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Leaf Decomposition (leaf + decomposition)
Selected AbstractsLeaf Decomposition in a Mountain Stream in the Sultanate of OmanINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2009Maha Al-Riyami Abstract Decomposition of Juglans regia leaves was studied in fine and coarse mesh bags in a permanent mountain stream in Oman. A rapid initial mass loss, attributed to leaching, was followed by a more gradual decline. Daily exponential decay rates (k) calculated over 32 days were 0.011 (fine mesh litter bags) and 0.014 (coarse mesh litter bags). The difference between bag types was not significant, suggesting limited impact of leaf-shredding invertebrates. Ergosterol levels on leaves from fine mesh bags peaked at 0.3 mg g,1 AFDM after 16 days of stream exposure. During the experimental period, which followed the annual leaf fall, the concentration of aquatic hyphomycete conidia in the stream varied between 82 and 1362 l,1. Based on the morphology of conidia found in the water column or released from leaves, we identified 14 species of aquatic hyphomycetes. Tetracladium apiense was the most common taxon (62.2% of conidia in water column during the field experiment). Three other Tetracladium species contributed another 8%. Plating out leaf particles yielded common epiphytic taxa such as Alternaria sp., Aureobasidium pullulans and Phoma sp. The measured metrics of leaf decay in this desert stream fall within the range of values observed in temperate and tropical streams, with clear evidence for an early leaching phase, and no evidence of a strong impact of leaf shredders. The community of aquatic hyphomycetes appears impoverished. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solar UVB and warming affect decomposition and earthworms in a fen ecosystem in Tierra del Fuego, ArgentinaGLOBAL CHANGE BIOLOGY, Issue 10 2009JOHANN G. ZALLER Abstract Combined effects of co-occurring global climate changes on ecosystem responses are generally poorly understood. Here, we present results from a 2-year field experiment in a Carex fen ecosystem on the southernmost tip of South America, where we examined the effects of solar ultraviolet B (UVB, 280,315 nm) and warming on above- and belowground plant production, C : N ratios, decomposition rates and earthworm population sizes. Solar UVB radiation was manipulated using transparent plastic filter films to create a near-ambient (90% of ambient UVB) or a reduced solar UVB treatment (15% of ambient UVB). The warming treatment was imposed passively by wrapping the same filter material around the plots resulting in a mean air and soil temperature increase of about 1.2 °C. Aboveground plant production was not affected by warming, and marginally reduced at near-ambient UVB only in the second season. Aboveground plant biomass also tended to have a lower C : N ratio under near-ambient UVB and was differently affected at the two temperatures (marginal UVB × temperature interaction). Leaf decomposition of one dominant sedge species (Carex curta) tended to be faster at near-ambient UVB than at reduced UVB. Leaf decomposition of a codominant species (Carex decidua) was significantly faster at near-ambient UVB; root decomposition of this species tended to be lower at increased temperature and interacted with UVB. We found, for the first time in a field experiment that epigeic earthworm density and biomass was 36% decreased by warming but remained unaffected by UVB radiation. Our results show that present-day solar UVB radiation and modest warming can adversely affect ecosystem functioning and engineers of this fen. However, results on plant biomass production also showed that treatment manipulations of co-occurring global change factors can be overridden by the local climatic situation in a given study year. [source] Litter decomposition in grasslands of Central North America (US Great Plains)GLOBAL CHANGE BIOLOGY, Issue 5 2009ELIANA E. BONTTI Abstract One of the major concerns about global warming is the potential for an increase in decomposition and soil respiration rates, increasing CO2 emissions and creating a positive feedback between global warming and soil respiration. This is particularly important in ecosystems with large belowground biomass, such as grasslands where over 90% of the carbon is allocated belowground. A better understanding of the relative influence of climate and litter quality on litter decomposition is needed to predict these changes accurately in grasslands. The Long-Term Intersite Decomposition Experiment Team (LIDET) dataset was used to evaluate the influence of climatic variables (temperature, precipitation, actual evapotranspiration, and climate decomposition index), and litter quality (lignin content, carbon : nitrogen, and lignin : nitrogen ratios) on leaf and root decomposition in the US Great Plains. Wooden dowels were used to provide a homogeneous litter quality to evaluate the relative importance of above and belowground environments on decomposition. Contrary to expectations, temperature did not explain variation in root and leaf decomposition, whereas precipitation partially explained variation in root decomposition. Percent lignin was the best predictor of leaf and root decomposition. It also explained most variation in root decomposition in models which combined litter quality and climatic variables. Despite the lack of relationship between temperature and root decomposition, temperature could indirectly affect root decomposition through decreased litter quality and increased water deficits. These results suggest that carbon flux from root decomposition in grasslands would increase, as result of increasing temperature, only if precipitation is not limiting. However, where precipitation is