Weight Of Leaf Litter Research Articles

Habitat amount interacting synergistically with cattle intrusion drives pervasive changes in leaf-litter ant assemblages in Amazonian Forest remnants

Deforestation driven by the expansion of cattle ranching activities towards the southern edge of the Amazon Forest transforms the landscape and is a threat to biological diversity. A secondary impact associated with this kind of fragmentation is cattle intrusion in Legal Reserves. To assess the fragmentation effect (habitat amount) and cattle intrusion on forest remnants, we sampled ground-dwelling ants in 24 forest remnants and the matrix adjacent to each remnant, in Meridional Amazon, Brazil. In all, we recorded 3,156 occurrences of ants, comprising 262 species. In addition to the natural characteristics of the areas (leaf-litter weight), the changes resulting from fragmentation (habitat amount) and cattle intrusion act synergistically affecting ground-dwelling ants’ assemblage. This result shows that the pervasive effect of habitat reduction due to forest fragmentation combined with habitat degradation (habitat quality) in the ground-dwelling ants’ assemblage.

Resilience underground: Understanding earthworm biomass responses to land use changes in the tropics

Soil biodiversity, like terrestrial biodiversity, is currently under threat by changes in land use. Intensively managed farming activities with agrochemicals have degraded both soil biodiversity and health. However, little is known about how these changes in land use affect the distribution of earthworm biomass in Southeast Asia. We conducted earthworm sampling across multiple habitats, including lowland forests, exotic monoculture plantations (e.g., oil palm and rubber tree), and agroforestry orchards. To survey earthworm populations, we excavated the top 30 cm of soil at 18 sites encompassing 399 plots distributed across natural and human-modified ecosystems in Selangor and Negeri Sembilan, Peninsular Malaysia. We found that earthworm abundance was negatively related to increasing soil compaction, leaf litter weight, soil pH, and undergrowth height, whereas it was positively associated with increasing undergrowth and canopy cover. Our findings demonstrated that agroforestry orchards, rubber tree plantations, and mature oil palm plantations had higher earthworm abundance than those in logged lowland forests. Earthworm abundance in unlogged lowland forests and young oil palm plantations, on the other hand, was lower than in logged lowland forests. Overall earthworm weight was greater in rubber tree plantations, agroforestry orchards, mature oil palm plantations, and unlogged lowland forests than those in logged lowland forests, while young oil palm plantations exhibited lower earthworm weight than logged lowland forests. Our data indicate that increases in soil compaction and leaf litter weight were associated with decreased earthworm weight. These results demonstrate the importance of site-level habitat management for maintaining healthy earthworm populations and soil biodiversity.

P, K AND Na LEACHING FROM LEAF LITTER OF MELIA AZEDARACH (LINN.)

Cations leaching from leaf litter of Melia azedarach (Linn.) was studied in laboratory. About 37% of initial dry weight of leaf litter was lost after 72 hours. Conductivity and total dissolved solid (TDS) of the leached water significantly (p<0.05) increased to 475 µS cm-1 and 227 mg l-1, respectively. pH of the leached water dropped to 5.64 at the end of the experiment. Conductivity and TDS showed significant (p<0.05, r=0.99) positive linear relationships with the weight loss of leaf litter. The concentration of P, K and Na in leaf litter significantly (p<0.05) decreased to 24 mg g-1, 2247 mg g-1 and 900 mg g-1, respectively and PO4, K and Na in leached water significantly (p<0.05) increased to 0.16 ppm, 5.44 ppm and 5.58 ppm, respectively. Nutrients (P, K and Na) in leaf litter showed significant (p<0.05, ranged from -0.92 to -0.99) negative relationship with the weight loss. But, nutrients (PO4, K and Na) in leached water showed significant (p<0.05, ranged from 0.90 to 0.98) positive linear relationship with the leaching time.

