Bird richness and composition along an agricultural gradient in New Guinea: The influence of land use,habitat heterogeneity and proximity to intact forest

Abstract We examined variation in bird species richness, abundance and guild composition along an agricultural gradient in New Guinea, and looked for any additive influence of habitat heterogeneity on these variables. The study was based on a grid of survey plots, six plots wide and 24 plots long with the long axis running from a settlement 2.4 km through active and abandoned agricultural plots towards a large area of forest. Each circular survey plot (25 m radius) was assigned to a broad habitat type, ten habitat measures taken, and birds counted for 1 h in each plot. Principal component analysis (PCA) habitat axis 1 described an axis of decreasing forest alteration (larger trees, greater tree densities, fuller canopy) that was positively correlated with distance from the settlement. Bird richness and abundance were highest at intermediate disturbance levels (plots with mid‐range axis 1 scores). Proportions of insectivores and frugivores increased with decreasing forest alteration, while proportions of nectarivores decreased. We calculated three measures of habitat heterogeneity by comparing each plot's PCA score to those of eight neighbouring plots (50–110 m away). These measures reflected how different the plot was to its neighbours, how variable the habitat was around the plot, and the degree to which the plot bordered less disturbed forest. We related these measures to plot bird variable scores independently, and to residuals following regressions of bird scores against PCA scores. Heterogeneity measures had no significant influence on abundance or richness measures, but there were greater proportions of frugivores in plots showing a given degree of habitat alteration if they bordered more pristine habitat. While we readily identified differences in bird communities along the agricultural gradient, the influences of habitat heterogeneity were not striking for birds at this fine scale.     

Strategies and models for agricultural sustainability in developing Asian countries

The green revolution of the 1960s and 1970s which resulted in dramatic yield increases in the developing Asian countries is now showing signs of fatigue in productivity gains. Intensive agriculture practiced without adherence to the scientific principles and ecological aspects has led to loss of soil health, and depletion of freshwater resources and agrobiodiversity. With progressive diversion of arable land for non-agricultural purposes, the challenge of feeding the growing population without, at the same time, annexing more forestland and depleting the rest of life is indeed daunting. Further, even with food availability through production/procurement, millions of marginal farming, fishing and landless rural families have very low or no access to food due to lack of income-generating livelihoods. Approximately 200 million rural women, children and men in India alone fall in this category. Under these circumstances, the evergreen revolution (pro-nature, pro-poor, pro-women and pro-employment/livelihood oriented ecoagriculture) under varied terms are proposed for achieving productivity in perpetuity. In the proposed 'biovillage paradigm', eco-friendly agriculture is promoted along with on- and non-farm eco-enterprises based on sustainable management of natural resources. Concurrently, the modern ICT-based village knowledge centres provide time- and locale-specific, demand-driven information needed for evergreen revolution and ecotechnologies. With a system of 'farm and marine production by masses', the twin goals of ecoagriculture and eco-livelihoods are addressed. The principles, strategies and models of these are briefly discussed in this paper.     

Drivers of change in global agriculture

As a result of agricultural intensification, more food is produced today than needed to feed the entire world population and at prices that have never been so low. Yet despite this success and the impact of globalization and increasing world trade in agriculture, there remain large, persistent and, in some cases, worsening spatial differences in the ability of societies to both feed themselves and protect the long-term productive capacity of their natural resources. This paper explores these differences and develops a countryxfarming systems typology for exploring the linkages between human needs, agriculture and the environment, and for assessing options for addressing future food security, land use and ecosystem service challenges facing different societies around the world.     

River-reef connectivity in the Meso-American Region

The accumulation and seasonal impact of riverine discharge on coral reefs of the Meso-American Region (MAR) were estimated using a numerical simulation of river runoff dispersion. River-reef connectivity, or source-sink dynamics of terrestrial runoff was further assessed from more than 400 watersheds of the region onto discrete coral reef areas. Using land use for 2003 and 2004 in the MAR, this work builds upon a Regional Ocean Modeling System simulation of the MAR validated by ocean color satellite data, and on the monthly river nutrient and sediment load and discharge provided by the World Resources Institute using the N-SPECT model. Analysis of the variability of simulated runoff transport to the reefs showed that reefs of the Mesoamerican Barrier Reef System (MBRS) were mostly impacted from June to September, following the peak time of river discharge. At that time, the coastal and oceanic circulations contribute quickly to expel the runoff from the MBRS. High runoff concentration waters leaving the eastern coast of Honduras during the months of October to December return to the southwestern MAR in March as they are entrained in a cyclonic gyre. Coral reefs of the MAR are thus impacted twice, first from the coastal side with runoff of local origin and later from the oceanic side with runoff from mixed origin. High probability of connectivity between rivers and remote reefs is established as this study revealed that river runoff from the north shore of Honduras has a wide-spread impact on most of the coral reefs of southern Belize, while watersheds on the Gulf of Honduras are mostly connected to coral reefs in the northern shore of Honduras. Although the level of remote influence (or runoff concentration reaching the reef) is lower than the local, the cumulative effect of numerous remote river-reef connections remains significant. Communicated by Biology Editor Michael Lesser     