limiting, increased temperature would decrease root decomposition, thus likely increasing carbon storage in grasslands. Under homogeneous litter quality, belowground decomposition was faster than aboveground and was best predicted by mean annual precipitation, which also suggests that the high moisture in soil accelerates decomposition belowground. [source] Nutrient enrichment overwhelms diversity effects in leaf decomposition by stream fungiOIKOS, Issue 2 2003Felix Bärlocher Mass losses of oak leaves were studied in microcosms, where numbers of aquatic hyphomycete species (1,5) and nutrient concentrations (2 levels each of N, P, and Ca) were varied. Species numbers, species identities, N, P and N×P interactions all had significant effects on leaf mass loss, but the magnitude of the effect was greater for N and P than for species numbers. Mass loss in multicultures was greater than predicted from average contributions of the component species in single cultures. This may have been due to sampling effects or niche complementarity. [source] Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Marací Island, Brazil1BIOTROPICA, Issue 3 2002Dora M. Villela ABSTRACT The forest type dominated by Peltogyne gracilipes (Caesalpiniaceae) on the riverine Marací Island is the least speciesrich of any recorded for Brazilian Amazonia. Because the forest has high soil and foliar Mg concentrations, and Mg is known to be toxic to plant growth at high concentrations, this study tested the hypothesis that dominance by Peltogyne is related to Mg leaf litter amounts and decomposition. We predicted that decomposition of Peltogyne leaves would differ from that of other species, and that their decomposition would result in a pulse of Mg release. Three plots (50 × 50 m) were established in each of three forest types: Peltogyne -rich forest (PRF; dominated by P. gracilipes),Peltogyne-poor forest (PPF), and forest without Peltogyne (FWP). Three leaf litter decomposition experiments tested if decomposition of mixed leaf litter in coarse- mesh (CM) litterbags differed among forests (experiment 1); whether or not decomposition and nutrient release of Ecclinusa guianensis, Lueheopsis duckeana, and Peltogyne in CM litterbags differed among forests and species (experiment 2); and using fine-mesh (FM) litterbags, investigated the differences in the influence of fauna! activity on Ecclinusa and Peltogyne decomposition (experiment 3). Decomposition was independent of the presence and dominance of Peltogyne, since decomposition rates in both PRF and FWP were in general lower than in PPF. These differences appeared to be related to fauna] activity. The decomposition of Peltogyne leaves was lower than that of the other species tested and was more affected by microbial and physical action. It is possible that the monodominance of Peltogyne is related to its deciduousness and faster decomposition in the dry season, which coincides with a large leaf fall. Magnesium was lost quickly from the Peltogyne leaves and the resultant pulses of Mg into the soil during the heavy rains at the beginning of the wet season may be deleterious for other species that are not adapted to high solution Mg concentrations. Results obtained were consistent with the hypothesis that Peltogyne dominance is related to the pattern of its leaf decomposition and the seasonal pulses of toxic Mg. RESUMO A floresta dominada por Peltogyne gracilipes (Caesalpiniaceae) na Ilha fluvial de Maracáé a mais pobre em espécies reportada para a Amazõnia brasileira. Devido a esta floresta possuir altas concentra¸ões de Mg no solo e nas folhas, e pelo fato de Mg ser conhecidamente tóxico para o crescimento das plantas quando em altas concentra¸ões, este estudo testou a hipótese de que a dominãncia de Peltogyne está relacionada com as quantidades de Mg e com a decomposi¸ão das folhas da serrapilheira. Esperou-se encontrar um padrão de decomposi¸ão diferente para folhas de Peltogyne, e que as folhas de Peltogyne apresentassem um pulso de libera¸ão de Mg. Três parcelas (50 × 50 m) foram estabelecidas em cada um dos três tipos florestais: floresta rica em Peltogyne (PRF; dominada por P. gracilipes), floresta pobre em Peltogyne (PPF) e floresta sem Peltogyne (FWP). Três experimentos de decomposi¸ão de folhas da serrapilheira testaram se a decomposi¸ão de folhas mistas da serrapilheira em sacos de serrapilheira de malha grossa (CM) difere entre florestas (experimento 1), se a decomposi¸ão e a libera¸ão de nutrientes de Ecclinusa guianensis, Lueheopsis duckeana, e Peltogyne em sacos de serrapilheira CM difere entre florestas e entre espécies (experimento 2), e usou sacos de serrapilheira de malha fina (FM) para investigar as diferen¸as na influência da atividade da fauna na decomposi¸ão de Ecclinusa e Peltogyne (experimento 3). A decomposi¸ão foi independente da presen¸a e dominãncia de Peltogyne, já que as taxas de decomposi¸ão em PRF e FWP foram em geral menores que em PPF. Estas diferencas parecem estar relacionadas à atividade da fauna. A decomposi¸ão de folhas de Peltogyne foi menor que a das demais espécies testadas e foi mais afetada pela a¸ão microbiológica e flsica. é possível que a dominãncia de Peltogyne esteja relacionada com a sua deciduidade e com a rápida decomposi¸ão na esta¸ão seca, a qual coincide com uma grande queda de folhas. Magnésio foi perdido rapidamente das folhas de Peltogyne e os pulsos resultantes de Mg no solo durante as fortes chuvas no início da esta¸ão chuvosa podem ser deletérios para outras espécies que não estão adaptadas as altas concentra¸ões deste íon. Os resultados obtidos foram consistentes com a hipótese de que a dominãncia de Peltogyne está relacionada com o padrão de decomposi¸ão de suas folhas e com os pulsos sazonais de Mg tóxico. [source] | ||||||||||