NUTRIENTS (N, P AND K) DYNAMICS ASSOCIATED WITH LEAF LITTER OF Albizia saman AND Leucaena leucocephala OF BANGLADESH

Albizia saman and Leucaena leucocephala are not native to Bangladesh, but they are widely planted in agroforestry and households for their commercial value. Selection of tree species with efficient return of nutrients is a vital challenge to maintain soil fertility for sustainable crop production. Therefore, a comparative study was conducted on nutrients (N, P and K) leaching from leaf litter of A. saman and L. leucocephala in laboratory condition. The initial dry weight of leaf litter of A. saman and L. leucocephala were significantly (p<0.05) decreased to 17% and 26%, respectively at the end (after 96 hours) of the experiment. Leucaena leucocephala showed comparatively (t-test, p<0.05) higher rate of weight loss, conductivity and TDS (Total Dissolved Solid) of leaching water. Comparatively, higher amount of N and K was released from leaf litter of A. saman and higher amount of P from leaf litter of L. leucocephala. Both the species showed similar pattern (K>N>P) of nutrient release during the leaching process and nutrients (N, P and K) concentration in leaf litter of these species showed significant (p<0.05) negative curvilinear relationships with the weight loss.

Fuel Briquettes from Sal (Shorea robusta) Forest Litter as an Alternative Cooking Fuel

Sal (Shorea robusta) forest leaf litter strongly influences seed germination and seedling survivorship. Therefore, it is crucial to open up the litter layer in such a forest with abundant leaf litter. Briquetting of Sal forest leaf litter can be an option for its management and meet the increasing energy demand. This research work is performed to quantify the amount of Sal forest litter and study the briquette’s combustion properties. The study was carried out in the Namuna Community Forest of Jhapa district. The average weight of leaf litter in the field was observed to be 851 g/m2 . Five varieties of briquettes were produced using different briquetting technologies. Proximate analysis results, calorific value and water boiling tests show these briquettes have good fuel characteristics and can be used as alternative cooking fuel.

Influence of saprophages (Isopoda, Diplopoda) on leaf litter decomposition under different levels of humidification and chemical loading

The paper presents a study about the influence of two saprophage groups (Isopoda, Diplopoda) on leaf litter decomposition under different levels of humidification and chemical stress. Because of their worldwide distribution, we focused on the common pillbug Armadillidium vulgare (Latreille, 1804) (Isopoda, Armadillidiidae), and the common millipede species Rossiulus kessleri (Lohmander, 1927) (Julida, Julidae). The function of environment creation by the given saprophages, as destructors of dead plant matter, supporting such ecosystem services as soil fertility improvement and nutrients’ turnover, is highlighted. To conduct the experiment, the animals were collected manually and using pitfall trapping. In order to bring the experimental conditions closer to the natural, the individuals were not sexed. The maximum consumption of leaf litter by woodlice was recorded in the conditions with adequate moisture (0.5 mL of distilled water per box) and amounted to 2.52 mg/10 individuals per day, which exceeds its consumption with low and increased moisture, respectively, by 1.82 and 1.24 times. As for the effect of interaction, the consumption of maple litter with optimal moisture (4.77 mg/10 individuals per day) was the greatest. The largest absolute difference between broad-leaved tree species in the average weight of leaf litter consumed by woodlice was between maple leaf litter and oak leaf litter, the minimum – between robinia leaf litter and oak leaf litter. According to the results of the obtained data (Diplopoda), it can be stated that there is a statistically significant effect of chemical stress and discrepancy of the average zinc content in the object of study (in Diplopoda and their faecal pellets). We found that the diet provided did not affect the distribution of zinc in Diplopoda under conditions of chemical stress. According to the results of pairwise comparisons, we determined that the zinc content in the Diplopoda clearly differs for control and almost every concentration of zinc sulfate solution – 0.03 and 0.15 g/L, the samples of which do not form a homogeneous group. The species composition, abundance and distribution in space of soil invertebrates are informative indicators which reflect the ecological state of soils, intensity in development of soil horizons as well as intensity of processes occurring in them.

