Annual Litter Production Research Articles

Temporal and structural effects of stands on litter production in Melaleuca quinquenervia dominated wetlands of south Florida

Melaleuca quinquenervia dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive tree. We delineated large-, intermediate-, and small-tree stands in non-flooded, seasonally flooded and permanently flooded areas of Florida in 1997, measured their biological attributes, and then quantified litterfall components for 3–4 year periods. Melaleuca wood components and mature seed-capsules comprised the largest and the smallest portions of aboveground biomass, respectively, while leaves, fine stems, mature fruits, bud scales, floral structures, and residues represented decreasingly smaller fractions of the litter during the succeeding year. Dry weight proportion of leaves in litter was greatest (80.9%) in non-flooded and least (69.1%) in permanently flooded habitats. It was also greatest in small (85.6%) and least in large (64.7%) tree stands. Reproductive structures and mature-fruit fractions in litter were highest in large-tree stands whereas the bud-scale fraction showed no relationship to tree size. Seasonally flooded habitats had the most litterfall, wherein small-, intermediate-, and large-tree stands generated 0.662, 0.882, and 1.128 kg m 2 yr 1 , respectively. Dry weight of stems, leaves, bud–scales, floral structures, and mature fruit fractions in litter increased as the predominant size of the trees in the stand increased. Total annual litter production was highest during 1999–2000. Leaf fall occurred year-round with maximal amount during April, July, and October. Highest amounts of bud scales and floral structures fell during October–January, which corresponded with flushes of vegetative growth and major flowering events. Overall, melaleuca alone accounted for nearly 99% of the total litterfall dry weight in all habitats and months sampled. The amount of non-melaleuca litter was greater in small-tree stands than in intermediate- or large-tree stands. Litterfall data of this nature will be helpful in detecting changes occurring in melaleuca canopies in response to biological control impact and in prescribing site-specific management strategies.

Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia

To determine annual litter production of regenerating forest areas in the Tigray highlands of northern Ethiopia monthly litter production was monitored over a two-year period in areas with varying degree of vegetation cover restoration. Total annual litter production varied from 30 to 425 g m −2 and increased significantly where areas were closed for a longer time. Litter production was depending on vegetation cover through an exponential relation and was influenced also by soil fertility. Leaf litter typically constituted between 70 and 85% of total litter production, while contributions of woody and reproductive litter varied according to species composition. Strong seasonality in litterfall was explained by pronounced seasonal variation in rainfall. Standing crop of litter built up once an area was closed for grazing, increasing from around 20 g m −2 in degraded grazing lands to nearly 600 g m −2 in an old exclosure. Litter accumulation was mainly determined by litter input, but was also influenced by litter quality, species composition and microclimate development in the restoring forest areas. A detailed study of nine dominant shrub and tree species revealed three distinct litter production patterns, corresponding to drought-deciduous species, evergreen species and (semi-)evergreen Acacia species respectively.

Litterfall and Decomposition of Rhizophora mangle L. in a Coastal Lagoon in the Southern Gulf of Mexico

The dynamics of Rhizophora mangle litter production and decomposition were studied in a tropical coastal lagoon on the Gulf of Mexico in Veracruz, Mexico over a year (October 2002–October 2003). This region is characterized by three seasons: northerly winds (called ‘nortes’), dry, and rainy. Annual litter production (1116 g m−2) followed a seasonal pattern with leaf litter as the main fraction (70%) with two peaks in the dry and one in the rainy season. Leaf decomposition was evaluated with two types of litter bag in each season: fine mesh (1×1 mm) and coarse mesh (3×7 mm). Decomposition data were adjusted to a single negative exponential model. The results indicated faster decomposition rates in the coarse litter bag and significant differences among seasons. However these differences occurred after the 60th day of decomposition, indicating that leaching and microbial action were responsible for more than 50% of mass loss. After this period, the effects of aquatic invertebrates were evident but depended on climatic conditions. In the rainy season, the gastropod Neritina reclivata was associated with increasing leaf decomposition rate. In the ‘nortes’ season, the effect of aquatic invertebrates was smaller, and there were no differences in the decay constants calculated for the two litter bag types. High litter production represents an important input of organic matter which, through decomposition, may represent an important source of C, N, and P in this aquatic system.

