbags. In the laboratory, sterilization and inoculation were adopted to investigate different enzyme dynamics with nematodes or only microbiota participating in litter decomposition. Invertase and amylase increased more for shorter food webs at the early stages of decomposition, while activities of endocellulase, β-glucosidase, xylanase and polyphenoloxydase increased to their maxima at the later stages, but greater increase occurred with extended food webs. Invertase and amylase had negative relationships and endocellulase, β-glucosidase, xylanase and polyphenoloxydase had positive relationships with litter decomposition (mass loss). The activities of enzymes responded to the process of litter decomposition. Invertase and amylase played key roles for microbiota utilizing the substrates at early stages of decomposition, while endocellulase, β-glucosidase, xylanase and polyphenoloxydase worked on the further decay of recalcitrant compounds at later stages. All enzymes related to carbon decay acted as effective indicators of litter decomposition. The decomposition of plant organic matter was essentially an enzymatic process. __________ Translated from Journal of Plant Ecology (Chinese Version), 2008, 32(3): 622–631 [译自: 植物生态学报]     

Leaf Litter Decomposition,Litterfall, and Effects of Leaf Mulches from Mixed and Monospecific Plantations in Costa Rica

Abstract

Rates of litter decomposition and nutrient release from litter provide valuable information on the capacity of different tree species to replenish soil nutrients in degraded tropical areas. Leaf litter decomposition, leaf litterfall, plantation floor leaf litter, and mulch performance were studied for four indigenous timber species, Virola koschnyiWarb, Dipteryxpanamensis(Pittier) Record and Mell, Terminalia amazonia(J.F. Gmel.) Exell., and Albizia gua-chapele(H.B.K.) Little, grown in mixed and monospecific plantations in the Atlantic humid lowlands of Costa Rica. Terminalia amazonialitter decomposed the fastest: no litter remained after 6 months. After 12 months, D. panamensis, A. guachapele, and the mixed litter decomposed completely, while 15% of the original weight of V. koschnyilitter remained. Differences in decomposition rates were closely related to leaf nutrient content. Total annual leaf litterfall was highest in T. amazonia(872.9 g/m²), followed by D. panamensis, V. koschnyi, and the mixed plots. A. guachapelehad the lowest leaf litterfall (236.0 g/m²). The highest plantation-floor leaf litter was found in V. koschnyiand D. panamensis.Both litterfall and plantation-floor litter accumulation fluctuated least in the mixed plots. A. guachapeleand D. panamensismulch most positively affected maize seedling growth, followed by the mixed mulch. Recommendations are drawn from the results to suggest species choice for sustainable land management in the region.     

Leaf-litter decomposition of 15 tree species in a lowland tropical rain forest in Sarawak: decomposition rates and initial litter chemistry

In a lowland tropical rain forest in Sarawak, leaf-litter decomposition and the initial litter chemistry of 15 tree species were studied. During 13 months of field experiment, weight loss of litter samples was between 44% and 91%, and calculated decomposition rate constants (k) ranged from 0.38 to 2.36 year⁻¹. The initial litter chemistry also varied widely (coefficients of variation: 19%–74%) and showed low N and P concentrations and high acid-insoluble residue (AIS) concentration. For nutrient-related litter chemistry, correlations with the decomposition rate were significant only for P concentration, C/P ratio, and AIS/P ratio (r _s = 0.59, −0.62, and −0.68, n = 15, P < 0.05, respectively). For organic constituents, correlations were significant for concentrations of AIS and total carbohydrates, and AIS/acid-soluble carbohydrate ratio (r _s = −0.81, 0.51, and −0.76, n = 15, P < 0.05, respectively). These results suggested that the relatively slow mean rate of decomposition (k = 1.10) was presumably due to the low litter quality (low P concentration and high AIS concentration), and that P might influence the decomposition rate; but organic constituents, especially the concentration of AIS, were more important components of initial litter chemistry than nutrient concentrations.     

模拟外源性氮磷对马占相思凋落叶分解及土壤生化特性的影响

[目的]研究外源性氮和磷对马占相思凋落叶的分解速率、分解过程中N、P、K含量和土壤生化特性的影响,以便为森林土壤养分管理提供参考。[方法]以广东省云勇林场马占相思林下凋落叶为试验材料,采用尼龙网袋分解法,设置对照(CK)、施N(10 g·m~(-2))、施P(5 g·m~(-2))、施N+P(N 10 g·m~(-2)+P 5 g·m~(-2))4种处理,每隔3个月取样1次,并测定凋落叶残留量和N、P、K含量。[结果]表明:施N、P和N+P处理对马占相思凋落叶的分解均为促进作用。各处理马占相思凋落叶的N含量在分解过程中大致保持稳定,施P和N+P处理的凋落叶P含量在分解过程中总体呈波动性上升,而各处理的凋落叶K含量变化规律不明显。施N、P和N+P处理提高了马占相思林土壤的有机质和全N含量,促进脲酶、磷酸酶及过氧化氢酶的活性。[结论]施N、P和N+P处理促进了马占相思凋落叶的分解,有利于马占相思林的养分循环。     

Decomposition of leaf litter of four native broad-leaved tree species in south China

Leaf litter decomposition of Castanopsis fissa, Cinnamomum camphora, Michelia macclurei and Mytilaria laosensis in mixed broad-leaved plantation and pine plantation was studied by the litterbag method for 1 year. Leaf litter decomposition rates of the four species were highest in Cinnamomum camphora, followed by Mytilaria laosensis, Michelia macclurei, and Castanopsis fissa. The decomposition rates of all four species were higher in the mixed than in pine plantation. The decomposition processes of all species followed Olson’s exponential model. The decomposition coefficients (k) of all species were also higher in the mixed plantation and had the same order as the decomposition rates. The nitrogen contents of leaf litter of the different species studied increased initially and then decreased with time. Net release of N only occurred in pine plantation. Potassium contents appeared to decrease first but later increase, and net release was only found in mixed plantation. Calcium, magnesium and boron all showed similar pattern of initial increase followed by later decrease. They all had net release in both mixed and pine plantations. The release of phosphorus varied greatly between species and showed no clear trend.     

