Litter Supply Research Articles

Dominant effects of litter substrate quality on the difference between leaf and root decomposition process above- and belowground

Initial decomposition rates, changes in organic chemical components (acid-insoluble fraction, holocellulose, polyphenols, soluble carbohydrates) and nutrient dynamics (K, Mg, Ca, P, N) were examined for fine roots and leaves of Japanese cypress (Chamaecyparis obtusa). Litterbag experiments designed to evaluate the relative effects of litter type and position of litter supply in the soil were carried out, considering that root and leaf litter typically occupy different locations and have different substrate qualities. Litterbags of roots and leaves were placed at two positions (on the soil surface and in the humus layer), and collected every 3 months over one year. The mass loss rate and N release were slower during root decomposition in the humus layer than during leaf decomposition on the soil surface. These differences between root and leaf decomposition were mainly caused by the litter type, and the effect of the position on decomposition was relatively small. Root litter was less influenced by position related effects, such as differences in humidity, than leaf litter, and this recalcitrant trait to environmental effects may be responsible for the slower mass loss rate and N release in root decomposition. The results of the present study suggest that fine roots are persistent in the soil and serve an important role in N retention in forest ecosystems because of their litter substrate quality.

Effect of decomposing litter on the mobility and availability of metals in the soil of a recently created floodplain

Some newly created wetland areas in the Scheldt estuary are heavily contaminated by metals. They are expected to be colonised by reed ( Phragmites australis) and, on a longer term, willow ( Salix ssp.). Supplying litter or stimulating plant biomass production on the short term could be possible management options to restrict metal mobility or availability in the upper soil layer. The influence of litter application on the mobility and availability of metals in the top layer of a soil of a recently created floodplain along the river Scheldt (Schelde) was studied in a greenhouse experiment. Reed stem, reed leaf and willow leaf litter were dried, ground and added to the soil. The treated soil was subsequently subjected to permanently flooded and alternately flooded/drained conditions. Metal concentrations were measured in the pore water, surface water above the soil and percolates. Moreover, reed plants ( P. australis), duckweed ( Lemna minor) and willows ( Salix cinerea) were allowed to grow on these soils. Metal concentrations in the plants, growth and chlorophyll fluorescence were measured. Decomposing litter was found to affect the metal mobility and availability. During the first weeks after litter supply, the concentrations of some metals (e.g. Cd, Cu, Ni and Zn) in the pore water markedly exceeded remediation thresholds for ground water. The metal concentrations started to decrease after some days or weeks, which might be attributed to re-adsorption to different soil phases, a decreasing presence of soluble organometallic complexes and a lowering competition with Ca 2+ for sorption to the solid soil phase. However, most data point towards a role of sulphide precipitation upon sulphate reduction, which is affected by the type of litter supplied to the soil. The used willow leaf material was found to release more sulphates compared to the litter originating from reed plants. When the soils were alternately flooded, metals were exported through the percolates. Total metal export substantially increased when litter was added. Growth and metal concentrations in duckweed, reed plants and willows were affected by the supply of litter, whereas photosynthesis was less affected. The experiments should still be performed on pilot scale before developing wetland management guidelines from these results.

The Analysis of Collembolan Species' Abundance Distribution in Beech and Spruce Forests Habitats in Jastrebac Mountain (Serbia)

ABSTRACTCollembola were sampled over a period of five consecutive years in beech and spruce forest on mountain Jastrebac (Serbia). The two identified Collembola communities were thought to respond to resource dynamics represented by litter supply and decomposition processes. The collembolan communities were dominated by two species: Folsomia quadrioculata and F. penicula. In both habitats phenological changes occur by a decrease in abundance of the dominant species followed by an increase in the abundance of accessory species. In the beech stands a large decrease in abundance of the dominant species with a moderate replacement was noted, whereas species replacement is greater relative to the decrease in abundance of the dominant species in spruce. In the analysis of community structure the ranked abundance curves were compared with corresponding theoretical curves of several S/N distributions, in order to identify the underlying models of community structure. The analysis of species' abundance curves showed a marked difference in summer compared to the spring and autumn periods. Comparing the observed distributions with different S/N models the “niche preemption” model and MacArthur's “broken stick” model were found to explain adequately the observed distributions.