长期施磷对黄壤旱地磷库变化及地表径流中磷浓度的影响

对贵州黄壤旱地进行采样以及盆栽试验,探索黄壤旱地磷库的变化及其对地表径流磷量的影响。结果表明,长期施磷后黄壤旱地无机磷占全磷的比例逐渐增高,Al-P、Fc-P和Ca-P积累的顺序为Fe-P>Al-P>Ca-P。长期施磷后黄壤旱地的有效磷和藻类可利用的总磷也不断积累,高磷（Olsen-P>25mg·kg^-1)旱地藻类可利用的总磷与Al-P、Fe-P和Ca-P的相关系数分别为0.859、0.903和0.650,Fc-P对藻类可利用磷量的影响起着最重要的作用。在模拟雨强为63.2mm·h^-1下,降雨30min后,低磷黄壤旱地（Olsen-P为4.62-15.9mg·kg^-1)径流中磷酸根磷含量仅为2.81-4.17μg·L^-1,生物有效性磷含量为0.723-0.876mg·L^-1;高磷黄壤旱地（Olsen-P)为29.4-59.2mg·kg^-1)径流中磷酸根磷含量达到0.026-0.714mg·L^-1,生物有效性磷含量增加到0.996-1.281mg·L^-1;高磷黄壤旱地地表径流磷量能加速水体富营养化的产生。     

污水污泥土地投放重金属的环境效应研究进展

本文综述了污水污泥土地投放中重金属的环境效应研究方面的进展,重点就污水污泥土地投放中对植物生长的影响、对土壤微生物、土壤酶及昆虫生长的影响、重金属向地下水中的迁移情况、重金属在土壤中的生物活性变化及其影响因素、污水污泥土地投放后重金属的长期变化及土壤修复剂对重金属毒性的控制等方面的研究进展进行综述。     

Reuse potential of agricultural wastes in semi-arid regions: Egypt as a case study

Agricultural wastes represent an important source of bio-energy and valuable products. In Egypt, 18% of the agricultural wastes is used directly as fertiliser. Another 30% is used as animal food. The remainder is burnt directly on the fields or is used for heating in the small villages, using low efficiency burners. These wastes can be used more efficiently as a source of energy and as organic fertiliser. The anaerobic bioconversion of these materials will result in a net energy production. The utilisation of agricultural wastes for the production of energy and compost, combined with using solar energy will save fossil fuel, improve health conditions and the general life quality in the villages. This revised version was published online in June 2006 with corrections to the Cover Date.     

Crop planting dates: an analysis of global patterns

Aim To assemble a data set of global crop planting and harvesting dates for 19 major crops, explore spatial relationships between planting date and climate for two of them, and compare our analysis with a review of the literature on factors that drive decisions on planting dates. Location Global. Methods We digitized and georeferenced existing data on crop planting and harvesting dates from six sources. We then examined relationships between planting dates and temperature, precipitation and potential evapotranspiration using 30‐year average climatologies from the Climatic Research Unit, University of East Anglia (CRU CL 2.0). Results We present global planting date patterns for maize, spring wheat and winter wheat (our full, publicly available data set contains planting and harvesting dates for 19 major crops). Maize planting in the northern mid‐latitudes generally occurs in April and May. Daily average air temperatures are usually c. 12–17 °C at the time of maize planting in these regions, although soil moisture often determines planting date more directly than does temperature. Maize planting dates vary more widely in tropical regions. Spring wheat is usually planted at cooler temperatures than maize, between c. 8 and 14 °C in temperate regions. Winter wheat is generally planted in September and October in the northern mid‐latitudes. Main conclusions In temperate regions, spatial patterns of maize and spring wheat planting dates can be predicted reasonably well by assuming a fixed temperature at planting. However, planting dates in lower latitudes and planting dates of winter wheat are more difficult to predict from climate alone. In part this is because planting dates may be chosen to ensure a favourable climate during a critical growth stage, such as flowering, rather than to ensure an optimal climate early in the crop's growth. The lack of predictability is also due to the pervasive influence of technological and socio‐economic factors on planting dates.     

高通量测序技术在农作物全基因组序列测定中的应用概览

近几年飞速发展的高通量测序技术(next generation sequencing,NGS)在生命科学研究的各个领域充分展现了其低成本、高通量和应用面广等优势。在现代农业生物技术领域,利用高通量测序技术,科学家们不仅能更经济而高效对农作物、模式植物或不同栽培品种进行深入的全基因组测序、重测序,也可以对成百上千的栽培品种进行高效而准确的遗传差异分析、分子标记分析、连锁图谱分析、表观遗传学分析、转录组分析,进而改进农作物的育种技术,加快新品种的育种研究。其中,获得农作物的全基因组序列是其他研究和分析的基础。本文通过介绍近年来发表的一些利用高通量测序技术进行的农作物全基因组测定和组装的工作,展示高通量测序技术在现代农业生物技术领域的广泛前景以及其建立起来的研究基础。