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EN
A decomposition study was carried out on the leaf litters of Leucaena leucocaephala to determine the rate of decomposition of its leaves with respect to its placement on above or below the ground levels in L. leucocaephala plantations of the Federal University of Agriculture, Abeokuta, Nigeria. In the study, leaf litter were randomly handpicked from the forest floor, of this, 40 g each were weighed into thirty (30) litter bags of 2 mm mesh size in which 15 were randomly placed on the forest floor (above-ground) and the remaining 15 were buried in the soil between 5-10 cm depth (below-ground). Data were analysed using descriptive statistical techniques such as percentage, while inferential statistics (simple linear regression) was used to determine relationships between various nutrient elements and days of decomposition (DOD). We noted that the percentage of mass loss of leaf litter increased with time in days after deposit and was higher (29.93%, 32.43 % and 33.25%, 41.65%) at 80 to 100 days of placement above- and below-ground, respectively. Moreover, the exchangeable basic cations and chemical compositions of litters were not consistent with respect to DOD. Regression analysis of nitrogen (N) and organic carbon (OC) showed that these elements significantly contributed to the high (86 %) overall decomposition of litter (p < 0.05, p < 0.01) below-ground level. It is, therefore, concluded that decomposition of leaf litters occur faster below ground than above ground within the forest plantation.
EN
In a mixed beech forest growing on limestone, the effect of an enhanced and a reduced layer of leaf litter on the emergence of parasitic Hymenoptera (as well as their hosts) was studied. A long term increase (4 years with an initially 5-fold value) of the leaf layer and a short term experiment (1 year, factor 5) resulted in arise of the total density of soil living parasitoids. The abundance of parasitoids which attack hosts in the herb layer or canopy declined. However, in both groups diversity and evenness was lowered. A reduction of the layer of leaf litter resulted in lower densities of the parasitoids of soil living hosts, but higher abundances of the parasitoids of hosts in other strata. The lacking leaf layer caused a reduction in the number of species and lowered both diversity and evenness. The lacking leaf layer also caused changes in the species composition. Experiments with dead snails to attract necrophagous insects and their parasitoids covered by different amounts of leaf litter revealed a species specific reaction to the leaf cover. Total parasitism rates were not reduced under a thick layer of leaf litter. No protective function of the leaf cover could be detected.
EN
Recent studies suggested a general warming trend in the Alps, resulting in a significant migration of forests to altitudes higher than the usual, regional tree line. As a consequence, some headwater streams will likely receive more allochthonous organic matter. For this reason, the dynamics of decomposition of terrestrial leaf detritus in stream reaches that naturally lacked this resource represents a subject of considerable interest, on which no information is currently available. The aim of this study was to analyse breakdown and macroinvertebrate colonisation of leaf bags in an Alpine headwater stream above the tree line. Results of this study indicate that decomposition of terrestrial leaves in a lotic alpine environment above the tree line takes place through a process similar to what happens at lower altitudes, but with some differences. The reduced rate of decomposition observed may be due to lower temperatures. At lower altitudes, tree cover provides a supply of organic material sufficient to support a rich guild of shredders. This study demonstrates that also above tree line, where communities are dominated by scrapers, an important part of the benthic community take part in the decomposition process of leaves. We can conclude that streams above the tree line, while hosting invertebrate communities dominated by rhithrophilous organisms that feed mostly on biofilm, also harbour a rich population of opportunist invertebrates. It seems that, in the case of expected temperature increase at higher altitudes , terrestrial organic detritus may be actively degraded by lotic benthic communities.
