Leaf Litter Loss Research Articles

Role of Substrate Cues in Habitat Selection by Recently Metamorphosed Bufo Terrestris and Scaphiopus Holbrookii

Amphibians exhibit high rates of evaporative water loss that can affect their distribution, movements, and patterns of habitat use. Forest clearcutting alters habitat and results in environmental changes such as canopy removal and leaf litter loss that may promote drier microclimates in harvested clearcuts. Subsequently, clearcutting has been shown to generally reduce amphibian abundances and richness. We investigated the role of substrate cues in habitat differentiation between clearcuts and forests in juvenile Southern Toads (Bufo terrestris) and Eastern Spadefoot Toads (Scaphiopus holbrookii) in laboratory experiments. Neither B. terrestris nor S. holbrookii exhibited a preference for a single substrate when offered the choice between forest soil and clearcut soil. However, S. holbrookii significantly preferred forest substrate over clearcut substrate when forest litter was added to the forest soil. The affinity for forest litter exhibited by juvenile S. holbrookii suggests that the availability of suitable microhabitats may be an important determinant of S. holbrookii distributions and may explain previously reported habitat associations in field studies.

Exposure to solar UV-B radiation accelerates mass and lignin loss of Larrea tridentata litter in the Sonoran Desert

We assessed whether exposure to solar ultraviolet-B radiation (UV-B) affects the mass loss of Larrea tridentata (creosotebush) litter in the Sonoran Desert of central Arizona. We placed three types of litter (leaves, twigs, or a natural mixture of leaves, twigs, and seeds) in bags constructed of UV-B-transmitting or UV-B- absorbing filter material that allowed either 85% (near-ambient UV-B treatment) or 15% (reduced UV-B treatment) of the biologically effective solar UV-B to reach litter inside the bags. Bags were placed outdoors for 4-5 months during the winter at two sites: a balcony or on the soil surface of the desert. Mass loss of leaf litter was greater under near-ambient UV-B than reduced UV-B at both sites: 21 (near-ambient) vs. 18% (reduced) on the balcony, and 18 vs. 14% at the desert site. Mass loss of twig litter was also greater under near-ambient UV-B at the desert site. Mass loss of the natural mixture of litter was also greater when exposed to near-ambient UV-B on the balcony, and tended to be greater at the desert site. We estimate that about 14-22% of the total mass loss of leaf litter during our 4-5 month experiments was attributable to solar UV- B exposure. Leaf litter exposed to near-ambient UV-B had lower concentrations of lignin, and fats and lipids, and slightly higher concentrations of holocellulose. The greater mass loss of litter under near-ambient UV-B appeared mainly attributable to loss of lignin, although losses of fats and lipids were also appreciable. A primary reason for greater mass loss of litter under solar UV-B appeared to be photodegradation, partic- ularly of lignin.

K AND Na LEACHING FROM LEAF LITTER OF ACACIA AURICULIFORMIS (CUNN. EX BENTH.)

Acacia auriculiformis (Cunn. Ex Benth.) is now widely planted in different agroforestry models. The prime use of this species is for fuel wood and to some extent as furniture timber at the northern and central part of Bangladesh. In agroforestry, trees and agricultural crops sharing the nutrients from the same piece of land. Trees uptake nutrients from the soil and some portion of that nutrient again back to the soil through the leaching process and decomposition of litter. K and Na leaching from leaf litter of Acacia auriculiformis was studied in the laboratory. About 16% of initial dry weight of leaf litter was lost after 168 hours. Weight loss of leaf litter, conductivity and TDS (Total Dissolve Solid) of leached water showed significant (p<0.05) positive curvilinear relationship with leaching time. The initial concentration of K and Na in leaf litter significantly (p<0.05) decreased to 2247 mg g-1 and 735 mg g-1 respectively after 96 hours and showed significant (p<0.05) negative curvilinear relationship with weight loss. The pattern of K and Na leaching from the leaf litter of Acacia auriculiformis might help agroforestry practitioners to add a new criteria to choose potential tree species for their farming system.