Organic matter dynamics control plant species coexistence in a tropical peat swamp forest

We studied the relationship between the coexistence of tree species and the dynamics of organic matter in forests. A tropical peat swamp forest was selected as a model ecosystem, where abiotic factors, such as geological topography or parent rock types, are homogeneous and only biological processes create habitat heterogeneity. The temporal or spatial variation of the ground elevation of peat soils is mainly caused by changes in the balance between organic matter inputs to soils and decomposition, which is affected by the growth and death of influential trees. To clarify the processes of elevation dynamics, we measured the microtopography around some tree groups, estimated organic matter (in the form of litter and roots) in soils under three kinds of microtopographic conditions, measured decomposition rates and detected dominant species' shifting distribution patterns in different stages of growth in relation to the locations of tree groups creating specific microtopographic conditions. We found that growth or death of buttressed trees has the greatest effects on the rising or sinking of ground surfaces through changes in litter supply and root production. We discuss here the possibility of extending our model to other forest types.

Spatial and temporal variation in podzol organic matter studied by pyrolysis‐gas chromatography/mass spectrometry and micromorphology

SummaryA well‐developed podzol hydrosequence that has been partially covered with drift sand, and partially subjected to improved drainage, provides new insights into the causes of variation in soil organic matter chemistry in such soils. While E horizons invariably move towards a dominance of aliphatic components reflecting residual accumulation, the chemistry of organic matter in well‐drained B horizons is determined mainly by decaying roots, which are transformed by microorganisms to humus aggregates. In poorly drained, stratified B horizons, humus coatings dominate and the chemistry is very close to that of dissolved organic carbon. When a sand cover inhibits the supply of fresh litter, microbial decomposition in the A horizon causes a shift in chemistry towards that of the E horizon. Similarly, upon improved drainage and removal of complexed metals from the top of the B horizon, microbial decomposition of all palatable organic matter in the top of the B horizon causes a shift towards E‐horizon chemistry. This is probably the mechanism by which most E horizons in podzols are formed, and not by re‐solution. Marked chemical changes upon improved drainage may take only decades. During microbial decay, small polysaccharide‐derived pyrolysis products (mainly furans, furaldehydes and acetic acid) remain abundant due to the contribution of microbial sugars. Both micromorphology and factor analysis on quantified results of pyrolysis‐gas chromatography/mass spectrometry contribute significantly to the interpretation of the humus chemistry of these profiles and thus to our understanding of soil genesis. Organic chemistry of the investigated podzols can be understood only in the context of their genesis.

Does forest type and vegetation patchiness influence horizontal distribution of soil Collembola in two neighbouring forest sites?

The influence of forest type and heterogeneity of understory vegetation on the horizontal distribution of soil living Collembola was studied in two neighbouring mountain forest sites—a 180-year old beech forest and a 70-year old natural spruce forest. Four homogenous patches with different understory vegetation were chosen within each forest site and sampled 12 times between 1997 and 1998. A total of 56 collembolan species were identified, 51 in the beech forest and 48 in the spruce site. Twenty-three species were rare—they were recorded with low constancy and density. Although both forest sites differed in soil type, humus form and soil chemical parameters, the species composition of their collembolan communities was quite similar (77% shared species). Nevertheless, soil collembolan communities of both forest sites were clearly delimited on both qualitative (presence–absence) and quantitative (in density of individual species) levels as well as in terms of total collembolan density. Mean collembolan density reached 26 650–44 030 ind/m 2 in the beech patches compared to 44 470–68 050 ind/m 2 found in the spruce patches. Considerably higher densities of several species in one forest site may indicate more suitable habitat. In spite of similar species composition and minor differences in qualitative parameters among different vegetation patches within one forest site, there was clear variation in density of individual species, particularly between patches with and without herb vegetation. This could reflect different microclimatic conditions, additional litter supply from herbs or indirect interactions of Collembola with their roots.

