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991.
992.
The Luquillo Experimental Forest (LEF) located on the Caribbean island of Puerto Rico has a rich history of ecological research, including a variety of avian studies, and is one of the most active ecological research sites in the Neotropics. The LEF spans an elevational range from 100 to 1075 m over which five life zones and four forest types are found in a warm, humid subtropical climate. A total of 23 bird species breeds here and another 76 species, mostly migrants, are known to occur. The food web of the forest in the lower elevations is especially well studied, which allows an assessment of the role of birds in the food web. The LEF is noted for its high densities of Eleutherodactylus frogs and Anolis lizards, which may depress insect densities thereby contributing to the low species richness and densities of most insectivorous birds. The signature species of the forest is the endangered Puerto Rican Parrot (Amazona vittata) that has been the focus of intensive long-term research and recovery efforts, which have spawned research on associated species, including long-term studies on the Pearly-eyed Thrasher (Margarops fuscatus) and botfly (Philornis spp.) ectoparasitism. Given the frequency of hurricane disturbance to the LEF and studies providing baseline for comparisons, research has made major contributions to an understanding of the effects of hurricanes on forest ecosystems including bird populations and their resources. We summarize these and other studies from the LEF to characterize the avifauna and its environment while noting studies with management implications and identify opportunities for future ornithological studies. 相似文献
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994.
995.
农村财务管理是农村工作的重点与难点。阐述了嘉兴市南湖区开展村级财务规范化管理工作的主要做法,并总结了其取得的成效,以期为嘉兴市南湖区开展村级财务规范化管理工作提供参考。 相似文献
996.
Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes within nano- to macroscales. The spatial and temporal heterogeneity of input of labile organics by plants creates microbial hotspots over short periods of time – the hot moments. We define microbial hotspots as small soil volumes with much faster process rates and much more intensive interactions compared to the average soil conditions. Such hotspots are found in the rhizosphere, detritusphere, biopores (including drilosphere) and on aggregate surfaces, but hotspots are frequently of mixed origin. Hot moments are short-term events or sequences of events inducing accelerated process rates as compared to the average rates. Thus, hotspots and hot moments are defined by dynamic characteristics, i.e. by process rates.For this hotspot concept we extensively reviewed and examined the localization and size of hotspots, spatial distribution and visualization approaches, transport of labile C to and from hotspots, lifetime and process intensities, with a special focus on process rates and microbial activities. The fraction of active microorganisms in hotspots is 2–20 times higher than in the bulk soil, and their specific activities (i.e. respiration, microbial growth, mineralization potential, enzyme activities, RNA/DNA ratio) may also be much higher. The duration of hot moments in the rhizosphere is limited and is controlled by the length of the input of labile organics. It can last a few hours up to a few days. In the detritusphere, however, the duration of hot moments is regulated by the output – by decomposition rates of litter – and lasts for weeks and months. Hot moments induce succession in microbial communities and intense intra- and interspecific competition affecting C use efficiency, microbial growth and turnover. The faster turnover and lower C use efficiency in hotspots counterbalances the high C inputs, leading to the absence of strong increases in C stocks. Consequently, the intensification of fluxes is much stronger than the increase of pools. Maintenance of stoichiometric ratios by accelerated microbial growth in hotspots requires additional nutrients (e.g. N and P), causing their microbial mining from soil organic matter, i.e. priming effects. Consequently, priming effects are localized in microbial hotspots and are consequences of hot moments. We estimated the contribution of the hotspots to the whole soil profile and suggested that, irrespective of their volume, the hotspots are mainly responsible for the ecologically relevant processes in soil. By this review, we raised the importance of concepts and ecological theory of distribution and functioning of microorganisms in soil. 相似文献
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998.
Belcy K Angarita Junjie Han Rodolfo J C Cantet Sarah K Chewning Kaitlin E Wurtz Janice M Siegford Catherine W Ernst Juan Pedro Steibel 《Journal of animal science》2021,99(5)
Automatic feeding systems in pig production allow for the recording of individual feeding behavior traits, which might be influenced by the social interactions among individuals. This study fitted mixed models to estimate the direct and social effects on visit duration at the feeder of group-housed pigs. The dataset included 74,413 records of each visit duration time (min) event at the automatic feeder from 135 pigs housed in 14 pens. The sequence of visits at the feeder was employed as a proxy for the social interaction between individuals. To estimate animal effects, the direct effect was apportioned to the animal feeding (feeding pig), and the social effect was apportioned to the animal that entered the feeder immediately after the feeding pig left the feeding station (follower). The data were divided into two subsets: “non-immediate replacement” time (NIRT, = 6,256), where the follower pig occupied the feeder at least 600 s after the feeding pig left the feeder, and “immediate replacement” time (IRT, = 58,255), where the elapsed time between replacements was less than or equal to 60 s. The marginal posterior distribution of the parameters was obtained by Bayesian method. Using the IRT subset, the posterior mean of the proportion of variance explained by the direct effect (Prp) was 18% for all models. The proportion of variance explained by the follower social effect (Prp) was 2%, and the residual variance () decreased, suggesting an improved model fit by including the follower effect. Fitting the models with the NIRT subset, the estimate of Prp was 20% but the Prp was almost zero and was identical for all models. For the IRT subset, the predicted best linear unbiased predictor (BLUP) of direct (Direct BLUP) and social (Follower BLUP) random effects on visit duration at the feeder of an animal was calculated. Feeder visit duration time was not correlated with traits, such as weight gain or average feed intake (P > 0.05), whereas for the daily feeder occupation time, the estimated correlation was positive with the Direct BLUP (= 0.51, P < 0.05) and negative with the Follower BLUP (= −0.26, P < 0.05). The results suggest that the visit duration of an animal at the single-space feeder was influenced by both direct and social effects when the replacement time between visits was less than 1 min. Finally, animals that spent a longer time per day at the feeder seemed to do so by shortening the meal length of the preceding individual at the feeder. 相似文献
999.
PGPR接种时期和AM真菌对番茄根结线虫病的影响 总被引:1,自引:0,他引:1
作者于温室盆栽条件下研究了植物促生根围细菌(plant growth promoting rhizobacteria,PGPR)Bacillus sp.接种时期和丛枝菌根(arbuscular mycorrhiza AM)真菌摩西球囊霉(Glomus mosseae)接种对番茄(Lycopersicum esculentum Mill)生长发育及根结线虫(Meloidogyne incognitaMi)病的影响。结果表明于番茄播种时接种AM真菌摩西球囊霉+移栽时接种芽孢杆菌(Bacillus sp.)和南方根结线虫(M.incognita)的处理植株发病率和和病情指数最低、防效最高,分别为24.5%、12.5%和70.90%;并且显著增加番茄植株节点数、株高、茎粗、地上部干重及地下部干重。认为播种时接种AM真菌配合移栽时接种PGPR可以显著减轻南方根结线虫对番茄生长发育造成的危害程度,并且对南方根结线虫有较强的抑制效果。 相似文献
1000.
考察云南贯众提取化合物山柰酚-3-α-L-(4-O-乙酰基)鼠李糖基-7-α-L-鼠李糖苷的驱除猪蛔虫效果。将自然感染猪蛔虫病猪25头随机分为5组,即贯众化合物高、中、低剂量组,伊维菌素对照组和空白对照组。结果云南贯众提取化合物高、中剂量组驱杀猪蛔虫效果明显,并与伊维菌素组效果相当,具有效果确实可靠、无毒副作用等特点。临床推荐剂量以0.3mg/kg为宜。 相似文献