Effects of carbendazim and lambda-cyhalothrin on soil invertebrates and leaf litter decomposition in semi-field and field tests under tropical conditions (Amazônia, Brazil)

Effects of the fungicide carbendazim and of the insecticide lambda-cyhalothrin on soil invertebrates and litter decomposition under tropical conditions were assessed in ecotoxicological semi-field studies using intact soil-core terrestrial model ecosystems (TMEs) and in a field test applying the litter-bag method. In the TME study, performed indoors under controlled conditions, earthworms, isopods and diplopods were added to intact soil cores and mortality of soil invertebrates and mass loss of leaf litter were assessed. The field study was performed on an abandoned rubber plantation near Manaus (Amazonia, Brazil). The measurement endpoints were abundance of the soil fauna and mass loss of leaf litter. In the TMEs carbendazim caused a decrease in the abundance of the introduced earthworm Pontoscolex corethrurus and, partly, of the milliped Trigoniulus corallinus. In the field carbendazim decreased the abundance of the native earthworm Andiorrhinus amazonius. Lambda-cyhalothrin was toxic to isopods and millipedes in the TMEs, whereas no effect on arthropods was detected in the field. Organic matter breakdown measured as mass loss of leaf litter in TMEs over time revealed that the two tested agrochemicals can have an impact on decomposition at field relevant concentrations. In the field the results were less obvious, due to spatial heterogeneity through which possible effects of the tested agrochemicals could have been masked.

The Timing of Winter-growing Shredder Species and Leaf Litter Turnover Rate in an Oligotrophic Lake, SE Sweden

Small freshwater systems often depend on allochthonous organic subsidies to sustain productivity. Benthic invertebrates consuming coarse detritus maintain the energy flow by conveying dead organic matter into prey items and increase the food availability for other consumers. Compared to lotic systems, the dynamics of coarse detritus decomposition has not received much attention in lakes. The objectives of this study were to investigate the seasonality of leaf litter turnover and the timing of abundance of potential shredder species in a typical oligotrophic boreal lake. Leaf litter was experimentally exposed in litterbags in the littoral zone in Lake Valen from autumn to late spring two consecutive years. The weight loss rate of leaf litter initially followed the same pattern during both winter periods, but was markedly influenced by freezing in late winter the second year. Further, the seasonal variation patterns in abundance in litterbags were quite different among the potential shredder species. Only the limnephilid caddis larvae showed a density variation pattern possible to connect to the weight loss of leaf litter in litterbags. Otherwise frequent detritivores such as Asellus aquaticus and Leptophlebia marginata displayed lowest density in litterbags during the main weight loss period. However, after the long ice period the second winter the remaining leaf litter seemed to be consumed by A. aquaticus. With increasing knowledge of the initial leaf breakdown process and the guild of shredders in lakes, the decomposition rate may also in this habitat become a useful instrument when evaluating the impact from perturbations on ecosystem function.

Do ectomycorrhizas alter leaf‐litter decomposition in monodominant tropical forests of Guyana?

This work tested the hypothesis that ectomycorrhizas (EM) of Dicymbe corymbosa alter leaf-litter decomposition and residual litter quality in tropical forests of Guyana. Mass loss of leaf litter in litter bags was determined on three occasions, in two experiments, during a 12-month period. Paired root-exclusion plots were located randomly within a D. corymbosa forest. Both D. corymbosa and mixed-species leaf litters were reciprocally transplanted into their respective forest types. Elemental analysis was performed on the residual D. corymbosa leaf litter after 1 yr. Leaf litter mass loss in the D. corymbosa forest was not influenced by EM, despite high EM colonization. Elemental analysis of D. corymbosa leaf litter residues demonstrated reduced calcium levels in the presence of EM, which were negatively correlated with EM rootlet-colonizing mass. The lack of EM effect on the litter decomposition rate, coupled with high EM colonization, suggests an important but indirect role in mineral nutrient acquisition. Lowered Ca concentration in leaf litter exposed to EM may suggest a high Ca demand by the ectotroph system.

Degradation rate of leaf litter of Bruguiera parviflora of Mangrove Forest of Kuala Selangor, Malaysia

Two exposure methods, leaf litter on string and leaf litter in bag, were used for leaf litter loss due to feeding plus mechanical breakdown and microbial degradation during dry and wet months respectively. Leaves in bags exhibited 48% and 60% of dry weight loss at 120 and 30 days during dry and wet months respectively. Comparatively a higher degradation rate occurred in the initial period of dry and wet months followed by lower rates thereafter. Comparatively a lower rate of leaf litter loss due to feeding plus mechanical breakdown was observed during the initial 5 days of dry and wet months. Relatively higher percentage of leaf litter loss (52.61% to 69.33%) was attributed to feeding plus mechanical breakdown by crabs while the microbial degradation ranged from 30.67% to 47.39%. The rate of microbial degradation found to be affected by dry and wet months but not the litter loss due to feeding plus mechanical breakdown by crabs.