Aboveground litter production, accumulation, decomposition, and tidal transportation of coral reef-type mangrove forest on Pohnpei Island, Federated States of Micronesia

Litter production, accumulation, and decomposition were examined on the seaward and landward sides of a long-term mangrove research site on Pohnpei Island, the Federated States of Micronesia, to estimate the contribution of litter deposited on the mangrove forest floor to carbon accumulation in mangrove forests. The annual litter production in the forest site was relatively high, 15 Mg ha-1 yr-1. The litterfall was composed of leaves (55%), reproductive organs such as flowers and seeds (34%), and bark and small branches (11%). The seasonal fluctuation of the litter was small. The amounts of litter deposited on the floor were 0.51 Mg ha-1 on the seaward side and 0.76 Mg ha-1 on the landward side. Compared with the mangrove substratum, the litter deposited on the forest floor has an extremely low capacity to act as a carbon sink. During the first year of the leaf decomposition, the mangrove leaves decomposed markedly (k = 7.0 - 18.2) faster than the leaves of the terrestrial mahogany forest (k = 0.3). The mangrove leaves decomposed rapidly, losing more than 60% of their initial weight in the first month. This high rate might result from leaching of labile fraction from the leaves by the high frequency of immersion as well as by the high levels of activity of decomposers on the forest floor at high temperatures and humidity. Moreover, the effect of crab’s feeding on the litter disappearance could not be disregarded. Tidal litter transportation rate was examined by collection of marked leaves along a tide level gradient. The transportation rate was greater as the highest tide level was higher. This study clarified that the disappearance of litter on the mangrove forest floor was strongly influenced by the tide, especially on the seaward side, as well as by the active microbial and faunal decomposability. We concluded that, despite the mangrove forest’s high litter production, litter on the forest floor did not contribute much to carbon accumulation, especially on the seaward side, since litter was disappeared rapidly from forest floor by tidal exportation and strong microbial activity.

Litter Production and Soil Condition Under Agroforestry Trees in Two Agroecological Zones of Southern Nigeria

ABSTRACT Tree species in agroforestry systems contribute to soil improvement through the litter produced on the soil surface and below-ground modification of soil structure by tree roots. Therefore, litter production and soil characteristics under 11 tree species were evaluated in the derived savanna (Ibadan) and humid tropical forest (Onne) zones of southern Nigeria between 1998 and 1999 in 7-year old arboreta. In Ibadan, the soil was a gravelly Alfisol, while in Onne it was an Ultisol. The trees were Alchornea cordifolia, Baphia pubescens, Calliandra calothyrsus, Dactyladenia barteri, Dialium guineense, Grewia pubescens, Inga edulis, Irvingia gabonensis, Nauclea diderrichii, Pterocarpus santalinoides and Treculia africana. Forest and natural regrowth (no-tree) plots were included as control. Litter-fall under the trees ranged from 5 to 14 t ha−1 y−1 compared to 15 t ha−1 y−1 for the forest at Ibadan, while it ranged from 7to16tha−1y−1 compared to 20t ha−1 y−1 for the forest at Onne. Litter production was high under D. barteri and I. edulis and relatively low under A. cordifolia, G. pubescens, I. gabonensis and P. santalinoides. There was a more drastic change in soil chemical properties in the Alfisol than the Ultisol, particularly with available P. Soil bulk density and penetrometer resistance were improved by A. cordifolia, C. calothyrsus, D. guineense, G. pubescens and T. africana. This study showed that ecological differences resulted in differences in annual litter production for only 33% of the species considered. However, the effects of the trees on soil properties were strongly linked to inherent soil properties.