Long-term, fire-induced changes in habitat structure and microclimate affect Cerrado lizard communities

Fire transforms the structure of natural habitats and, consequently, modifies microclimates affecting ectotherm organisms that are particularly susceptible to changes in the thermal environment. Nevertheless, the effects of fire-induced microclimatic shifts upon natural populations have been neglected. We measured the central tendency and variation of habitat structural and microclimatic variables in experimental plots of Neotropical savanna vegetation subjected to different fire regimes and assessed their effects upon lizard community structure. In addition, we evaluated the underlying mechanisms linking fire-induced environmental changes to community structure, by comparing lizard body condition and survival between different fire regimes. Fire suppression promoted increased tree density, canopy cover and leaf-litter weight, whereas burning had the opposite effects, reducing the habitat structural complexity. The best predictors of fire regimes were means of structural variables, but variances of microclimatic variables, and the reduced structural complexity of burned plots both increased and decreased the variation of microclimatic variables. Lizard community structure was chiefly described by a gradient of decreasing tree density, canopy cover and leaf litter weight with increasing fire severity. About half of the lizard species were favored in the fire-protected plot, while the other half was favored in the burned plots, with most of the variation being explained by structural variables. Lizard body condition and survival rates were not affected by fire regimes, suggesting a dominant role of thermoregulation opportunities afforded by habitat structure—instead of food availability or predation rates—upon community structure. Our findings indicate that even sporadic fires can have profound effects upon lizard communities and that protecting some habitat patches from burning is essential to maximize lizard diversity in Cerrado landscapes.

Effects of Turbidity and Acidity on Predator-Prey Interactions

Predator-prey interactions are influenced by environmental condition changes, such as increased turbidity and acidification caused by human disturbance. These anthropogenic factors can affect trophic interactions from pisciovorous fish, invertivorous fish, and shredder invertebrates to leaf litter leaching. In this study, we investigated effects of increased turbidity and acidification on predator-prey interaction through a four-level detritus-based food chain, which are top predator (pisciovorous fish), intermediate predator (invertivorous fish), shredder invertebrates, and allochthonous leaf litter. The experiment had a top predator-snakehead (Channa argus), an intermediate predator-black carp (Mylopharyngodon piceus), shredder prey-a freshwater crustacean isopods (Asellus sp.), and allochthonous leaf litter sakura (Cerasus sp.). The pisciovorous snakehead was caged, providing non-lethal predation effect on black carp. The effects of turbidity condition changes with different Nephelometric Turbidity Unit (high level: 60 NTU, and low: 10 NTU) and acidic condition changes (weakly acidic: pH 6.0 and normal: pH 7.5) on leaf litter weight loss. The experiment measured shredder density change and leaf litter weight change that was caused by both leaf litter leaching and shredder’s foraging processes. Results indicated that: the high turbid treatment (60 NTU) reduced the black carp’s antipredator defense to snakehead, so that the black carp’s foraging caused the high mortality of isopod shredders, which reduced leaf litter weight loss. By contrast, the weakly acidic treatment (pH=6.0) did not influence black carp’s top-predator avoidance, but induced the loss of predator avoidance of isopod Asellus sp. shredders that caused isopod high mortality. The acidic treatment did not influence litter weight change. Our study highlights that increased turbidity can influence predator-prey interactions and affect leaf litter weight change that caused by both shredder foraging and litter leaching processes in freshwater systems. The increased acidic condition also had a significant effect on predator-prey interaction. With intensified urbanization and increased climate change, such anthropogenic impacts with multiple stressors on predator-prey interaction should be further investigated for understanding their ecological mechanisms.

Effects of alternative silvicultural systems on litter decomposition and nutrients dynamics in sub-Antarctic forests

Forest harvesting is one of the main economic practices in South Patagonia. The impacts produced by forest harvesting have been studied by numerous investigations. And it is known that forest harvesting affects the decomposition of soil organic matter. However, there is no data about how the harvesting by variable-retentions affect this decomposition. Our objective was to determine how impact variable-retention upon decomposition and nutrient release in Nothofagus pumilio forest soils. We hypothesized that variable-retention accelerate decomposition and nutrient release. We compared primary and harvested forests with two types of retentions (aggregated and dispersed) and two times [1 and 5 years after harvesting (YAH)]. To measure litter decomposition, we used bag technique for to determine organic matter loss. We determined carbon; nitrogen; calcium; potassium; magnesium and lignin concentrations in decomposing material. We analysed the data using linear mixed models ANOVA. Decomposition rates were estimated as derivate of the linear mixed model for the logarithm of the remaining leaf litter weight. We found that dispersed retentions treatment had the highest decomposition rates. Primary forest and aggregated retentions had the smaller slopes of the decomposition model. Dispersed and aggregated retention 5 YAH retained more nitrogen compared to primary forest. Dispersed retention 5 YAH had the lowest C/N ratio. Primary forest had higher Lignin/N ratio at 540 incubation days. Dispersed retention 5 YAH released more phosphorus compared to primary forest. Dispersed and aggregated retention 1 YAH had higher C/P ratio. Dispersed retention 5 YAH presented the most mineralization of potassium in the initial time of decomposition. We conclude that the harvesting by variable-retentions had an immediate negative effect on litter decomposition and the nutrients dynamics.