Do woodlice and earthworms interact synergistically in leaf litter decomposition?

SummaryIn laboratory microcosms, we investigated the influence of diversity of both leaf litter and detritivores on decomposition processes. Either woodlice or earthworms, or a combination of woodlice and earthworms, fed on leaf litter of either oak or alder, or oak and alder for 8 weeks. Mass loss of leaf litter, soil microbial respiration and soil nutrient concentrations were determined every 2 weeks.For four out of seven decomposition parameters, the joint effects of woodlice and earthworms were stronger than the sum of single‐species effects when they had fed on alder litter. When feeding on oak litter, however, woodlice and earthworms together revealed lower decomposition rates than predicted from their single effects. Joint effects of detritivores on decomposition of mixed litter were always lower than predicted from the sum of their effects.In mixed‐litter assays, we obtained intermediate values of decomposition parameters, indicating that doubling the species richness of leaf litter from one to two species did not promote decomposition processes. Effects of mixing litter were, thus, mostly additive; essentially only when earthworms fed on mixed litter we observed, mostly positive, non‐additive effects of diverse litter.Our findings provide evidence for a potential effect on ecosystem functioning through joint action of detritivores even at low species diversity, while litter diversity seems to be less significant. On high‐quality litter, isopods and earthworms are not functionally redundant but act synergistically on litter decomposition. The effects of detritivore diversity on ecosystem processes, however, are context‐specific and depend on the quality and diversity of the available food sources, and on species‐specific characteristics of the detritivores.

Leaf litter processing rates in a Kenyan highland stream, the Njoro River

Mass loss of leaf litter from five common riparian trees in Kenya was determined using mesh bags over a 70-day period. The study was carried out in a river which previous research has shown to be apparently devoid of invertebrate shredders. There was a five fold difference between the most rapid and slowest decay rates, but all were within the fast range identified from temperate zone trees, demonstrating high rates of microbial activity. We conclude, therefore, that the low biomass of invertebrate shredders in Kenyan highland streams cannot be explained by poor quality of the leaf litter that enters them.

Comparative performance and restoration potential of two Albizia species planted on mine spoil in a dry tropical region, India

This study focussed on the comparative impact of young high density plantations of two Albizia species ( Albizia lebbeck and Albizia procera) on the soil redevelopment process during early phase of mine spoil restoration in a dry tropical environment. Plant-hostile features such as high levels of pyrites, etc. were not present. We compared vegetational (biomass, net primary production (NPP), production efficiency, litter fall and its decomposition rate) and soil characters (soil nutrients, microbial biomass and N-mineralization rate) for these plantations. The A. lebbeck plantation accumulated greater biomass and exhibited higher net primary production than the A. procera plantation. The tree layer NPP of A. lebbeck plantation at 6 years age (25.4 t ha −1 years −1) was even higher than that of native dry deciduous forest. The short-lived components (foliage, fine roots) accounted for a greater proportion of ecosystem function (productivity) than the long-lived component (stem). The efficiency of foliage for NPP was greater in A. lebbeck than in A. procera. Decomposition of leaf litter of A. lebbeck was faster than that of A. procera. Ninety five percent mass loss of leaf litter would require 922 days in A. lebbeck and 1328 days in A. procera. Amounts of N and P deposition through leaf fall and release of these nutrients increased with the age of plantation in both species but were higher for A. lebbeck plantation. There was a significant improvement in soil properties due to plantation of both species, but the organic C and kjeldahl N levels were higher in A. lebbeck plantation as were the N-mineralization rates and soil microbial biomass. The proportional increase in soil biomass was much higher than that in soil organic C. The study indicated that the restoration efficiency of A. lebbeck was greater than that of A. procera.

