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Nutrient Release (nutrient + release)
Selected AbstractsNutrient release from coastal aquaculture: the importance of temporal aspects in species-specific production cyclesAQUACULTURE RESEARCH, Issue 13 2009Trisha L Amundrud First page of article [source] The angiosperm radiation revisited, an ecological explanation for Darwin's ,abominable mystery'ECOLOGY LETTERS, Issue 9 2009Frank Berendse Abstract One of the greatest terrestrial radiations is the diversification of the flowering plants (Angiospermae) in the Cretaceous period. Early angiosperms appear to have been limited to disturbed, aquatic or extremely dry sites, suggesting that they were suppressed in most other places by the gymnosperms that still dominated the plant world. However, fossil evidence suggests that by the end of the Cretaceous the angiosperms had spectacularly taken over the dominant position from the gymnosperms around the globe. Here, we suggest an ecological explanation for their escape from their subordinate position relative to gymnosperms and ferns. We propose that angiosperms due to their higher growth rates profit more rapidly from increased nutrient supply than gymnosperms, whereas at the same time angiosperms promote soil nutrient release by producing litter that is more easily decomposed. This positive feedback may have resulted in a runaway process once angiosperms had reached a certain abundance. Evidence for the possibility of such a critical transition to angiosperm dominance comes from recent work on large scale vegetation shifts, linking long-term field observations, large scale experiments and the use of simulation models. [source] Comparison of different phosphorus-fertiliser matrices to induce the recovery of phosphorus-deficient maize plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2009Javier Erro Abstract BACKGROUND: Previous studies have demonstrated the capacity of a new type of mineral fertiliser, known as rhizosphere-controlled fertiliser (RCF), to supply adequate nutrition to plants while minimising nutrient losses. This fertiliser family is based on the presence a phosphoric matrix composed of metal,humic,phosphates, soluble not in water but in the rhizospheric acids released by plant roots as an expression of nutritional needs, principally citric acid. The aim of this study is to investigate the capacity of the RCF matrix and other phosphorus-containing products to induce the recovery of phosphorus-deficient maize plants. RESULTS: The results showed that RCF-based P fertilisers were able to facilitate plant recovery, measured by the dry root and shoot weights, to the same extent as a water-soluble P fertiliser (monopotassium phosphate). This fact was well correlated to both the variation pattern of citric and trans -aconitic acids in the shoot and roots during the treatment, and P shoot and root contents. Likewise the analysis of the variation of P concentration in the nutrient solution during the treatment indicates that plant recovery is associated with the capacity of the plant to mobilise P from the different fertiliser matrices studied. CONCLUSION: These results confirm the findings obtained in previous in vitro studies and indicate the suitability of RCF strategy for the preparation of mineral fertilisers with a nutrient release pattern more sensitive to plant nutritional needs. Copyright © 2009 Society of Chemical Industry [source] Insect herbivores and their frass affect Quercus rubra leaf quality and initial stages of subsequent litter decompositionOIKOS, Issue 1 2008Christopher J. Frost Defoliation-induced changes in plant foliage are ubiquitous, though factors mediating induction and the extent of their influence on ecosystem processes such as leaf litter decomposition are poorly understood. Soil nitrogen (N) availability, which can be affected by insect herbivore frass (feces), influences phytochemical induction. We conducted experiments to test the hypotheses that insect frass deposition would (1) reduce phytochemical induction following herbivory and (2) increase the decomposition and nutrient release of the subsequent leaf litter. During the 2002 growing season, 80 Quercus rubra saplings were subjected to a factorial experiment with herbivore and frass manipulations. Leaf samples were collected throughout the growing season to measure the effects of frass deposition on phytochemical induction. In live foliage, herbivore damage increased tannin concentrations early, reduced foliar N concentrations throughout the growing season, and lowered lignin concentrations in the late season. Frass deposition apparently reduced leaf lignin concentrations, but otherwise did not influence leaf chemistry. Following natural senescence, litter samples from the treatment groups were decomposed in replicated litterbags for 18 months at the Coweeta Hydrologic Laboratory, NC. In the dead litter samples, initial tannin concentrations were lower in the herbivore damage group and higher in the frass addition group relative to their respective controls. Tannin and N release rates in the first nine months of decomposition were also affected by both damage and frass. However, decomposition rates did not differ among treatment groups. Thus, nutrient dynamics important for some ecosystem processes may be independent from the physical loss of litter mass. Overall, while lingering effects of damage and even frass deposition can therefore carry over and affect ecosystem processes during decomposition, their effects appear short lived relative to abiotic forces that tend to homogenize the decomposition process. [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] | ||||||||||