Evaluation of a method for removing cesium and reducing the volume of leaf litter from broad-leaved trees contaminated by the Fukushima Daiichi nuclear accident during the Great East Japan Earthquake

The town of Marumori in southern Miyagi Prefecture borders on Fukushima Prefecture, and following the accident at the Fukushima Daiichi nuclear power plant, there were concerns about cesium deposition in forested areas. One of the authors of this paper has continually surveyed leaf litter from the forested areas. As leaf litter may be a source of cesium contamination from the forest to downstream areas, we considered a simplified version of wet oxidation, a method previously presented by one of the authors of this study, as a technology to reduce leaf litter weight and cesium concentration, separating radioactive nuclides from non-radioactive ones, in leaf litter. We tested our method in three experiments. Experiment 1 used new leaf litter (232 Bq/kg) from the surface of a small stream at the forest edge nearby an area with air dose level higher than the national standard threshold of 0.23 μSv/h for the implementation of governmental decontamination works. Experiment 2 applied wet oxidation to older leaf litter (705 Bq/kg) harvested from a pasture nearby the stream mentioned above. We also used the same leaf litter in experiment 3 for a cesium release tests using pure water. In experiment 1 and 2 we treated leaf litter with a sodium hypochlorite solution, optimizing sodium hypochlorite concentration and reaction temperature. We measured a 50–60% decrease in the leaf litter weight and a 60% decrease in the cesium concentration. Moreover, we also measured the amount of cesium washout. The cesium budget of experiment 1 showed no cesium gasification (wet oxidation avoids airborne cesium as this element is prone to be volatile at 600 °C), and that high sodium hypochlorite concentration and high temperature had a strong positive effect on leaf litter volume reduction and cesium decontamination. Experiment 2 confirmed the reproducibility of these results in leaves with different cesium concentration and harvested in different conditions. We could also explain the mechanism behind leaf litter weight and cesium concentration reduction. Experiment 3 helped us to investigate the effects of the matter present on the surface of the water and the contribution of water soluble cesium. Concurrent experiments on changes in leaf litter chemical composition confirmed that our modified wet oxidation method had an effect on the removal of acid-insoluble lignin. Removal of lignin, a refractory component, might allow for a better utilization of the residue left after implementation of the proposed simplified wet oxidation. Thus, real wastes could be smaller than the residues. Together with the observed smaller cesium concentration in the residue, the proposed method in this study is expected to contribute to mitigate the risk due to the fallen leaves containing cesium.

Nutrients (N, P and K) dynamics associated with the leaf litter of two agroforestry tree species of Bangladesh

Eucalyptus camaldulensis (Dehnh.) and Swietenia macrophylla (King.) are not native to Bangladesh, but they are widely used in agroforestry practices for their commercial values. Selection of tree species with efficient return of nutrients is a vital challenge in agroforestry practices to maintain the soil fertility for sustainable crop production. Therefore, a comparative study was conducted on nutrients (N, P and K) leaching from leaf litter of E. camaldulensis and S. macrophylla in laboratory condition. The initial dry weight of leaf litter of E. camaldulensis and S. macrophylla were significantly (p<0.05) decreased to 18% and 10%, respectively at the end of the experiment. Eucalyptus camaldulensis showed comparatively (t-test, p<0.05) higher rate of weight loss, conductivity and TDS (Total Dissolved Solid) of leached water. Comparatively, higher amount of N (48 μg g-1) was released from leaf litter of E. camaldulensis whereas higher amount of P (0.8 µg g-1) and K (23 mg g-1) from S. macrophylla, leaf litter and both the species showed similar pattern of nutrient (K>N>P) release during the leaching process. Nutrients (N, P and K) concentration in leaf litter of these species showed significant (p<0.05) negative exponential curvilinear relationships with the weight loss. Result of this study suggests that E. camaldulensis is the best in terms of N return and S. macrophylla the best in terms of P and K return.