Decomposition of and nutrient dynamics in leaf litter and roots of Poa ligularis and Stipa gyneriodes

A field experiment was conducted in a temperate semi-arid grassland of central Argentina to determine mass loss and P and N concentrations of decaying leaf litter and roots of Poa ligularis (high-quality litter) and Stipa gynerioides (poor-quality litter). Leaf litter and roots of each species were incubated on sites dominated by P. ligularis and on sites dominated by S. gynerioides, to separate species from site effects. The experiment lasted up to 21 months. Mass loss of leaf litter and roots was higher ( p<0.01) in P. ligularis than in S. gynerioides. Mass loss of leaf litters were higher ( p<0.01) on P. ligularis sites, whereas mass loss of roots were similar ( p>0.05) on both type of sites. Both species showed similar pattern of P and N dynamics in the leaf litter and roots, but net mineralization was higher ( p<0.01) in P. ligularis than in S. gynerioides.

Is decomposition of woodland leaf litter influenced by its species richness?

Decomposition of leaf litter was surveyed during the first nine months of decomposition in the field. At three woodland sites that differ with respect to leaf litter species richness, as well as to microbial activity and the abundance of terrestrial isopods, being the most numerous representatives of the saprophagous macrofauna at these sites, changes in the chemical composition of the mixed leaf litter were monitored on a three-monthly basis. Six out of seven leaf litter compounds exhibited changes in their contents that were positively correlated with high microbial activity and/or high isopod abundance during decomposition. Further, site characteristics other than soil pH, water holding capacity (WHC) or percent sand, significantly explained the variance in decomposition of five different chemical compounds, as well as the overall mass loss of leaf litter. These site characteristics include the site-specific species richness of the litter layer. At the site with low microbial activity and low isopod numbers but a leaf litter mixture of nine species, decomposition did not proceed more slowly than at that site with high microbial activity and high isopod abundance but leaf litter made up by only five species. From these results, I hypothesize that a diverse vegetation, resulting in leaf litter of high species richness, promotes decomposition processes, and thus nutrient recycling.

UV‐B effect on Quercus robur leaf litter decomposition persists over four years

SummaryThe effects of elevated UV‐B (280–315 nm) radiation on the long‐term decomposition of Quercus robur leaf litter were assessed at an outdoor facility in the UK by exposing saplings to elevated UV‐B radiation (corresponding to a 30% increase above the ambient level of erythemally weighted UV‐B, equivalent to that resulting from a c. 18% reduction in ozone column) under arrays of cellulose diacetate‐filtered fluorescent UV‐B lamps that also produced UV‐A radiation (315–400 nm). Saplings were also exposed to elevated UV‐A radiation alone under arrays of polyester‐filtered fluorescent lamps and to ambient solar radiation under arrays of nonenergized lamps. After 8 months of irradiation, abscised leaves were placed into litter bags and allowed to decompose in the litter layer of a mixed deciduous woodland for 4.08 years. The dry weight loss of leaf litter from saplings irradiated with elevated UV‐B and UV‐A radiation during growth was 17% greater than that of leaf litter irradiated with elevated UV‐A radiation alone. Annual fractional weight loss of litter (k), and the estimated time taken for 95% of material to decay (3/k) were respectively increased and decreased by 27% for leaf litter exposed during growth to elevated UV‐B and UV‐A radiation, relative to that exposed to UV‐A alone. The present data corroborate those from a previous study indicating that UV‐B radiation applied during growth accelerates the subsequent decomposition of Q. robur leaf litter in soil, but indicate that this effect persists for over four years after abscission.

Nutrient cycling in a natural beech forest and adjacent planted pine in northern Spain