EN
The richness and diversity of filamentous fungi associated with the decomposition of leaf litter of three tree species (Castanopsis accuminatissima, Styrax benzoides, and Dipterocarpus (grancilis) in evergreen tropical forest in the northeast of Thailand were studied at 6 and 12 months after leaf fall. A total of 125 taxa were identified through examining 4,362 isolates. These comprised 6 species of Zygomycetes, 19 species of Ascomycetes, 62 species of Deuteromycetes, and 38 taxa of unidentified sterile mycelium. Each decaying stage of leaf litter had a different composition of taxonomic groups. The average percent similarity between fungi assemblages of different species litter and of decomposition stage ranged between 37-44% and 6-13%, respectively. The majority of fungal taxa found had a low frequency of occurrence. Six month decaying leaves had the highest number (2,093) of fungal isolates but the fungal taxa number (35) was much lower than in freshly fallen leaves and equal to 12 month decaying leaves. The freshly fallen leaves gave the lowest number (1,103) of isolates but the number (69) of fungal taxa was much higher than that found in the 6 month and 12 month decaying leaves. The most dominant fungal taxon was Trichoderma koningii. The Shannon-Wiener diversity index showed that the initial diversity (H.) of fungal taxa from freshly fallen leaves was the highest and equals to 2.9, 2.8 and 3.0 in C. accuminatissima, S. benzoides, and D. (grancilis) respectively.
EN
The influence of fertilization with the compost prepared from treated sewage sludge with bark additive and mulching with the fresh forest ectohumus on the soil conditions, chosen parameters of two- and three-year old littleleaf linden seedlings growth as well as the occurrence of soil mites (Acari) was investigated in the paper. The experiments were carried out in 2009–2010 at forest nursery Białe Błota (Forest District Bydgoszcz) on the rusty soil. The whole area of the experiment was irrigated with the use of stationary sprinkling machine. The soil was characterized by the alkaline reaction (pH in H2O was in the range 7.2–7.4), the low content of available potassium and available phosphorus as well as the content of C-org from 35.7 to 38.4 g kg-1),. The C:N ratio ranged from 14.3 to 14.9. Two- and three-year old seedlings of littleleaf linden grown on plots fertilized with the compost were higher than those cultivated on plots with mineral fertilizer and they were also characterized by the higher number of leaves and the higher leaf area. Mulching – which was carried out in September of the first growing season – did not influence significantly on the growth parameters of two-year old seedlings (with the exception of the decrease in a leaf area). In the third growing season the mulching significantly influenced on all the seedling growth parameters tested, and – furthermore – there was also a significant interaction between the both studied treatments in shaping of the all growth parameters (with the exception of the plant height) of littleleaf linden seedlings. The density of mites in the soil was distinctly increased after the mulch-ing treatment , and it was many fold higher as compared to the control plot MC. On the base of the analysis it was found that the mulching and the fertilization with compost prepared from municipal sewage sludge influenced positively on the abundance of mites, especially oribatid mites as well as on their species diversity. Tectocepheus velatus was the most abundant species among the oribatid mites on all the stands of littleleaf linden cultivation. Abundance dynamics of this oribatid species in the two-years period of the study, especially on the variant with mulching and organic fertilization, indicates the upward trend in the number of its population.
EN
The relationship between litter decomposition and forest succession in addition to the influence of climate variables on the rate of litter decomposition in forest ecosystems are poorly understood. In this study, the effects of forest successional stages, climate, and litter quality on litter decomposition rates were investigated in five sites located in China. The selected sites cover 29 degrees of latitude from 18° N to 47° N and spans more than 5,000 km in length along a temperature gradient that transverses across eastern China. This zonal gradient includes five climate zones from temperate to subtropical to tropical zones. Forest types include broad-leaved Korean pine, deciduous broad-leaved, evergreen broad-leaved, monsoon evergreen broad-leaved, and tropical rain forests. The North-South Transect of Eastern China (NSTEC) is one of fifteen international standard transects setup by Global Change and Terrestrial Ecosystems (GCTE). NSTEC is a key component of the International Geosphere-Biosphere Programme (IGBP). The litterbag method was used in this study to determine mass loss and annual decomposition rates of eight tree species (Pinus massoniana Lamb., Cunninghamia lanceolata (Lamb.) Hook., Schima superba Gardn. et Champ., Cinnamomum camphora (L.) Presl., Cyclobalanopsis glauca (Thunb.) Oerst., C. gracilis (Rehd. et Wils.) Cheng et T. Hong, Michelia chapensis Dandy, and Castanopsis eyeri (Champ.) Tutch. Through a timeframe starting in May, 2006, and ending in May, 2008. Litterbags 15 x15 cm and 0.5 x 1.0 mm mesh were filled with 10 g of leaf litter collected from the subtropical forest region and then placed onto the forest floor in triplicate samples for each eight species in all five sites. Three litterbags per species were retrieved from each of the five sites at two month intervals during the two year experimental period. Results suggest that species litter in the climax stage (C. glauca, C. gracilis, and M. chapensis) tended to decompose faster than those in the pioneer stage (P. massoniana and C. lanceolata). Initial phosphorous (P) and nitrogen (N) concentrations of leaf litter were the most critical variables of litter quality in relation to the impact on the rate of litter decomposition. Litter decomposition at different successional stages was found to be directly related to climatic variables such as mean annual precipitation (MAP) and mean annual temperature (MAT). MAP and initial P and N concentrations could therefore be considered good indicators of rates of decomposition.
