Total Litterfall Research Articles

Litterfall production of mangrove forest in the beach waters of Sepi Bay, West Lombok

Litterfall production of mangrove forest study was carried out in the beach water of Sepi Bay, West Lombok, from July to October 2007. The collection of litter was done every 10 days, and then the litter was dried at 75oC to constant weight and separated into leaves, reproduction organs, and wood part components. The total mangrove litter fall average was 2.71 g/m2/day or 9.9 ton/ha/year, with the leaf, reproduction organs, and branch components being 87.56%, 11.33% and 1.54%. Contribution of Rhizophora mucronata litter fall was 1.48 g/m2/day, R. apiculata 0.49 g/m2/day, Sonneratia alba 0.48 g/m2/day, R. stylosa 0.25 g/m2/day, and Aegiceras corniculatum 0.01 g/m2/day.Key words: mangrove, litterfall, Sepi Bay.

High litterfall in old-growth and secondary upper montane forest of Costa Rica

Tropical upper montane forests usually comprise trees of small stature with a relatively low aboveground productivity. In contrast to this rule, in the Cordillera de Talamanca (Costa Rica), tall trees (>35 m in height and more than 60 cm in diameter) are characteristic for the upper montane old-growth oak forests which are growing at an altitude of almost 3,000 m close to the alpine timberline. For these exceptional forests, productivity data are not yet available. In this study, we analyzed litterfall and its components (tree leaves, litter of epiphytic vascular and non-vascular plants, mistletoes, twigs and other canopy debris) in three forest stands belonging to different successional stages and related seasonal changes in litterfall to micrometeorological variables. The studied stands were early-successional forest (10–15-year-old), mid-successional forest (40-year-old), and old-growth forest. The stands are dominated by Quercus copeyensis and are located at 2,900-m altitude. Total litterfall was highest in the mid-successional forest (1,720 g m−2 y−1), and reached 1,288 g m−2 y−1 in the old-growth forest and 934 g m−2 y−1 in the early-successional forest. Litter mass was dominated by leaves in all stages (56–84% of total litterfall). In the old-growth forest, however, twigs and small canopy debris particles (33%), epiphytes (6%), and mistletoes (5%) also contributed substantially to litter mass. Leaf litterfall showed a clear seasonal pattern with a negative correlation to monthly precipitation and highest values in the dry season (January–April). However, the strongest correlation existed with minimum air temperature (negative), probably because temperatures already dropped at the end of the rainy season, when precipitation had not yet declined and leaf shedding already increased. In contrast, litterfall of epiphyte mass, and twigs and other debris was mostly dependent on occasional strong winds. We conclude that the upper montane oak forests of the Cordillera de Talamanca are exceptional with respect to the large tree size and the relatively high productivity as indicated by litterfall. Litter mass was especially high in the mid-successional and old-growth forests, where the observed annual totals are among the highest recorded for tropical forests so far.

Soil respiration and aboveground litter dynamics of a tropical transitional forest in northwest Mato Grosso, Brazil

Measurements of soil CO2 efflux, litter production, and the surface litter pool biomass were made over a 1 year period in a tropical transitional forest near Sinop, Mato Grosso, Brazil with the aim of quantifying the seasonal variation in soil respiration and litter decomposition and the annual contribution of litter decomposition to soil CO2 efflux. Average annual soil CO2 efflux (±95% confidence interval (CI)) was 7.91 ± 1.16 g C m−2 d−1. Soil CO2 efflux was highest during the November–February wet season (9.15 ± 0.90 g C m−2 d−1) and lowest during the May–September dry season (6.19 ± 1.40 g C m−2 d−1), and over 60% of the variation in seasonal soil CO2 efflux was explained by seasonal variations in soil temperature and moisture. Mass balance estimates of mean (±95% CI) decomposition rates were statistically different between the wet and dry seasons (0.66 ± 0.08 and 1.65 ± 0.10 g C m−2 d−1, respectively), and overall, decomposition of leaf litter comprised 16% of the average annual soil respiration. Leaf litter production was higher during the dry season, and mean (±95% CI) leaf litter fall (5.6 ± 1.7 Mg ha−1) comprised 73% of the total litter fall (7.8 ± 2.3 Mg ha−1). Average (±95% CI) annual litter pool biomass was estimated to be 5.5 ± 0.3 Mg ha−1, which was similar to the measured pool size (5.7 ± 2.2 Mg ha−1). Overall, seasonal variations in environmental variables, specifically water availability (soil moisture and rainfall), had a profound influence on litter production, soil respiration, and surface litter decomposition.