Spatial patterns of litter-dwelling taxa in relation to the amounts of coarse woody debris in European temperate deciduous forests

We studied the leaf litter-dwelling fauna of managed deciduous forests and primeval reference sites in Western and Central Europe and addressed the questions if the higher overall species richness close to downed coarse woody debris (CWD) is related to intra-specific or inter-specific aggregation, if the aggregation pattern changes with the amount of CWD on the forest floor, and how much CWD is needed for different taxa. The analysis is based on shelled Gastropoda, Diplopoda/Isopoda, Chilopoda and Coleoptera. Among-sample heterogeneity was lower close to CWD than distant from CWD. This was most pronounced in Diplopoda/Isopoda and Gastropoda. Diplopoda/Isopoda are comparatively mobile and assemblages were already quite homogenous close to CWD at levels above 5 m 3 downed deadwood ha −1. Gastropoda have a low mobility, and more than 20 m 3 downed deadwood ha −1 is needed for assemblage homogeneity. We further focused on the Gastropoda as sensitive indicators. Enhanced densities and species richness close to CWD were not a simple function of leaf litter weight, thus effects of densities on heterogeneity are not solely driven by leaf litter accumulation close to CWD. In contrast to euryecious litter-dwellers such as the Punctidae, stenecious slow active dispersers such as the Clausiliidae clearly require more than 20 m 3 CWD ha −1 for an even distribution. Specialists depending on CWD even seem to have gone extinct in some managed forests. For conserving the litter-dwelling fauna, we propose a target of at least 20 m 3 downed CWD ha −1 in already managed forests and rigorous restrictions for deadwood removal from still (almost) pristine systems.

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&lt;0.05) positive curvilinear relationship with leaching time. The initial concentration of K and Na in leaf litter significantly (p&lt;0.05) decreased to 2247 mg g-1 and 735 mg g-1 respectively after 96 hours and showed significant (p&lt;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.

Soil-inhabiting Tardigrade Communities in Forests of Central Japan

This study was carried out for the purpose of detecting the relationship between soil-inhabiting tardigrade communities and environmental factors of various forests. Nine forests in the southern part of Kanagawa Prefecture, Central Japan, were selected for this study. Four vegetation types were designated; broadleaved (evergreen/deciduous), coniferous and orchard. In these sites, dry weight of leaf litter, soil pH, soil hardness, soil moisture content and porosity ratio were measured. Wet soil faunal frequencies were also described. The Baermann funnel method was adopted for collecting tardigrades, and DIC microscopy was used for specific identification. To clarify the correlation between environmental variables and tardigrade faunae, multivariate analysis was applied. The tardigrade fauna occurred as two distinct groups. The first group primarily contained Macrobiotus species. The second group contained the genus Diphascon (e.g. D. nobilei, D. patanei, D. prorsirostre). An exception to this was D. pingue, included in the former. Most of the Diphascon species were concentrated in Nebu (coniferous forest site), while, Macrobiotus species were dominant in other sites. Distinct environmental factors could not be identified, but the nematodal frequency was recognized as the main factor in forming these groups. The uniqueness of Nebu, which does not correspond to large-scaled vegetational classification, was substantiated by statistical data. Nebu’s coniferous forest apparently has created a unique environment for sustaining rare species (Diphascon species). This study concluded that forests should be evaluated not only by the macroscopic factors, such as landscape, but also by the microscopic communities, such as those including the tardigrades.