Leaf litter production and decomposition in a poplar short‐rotation coppice exposed to free air CO2 enrichment (POPFACE)

AbstractThe capacity of forest ecosystems to sequester C in the soil relies on the net balance between litter production above, as well as, below ground, and decomposition processes. Nitrogen mineralization and its availability for plant growth and microbial activity often control the speed of both processes. Litter production, decomposition and N mineralization are strongly interdependent. Thus, their responses to global environmental changes (i.e. elevated CO2, climate, N deposition, etc.) cannot be fully understood if they are studied in isolation. In the present experiment, we investigated litter fall, litter decomposition and N dynamics in decomposing litter of three Populus spp., in the second and third growing season of a short rotation coppice under FACE. Elevated CO2 did not affect annual litter production but slightly retarded litter fall in the third growing season. In all species, elevated CO2 lowered N concentration, resulting in a reduction of N input to the soil via litter fall, but did not affect lignin concentrations. Litter decomposition was studied in bags incubated in situ both in control and FACE plots. Litter lost between 15% and 18% of the original mass during the eight months of field incubation. On average, litter produced under elevated CO2 attained higher residual mass than control litter. On the other end, when litter was incubated in FACE plots it exhibited higher decay rates. These responses were strongly species‐specific. All litter increased their N content during decomposition, indicating immobilization of N from external sources. Independent of the initial quality, litter incubated on FACE soils immobilized less N, possibly as a result of lower N availability in the soil. Indeed, our results refer to a short‐term decomposition experiment. However, according to a longer‐term model extrapolation of our results, we anticipate that in Mediterranean climate, under elevated atmospheric CO2, soil organic C pool of forest ecosystems may initially display faster turnover, but soil N availability will eventually limit the process.

Litter dynamics and particulate organic matter outwelling from a subtropical mangrove in Okinawa Island, South Japan

Litter dynamics and outwelling of particulate organic matter (POM) was investigated in a subtropical mangrove (Okinawa Island, South Japan) in order to quantify the impact of mangrove POM on adjacent intertidal sediments. A distinct seasonal pattern was found with maximum litter fall during the autumn season, and minimum during winter. Total litter production between sites did not differ significantly. Tall mangroves (average 7 m) did not show any higher contribution to the litter production than short mangroves (average 4 m). The mean annual litter production was 12.95 ± 2.95 t ha −1 (dry weight) with leaf fall contributing more than 70% of the total litter production. Analysis of fatty acids (FAs) in the surface sediments of an adjacent mud flat and sand flat during the winter, spring and autumn seasons indicated that outwelling of POM from the mangrove ecosystem occurs. However, it is spatially restricted to within 300 m from the mangrove forest. The magnitude of the outwelling increased during spring and autumn consistent with the increase in the total litter production. Despite the presence of mangrove-derived organic matter in the estuarine surface sediments, autochthonous sources of organic matter, green macroalgae ( Ulva pertusa and Enteromorpha intestinalis), diatoms and bacteria are the main contributors of sedimentary organic matter and ω3 and ω6 PUFAs than mangrove-derived (POM) during winter and spring. While the contribution of mangrove-derived POM to sedimentary organic matter is limited to the autumn season.

Aspectos da ciclagem de nutrientes em uma formação de restinga na Ilha do Mel, Paranaguá-PR

The present study approached some aspects of the nutrient cycling in a Restinga formation, at Ilha do Mel, Paranagua, Parana, Brazil. The monthly and annual litter production and accumulation, as well as nutrient contents; the nutrient contents in fresh leaves and in the litterfall of the most important species of community; the decomposition and the nutrient renovation rates of accumulated litterfall; the foliar litterfall decomposition and the nutrient mineralization were studied. The annual litter production (5080,6 kg. ha-1), as well as other Restinga formation, is inferior than those of the majority of the tropical forests, probably due to the edaphic conditions. The litter production, caracterized by foliar fraction, was more intense in high temperature and precipitation period. The annual medium concentrations of nutrients in the produced foliar litterfall are whithin the variations found in tropical forests, highligthing the low concentrations of N, Cu, Mn and Fe, while Ca, P and B presented relatively high discharges. Ternstroemia brasilienses, Tapirira guianensis, Guapira opposita, Ilex theezans and Clusia criuva represented 60,3% of the total of leaves deposited during the year. The medium contents of Ca, N, P and Mg, obtained in fresh leaves of the four analyzed species (Guapira opposita, Ocotea pulchella, Tapirira guianensis, Ternstroemia brasiliensis), showed higher than those described for other forests on sandy soils. The results suggest an strong influence of the salt spray in the input of the nutrients to the ecossystem, mainly Ca, Mg and B. A great litter accumulation (5541,9 Kg. ha -1ano-1) was not observed, in despite of the calculated decomposition coefficient values are considered low for tropical forests. The slow decomposition observed in the restinga ecosystems is probably due to the high degree of vegetable scleromorphy, which is allied to the edaphic conditions. This characteristic, as well as the synchrony observed between