Litter dynamics and soil properties under different tree species in a semi-arid region of Rajasthan, India

Litterfall and decomposition are the two main processes accounting for soil enrichment in agroforestry. The extent of enrichment in soil properties depends on the tree species, management practices and the quantity and quality of litter. A field investigation was carried out to study litterfall production, decay rates, release of nutrients and consequent changes in soil physicochemical properties under crowns of four multipurpose tree species (MPTs) in irrigated conditions in farm fields. The species were Prosopis cineraria (L.), Dalbergia sissoo (Roxb.) ex DC, Acacia nilotica (L.) Del. and Acacia leucophloea (Roxb.) Willd. Annual accretion of litter ranged from 36 to 54 kg tree−1 year−1 and was highest under D. sissoo and lowest under A. nilotica. Total litterfall production was in the order: P. cineraria > A. leucophloea > A. nilotica > D. sissoo. P. cineraria showed the highest NPK concentration in litter. For all MPTs, a large pulse of litterfall coincided with the winter season (November to February). Litter of P. cineraria decomposed fastest while that of A. nilotica was slowest. More than 95% of the leaf litter of P. cineraria decomposed in 6 months, of D. sissoo in 7 months and A. leucophloea and A. nilotica in 9 months. Decomposition rate of litter was highly correlated with neutral detergent fibre (NDF) (r = −0.94) and P (r = −0.91) concentration. N, P and K release were best correlated with NDF, acid detergent fibre (ADF), P, lignin, lignin/N and C/P ratios and NDF alone explained 88% to 94% of the variability in litter decomposition and nutrient release rates. There was significant build up of soil organic carbon and available NPK in the agrisilvicultural systems but also a decrease in soil pH. Build up in soil fertility was significantly correlated with litterfall and soil improvement was greatest under P. cineraria.

Contribution of a liana species, Mucuna macrocarpa Wall., to litterfall production and nitrogen input in a subtropical evergreen broad-leaved forest

Annual amounts of litterfall and nitrogen input by litterfall were measured in a subtropical evergreen broad-leaved forest to examine the contribution of a liana species, Mucuna macrocarpa Wall., to the spatial heterogeneity of litterfall production and nitrogen input. The total litterfall in the study plot was 7.1 t ha−1 year−1. The amount of litterfall varied with topography and was greatest at the valley bottom and decreased toward the ridges. Macuna macrocarpa litterfall was absent on the ridges although it accounted for the largest percentage, 32%, of total leaf litter production in the valley. Nitrogen input by litterfall was 69 kg ha−1 year−1 in the plot. Nitrogen input by litterfall was also largest at the valley bottom and decreased toward the ridges. Leaf litter of M. macrocarpa had approximately twice the nitrogen concentration of litterfall of other species. Macuna macrocarpa accounted for 42% of nitrogen input by leaf litter in the valley. The abundance and the high nitrogen concentration of M. macrocarpa intensified differences in the amount of litterfall and nitrogen input by litterfall between valleys and ridges. It was concluded that a liana species, M. macrocarpa, can contribute to the spatial heterogeneity of litterfall and may subsequently affect nutrient cycling in a subtropical evergreen broad-leaved forest on Okinawa Island.

Landscape patterns of overstory litterfall and related nutrient fluxes in a cool-temperate forest watershed in northern Hokkaido, Japan

Within a forested watershed at the Uryu Experimental Forest of Hokkaido University in northern Hokkaido, overstory litterfall and related nutrient fluxes were measured at different landscape zones over two years. The wetland zone covered with Picea glehnii pure stand. The riparian zone was deciduous broad-leaved stand dominated by Alnus hirsuta and Salix spp., while the mixture of deciduous broadleaf and evergreen conifer dominated by Betula platyphylla, Quercus crispula and Abies sachalinensis distributed on the upland zone. Annual litterfall averaged 1444, 5122, and 4123 kg·hm−2·a−1 in the wetland, riparian and upland zones, respectively. Litterfall production peaked in September–October, and foliage litter contributed the greatest amount (73.4%–87.6 %) of the annual total litterfall. Concentrations of nutrients analyzed in foliage litter of the dominant species showed a similar seasonal variation over the year except for N in P. glehnii and A. hirsuta. The nutrient fluxes for all elements analyzed were greatest on riparian zone and lowest in wetland zone. Nutrient fluxes via litterfall followed the decreasing sequence: N (11–129 kg·hm−2·a−1) > Ca (9–69) > K (5–20) > Mg (3–15) > P (0.4–4.7) for all stands. Significant differences were found in litterfall production and nutrient fluxes among the different landscape components. There existed significant differences in soil chemistry between the different landscape zones. The consistently low soil C:N ratios at the riparian zone might be due to the higher-quality litter inputs (largely N-fixing alder).