Summary Above-ground leaf biomass, leaf litterfall, leaf weight loss due to decomposition, redistribution of leaf litter and C and N return to the soil, and seasonal leaf nutrient dynamics have been studied in the Sierra de la Demanda, Spain, a Mediterranean climatic zone. The tree species considered were a climax beechwood (Fagus sylvatica L.) at ‘Tres aguas’ and planted Scots pine (Pinus sylvestris L.) at ‘La Rasada’. The above-ground biomass was estimated by cutting and weighing seven trees from each site according to their diameter classes, recording the categories of trunk, branches and leaves. The carbon and nitrogen contents in the different fractions were also analysed. The calculated total biomass ranged from 132.7 Mg ha ‐1 in the beech stand to 152.1 Mg ha ‐1 in the pine stand, and leaf biomass from 3.4 Mg ha ‐1 to 7.0 Mg ha ‐1 in the beech and pine, respectively. The C : N (carbon : nitrogen) ratio was greater in the pine forest leaves. The total litterfall was 5791 kg ha ‐1 per year in the pine forest and 4682 kg ha‐1 per year and the leaf litterfall was 2917 kg ha‐1 per year and 2897 kg ha‐1 per year in the pine and beech sites, respectively. The annual mean amount of N returning to the soil substrate was 29.9 kg ha‐1 per year on the beech and 23.3 kg ha‐1 per year on the pine. Weight loss of leaf litter due to decomposition was monitored for 2 years in the two forest ecosytems studied. The results indicated that weight loss was similar at the end of the experimental period in the two forest stands: 40 per cent in beech and 43 per cent in pine. Jenny’s decomposition index (K) and Olson’s decomposition index (KO) were higher for the pine stand than for the beech stand. The dynamics of total C and N throughout the study period was similar on both experimental plots. The evolution of N in green leaves follows the same pattern in beech and pine stands. The highest leaf N concentration was observed in the spring and summer months, during initial leaf growth. Thereafter, it decreased due to retranslocation during the period of leaf-fall in autumn.

Changes in the fauna and its contribution to mass loss and N release during leaf litter decomposition in two deciduous forests

Summary Investigations on the mass loss of leaf litter were carried out between 1992 and 1994 using litter bags of 0.02 mm and 5 mm mesh sizes in a beech and a mixed forest in northern Germany. The two forests on moder humus differed in soil faunal composition, vegetation type, and nutrient supply. Mass loss and N and C concentrations were determined from the litter at bimonthly intervals. From subsamples macrofauna were sorted by hand and mesofauna was extracted by heat. The biomass and N content of the litter bag fauna was estimated. Mass loss, particularly that attributed to the fauna, was different between the two sites with highest rates in the mixed forest and lowest at the beech site. A significantly higher rate of N release was found for the litter extracted from 5 mm mesh size litter bags in the mixed forest but not in the beech forest. Collembola and Cryptostigmata changed in numbers during litter breakdown. Collembola reached high numbers in the beginning, whereas Cryptostigmata dominated later. The diversity of Cryptostigmata increased at both sites during litter breakdown, whereas collembolan diversity only increased in the beech forest and remained at the same level in the mixed forest. Several species of Collembola and Cryptostigmata occurred earlier in the mixed forest than in the beech forest. Mass loss rate attributable to the fauna did not correspond to total faunal biomass. Only Isopoda, Diplopoda and Cryptostigmata appeared to affect the mass loss positively, whereas the biomass of Lumbricidae was negatively correlated with mass loss, particularly in the beech forest. On the other hand, the release of N attributable to the fauna was positively correlated with the total faunal biomass in the beech forest and Lumbricidae in particular were positively correlated with N-release at both sites.

Influence of forest floor type on rates of litter decomposition in microcosms

Rates of mass loss of leaf litter of paper birch were measured during a 70 wk laboratory incubation in microcosms containing forest floor material from red alder (C-to-N ratio = 27), Douglas fir (C-to-N, 32), and lodgepole pine (C-to-N, 59) forests. Mass loss from leaf litter was fastest in alder forest floors and slowest in pine, and so was related to the C-to-N ratio of the forest floors. The decomposition rate was related to the amount of KCl-extractable NH 4 +N and NO 3 −N in each microcosm, but not to the concentrations of extractable N (mg g −1), which were greater in Douglas fir forest floors than in alder for most of the incubation. There were larger amounts of faecal material from soil fauna in the litter incubated in the alder forest floors, indicating greater faunal activity in these floors. The relationship between rates of decomposition and N concentrations may be due to the influence of soil fauna activity on both factors, rather than to a direct influence of N availability on rates of litter decomposition.