Experimental studies on rain splash erosion of forest soils after clearing in Okinawa using an artificial rainfall apparatus

The main island of Okinawa, in southwestern Japan, is characterized by a subtropical climate, coral reefs, and “reddish soils,” which contain Acrisols and Cambisols (FAO/UNESCO classifications). Recently, due to soil erosion on hilly lands, the coral reefs have been damaged by an inflow of reddish soil. Forest clearing is thought to one of the factors increasing rain splash erosion rates on hilly lands, because it is believed that clearing disturbs the forest floor and causes the supply of litter to stop. After clearing, A0, A and B horizons will be denuded, one after the other, by rain splash. In this study, we measured rain splash erosion rates of undisturbed samples of A0, A and B horizons using an artificial rainfall apparatus. The results of experiments on rain splash erosion clarified several aspects of the erosion process in a clearing site. First, it was found that the rain splash erosion rates were higher in fresh litter than in decomposed litter, in decomposed litter than in the A horizon, and in the A horizon than in the B horizon. Thus, the erosion rate increases with soil depth. Secondly, surface-gleyed red and yellow soils are mostly vulnerable to rain splash erosion. The erosion rates of these soils are two to three times higher than those of the red soil and the yellow soils. Thirdly, the erosion rates are affected mainly by bulk density and saturated hydraulic conductivity, not by clay ratio and dispersion ratio. Lastly, the difference between erosion rates of surface-gleyed red and yellow soils and other soils will be even greater if a soil crust has formed, because the formation of a soil crust increases the rain splash erosion rate.

EFFECTS OF MUD LITTER ON PROCESSING TOMATO YIELD AND FRUIT SIZE

In the view to study the possibility of using the mud litter in the sandy soils of the Mostaganem region, processing tomato was grown after supply of mud litter or of bovine manure or without organic amendment. The yield and fruit size were highest with mud litter supply and they were lowest in the control without organic amendment. The mud litter seems to be an organic amendment acceptable. However, the causes of these differences were not precisely identified. Additional research is necessary, in particular to verify by detailed analysis that the organic sources do not contain harmful toxic elements.

Seasonal changes in organic compounds in soil solutions obtained from volcanic ash soils under different land uses

We investigated the organic matter composition in soil solutions as influenced by land use. Undisturbed mineral soils were collected periodically from mineral layers of Andosols under coniferous and deciduous forest, grasslands and upland fields for 1 year using soil core samplers. Soil solutions were obtained by centrifugation under −1.55×10 6 Pa condition, which equals to 4.2 pF. The dissolved organic carbon (DOC), hexoses, pentoses, phenolic acids and amino acids in soil solutions were determined. The concentrations of DOC under forest and grassland stands were not influenced by precipitation, but were negatively correlated to the yield of soil solution ( P<0.01). Temporal variations in concentrations of hexoses were similar to those of DOC at all Fujisawa sites but not at the Tsukui sites. Except for one forest stand, the concentrations of hexoses increased from autumn to winter. Concentrations of pentoses and phenolic acids showed similar seasonal variation in the forests and grasslands, and peaked in autumn and spring. Variations in the concentrations of pentoses corresponded to litter fall and ground grass cutting in forests, drying of grass at grasslands and harvest at upland fields. Although the concentrations of phenolic acids varied with seasons, differences between land uses were not clear. The release of phenolic acids might depend on the variation of the temperature. Correlations between pentoses and phenolic acids and DOC were weak. The concentrations of amino acids were lower than those of other organic compounds at all sites. At the upland fields, the concentrations of amino acids were significantly ( P<0.01) correlated with those of hexoses. The composition of dissolved organic matter (DOM) varied throughout the year. Seasonal changes in organic matters in soil solutions depended on yields of soil solution, temperature variations and the timing of litter supply under different land use.

