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1.
The multiple new challenges facing agriculture require the development of innovative cropping systems with high environmental, economic and social performances. Many research programmes are currently focusing on the design of such cropping systems. Some include the multicriteria assessment of cropping systems by diverse methods and approaches. Some of these research programmes are supported by experimental or farmers’ networks, generating new opportunities for data analysis and raising new research and methodological questions. In this article, we provide an overview based on a review of 56 articles, comparing the various methods for sustainability assessment in single- and multi-site studies. Articles were classified according to three characteristics: (i) their objectives, (ii) the study design (single- vs. multi-site), (iii) the type of system assessed (fictitious vs. real). Our analysis was structured around four items: (i) the variables used to describe cropping systems and production situations and the use of these variables in the assessment process, (ii) the criteria and associated indicators assessed, (iii) the methods used to explore multiple aspects of the performance of cropping systems, (iv) the use of reference values. We identified key points to be taken into account in multi-site studies. The application of the proposed guidelines to experimental networks should facilitate the identification of high-performance cropping systems and the identification of the drivers of cropping system performance.  相似文献   
2.
We present a new indicator taxa approach to the prediction of climate change effects on biodiversity at the national level in Switzerland. As indicators, we select a set of the most widely distributed species that account for 95% of geographical variation in sampled species richness of birds, butterflies, and vascular plants. Species data come from a national program designed to monitor spatial and temporal trends in species richness. We examine some opportunities and limitations in using these data. We develop ecological niche models for the species as functions of both climate and land cover variables. We project these models to the future using climate predictions that correspond to two IPCC 3rd assessment scenarios for the development of ‘greenhouse’ gas emissions. We find that models that are calibrated with Swiss national monitoring data perform well in 10-fold cross-validation, but can fail to capture the hot-dry end of environmental gradients that constrain some species distributions. Models for indicator species in all three higher taxa predict that climate change will result in turnover in species composition even where there is little net change in predicted species richness. Indicator species from high elevations lose most areas of suitable climate even under the relatively mild B2 scenario. We project some areas to increase in the number of species for which climate conditions are suitable early in the current century, but these areas become less suitable for a majority of species by the end of the century. Selection of indicator species based on rank prevalence results in a set of models that predict observed species richness better than a similar set of species selected based on high rank of model AUC values. An indicator species approach based on selected species that are relatively common may facilitate the use of national monitoring data for predicting climate change effects on the distribution of biodiversity.  相似文献   
3.
为科学分析区域土地利用结构与区域经济发展之间的协调程度,基于土地利用数量结构特征和区域实际建立定量测度指标体系,以海口市2011年土地变更调查数据及相应时点社会经济数据为基础数据,对海口市土地开发利用程度、集约程度和综合效益、组合类型、多样化程度、集中化程度及区位指数等6个指标进行测度。结果表明指标测度分析结果与区域实际一致,不同测度指标结果相互验证,说明基于区域土地利用特点建立的测度指标体系是合理的。研究发现,根据海口市各区经济发展实际情况及各区土地利用组合类型结果,海口市域可以根据土地利用相似情况划分建设用地集中及集约利用区、土地类型多样及适度发展区、土地类型集中区等3个综合区。  相似文献   
4.
《Veterinary parasitology》2015,207(1-2):85-93
Identifying which sheep to treat as part of a Targeted Selective Treatment approach to gastro-intestinal nematode control relies entirely on the efficacy of the indicators. Indicators such as FAMACHA© (anaemia), DISCO (diarrhea) and reductions in weight gains were designed specifically to reflect those sheep experiencing symptomatic consequences of infection. Using the gastro-intestinal nematode Haemonchus contortus as a model species, this study explored the utility and sensitivity of these indicators under controlled experimental conditions on 63 adult sheep. The potential effect of sheep with different H. contortus resistance phenotypes on indicator efficacy was compared in three different phenotypes, i.e. high (Blackbelly females), medium (Blackbelly rams) and low resistance (Romane rams). The potential effect of the H. contortus isolate on indicator efficacy was also explored by using four different isolates, with varying anthelmintic resistance capacities, to infect the sheep. We limited the study to the first month of infection to evaluate the interest of these indicators as an early predictive means for controlling infection. The pathophysiological indicators FAMACHA© and DISCO do not reflect infection intensity based on Faecal Egg Counts, nor do reductions in weight gains. FAMACHA© was however a good indicator of anaemia with strong correlations to haematocrit. There was little agreement among the three indicators to identify the same animals in need of treatment and even combining them did not increase their predictive value of infection intensity or relative host damage from infection. The indicator sensitivity was influenced by the H. contortus isolate and sheep resistance phenotype in which they were tested. One isolate was poorly infective but induced high levels of anaemia (FAMACHA©) and diarrhea (DISCO) compared to the three others. The FAMACHA© and DISCO had higher values in the sheep group with a medium resistance phenotype (Blackbelly rams) indicating higher levels of damage compared to the high and low resistance phenotypes. We conclude that there is no ‘one size fits all’ approach to the use of indicators for Targeted Selective Treatment and the indicators should be calibrated to farm-specific conditions to increase their efficacy.  相似文献   
5.
