The impact of integrated aquaculture-agriculture on small-scale farm sustainability and farmers’ livelihoods: Experience from Bangladesh

Intensification of agriculture often requires external inputs, has negative environmental effects and increases risk, especially for small-scale producers. Integrated aquaculture-agriculture (IAA) instead uses on-farm synergy effects of crop and fish production. The impact of long-term IAA training provided to small-scale farmers in Bangladesh is assessed using panel data from 260 project and 126 control farmers who were monitored from 2002/2003 to 2005/2006. We find that the training had a significant positive impact on farmers’ technical efficiency, total factor productivity and net incomes. These result in higher food consumption and better nutrition for trained households compared to control farmers.     

华北落叶松人工林不同阶段经营密度研究

林分密度是指林木生长过程中单位面积上的立木株数,它与林分的生长发育、稳定性、林分产量、质量等因素有着重要的联系。通过对河北省木兰国营林场不同林分密度的华北落叶松人工林进行调查,采用Hegyi单木竞争指数模型,提出了冠幅竞争指数。通过拟合实测冠幅、胸径和相对冠幅竞争指数,得出了竞争指数分别为0.2,0.4,0.6,0.8时,所对应的华北落叶松的不同经营密度值。     

No ‘home’ versus ‘away’ effects of decomposition found in a grassland-forest reciprocal litter transplant study

Plant litter often decomposes faster in the habitat from which it was derived (i.e. home) than when placed in foreign habitats (i.e. away), which has been called the home-field advantage (HFA) of litter decomposition. We tested whether the HFA of litter decomposition is driven by decomposer communities being specialized at decomposing litter in their home habitat, by reciprocally transplanting litter from grassland to early-successional forest. Unexpectedly, we found an overall disadvantage for at-home decomposition despite large differences in litter quality (lignin:N) between the two habitats. We found more evidence for habitat specialization among secondary decomposers (mites) than the primary decomposers (bacteria and fungi), suggesting that soil animals may be important in driving HFA patterns where they do exist. Grass litter decomposition in forest slowed down and became more fungal-based, while tree litter decomposition in grassland increased yet showed no shift to being bacterially-based, relative to ‘at home’ decomposition. This suggests a biological explanation for why a positive HFA was not observed. Our results highlight that both environmental context and soil biology can play an important and sometimes counter-intuitive role in modifying decomposition. A better understanding of the interaction between all three primary drivers of decomposition (the environment, litter quality and soil organisms) is necessary for reliable prediction of decomposition at global scales.     

Collembola species composition and diversity effects on ecosystem functioning vary with plant functional group identity

The relationship between decomposer diversity and ecosystem functioning is little understood although soils accommodate a significant proportion of worldwide biodiversity. Collembola are among the most abundant and diverse decomposers and are known to modify plant growth. We examined the effects of Collembola species diversity (one, two and three species belonging to different life history groups) and composition on litter decomposition and the performance of plant communities (above- and belowground productivity) of different functional groups (grasses, forbs and legumes). Collembola densities did not increase with diversity indicating niche overlap. Generally, Collembola species composition was a better predictor for ecosystem functioning than Collembola species number with the impacts of Collembola diversity and composition on ecosystem functioning strongly depending on plant functional group identity. Non-linear effects of Collembola diversity on litter decomposition and plant productivity suggest pronounced and context dependent species interactions and feeding habits. Net surface litter decomposition was decreased by Collembola, whereas root litter decomposition was at maximum in the highest Collembola diversity treatment. Forbs benefitted most from the presence of three Collembola species. Similarly, Collembola diversity influenced root depth distribution in a plant functional group specific way: while grass root biomass decreased with increasing Collembola diversity in the upper and lower soil layer, legume root biomass increased particularly in the lower soil layer. Idiosyncratic and context dependent effects of Collembola diversity and composition even in rather simple assemblages of one to three species suggest that changes in Collembola diversity may have unpredictable consequences for ecosystem functioning. The finding that changes in Collembola performance did not directly translate to alterations in ecosystem functioning indicates that response traits do not necessarily conform to effect traits. Distinct plant functional group specific impacts of Collembola diversity on root depth distribution are likely to modify plant competition in complex plant communities and add a novel mechanism how decomposers may affect plant community assembly.     