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As an important non-wood forest product and wood substitute, Moso bamboo grows extremely rapidly and hence acquires large quantities of nutrients from the soil. With regard to litter decomposition, N and P release in Moso bamboo forests is undoubtedly important; however, to date, no comprehensive analysis has been conducted. Here, we chose two dominant species (i.e., Cunninghamia lanceolata and Phoebe bournei), in addition to Moso bamboo, which are widely distributed in subtropical southeastern China, and created five leaf litter mixtures (PE100, PE80PB20, PE80CL20, PE50PB50 and PE50CL50) to investigate species effects on leaf litter decomposition and nutrient release (N and P) via the litterbag method. Over a one-year incubation experiment, mass loss varied significantly with litter type (P < 0.05). The litter mixtures containing the higher proportions (>80%) of Moso bamboo decomposed faster; the remaining litter compositions followed Olson's decay mode well (R2 > 0.94, P < 0.001). N and P had different patterns of release; overall, N showed great temporal variation, while P was released from the litter continually. The mixture of Moso bamboo and Phoebe bournei (PE80PB20 and PE50PB50) showed significantly faster P release compared to the other three types, but there was no significant difference in N release. Litter decomposition and P release were related to initial litter C/N ratio, C/P ratio, and/or C content, while no significant relationship between N release and initial stoichiometric ratios was found. The Moso bamboo-Phoebe bournei (i.e., bamboo-broadleaved) mixture appeared to be the best choice for nutrient return and thus productivity and maintenance of Moso bamboo in this region.
EN
The influence of distance between host trees and leaf litter removal on population density of Cameraria ohridella have been for the first time examined in an isolated population of horse chestnut (Aesculus hippocastanum L.) trees. The observation was performed in the small town (area 13,58 km²) in Wielkopolska region (West Poland) on the total number of 49 trees: 31 (11 clumps) of them with autumnal leaves removal (controlled sites), and 18 (5 clumps) without this procedure (uncontrolled sites). The main factors determining the extent of the leaf destruction by larvae were the leaf litter removal and the number of subsequent generations on a given tree. The effect of mean distance between trees on the infestation level was statistically significant only for the third generation larvae, when analyzing all sites. There was no significant correlation when checking the impact of mean and short distance on the leaves infestation between controlled and uncontrolled sites. The abundance of the first generation of the larvae of raked sites is possibly a result of low number of in situ overwintering individuals and the number of immigrants from uncontrolled areas. Assuming the random choice of direction of the migration, the effect of the immigrants on the trees which leaves have been disposed of is not as high as it should be expected. Additionally, the moths can be blown away by the wind in a random direction. Consequently, the noted increase in the leaves infestation by the third generation larvae can be result of the rate of population increase innate for the species and only partly a result of immigration from refuge areas.