CASSAVA LEAF LITTER ESTIMATION IN ON-FARM TRIALS

Cassava (Manihot esculenta) returns organic matter and nutrients to the soil through leaf litter and these amounts need to be quantified to help understand and design sustainable cropping systems. Our objectives were to estimate dry matter and nutrient contents in cassava leaf litter and to derive relationships between litter fall and easily measurable cassava yield components. Litter traps (1 m2) were placed in farmers' fields for monthly monitoring during a three year period. Maximum monthly leaf litter production ranged from 0.5 to 1.0 t ha−1, and occurred at the end of the first rainy season and at the onset of the next rainy season. In the first year, the mean dry matter of leaves collected during 12 months of growth was 3.4 t ha−1 for the unamended treatment, and 4.1 t ha−1 when N-P-K fertilizer was applied. The totals were 2.4 and 3.0 t ha−1 in 2000–2001 and 1.6 and 2.5 t ha−1 in 2001–2002, respectively. Annual differences were apparently related to rainfall. The relationship with fresh root yield was best described using one slope and yearly intercepts giving an r2 of 0.63. This relationship can be exploited for estimating litter dry matter in agronomic experiments when rough estimates are sufficient, keeping in mind that the relationship may not be the same for cultivars of differing architecture. Otherwise, the use of litter traps gives the best estimate of annual litter production.

LITTER PRODUCTION AND LITTER NUTRIENT CONCENTRATIONS IN A FRAGMENTED AMAZONIAN LANDSCAPE

We analyzed the effects of distance to forest edge and soil texture on fine‐litter production and on nutrient concentrations in the leaf fall in an experimentally fragmented landscape in Brazilian Amazonia. Production of fine litter (leaves, twigs <2 cm in diameter, flowers, and fruits) was measured over a 3‐yr period. Litter traps were installed in plots located near (<100 m) and far (>250 m) from forest edges, and in clayey or sandy soils. In total, 28 plots were established, with 10 litter traps per plot. Results reveal a significant effect of distance to forest edge on litter production, but no significant effect of soil type or interaction between soil type and edge distance. On average, annual litter production on edge plots exceeded that on the interior plots by 0.68 Mg/ha (9.50 ± 0.23 vs. 8.82 ± 0.14 Mg·ha−1·yr−1, mean ± 1 se, based on a 3‐yr period). With regard to nutrient concentrations in the leaf fall, we detected a significant effect of soil type on three of eight nutrients analyzed. Concentrations of N, Mg, and Mn were greater in leaves on clayey than on sandy soils. Distance to forest edge only significantly affected the concentration of Ca, which was greater near than far from edges, perhaps due to strong Ca mobilization by the roots of pioneer trees.Several factors may account for the observed increase in litterfall near forest edges, including the greater prevalence of winds, increased plant desiccation stress, and higher rates of tree recruitment, especially of pioneer trees, near edges. Elevated rates of litterfall are likely to have cascading effects on the ecology of fragmented forests, affecting the invertebrate fauna, increasing seed and seedling mortality, and causing forest fragments to be more vulnerable to destructive surface fires.

TWENTY YEARS OF LITTER FALL DYNAMICS IN SUBTROPICAL EVERGREEN BROAD-LEAVED FORESTS AT THE DINGHUSHAN FOREST ECOSYSTEM RESEARCH STATION