Litter production and decomposition dynamics in moist deciduous forests of the Western Ghats in Peninsular India

A field study was conducted in the moist deciduous forests of the Western Ghats (India) to test the following three hypotheses: (1) Litter production in tropical forests is a function of the floristic composition, density, basal area and disturbance intensity; (2) Decay rate constants of tropical species is an inverse function of the initial lignin/nitrogen ratio; (3) Decomposition rates in tropical forests are faster than temperate forests.

Litter fall was estimated by installing 63 litter traps in the moist deciduous forests of Thrissur Forest Division in the Western Ghats at three sites. Litter fall followed a monomodal distribution pattern with a distinct peak during the dry period from November–December to March–April.Dillenia pentagyna, Grewia tiliaefolia, Macrosolen spp.,Xylia xylocarpa, Terminalia spp.,Lagerstroemia lanceolata, Cleistanthus collinus, Bridelia retusa, andHelicteres isora were the principal litter producing species at these sites. The annual litter fall ranged from 12.18 to 14.43 t ha⁻¹. Structural attributes of vegetation such as floristic composition, basal area, density and disturbance intensity did not directly influence litter fall rates.

Leaf litter decay rates for six dominant tree species were assessed following the standard litter bag technique. One hundred and eight litter bags per species containing 20 g samples were installed in the forest floor litter layer at the same three sites selected for the litter fall quantification exercise. The residual litter mass decreased linearly with time for all species. In general, less disturbed sites and species adapted to higher nitrogen availabilities exhibited relatively higher decay rate coefficients (k). The rapid organic matter turnover observed in comparison with published temperate forest litter decay rates confirms that tropical moist deciduous forest species are characterised by faster decomposition rates.

Mean concentrations of N, P and K in the litter were profoundly variable amongst the dominant species. Initial nitrogen content of the leaf litter varied from 0.65 to 1.6%, phosphorus from 0.034 to 0.077% and potassium from 0.25 to 0.62%.C. collinus, an understorey shrub consistently recorded the lowest litter concentrations for all nutrients. The overriding pattern is one of higher nutrient levels in the overstorey leaf litter and lower concentrations in the understorey litter. Furthermore, as decomposition proceeded, the nitrogen concentration of the residual biomass increased.     

Biomass,decomposition and nutrient release of Vaccinium myrtillus leaf litter in four forest stands

Biomass and nutrient transfer (N, P, K, Ca, Mg) of bilberry (Vaccinium myrtillus L.) leaf litter fall, as well as decomposition and nutrient release, were studied in four mature forest stands situated in Central and South Sweden. Bilberry leaf litter fall amounted to between 33 and 55 kg ha^‐1 yr^‐1 in the four stands. Only minor differences between sites were noted for litter concentrations of N, P and Ca, whereas K and Mg showed somewhat larger variability. Relative amounts of the five nutrient elements in the litter fall were generally in the order N > Ca > K > Mg > P. The amounts of nutrients returned to the forest floor by the annual leaf litter fall in the stands ranged from 0.4 to 0.8 kg ha^‐1 for N, 0.4 to 0.6 kg ha^‐1 for Ca, 0.2 to 0.7 kg ha^‐1 for K, 0.1 to 0.2 kg ha^‐1 for Mg and 0.04 to 0.08 kg ha^‐1 for P.

The decomposition of the local bilberry leaf litter was followed by means of litterbags during three years. At all sites there was an extremely rapid mass loss from the litter (between 45% and 54%) during the first four to five months of decomposition. After this initial phase, the decomposition rates decreased markedly and after three years the accumulated mass losses of the litters varied between 64% and 78% at the studied sites. After two and three years of decomposition, three of the sites exhibited almost similar litter mass losses whereas at the fourth site the litter was decomposed to a significantly lower degree. The pattern of nutrient release from the decomposing bilberry leaf litter differed somewhat from site to site. Minor differences were, however, noted for P, Ca and Mg while N and K were more strongly retained in the litter at one of the sites.     

A comparison of decomposition dynamics among green tree leaves,partially decomposed tree leaf litter and their mixture in a warm temperate forest ecosystem

Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter (i.e., decayed tree leaf litter on forest floor) and a mixture of the two in a warm temperate forest ecosystem in central China to test the influence of litter chemical quality on the degree of decomposition. The study was conducted in situ at two contrasting forest sites, an oak forest dominated by Quercus aliena var. acuteserrata Maxim., and a mixed pine and oak forest dominated by Pinus armandii Franch. and Q. aliena var. acuteserrata. We found marked differences in the rate of decomposition among litter types at both forest sites; the litter decomposition constant, k, was about 39 % greater at the oak forest site and more than 70 % greater at the pine-oak forest site, for green leaves than for partially decomposed leaf litter. The decomposition dynamics and temporal changes in litter chemistry of the three litter types also greatly differed between the two forest sites. At both forest sites, the higher rate of decomposition for the green leaves was associated with a higher nitrogen (N) content and lower carbon to N ratio (C/N) and acid-unhydrolyzable residue to N ratio (AUR/N). We did not find any non-additive effects when mixing green leaves and partially decomposed leaf litter. Our findings support the contention that litter chemical quality is one of the most important determinants of litter decomposition in forest ecosystems at the local or regional scale, but the effect of litter chemical quality on decomposition differs between the contrasting forest types and may vary with the stage of decomposition.