Comparisons of litterfall, litter decomposition and nutrient return in a monoculture Cunninghamia lanceolata and a mixed stand in southern China

Litter production, leaf litter decomposition and nutrient return were compared in a monoculture Cunninghamia lanceolata and a mixed stand in southern China. The mean annual litter production was significantly higher 24% in the mixed stand than the monoculture C. lanceolata stand. Within the mixed stand, about 38% of the total litterfall was from broadleaved tree Michelia macclurei. The litterfall was concentrated during the cool and dry period (November-March) and about 65% of total litterfall occurred during this period. The mass loss of leaf litter was positively correlated with N and P content and negatively correlated with C/N ratio. The decomposition rate of leaf litter in the pure stand was increased in the order: C. lanceolata < mixture of C lanceolata and M. macclurei < M. macclurei. Soil conditions also affected litter decomposition. The decomposition rate of mixed litter was slightly, but not significantly, faster in the mixed stand than the pure stand. N concentration in all leaf litters increased over time during decomposition, whereas the remaining amount of N decreased. The returns of N, P and K via leaf litter were significantly higher in mixed stand than pure stand, but the returns of C, Ca and Mg between tooth stands did not differ significantly. The percent contribution of M. macclurei leaf litter to total nutrient return varied from 23% to 79% in the mixed stand. Our results indicated that introduction of broadleaved tree into monoculture coniferous stand could increase litter production, nutrient return and thus it had advantages in degraded soil restoration and sustainable land management. (c) 2007 Elsevier B.V. All rights reserved.

The potential for forest canopy litterfall interception by a dense fern understorey, and the consequences for litter decomposition

Most studies on litter decomposition have assumed that all falling plant litter reaches the ground where it then decomposes. In many forests a proportion of this litter may in fact be intercepted by understorey vegetation, but the ecological significance of this remains poorly understood. We performed two experiments in a temperate rainforest in southern New Zealand, in which there was a dense understorey of the crown fernBlechnum discolor. The fronds of this fern originate from a crown, and have a funnel‐like arrangement that can trap falling litter and prevent it from reaching the ground. The first experiment measured the effects of ferns on the spatial distribution of litter accumulation over one year. The ferns intercepted a substantial proportion of the total litterfall, and the fern crowns (from which the fronds originate) retained 10% of the total incoming litterfall (despite occupying only 2% of the ground area). The retained litter had a substantially higher ratio of twig to foliar litter than did the incoming litterfall. Further, much of the litter not retained on the crowns of the ferns accumulated at the base of the fern trunks. The second experiment considered litter decomposition in fern crowns versus the ground under the ferns. The litter that had accumulated in the crowns was characterized by higher microbial basal respiration and active microbial biomass than was the litter that had accumulated on the ground. The use of litterbags revealed that litter decomposition rates were significantly higher on the fern crowns than on the ground at 30 cm and 60 cm from the fern trunks. These results show that litter interception ameliorates the decomposer environment and increases the rate of litter decomposition. In total, this study provides evidence for understorey ferns greatly influencing both the spatial distribution of litterfall and the decomposition of plant litter. Although the ecological role of understorey vegetation in forested ecosystems has received little attention to date, our results point to understorey species as an important driver of forest ecosystem processes.