In this paper, we summarize 20 years of observations and measurements on the production, composition, and seasonal dynamics of litter and leaf litter production of dominant species in the southern subtropical evergreen broad-leaved forests at the Dinghushan Forest Ecosystem Research Station. Annual litter production ranged from 6.39 t·hm -2 to 11.04 t·hm -2 with an average of 8.45 t·hm -2. The variation in the annual litter fall was remarkable. Total litter production decreased over the past 20 years reflecting changes in the compositional characteristics and successional stages of the forest. There were two litter fall peaks each year: one at the beginning of the rainy season (April and May) and the other at the end of the rainy season (August and September). The different components of litter production showed a consistent annual temporal sequence in the following order: leaves; flowers and other mixed-materials; branches. The mean annual leaf litter production of Castanopsis chinensis, Schima superba, Cryptocarya chinensis and Cryptocarya concinna was 1.86, 0.50, 0.26 and 0.40 t·hm -2, respectively, which accounted for about 70% of the total leaf litter production. Leaf litter production of the dominant species greatly influenced the dynamics of total litter production, and, to some degree, the dynamics of litter production reflected changes in the forest biomass and community composition over the past 20 years.

Litter-fall and litter decomposition in a low Mediterranean shrubland

Annual production of litter by Cistus incanus (L.) and Myrtus communis (L.) and decomposition dynamics of leaf litter of these species was studied in a Mediterranean shrubland. Myrtus and Cistus produced 472 and 429 g dry weight litter m-2 year-1, respectively. Leaves were the predominant litter component for both species. The average decay constant of Myrtus and Cistus litters enclosed in litter bags, calculated over the whole study period (38 months), was 0.71 year-1 and 0.31 year-1 respectively. In green leaves the N content differed during growth seasons for both species, whereas the content of Ca, Mg, P, K, and Na did not show significant changes. Abscised leaves had lower N, P and K contents than green leaves, evidencing that a nutrient translocation before abscission occurred from senescent leaves. The nutrient contents of the leaves at abscission time, generally higher in Cistus than in Myrtus, allowed us to estimate the annual nutrient input to the soil. Phosphorus and K more than N were rapidly released by the decomposing litters after exposure. Nutrient limitation, in particular P, might be considered the main growth limiting factor for Myrtus and Cistus. Both species were adapted to recovery and rapidly recycle P more than N and K in the living biomass through retranslocation from green leaves before abscission and/or a high release rate from the decomposing litter. The former strategy was better used by Cistus, the latter by Myrtus.

Produção e decomposição de serapilheira em um sistema agroflorestal implantado para recuperação de área degradada em Viçosa-MG

Este estudo teve por objetivos quantificar a produção e decomposição de serapilheira em um sistema agroflorestal em Viçosa-MG e comparar a produção de serapilheira com resultados obtidos em florestas estacionais semideciduais da Região Sudeste do Brasil. Foram utilizados 20 coletores de 0,5 x 0,5 m com fundo em tela de náilon com 1,0 mm² de malha, colocados a 10 cm acima da superfície do solo. As coletas foram realizadas mensalmente, durante o período de um ano, de setembro de 2000 a agosto de 2001. Em laboratório, o material depositado mensalmente nos coletores foi triado nas frações folhas, ramos (até 2,0 cm de diâmetro) e material reprodutivo, seco em estufa a 70 ºC e pesado em balança de precisão. A produção anual de serapilheira foi estimada em 10.165,13 kg/ha (67,46% de folhas, 19,87% de material reprodutivo e 12,67% de ramos). Os maiores valores de produção ocorreram no final da estação seca, atingindo valor máximo em setembro. O coeficiente de decomposição (K) foi de 1,17 e o tempo necessário para o desaparecimento de 50% da serapilheira foi estimado em 215 dias.

Litter production and nutrient return in agroforestry system

A field study was conducted to investigate the litter production and nutrient return behaviour of Bamboo in an agroforestry system. The combined crop of bamboo plantation intercropped with Pigeon pea produced higher quantity of litter than pure bamboo stand alone. The litter fall for all ages of plant indicated bimodel pattern with a principal peak in the winter and another in the late summer. Of the total annual litter production, leaf-litter accounted for 58% and twig-litter 42%. The annual litter production was 13.5 t ha-1 in pure bamboo stand and 15.7 t ha-1 in the above agroforestry system. With regards to nutrients highest concentration of N, P, Ca and Mg was in leaf-litter. In twig litter maximum concentration of K was observed. On an annual basis, 89, 6, 78, 42 and 49 kg ha-1 (Pure bamboo stand) and 113, 9, 106, 52 and 60 kg ha-1 (Agroforestry system) of N, P, K, Ca and Mg respectively were returned through litter fall. Maximum amount of all the nutrients were returned through leaf-litter and lowest through twig litter.