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Contrasting responses of a simple terrestrial ecosystem model to global change

A simple parameter-scarce model of vegetation dynamics is introduced which describes a single dominant vegetation type using three equations for vegetation carbon, fractional coverage by the vegetation and soil carbon. The model is driven by net primary productivity, as calculated by a submodel of photosynthesis and plant respiration. Three categories of response to prescribed increases in atmospheric CO 2 concentration and temperature are identified: (1) The emergence of a new dominant vegetation type in a cold environment. When the vegetation is establishing, there is a long period (dependent upon the ‘seeding’ fraction) of slow vegetation spread. This is followed by a rapid increase in fractional cover as the vegetation moves to being in near equilibrium with the perturbed climate, causing a pulse of positive Net Ecosystem Productivity (NEP). (2) Robust behaviour of an established vegetation in a warm environment. Extra carbon assimilated is mostly allocated to spreading, but because the fractional cover is nearly complete, the carbon is further diverted into extra litter fall (‘self shading’). The soil carbon reservoir grows and NEP is initially weakly positive. However, soil respiration increases more rapidly with warming than net primary production, causing a gradual switch to weakly negative NEP. (3) ‘Die-back’ can occur at high temperatures. Net primary productivity starts to decrease, causing a decline in litter supply and shrinkage of the soil carbon reservoir. Eventually, there is not enough incoming carbon to match natural disturbance rates and the vegetation rapidly decreases in fractional coverage until it disappears. This causes a large pulse of negative NEP. The timing of such ‘die-back’ is strongly linked to the chosen description of how dark and plant respiration depend upon temperature.

Effects of supply of deciduous broad-leaved litter to the forest floor on the soil fertility of a Japanese cypress (Chamaecyparis obtusa) forest

Effects of supply of deciduous broad-leaved litter to the forest floor on the soil fertility of a Japanese cypress (Chamaecyparis obtusa) forest

Scales of observation of riparian forests and distributions of suspended detritus in a prairie river

1. Detrital inputs from riparian forests can provide the main source of energy to aquatic consumers in stream communities. However, the supply of coarse organic detritus to stream communities is difficult to predict. Patchy riparian inputs and connectivity between reaches have complicated studies and disrupted patterns of the distribution of suspended coarse particulate organic matter within streams and rivers.2. In this study we emphasize the importance of spatial and temporal scales in determining potential distribution of instream leaf litter. Although large pulses of detritus are transported by streams during storm flows, the main supply of benthic leaf litter used by shredders and of suspended particulate organic matter used by filter feeders is transported during prolonged periods of baseflow. The local, fine‐scale distribution of this organic matter is determined by the location and continuity of leaf litter sources (riparian vegetation) and specific features of channel roughness (such as woody debris, roots and rocks).3. Viewing riparian vegetation at several scales results in variable conclusions regarding the amount of potential source area of leaf detritus. The percentage of suspended whole leaves at sites in the Little Washita River, Oklahoma, U.S.A. was best explained by the percentage of riparian forest cover in 500 m and 1000 m reaches upstream of the sites, as viewed by remote sensing imagery. The amount of leaf fragments was best explained by distance downstream along the longitudinal gradient. Ash‐free dry mass of suspended coarse particulate matter did not correlate with any measures of riparian cover.4. Our results suggest that leaves originate over longer reach lengths than those generally considered as source areas. Scale is an important consideration in studies of riparian patterns and related instream processes because of the need to integrate point dynamics as well as upstream influences.

EFFECTS OF VOLCANIC ACID DEPOSITION ON SOIL CHEMISTRY

Eleven soil cores (30–40 cm length, primarily O2/A/B, soil type: volcanogenous regosol) were collected near fumaroles in Oniishi, Osorezan, an active volcanic region of Japan. The retrieved cores were cut into ca. 5-cm sections and analyzed for pH, C and N exchangeable (Ex-) cations, and chemical states of S. The soils exhibited extremely low pH {pH(H2O): 2.49–3.93, av. = 3.21; pH(KCl): 2.06–3.42, av. = 2.80)} and were depleted not only in Ex-base cations (base saturation: 0.2–19, av. = 3.8%), but, to a considerable extent, in Ex-Al. The short-term pH-buffering of soil appears to involve Fe-oxide dissolution and subsequent Fe3+ -hydrolysis in the soil water and H+-exchange at strong acid sites where soluble and insoluble organic matter and clays are present. About 90% of cation exchange capacity (CEC) resulted from organic matter in the organic (av. C = 19.4%) layers, while more than 80% of CEC was due to clays and Fe-oxides in the mineral (av. C = 4.4%) layers. In spite of the continuous exposure of soil to volcanic H2S up to 2300 μg S/cm2/month, S-species other than organic S and SO42- could not be detected in the soil, except for FeS2, which was present as a minor S-constituent at the surface, suggesting rapid H2S-oxidation. SO42- was retained by poorly crystallized Fe-oxides in the mineral layers not only by adsorption, but also by occlusion, although such SO4-retention was inhibited by organic matter. A dense population of Sasa kurilensis significantly affected the soil chemistry, probably due to supply of fresh litter and recycling of elements within the plant-rhizosphere ecosystem.