The localized environmental degradation of protected areas adjacent to bird feeding stations: a case study of the Australian brush-turkey Alectura lathami

This study investigated the potential for wildlife feeding to artificially increase population densities of the Australian brush-turkey, Alectura lathami and assessed the indirect adverse effects that this may have on surrounding forest floor vegetation. Census counts and observations of feeding activity conducted in recreation areas of Australia's Gold Coast hinterland confirmed that brush-turkey population densities were significantly elevated by the provision of food by humans. Brush-turkey densities were high at sites where birds are actively fed, moderate at sites where birds feed opportunistically and low at sites where humans have negligible impact on local food availability. Brush-turkeys caused significant environmental impact at sites where their population densities have been substantially elevated by active feeding. Across all sites, increases in brush-turkey density were accompanied by a significant decline in ground cover, leaf litter weight, seed density and seedling density. Natural environmental variables such as gradient, vegetation type and canopy cover did not explain the observed impacts. The impacts were consistent with those described in trampling studies and suggest that at high density, even small animals can have significant trampling impacts on their local environment. This study demonstrates that wildlife feeding can have detrimental impacts on the integrity of local environments and recommends greater consideration of small animals and their potential indirect impacts when regulating wildlife feeding in National Parks and other nature conservation areas.

Effect of earthworm addition on soil nitrogen availability, microbial biomass and litter decomposition in mesocosms

The aim of the study was to determine the effect of adding two tropical earthworm species, Rhinodrilus contortus and Pontoscolex corethrurus, to mesocosms on the availability of mineral N (NH4+ and NO3−concentrations), soil microbial biomass (bio-N), and the decomposition rates of three contrasting leaf litter species, in a glasshouse experiment. The mesocosms were filled with forest soil and covered with a layer of leaf litter differing in nutritional quality: (1) Hevea brasiliensis (C/N=27); (2) Carapa guianensis (C/N=32); (3) Vismia sp., the dominant tree species in the second growth forest (control, C/N= 42); and, (4) a mixture of the former three leaf species, in equal proportions (C/N=34). At the end of the 97-day experiment, the soil mineral N concentrations, bio-N, and leaf litter weight loss were determined. Both earthworm species showed significant effects on the concentrations of soil NO3−(p<0.01) and NH4+ (p<0.05). Bio-N was always greater in the mesocosms with earthworms (especially with R. contortus) and in the mesocosms with leaf litter of H. brasiliensis (6 µg N g−1 soil), the faster decomposing species, than in the other treatments (0.1–1.6 µg N g−1). Thus, earthworm activity increased soil mineral-N concentrations, possibly due to the consumption of soil microbial biomass, which can speed turnover and mineralization of microbial tissues. No significant differences in decomposition rate were found between the mesocosms with and without earthworms, suggesting that experiments lasting longer are needed to determine the effect of earthworms on litter decomposition rates.

The Decomposition of Leaf Litters of Some Tree Species in Temperate Deciduous Forest in Korea I. Losses in Dry Weight of Leaf Litter

Losses in the dry weight of leaf litter from six tree species were studied during 16 months on the forest floor in temperate deciduous forest of Mt. Cheonma in the vicinity of Seoul in Korea by using litter bag method. The decomposition rate of each leaf litter varies with each species. After 16 months elapsed, the leaf litter of Acer pseudo-sieboidianum showed the highest decomposition constant (0.82) as Olson´s decomposition constant, while that of Pinus densiflora showed the lowest decomposition constant (0.33). The decomposition constant of Quercus mongolica, Q. serrata, Betula ermani and Carpinus laxiflora showed 0.43, 0.37, 0.66 and 0.75, respectively. The decomposition constant of leaf litter was considered with temperature and precipitation which accumulated daily during each term of litter bag collection. The decomposition constant of leaf litter showed closely positive correlation with daily accumulative temperature and precipitation. The relationships between decomposition constant and the daily accumulative temperature and precipitation at each period of litter bag collection were analyzed through multi-regression analysis. The correlation coefficients as a result of multi-regression analysis in Q. mongolica, Q. serrata, P densiflora, B. ermani, C. laxiflorais and A. pseudo-sieboldianum were 0.83, 0.81, 0.69, 0.77, 0.77 and 0.62, respectively. The precipitation showed higher effect, about 10 times, on the leaf litter decomposition than the daily accumulative temperature.