Litterfall and Leaf Area Index in the CONECOFOR Permanent Monitoring Plots

Forest canopies are more sensitive and react more promptly to abiotic and biotic disturbances than other stand structural components. Monitoring crown and canopy characteristics is therefore a crucial issue for intensive and continuous monitoring programs of forest ecosystem status. These observations formed the basis for the measurement of annual litter production and leaf area index (LAI) in the Italian permanent monitoring plots (CONECOFOR program) established within the EC-UN/ECE program "Intensive Monitoring (Level II) of Forest Ecosystems". Preliminary results after three years of observation are presented. The low value of within plot mean relative standard deviation (20.8 ± 1.9%) of litter production, which in any case never exceeded 30%, accounted for the good sampling error and accuracy of the chosen method, which seems to be accurate enough to detect changes in litter production through the years. The higher inconsistency of the amount of woody and fruits fractions over the years demonstrated the greater reliability of leaf fraction or, on the other hand, of LAI compared to total litter. Mean values of annual leaf-litter and total litter production and LAI were rather high in comparison with data reported in literature for similar stands, and reflected both a medium-high productivity and a juvenile phase in the development of the selected stands on average. Focusing on changes in litter production through the years, statistical analysis on a sub-sample of plots showed the existence of significant differences both in leaf litter and total litter production. These findings seem to attribute to the "year" factor a driving role in determining changes in litter production and LAI. Temporal intermittence in data collection, together with the shortness of the monitoring period, make it difficult to speculate or arrive at definitive conclusions on changes in litter production due to time-dependent factors. The importance of having a complete database to increase index representativeness and reliability and, on the other hand, of performing an integrated results analysis which takes into account the outcomes of other research actions, is recognized as an indispensable requirement for achieving the goals of the monitoring program.

Litter Production and Nutrient Return in Bambusa bambos Plantation

From January 1992 to December 1994 we investigated the litter production and nutrient cycling behavior of Bambusa bambos plantations of different ages. The annual litter production was 15.4 t ha▭ 1, 17 t ha▭ 1, and 20.3 t ha▭ 1 in 4-, 5- and 6-year-old plantations. Litter production was significantly higher compared to other plantations of similar age. Litter fall had a bimodel pattern with a principal peak in the winter and another in the late summer in all ages. Of the total annual litter production, leaf-litter accounted for 58% and twig-litter 42%. With regards to nutrients, the highest concentration of N, P, Ca and Mg was in leaf litter. On an annual basis, 120, 10, 101, 60 and 66 kg/ha (4 year), 141, 13, 121, 72 and 79 kg/ha (5 year) and 184, 16, 183, 91 and 96 kg/ha (6 year) of N, P, K, Ca and Mg were returned through litter fall. The maximum amount of all nutrients was returned through leaf-litter and lowest amount through twig-litter.

Ecological Studies on Subtropical Evergreen Broad-leaved Forest in Okinawa, Japan: Litter Production and Nutrient Input

Patterns of litterfall and nutrient input in a subtropical evergreen broad-leaved forest in northern Okinawa, Japan, were studied during May, 1996–April, 1999. The mean annual rate of litterfall in the five sampling plots ranged from 6.84 to 8.93 Mg ha− 1 yr− 1, of which 63.3–68.5% were leaves; 22.4–29.1% woody parts (including branches < 5.0 cm in diameter and bark); 2.8–5.0% sexual organs and 4.6–6.3% miscellaneous material. Significant differences were found among plots and among years. Significantly monthly differences pronounced seasonal patterns in litterfall were observed. Total litterfall and leaf litter showed negative correlations with relative basal area of the dominant species,Castanopsis sieboldii; and showed positive correlations with mean height of the stands. The dominant species,C. sieboldii produced an average of 2.36 Mg ha − 1 yr − 1 of leaf litter, which covered 30.5% of the annual litter production, and the nutrient input from those litterfall contributed 32.3, 28.3, 30.2, 22.2, 32.5, and 30.5% of total N, P, K, Ca, Mg, and Na, respectively. Nutrient use efficiency in litter production was high, especially for P and K compared with other broad-leaved forests in Japan indicating that P and K may be limiting in Okinawan evergreen broad-leaved forest.