Reactions of the Macrofauna of a Forest Mull to Experimental Perturbations of Litter Supply

Jean-Fransois David, Jean-Fransois Ponge, Pierre Arpin, and Guy Vannier David J.-F., Ponge, J.-F., Arpin, P. and Vannier, G. 1991. Reactions of the macro- fauna of a forest mull to experimental perturbations of litter supply. - Oikos 61: 316-326. The effects on forest soil macrofauna of two treatments, viz. litter interception and twofold litter supply, were studied for five yr in the field. Results concern five saprophagous groups (Lumbricidae, Diplopoda, Isopoda, Coleoptera larvae, Diptera larvae) and five zoophagous groups (Geophilomorpha, Lithobiomorpha, Pseudo- scorpionida, Coleoptera larvae, Diptera larvae). The litter interception had a nega- tive effect on the abundance of most taxa, but was rather slow; there was no significant decrease in abundance before at least 1 yr in Lumbricidae, 2 yr in Isopoda and zoophagous Diptera larvae, 2.5 yr in Diplopoda, saprophagous Diptera larvae, Geophilomorpha and Lithobiomorpha. The twofold litter supply had no significant effect on the abundance of most taxa; on the other hand, it initiated a process of dead leaf accumulation in relation to control, with an annual decomposition rate (k') higher on the control plot than on the plot with an increased litter supply. The results do not support the assumption that saprophagous soil macrofauna are food-limited in acid mull conditions.

Selection of incubation mound sites by the Australian Brush‐turkey Alectura lathami

Environmental characteristics associated with siting of the incubation mounds of the megapode, the Australian Brush‐turkey Alectura lathami were investigated in three rainforest locations in southeast Queensland. Seventeen environmental variables were measured for 52 mounds and 137 non‐mound sites. Most mounds were constructed on top of old mounds which had not been used during the previous year. A Discriminant Function Analysis obtained a clear separation between mound and non‐mound sites, based primarily on three variables: (1) the number of saplings growing within the mound or centre of the site: this was considered to be a result of the germination of seeds raked in earlier years; (2) the proportion of Lantana camara thicket occupying the site. Approximately half of the mounds constructed during a season were abandoned by their constructor due to expulsion by a neighbouring male. Brush‐turkeys could more easily establish mounds next to thickets since the efficiency of defence by other males was reduced in these areas; and (3) the openness of the canopy. Areas with greater canopy cover provided two important mound resources: a good supply of leaf litter, and protection of the mound from dessication.

The humus profile - concept, class and reality

This field and microscope study explores the micromorphological changes occurring in humus profiles of the Canadian boreal forest which have been variously affected by factors of disturbance: fire, dehydration and overland flow after storms. It compares the materials and profiles of undisturbed sites to those of recently disturbed and recolonized sites. A wide range of changes was observed: cracking and abrasion of bark and roots, distortion and compression of softer tissues, accompanied by biotic consumption. Hyphae are the initiators of decay at points of breakage. Litter input in recent burn sites is frequently from recolonizing vegetation rather than tree litter. Most burned areas are coincident with a lesser degree of podzolisation than exists in unburned areas. Compaction and intense pelletization are frequent in burned profiles and the term ‘pyroturbation’ is proposed for the disruptive effects of fire on the humus profile and the subjacent mineral layers. Concepts of the balance of litter supply and biotic consumption are advanced, as well as regressive and progressive development of the boreal humus profile.