Decomposition of Bauhinia purpurea leaf litter in a polluted and unpolluted Hong Kong waterway

Decomposition of Bauhinia purpurea L. leaves in litter bags submerged in the Tai Po Kau Forest Stream (TPKFS) and the Lam Tsuen River (LTR) was investigated during the winter of 1988 and the summer of 1989. At every collection, temperature, pH, turbidity, dissolved oxygen, and biological oxygen demand (BOD5) were measured. In winter, the organically enriched LTR was categorized as polluted based on BOD5, turbidity, and heterotrophic bacteria counts, whereas the TPKFS was always relatively clean. Weight loss of leaf litter at both sites was very rapid when compared with published values and exhibited a distinct seasonal pattern. The decomposition rate of leaf litter (using the single exponential decay model) varied linearly with mean water temperature. Carbon content of the leaf litter decreased during decomposition and was, as expected, negatively correlated with the percent ash content. Except in the first 2 weeks, the nitrogen content of decomposing leaf litter decreased with time at a rate correlated with the abundance of heterotrophic bacteria in winter leaf litter (insufficient data were available in summer). Based on the results of the winter study only, the decomposition of leaf litter seems to be suppressed in the polluted river. Key words: decomposition, carbon, nitrogen, water pollution, heterotrophic bacteria.

Dynamics and Weight Loss of Leaf Litter in Central Himalayan Forests: Abiotic Versus Litter Quality Influences

., -' SUMMARY (I) Decomposition often Central Himalayan forest litter species was studied for two years to examine: (i) the temporal changes in nutrient concentration and weight loss and its spatial patterns; and (ii) to develop a regional model oflitter weight loss based on the dual controls of climate and substrate quality. (2) The experiments involved five forest communities in an altitudinal gradient, each with distinct vegetation and soil. In addition, a standard leaf litter was placed on the forest floor of each of these forests. (3) Litters high in cell wall constituents tend to be lower in nutrient concentrations. Relative patterns of change in K and Ca concentrations tended to differ from those ofN, P and Na. (4) Monthly rainfall could account for 25-89% of monthly weight loss of litter on each site. Analysis of the variation in annual weight loss from site to site indicates that the annual temperature, actual evapotranspiration (AET) and altitude explained, respectively, 48.7%, 53.6% and 49.1% of the variability. (5) Measures of cell wall constituents, e.g. lignin concentration, could account for up to 60% of the variability in weight loss in the first year; however, lignin, as a predictor of I weight loss rate, contains considerable information about plant nutrients. Linear combinations of lignin, annual temperature and AET/lignin, produced an r2 of >0,78. (6) In warm temperate and subtropical climates the cell wall constituents seem to be good predictors of weight loss in the first year while in cool temperate to arctic climates, the early stages of decay are prolonged, resulting in good prediction by litter nutrients.

Effects of flooding on decomposition and nutrient cycling in a louisiana swamp forest

A field and laboratory study was conducted to determine decomposition rates and nutrient flux in an impounded, managed swamp forest in the headwater swamp forests of the Barataria Basin. The role of redox potential and heterotrophic immobilization in determining floodwater nutrient concentrations were examined in the field and in laboratory microcosms. Twenty-six percent of the nitrogen and 40 percent of the phosphorus introduced into the system were retained in teh swamp impoundment, mainly as a result of the settlement of particulate matter. Weight loss of leaf litter in the microcosms closely followed field samples, but decomposition was more rapid and complete in the field. This greater efficiency of breakdown in the field may be the result of the exclusion of macrofauna in the microcosms and greater turbulence under field conditions. Overall results indicate that the area is a long-term sink for both nitrogen and phosphorus via the burial of partially decomposed organic matter under reduced conditions and denitrification.

Colonization of decomposing deciduous leaf litter by Testacea (Protozoa, Rhizopoda): Species succession, abundance, and biomass.

The colonization of leaf litter by testate amoebae in a cool temperate deciduous forest was studied over the first 60 months of decomposition. No colonization of fresh leaf litter by Testacea was recorded before the first spring thaw period. Colonization of aspen and balsam leaves was similar in terms of species and numbers of species, with the balsam litter being colonized by slightly fewer species. In the aspen litter bags, all the L-layer species were present after 18 months, and all the species recorded in all soil layers were found after 60 months. The proportion of species which constructed their tests from platelets rather than sediment was 70% of the total number of species for the first 36 months of colonization of both litter types. After 60 months, seven species comprised 70% of the total numbers of Testacea but only 33-38% of the total biomass. Significant, positive correlation existed between the dry weight loss of leaf litter and the total number of active Testacea, the total number of living Testacea, and the total number of species present. The prime limitations to testacean colonization of decomposing leaf litter appeared to be substrate quality, food supply and/or availability of test-building materials.