Produção de serapilheira em clareiras de uma floresta estacional semidecidual no município de Campinas, SP

Litter production was studied in 10 natural gaps of Santa Genebra Municipal Reserve (22°49'45S and 47°06'33W) in Campinas, Sao Paulo state. Thirty wooden litter traps of 0.5 x 0.5 m with nylon screen bottoms and 1.0 mm2 mesh were used, placed 10 cm above the surface of the soil. Collections took place on a monthly basis, from January to December of 1997. In laboratory, the material deposited in the traps was separated in the fractions of leaves, branches (up to 2.0 cm of diameter), flowers and fruits, dried in stove to 70°C and weighed in analytic scale. The annual litter production for the gaps as a whole was estimated in 5968 kg.ha­1, the fraction leaves accorenting for 75.87% of the total dry weight, followed by branches, fruits and flowers with 19.27%, 3.17% and 1.69%, respectively. Litter production was uniform throughout the year, thus showing a seasonal pattern with the largest values at the end of the dry season, reaching a maximum value in September. Among gaps, litter production was significantly and positively correlated with the dominance of pioneer species.

Litter production and leaf-litter decomposition of selected tree species in tropical forests at Kodayar in the Western Ghats, India

Litter production, standing crop of litter on forest floor and leaf-litter decomposition of selected dominant tree species were studied in the tropical forests at Kodayar in the Western Ghats, India. Mean annual litterfall in the study sites ranged from 5.63 to 8.65 Mg ha −1 year −1. A greater amount of annual litter production was observed in sites II and III, when compared to sites I and IV. This variation in litterfall pattern among the sites could be attributed to species composition. Monthly variation in litterfall pattern showed two peaks, one in the dry season (January–April) and another in November. Contribution of leaf litter to the total litter was significantly ( p < 0.01) greater compared to other components (woody litter and reproductive parts). In deciduous forests, Terminalia contributed significantly ( p < 0.05) greater amount of leaf litter to annual litter production, followed by Careya arborea, Macaranga peltata, Aporosa lindleyana and Dillenia pentagyna, whereas in evergreen forests, Hopea parviflora contributed the most. The results suggest that species composition and their contribution toward litter becomes important in overall community or site litter production as observed in sites II and III. The litter mass decreased linearly with time. Thin and smooth leaf without prominent skeletal tissues decomposed more rapidly, while thick and tough leaves with prominent midribs and veins took longer time for complete decomposition. The species with high nitrogen content exhibited relatively faster decomposition except in H. parviflora and V. indica. The differences in decay rates and half-life periods are related to structure and nutrient concentration of leaf litter and the environmental factors.

Litter of multipurpose trees in Kerala, India: variations in the amount, quality, decay rates and release of nutrients

Abstract In a field study involving 8–9 year-old woodlots of nine fast growing tree species in Kerala, India, the amount and nutrient content of litterfall were monitored. Decay rate constants and litter half-lives were estimated by fitting a single exponential model to the litter decomposition data. Annual litter production ranged from 3.43 Mg ha−1 (Pterocarpus) to 12.69 Mg ha−1 (Acacia). Litterfall of Acacia, Ailanthus, Pterocarpus and Casuarina followed a uni-modal distribution pattern. Nutrient content of litter samples showed considerable variations, owing to species and sampling time. Based on mean litter N content, the nine species were broadly divided into high, medium and low detrital N species. Litterfall accounted for substantial nutrient recycling within the system. Results of the litter bag study revealed that residual litter mass declined exponentially with time for Ailanthus, Pterocarpus, Casuarina and Leucaena. Paraserianthes showed a linear trend, while Emblica and the two Artocarpus species exhibited a bi-phasic pattern of mass loss. Both initial lignin content and lignin–N ratio had a negative, although modest influence on decay rate coefficients, while initial N content exerted a positive influence. Nutrient release from the decomposing litter followed either a tri-phasic pattern characterised by an initial accumulation, followed by a rapid release and a final slower release phase, or a bi-phasic pattern that is devoid of the initial accumulation phase.