Clearcutting Brazilian caatinga: assessment of a traditional forest grazing management practice

Clearcutting is a common practice for removing woody vegetation in the semiarid tropics of northeast Brazil. The prevalent belief is that clearing increases carrying capacity for livestock by increasing herbaceous vegetation, yet little empirical evidence exists to support or refute the contention. We investigated the implications to small ruminant nutrition of clearcutting in the semiarid tropics of northeast Brazil. We found that biomass of herbaceous species increased sixfold following cutting of trees, but much of this increase was in the form of poorly palatable stem. The large supply of leaf litter from woody species that was typical of uncleared areas during the dry season was replaced by persistent green foliage on coppicing trees the year following clearing. This green foliage may enhance the nutritional quality of the diets of sheep and goats foraging on cleared areas during the dry season.

Effects of Food Quality on Isopod Population Dynamics

1 Growth and survival of juvenile Armadillidium vulgare (Latrielle) in the laboratory were greatest on a diet of an excess of freshly fallen leaves from dicotyledonous plants but decreased with decreasing supply of this food, even though alternative lower quality foods were provided in excess. Growth in the laboratory was positively related to temperature but mortality was not clearly related to temperature over the range observed in the field. 2 Growth and survivorship of a field population on a Breckland grass heath are described for a 2-year period during which density declined from 673m-2 to 102 m-2. The demand for high-quality food by the field population peaked during a period of rapid growth in spring and early summer when supply of leaf litter from dicotyledonous plants was at a minimum. Litter production peaked in autumn after isopods had finished breeding and when low temperatures reduced their consumption rates. 3 Competition for high-quality food in spring and early summer during this period could have reduced growth and survivorship sufficiently to account for the observed decline in population density. 4 A simulation model, based on laboratory observations, closely predicted the observed decline in the field population. Further simulations also predicted the higher population densities observed in the field before this study and also the lower equilibrium densities found on the site since the study. Key-words: Population dynamics, competition, food quality, woodlouse, Armadillidium vulgare, densitydependence, growth, survivorship, consumption * Present address: Dr S.P. Rushton, Department of Agricultural Biology, The University, Newcastle-uponTyne NEl 7RU, UK. Introduction The role of food quality in the population dynamics of herbivores has been intensively studied and its importance in limiting populations widely recognized (Lawton & McNeil, 1979; Crawley, 1983; Dempster, 1983). In contrast, the influence of food quality on the population dynamics of decomposers has received little attention. As most decomposers have a broad range of diet and dead organic material is relatively abundant in most ecosystems, it is often assumed that detrivores are surrounded by an abundance of suitable food. For this reason Warburg, Linsenmair & Bercovitz (1984), in a comprehensive review, suggest that food is not important in influencing population fluctuations of terrestrial isopods; instead they propose that the dynamics of isopod populations are primarily controlled by climatic variables, such as temperature and humidity, since these strongly affect growth, survivorship and reproduction of isopods. Growth and survivorship are also importantly influenced by food quality, as demonstrated for Armadillidium vulgare (Latreille) by Cromack (1967) and Merriam (1971). The quality of isopod foods in the field shows much variation (Hassall & Rushton, 1984) but this would not limit isopod populations if optimal quality foods were always present in excess. However, populations could be adversely affected by either a shortage of the best quality foods or by a temporal separation in supply and demand of optimal food as is the case for herbivores in the African savannah (Sinclair,

Cycling of soil carbon in a Japanese red pine forest II. Changes occurring in the first year after a clear‐felling

AbstractCycling of soil carbon in the first year after a clear‐felling was compared with that before the felling in a Japanese red pine forest in Hiroshima Prefecture, west Japan. The daily mean temperature at the soil surface in summer was increased after the felling in comparison to that before felling, and the water content of both the A0 layer and the surface mineral soil was decreased due to the loss of the forest canopy. The rate of weight loss of the A0 layer was reduced after felling. However, accumulation of the A0 layer rapidly decreased because of the lack of litter supply to the forest floor. Low soil respiration after felling was mainly caused by the cessation of root respiration. Analysis of annual soil carbon cycling was then conducted using a compartment model. The relative decomposition rate of the A0 layer decreased whereas that of humus and dead roots in mineral soil increased to some extent after felling. The accumulation of carbon in mineral soil, however, increased slightly due to the supply of humus from roots killed by the felling.