EN
The potential differentiations in litter chemistry among native and non-native trees are poorly understood. We compared the chemical composition of leaf litterfall of 11 exotic tree species, e.g. coniferous: Abies cephalonica, A. grandis, A. procera, Chamaecyparis pisifera, Pinus peuce, Pseudotsuga menziesii, Thuja plicata, and deciduous: Acer rubrum, A. saccharum, Betula alleghaniensis and Quercus rubra, with that of a native European conifer, Pinus sylvestris (as reference to coniferous species) anda mixture of native European Quercus robur, Carpinus betulus, Tilia cordata, T. platyphyllos and Corylus avellana leaves (as a reference mixture of deciduous species). We found significant differences among the species studied in nitrogen and carbon content in needles/leaves, C/N ratio, as well as total soluble phenolic compounds (TPh) and total nonstructural carbohydrates (TNC) content, including soluble carbohydrates and starch. However, we found no clear differentiation of exotic from native tree species in the analyzed elements and metabolites. Among the exotic coniferous tree species, P. menziesii stood out among the species studied – fallen needles of this species were characterized by relatively high TPh and TNC content. The relationships between TPh and TNC content in leaf and needle litter among tree species were similar among two consecutive years. For deciduous tree species, the tendency of higher TPh content and C/N ratio in leaves falling earlier (September; leaves of sun-type) than later (November; leaves of shade-type) was more distinct than in coniferous tree species. Generally, we cannot see any special differences in the levels or mutual quantitative relationships of the chemical compounds studied in fallen needles/leaves of exotic tree species in comparison with native tree species.
EN
The canopy samples such as trapped leaf litter, trapped sediment (during summer), stemflow and throughfall (during monsoon) from five common riparian tree species (Artocarpus heterophyllus, Cassia fistula, Ficus recemosa, Syzygium caryophyllatum and Xylia xylocarpa) in Kaiga forest stand of the Western Ghats of southwest India were evaluated for the occurrence of water-borne hyphomycetes. Partially decomposed trapped leaf litter was incubated in bubble chambers followed by filtration to assess conidial output. Sediments accumulated in tree holes or junction of branches were shaken with sterile leaf disks in distilled water followed by incubation of leaf disks in bubble chamber and filtration to find out colonized fungi. Stemflow and throughfall samples were filtered directly to collect free conidia. From five canopy niches, a total of 29 water-borne hyphomycetes were recovered. The species richness was higher in stemflow and throughfall than trapped leaf litter and sediments (14-16 vs. 6-10 species). Although sediments of Syzygium caryophyllatum were acidic (5.1), the conidial output was higher than other tree species. Stemflow and throughfall of Xylea xylocarpa even though alkaline (8.5-8.7) showed higher species richness (6-12 species) as well as conidial load than rest of the tree species. Flagellospora curvula and Triscelophorus acuminatus were common in trapped leaf litter and sediments respectively, while conidia of Anguillospora crassa and A. longissima were frequent in stemflow and throughfall. Diversity of water-borne hyphomycetes was highest in throughfall of Xylea xylocarpa followed by throughfall of Ficus recemosa. Our study reconfirms the occurrence and survival of diverse water-borne hyphomycetes in different niches of riparian tree canopies of the Western Ghats during wet and dry regimes and predicts their possible role in canopy as saprophytes, endophytes and alternation of life cycle between canopy and aquatic habitats.
EN
To assess nitrogen (N) resorption patterns in semi-arid sandy land, N concentrations in green leaves (Ng) and senesced leaves (Ns) of 35 species of shrubs and herbages were measured along habitats of decreasing soil total N (0.54 to 0.041 g g⁻¹ d.w. of top soil level) in Horqin Sandy Land (Inner Mongolia, China). These habitats are following: inter-dune grassland (IDG), fixed sand dune (FD), semi-fixed sand dune (SFD), semi-mobile sand dune (SMD), and mobile sand dune (MD) were considered. Results showed that Ng and Ns (i.e. nitrogen resorption proficiency, NRP) increased and leaf nitrogen use efficiency (NUE) decreased significantly with increasing soil N status across the above habitas, but nitrogen resorption efficiency (NRE) was not affected. The levels of Ng, Ns and NUE experience two stages across habitats: first, there were low Ng and Ns and high NUE in MD and SMD; second, there were high Ng and Ns and low NUE in IDG, FD and SFD. Plants from IDG, FD and SFD had incomplete N resorption during foliar senescence, but plants from MD and SMD had complete N resorption. Leaf NRE was determined by life forms which had no significant effect on Ng but on Ns and NUE. For all plants in the five habitats, NRE and NUE decreased with the sequence of grass, herb, shrub, while Ns showed a contrary tendency. Plants from strong N limitation habitats did not show higher NRE, but showed higher NRP and leaf NUE, so NRP was a more sensitive indicator of changes in N status than NRE. In conclusion, Leaf N resorption patterns were mainly determined by soil N status across habitats, and there were some consistent patterns among life forms.
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