Effect of fertilizer on microbial decomposition of leaf litter of a regenerating bush-fallow in sub-humid tropical Nigeria

A 5-month study of the effects of urea and NPK-mixtures on microbial litter decomposition process was carried out on the leaf litter of a regenerating secondary forest at Ile-Ife, Nigeria. The litter was treated with urea and an NPK-mixture separately at three levels of concentrations calculated on the basis of the fertilizers. Addition of urea and an NPK-mixture at 5, 10 and 15 mg g −1 air-dried litter increased microbial population, activity and the rate of decomposition of litter as compared with the control. In the case of the NPK-mixture, the increase was more pronounced as the concentration increased, but in the case of urea, the increasing trend was reversed after two months, even though bacterial population maintained a steady increase. The nutrient element dynamics of decomposing leaf litter in relation to fertilizer treatment was examined. N, P and Mg concentrations in leaf litter declined in the first two months of sampling. However, N and P remained relatively constant despite about 30% loss in weight of leaf litter during subsequent sampling periods. The rate of loss of Mg was somewhat faster than that of the organic matter. K and Ca showed marked contrasts both with N, P and Mg and with one another.

Litterfall and nutrient returns in red alder stands in western Washington

Litterfall was collected over 1 year from eight natural stands of red alder growing on different sites in western Washington. The stands occurred at various elevations and on different soils, and differed in age, basal area, and site index. Most litterfall was leaf litter (average 86 percent). Amounts of litterfall and leaf litter varied significantly (P<0.05) among the sites. Average weights of litterfall and leaf litter in kg ha−1 yr−1, were 5150 and 4440, respectively. Weight of leaf litter was not significantly (P<0.05) related to site index, stand age, or basal area. The sites varied significantly (P<0.05) in concentrations of all elements determined in the leaf litter, except Zn. Average chemical concentrations were: N, 1.98 percent; P, 0.09 percent; K, 0.44 percent; Ca, 1.01 percent; Mg, 0.21 percent; S, 0.17 percent; SO4−S, nil; Fe, 324 ppm; Mn, 311 ppm; Zn, 53 ppm; Cu, 13 ppm; and Al, 281 ppm. There were significant correlations between some stand characteristics and concentrations of some elements, and among the different chemical components of the leaf litter. Important correlations were found between stand age and P concentration (r=−0.84,P<0.01); weight of leaf litter and P concentration (r=0.74,P<0.05); weight of leaf litter and K concentration (r=0.71,P<0.05); concentrations of N and S (r=0.81,P<0.05); and concentrations of Fe and Al (r=0.98,P<0.01). Returns of the different elements to the soil by leaf litter varied among the different sites. Average nutrient and Al returns, in kg ha−1 yr−1, were: N, 82; Ca, 41; K, 19; Mg, 8; S, 7; P, 4; Fe, 1; Mn, 1; Al, 1; Zn, 0.2, and Cu, <0.1.

Herbicide Effects on Leaf Litter Decomposition Processes in An Oak‐Hickory Forest

Herbicide treatments (2, 4, 5—Trichlorophenoxyacetic acid) of 0.225 g/m2 and 2.250 g/m2 were applied in a Latin square design to the forest floor of an oak—hickory forest in Georgia. White oak (Quercus alba) leaf litter decomposition and litter and soil microarthropod populations were studied in control and treated areas. Weight loss of natural white oak leaf litter averaged 35% for the 1st yr and reached 67% after 2 yr. Litter decomposition rates were similar in control and treated areas. However, white oak leaves defoliated through stem injections lost 59% of their biomass in 1 yr. Decomposition was increased because of initially higher N levels and a lower C:N ratio in defoliated leaf tissue. Herbicide spray treatment increased microarthropod densities for up to 8 mo after application. The herbicide spray apparently influenced springtail and mite reproductive activity in treated areas. The increases in soil and litter microarthropod densities were not sufficient to affect leaf litter weight losses. Repeated defoliation of plant communities and the resulting increased decomposition rates could cause imbalances in litter dynamics and cycling processes. Changes in the timing of annual litterfall and the rates of nutrient release may thus lead to soil desiccation and the depletion of available nutrient pools.