Fine Root Production across a Primary Successional Ecosystem Chronosequence at Mt. Shasta, California

Estimating changes in belowground biomass and production is essential for understanding fundamental patterns and processes during ecosystem development. We examined patterns of fine root production, aboveground litterfall, and forest floor accumulation during forest primary succession at the Mt. Shasta Mudflows ecosystem chronosequence. Fine root production was measured using the root ingrowth cores method over 1 year, and aboveground litterfall was collected over 2 years. Fine root production increased significantly with ecosystem age, but only the youngest ecosystem was significantly different from all of the older ecosystems. Root production was 44.5 ± 13.3, 168.3 ± 20.6, 190.5 ± 33.8, and 236.3 ± 65.4 g m−2 y−1 in the 77, 255, 616, and >850-year-old ecosystems, respectively. Generally, aboveground litterfall and forest floor accumulation did not follow the same pattern as root production. The relative contribution of fine root production to total fine detrital production increased significantly with ecosystem age, from 14 to 49%, but only the youngest ecosystem was significantly different from all of the older ecosystems. Fine root production was significantly correlated with some measures of soil fertility but was not correlated with leaf or total litterfall, or forest floor accumulation. It was best predicted by soil N concentration alone, but this relationship may not be causal, as soil N concentration was also correlated with ecosystem age. For the oldest ecosystem, fine root production was also measured using the sequential intact cores/compartment-flow model method, and the difference between the two estimates was not significant. Our study suggests that the relative contribution of fine roots to fine detrital production, and hence to soil organic matter accumulation, may increase during forest primary succession.

Litterfall and nutrient return in a semi-arid southern African savanna woodland dominated by Colophospermum mopane

The objective of this study was to investigate litter production, litter standing crop and nutrient return to soil in a semi-arid southern African savanna in Bulawayo, Zimbabwe. We used a randomized block design with five blocks of 100 × 100 m demarcated in a 10-ha pocket of Colophospermum mopane-dominated open woodland protected from grazing and fire. Litter traps were installed beneath large (8.3 m crown diameter) and small mopane trees (2.7 m crown diameter) and in the intercanopy area, representing 27, 3 and 62% of the woodland area, respectively. Mean annual total litterfall over 2 years of observations was 197, 83 and 35 g m−2 yr−1 beneath large and small trees as well as in the intercanopy area, respectively. Leaf proportions of total litterfall beneath large and small trees and in the intercanopy area were 68.6, 73.0 and 75.3%, respectively. Litterfall followed a uni-modal distribution pattern and was much higher during the period of May–September (dry period) compared to other months. The total potential annual element inputs via litterfall beneath large trees were 2 and 5 times greater than beneath small trees and in the intercanopy area, respectively. Total litter standing crop was 405, 177 and 67 g m−2 beneath large and small trees and in the intercanopy area, respectively. Concentrations of N, P and K in litterfall and surface soil were closely correlated with each other. At all sampling sites, element accession to soil through litterfall followed the decreasing sequence C > Ca > N > Mg > K > P. These results suggest that litterfall is a major process responsible for soil organic matter and nutrient enrichment beneath isolated trees in semi-arid savannas.

Litter production, leaf litter decomposition and nutrient return in Cunninghamia lanceolata plantations in south China: effect of planting conifers with broadleaved species

This study compared litter production, litter decomposition and nutrient return in pure and mixed species plantations. Dry weight and N, P, K, Ca, Mg quantities in the litterfall were measured in one pure Cunninghamia lanceolata plantation (PC) and two mixed-species plantations of C. lanceolata with Alnus cremastogyne (MCA) and Kalopanax septemlobus (MCK) in subtropical China. Covering 6 years of observations, mean annual litter production of MCA (4.97 Mg center dot ha(-1)) and MCK (3.97 Mg center dot ha(-1)) was significantly higher than that of PC (3.46 Mg center dot ha(-1)). Broadleaved trees contributed 42% of the total litter production in MCA and 31% in MCK. Introduction of broadleaved tree species had no significant effect on litterfall pattern. Total litterfall was greatest in the dry season from November to March. Nutrient returns to the forest floor through leaf litter were significantly higher in both MCA and MCK than in PC (P < 0.05). The amounts of N, K, and Mg returned to the forest floor through leaf litter were highest in the MCA, and P and Ca returns were highest in the MCK. Percent contribution of broadleaf litter to total nutrient returns ranged from 41.7% to 86.9% in MCA and from 49.3% to 74.8% in MCK. The decomposition rate of individual leaf litter increased in the order: C. lanceolata < K. septemlobus < A. cremastogyne. Litter mixing had a positive effect on decomposition rate of the more recalcitrant litter and promoted nutrient return. Relative to mass loss of A. cremastogyne decomposing alone, higher mass loss of the mixture of C. lanceolata and A. cremastogyne was observed after 330 days of decomposition. These results indicate that mixed plantations of different tree species have advantages over monospecific plantations with regards to nutrient fluxes and these advantages have relevance to restoration of degraded sites.