The global extent and character of marine mammal consumption by humans: 1970–2009

The killing and consumption of marine mammals fuels tense global struggles between advocates of sustainable use and advocates of complete protection for these animals. However, reporting on the extent and character of marine mammal consumption by people is uneven and often anecdotal. We developed a consistent approach to summarize information from approximately 900 sources. It is now clear that human consumption of marine mammals is geographically widespread, taxonomically diverse, and often of uncertain sustainability. Since 1990, people in at least 114 countries have consumed one or more of at least 87 marine mammal species. Although changing social, ecological, or political circumstances are leading to reduced killing and consumption of marine mammals in some regions, in other regions the prevailing socio-economic conditions and new technologies are leading to increased killing and consumption, particularly of small cetaceans. Consumption of marine mammals is considered a significant aspect of food security and cultural well being in many regions, and provides some economic (including cash) benefits to people in at least 54 countries. Our review highlights an escalation in utilization of small cetaceans caught in conjunction with fishing activities since 1970, a form of fishing-up-the-food-chain. Where consumption relates to food security and poverty, we found evidence of deliberate killing of animals caught both deliberately and accidentally in fishing gear. Constraints on government agencies responsible for implementing regulations, often due to the geographic remoteness of catches, mean that greater understanding is needed of the motivations that underlie consumption of marine mammals so that more effective conservation measures can be designed and implemented.     

蓝鹇等3种雉鸡的饲料和营养摄入初步研究

2008年11月20日～12月20日（冬季）和2009年2月24日～6月14日（春季）期间,对成都动物园圈养的2对蓝鹇、5只白鹇和5只白腹锦鸡每天的饲料和营养摄入量进行了记录和分析。结果显示：白腹锦鸡的饲料摄入量显著低于白鹇和蓝鹇（P〈0.01）;3种雉鸡冬季的饲料摄入量显著低于春季（P〈0.01）;光照度高的圈舍内雉鸡饲料摄入量较高。统计分析表明,除铜和锰外,每只雉鸡春季的其他营养摄入量极显著高于冬季（P〈0.01）;光照对雉鸡的营养摄入量有显著的影响（P〈0.01）。根据雉鸡的产蛋量和受精率情况,我们认为本研究中的饲料搭配和营养供给比较适宜,能够满足雉鸡的健康和繁殖需要。     

口蹄疫O型固相竞争ELISA抗体检测试剂盒的临床应用

用口蹄疫O型固相竞争ELISA检测血清1 150份,口蹄疫O型免疫血清820份,敏感性为91.83%;试剂盒特异性评价检测血清180份,其特异性为89.4%;固相竞争ELISA和液相阻断ELISA共同检测血清100份,其相关性分析为0.964 1,R2为0.929 5,属于高度相关。3批试剂盒检测血清样品50份,检测结果差异不显著,口蹄疫O型固相竞争ELISA抗体检测试剂盒检测结果比较稳定,具有良好的批间可重复性和稳定性。     

人工草地种内种间竞争与生产稳定性

种内种间竞争是研究人工草地极其重要的理论基础,草地生态与生产稳定性是建立人工草地的根本目标。单播人工草地种内竞争尽管是相互的,但主要由密度依赖机制控制着种群动态。资源的数量、质量和分布等特征决定着混播人工草地种间竞争的过程和结局。虽然存在竞争排斥,但生态位相似、竞争能力相当的2～3个草种混播是比较适宜的。要获得人工草地...     

Temporal niche overlap among insectivorous small mammals

Being active in the same environment at different times exposes animals to the effects of very different environmental factors, both biotic and abiotic. In the present study, we used live traps equipped with timing devices to evaluate the potential role of biotic factors (competition and food abundance) on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high‐elevation grassland fields (‘campos de altitude’) of southern Brazil. Based on resources availability (invertebrates), data on animal captures were pooled in 2 seasons: ‘scarcity’ (June 2001–September 2001) and ‘abundance’ (November 2001–May 2002) seasons. We tested for non‐random structure in temporal niche overlap among the species in each season. These species were the rodents Oxymycterus nasutus (Waterhouse, 1837), Deltamys sp., Akodon azarae (Fischer, 1829), and the marsupial Monodelphis brevicaudis Olfers, 1818. The studied community was mainly diurnal with crepuscular peaks. Simulations using the Pianka index of niche overlap indicated that the empirical assemblage‐wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season. All the species showed an increase in temporal niche breadth during the abundance season, which appears to be related to longer daylength and high nocturnal temperatures. Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources. Therefore, we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.