Litter fall and decomposition in primary, secondary and plantation forests in the Brazilian Amazon

Litter fall and leaf decomposition represent important functional processes, yet we have a limited understanding of these processes in disturbed and regenerating tropical habitats. Litter production, litterfall phenology and leaf decomposition were examined in primary forests, 14–19-year-old secondary forests and 4–5-year-old Eucalyptus urophylla plantations in the north-east Brazilian Amazon. Total annual litter fall was similar in primary and secondary forests, and lower in plantations. Leaf fall in primary and secondary forests was negatively associated with rainfall, and was highest in the dry season. Leaf fall in Eucalyptus plantations showed an opposite response, and peaked during the wet season. Decomposition experiments were carried out in the three habitats using 1200 litter bags (1 mm mesh) filled separately with leaves from four different species of tree, including an exotic plantation species ( E. urophylla) and trees typical of secondary ( Bellucia spp. and Vismia spp.) and primary forests ( Bertholettia excelsa). Litter bags were re-weighed at 3-month intervals 3, 6, 9 and 12 months after being placed on the forest floor. A repeated measures General Linear Model showed that litter decomposition was similar in the primary and secondary forest, and slowest in the Eucalyptus plantations. Leaves decomposed, from fastest to slowest, in the following order: E. urophylla > B. excelsa > Vismia spp. > Bellucia spp. There was no significant interaction between leaf species and habitat type. Our results indicate that secondary forests regenerating on abandoned and degraded Amazonian lands can be effective at restoring ecosystem processes such as litterfall and decomposition.

Estimates of biomass and primary productivity in a high‐altitude maple forest of the west central Himalayas

AbstractThe paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha−1, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest‐floor litter mass varied between 5.4 t ha−1 (in rainy season) and 6.6 t ha−1 (in winter season). The annual litter fall was 6.2 t ha−1, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation was 19.5 t ha−1 year−1. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g−1 foliage mass year−1) than those of the low‐altitude forests of the region.

Double sampling may improve the efficiency of litterfall estimatesContribution No. 2335 of the New Hampshire Agricultural Experiment Station, Durham, N.H.

The effort required for an extensive litterfall measurement campaign can be prohibitive. We propose a double sampling approach, in which a large set of traps is used in each stand to estimate total litterfall, and only a subset of these traps is sorted to the relevant components. We examine its feasibility using data from a regional litterfall study of eastern white pine ( Pinus strobus L.), in which the variables of interest were biomass of foliar litterfall from pine and nitrogen content of foliar litterfall from all vegetation. Double sampling was more efficient than simple random sampling but only if every trap received a rapid presorting to remove twigs and cones. The optimal strategy when pine foliar litterfall biomass was the target variable was to conduct full sorting on 33% of the traps. When foliar litterfall N was the target, sorting only 20% of the traps was optimal. Holding time costs constant, the variance of estimated pine foliar litterfall biomass could be reduced by 18%, whereas that for foliar litterfall N could be reduced by 49%. Alternately, when variance was held constant, the time cost could be reduced by 17% for pine foliar litterfall biomass or 44% for foliar litterfall N.

Predicting annual canopy litterfall production for Norway spruce ( Picea abies (L.) Karst.) stands

Canopy annual litterfall production in 18 Norway spruce stands in Finland was studied and predictive models developed. The stands ranged in age from 32 to 163 years old and located at latitudes from 60 to 68°N. Stand litterfall had been continuously collected using 6–12 traps per stand for periods of 1–43 years. Dry weight annual total litterfall production (LF total) values ranged from 44 to 677 g m −2 and needle litterfall production (LF needle) values from 27 to 465 g m −2. Stand characteristics (stocking density, height, breast height diameter, stem volume and basal area) were measured and canopy needle biomass estimated using an allometric function. Both mean LF total and LF needle were significantly and negatively correlated with latitude, which was considered to reflect the effects of climate. Of the stand characteristics, mean height was the most important. More detailed analysis revealed that observed inter-annular variability in both LF total and LF needle was related to the effective temperature sum, July temperature and annual precipitation amount, and that significant lag effects for up to 3 years occurred. Multiple linear regression (MLR) models could explain 88% and 82% of the variation respectively in mean LF total and LF needle when only stand and site variables were allowed to enter the model. Corresponding S.E. est values, reflecting model precision, were 33 and 23 g m −2. Interestingly, latitude did not enter the model. MLR models to predict LF total and LF needle for any specific year (by allowing specific weather variables to enter) explained 80% of LF total variability and nearly 70% of LF needle variability. After testing the models with an independent data set from Sweden, we concluded that the models can be used to predict annual canopy litterfall of mature Norway spruce stands for sites in the boreal zone.

Litter Production and Nutrient Contents of Litterfall in Oak and Pine Forests at Mt. Worak National Park

Litter production, nutrient contents of each component of litterfall and amount of nutrients returned to forest floor via litterfall were investigated from May 2005 through April 2006 in Quercus mongolica, Quercus variabilis and Pinus densiflora forests at Mt. Worak National Park. Total amount of litterfall during one year in Q. mongolica, Q. variabilis and P. densiflora forests was 542.7, 459.2 and <TEX>$306.9\;g\;m^{-2}\;yr^{-1}$</TEX>, respectively. Of the total litterfall, leaf litter, branch and bark, reproductive organ and the others occupied 50.3%, 22.7%, 10.1 % and 16.9% in Q. mongolica forest, 81.9%, 7.2%, 3.1% and 7.9% in Q. variabilis forest, 57.4%, 12.8%, 5.6% and 24.1 % in P. densiflora forest, respectively. Nutrients concentrations in oak litterfall were higher than those in needle litter. N, P, K, Ca and Mg concentration in leaf litterfall were 13.8, 1.1, 7.2, 4.2 and 1.3 mg/g for Q. mongolica forest, 10.5, 0.7, 3.2, 3.7 and 1.6 mg/g for Q. variabilis forest, 5.3, 0.4, 1.2, 2.8 and 0.6mg/g for P. densiflora forest, respectively. The amount of annual input of N, P, K, Ca and Mg to the forest floor via litterfall was 43.36, 2.89, 21.38, 23.31 and <TEX>$5.62\;kg\;ha^{-1}\;yr^{-1}$</TEX> for Q. mongolica forest, 32.28, 2.01, 10.23, 20.29 and <TEX>$7.78\;kg\;ha^{-1}\;yr^{-1}$</TEX> for Q. variabilis forest, 15.80, 1.04, 3.99, 9.70 and <TEX>$2.10\;kg\;ha^{-1}\;yr^{-1}$</TEX> for P. densiflora forest, respectively.

Litterfall, litter decomposition and nutrient dynamics in a subtropical natural oak forest and managed plantation in northeastern India

In northeastern India, subtropical forests are over-exploited for timber, fuel wood and common agricultural practice like shifting cultivation, which are responsible for the degradation of natural forest. In degraded areas, large-scale plantations of different species of Quercus have been raised since 1980 for the production of economic Tasar silk. Conversion of natural forest into plantation affects the process of nutrient cycling due to management practices. Thus, it would be of importance to study the litterfall, litter decomposition process and the factors regulating the rate of litter decay in these ecosystems to improve recommendations for their management and conservation. We recorded litterfall by using litter traps and decomposition of leaf litter by nylon net bag technique to understand the amount of organic matter and nutrient return and their release in soils of forest and plantation in Manipur, northeast India. Total litterfall was 419.9 g m −2 year −1 in plantation and 547.7 g m −2 year −1 in forest. Litter decomposition rate was faster at plantation site than the forest in the early stage of litter decomposition whereas the reverse was observed at later stages of decomposition. Stepwise regression analysis showed the significant role of relative humidity and mean temperature on mass loss rates in the forest. Relative humidity, maximum temperature, population of fungi and actinomycetes were the best predictor variables for mass loss rates in plantation. Nutrient retranslocation efficiency and the immobilization of N and P in forest litter were higher than plantation. This suggests that Q. serrata growing in natural ecosystem in oligotrophic condition adapted strong nutrient conservation mechanisms to compete with the other plant species for the meager soil nutrients. The same species in plantation loses these adaptive capabilities because of exogenous supply of nutrients and in the absence of intense competition with other plant species. Thus, the optimization of organic and chemical fertilizer input in plantation is recommended for maintaining the soil fertility level to produce quality leaf for silkworm by conserving essential nutrients in the system.

Changes in the ratio of twig to foliage in litterfall with species composition, and consequences for decomposition across a long term chronosequence

In the past two centuries, anthropogenic fire suppression has affected many biomes, including boreal forests. Absence of fire in the boreal zone is often linked to declining soil fertility and increased carbon sequestration in the humus through changes in NPP and litter decomposition. We studied tree litterfall and litter decomposition for thirty lake islands in the boreal forested zone of Sweden, which differ naturally in fire regime: larger islands have burned far more frequently than smaller ones because they are intercepted more often by lightning. We used litter trays to show that the ratio of twig to foliar litterfall for Picea abies with prolonged absence of fire is largely responsible for the concomitant increased twig proportion in the total litterfall. We hypothesised that the increased twig proportion in the litterfall with time since fire would affect overall decomposition by reducing net litter quality and through impairing decomposition of associated foliar litters. We established a litter decomposition mesocosm experiment based on litter from the three main tree species found on the islands. From each of the thirty islands, we prepared a set of litterbags comprising three mixtures (all foliar litters combined, all twig litters combined, and all twig and foliar litters combined), plus monotypes (i.e. each of the separate foliage and twig litters for each species). Unlike most studies, we used the natural litterfall proportions in the mixtures. We found a (negative) effect of time since wildfire on decomposition rate for only the foliage‐twig mixtures, although twig litter did not inhibit the decomposition of foliar litter within these mixtures. The reduced decomposition rate in the foliage‐twig mixture from the small islands was therefore due to the increased proportion of twigs in the mixtures from these islands. Our results suggest that, with prolonged absence of fire, the increase of twig proportion in the foliage‐twig litterfall for P. abies combined with the shift to canopy dominance by P. abies may be important in contributing to reduced decomposition rates in boreal forest soils.

Influence of site characteristics and thinning intensity on litterfall production in two Pinus sylvestris L. forests in the western Pyrenees

Litterfall production was studied for 30 months in two contrasting Pinus sylvestris L. stands in the western Pyrenees managed under two low thinning intensities: Aspurz (625 m a.s.l., Mediterranean climate) and Garde (1335 m a.s.l., continental climate). Nine 0.12 ha plots per site were set up with three treatments three times repeated: removal of 0% (not thinned, P0), 20% (P20) and 30% (P30) of initial basal area. Total litterfall was significantly higher in Aspurz (5533 kg ha −1 year −1) than in Garde (3986 kg ha −1 year −1). Maximum annual needle fall values were in September (Aspurz) or October (Aspurz and Garde), and second order peaks were in June or July at both sites. In both sites, cones and other pine organs (e.g., seeds, inflorescences) showed the same seasonal patterns, while bark and branches, affected by sporadic occurrence of storms or snowfalls, followed no clear pattern. Low thinning effects were site-dependent (e.g., needles; Aspurz, P0 > (P20 = P30); Garde, P0 > P20 > P30) due to between site differences in stand structure. Thus, more dominant and codominant trees (i.e., high litterfall producers) were felled in P30 than in P20 in Garde relative to Aspurz. Needle fall in Aspurz showed unique significant positive correlations with days of dryness and moisture deficit, probably reflecting its Mediterranean climate. However, relative to Aspurz, Garde exhibited significant retarded responses of total litterfall and needle fall to changes in air temperature, soil temperature and soil moisture suggesting in part that Garde's needles are more resistant to climatic stress. Furthermore, litterfall was better predicted in Aspurz than in Garde, partly due to the greater influence of sporadic windstorms and snowstorms in Garde. It appears that in these Pyrenean P. sylvestris stands, site-dependent climatic variables have an important control on litterfall. At the local scale, however, stand structure influences effects of thinning on litterfall.

Input, accumulation and turnover of organic matter, nitrogen and phosphorus in surface organic layers of an upper montane rainforest in Sri Lanka

Summary Small litterfall was collected monthly for 3 years from traps in an upper montane rainforest at Hakgala in Sri Lanka. The range of mean total litterfall was 6.6–8.7 Mg ha −1 yr −1 of which 77–83% was leaf litter. The inputs of N and P in litterfall were 111.7 and 5.4 kg ha −1 yr −1 , respectively. The mean accumulation of litter on the forest floor was 10.16 Mg ha −1 of which 72% was woody litter. The turnover time of total fine litter was 1.3 years while that of N and P was 1.0 and 0.7 years, respectively, indicating high nutrient circulation. There was low stand use efficiency for N and P (69 and 1437, respectively). Brief comparison is made of the data from this tropical montane forest with other tropical montane forests.