葫芦岛市春旱监测和春季第一场透雨指标的确定   总被引:4,自引:0,他引:4  
利用葫芦岛地区1959年到2005年3~5月的逐日气温和降水资料,确立了不同干旱程度下春季第一场透雨指标,并对春季干旱进行了分析。  相似文献   
6.
Tropical plantation forests are meeting an increasing proportion of global wood demand and comprehensive studies assessing the impact of silvicultural practices on tree and soil functioning are required to achieve sustainable yields. The objectives of our study were: (1) to quantify the effects of contrasting organic residue (OR) retention methods on tree growth and soil nutrient pools over a full Eucalyptus rotation and (2) to assess the potential of soil analyses to predict yields of fast-growing plantations established on tropical sandy soils. An experiment was set up in the Congo at the harvesting of the first rotation after afforestation of a native herbaceous savanna. Six treatments were set up in 0.26 ha plots and replicated in 4 blocks, with OR mass at planting ranging from 0 to 46.5 Mg ha−1. Tree growth over the whole rotation was highly dependent on OR management at planting. Over-bark trunk volume 7 years after planting ranged from 96 m3 ha−1 in the treatment with forest floor and harvest residue removal at planting to 164 m3 ha−1 in the treatment with the largest amount of OR. A comparison of nutrient stocks within the ecosystem at planting and at the end of the rotation suggested that nutrient contents in OR were largely involved in the different response observed between treatments. OR management treatments did not significantly modify most of the nutrient concentrations in the upper layers of the mineral soil. Conventional soil analyses performed before planting and at ages 1 and 3 years were unable to detect differences between treatments despite large differences in tree growth. In contrast, linear regressions between stand aboveground biomass at harvesting and OR mass at planting (independent variable) showed that OR mass was an excellent predictor of stand yield (R2 = 0.99). A large share of soil fertility comes from organic material above the mineral soil in highly weathered sandy soils and OR mass at planting might be used in conjunction with soil analyses to assess the potential of these soils to support forest plantations.  相似文献   
7.
为了客观衡量农业综合开发的实际业绩和效率,设定定量与定性指标,构建了农业综合开发绩效评价指标体系,并将绩效评价指标体系应用到2009-2012年农业综合开发3年总验收工作中,以进一步验证指标标准的合理性和数据资料的评价的准确性,科学地指导验收工作。  相似文献   
8.
[目的]研究毛乌素沙地与植被有关的地下水环境。[方法]选择毛乌素沙漠腹地,研究沙漠地区植被与地下水的关系,建立了沙漠地区的研究植被与地下水关系的指标体系,即植被的种群、地下水埋深、包气带含水率、地下水矿化度和包气带含盐量等,以及相应的野外工作方法。[结果]结果表明,研究区分布有9个主要的植被种群,沙蒿(Artemisia)、沙柳(Salixpsammophila)和苔草(Carex)是优势植被;地下水矿化度在沙丘地区为100~300mg/L,滩地为800mg/L左右;包气带含水率全年维持在8%~16%;沙丘含盐量小于0.2%,滩地含盐量大于0.3%。[结论]这些成果为研究该区植被与地下水的关系提供了依据。  相似文献   
9.
The environmental yardstick for pesticides has been developed as a tool for farmers to select pesticides with the least environmental impact and to quantify the impact of their use at the crop/farm level, regional level and national level. For each pesticide the yardstick assigns environmental impact points for the risk to water organisms, the risk of groundwater contamination and the risk to soil organisms. It is presently used in the Netherlands as a management tool for farmers and technical consultants, as a tool for monitoring the environmental performance of farmers, as a tool for setting standards for ecolabels and as a policy evaluation tool.  相似文献   
10.
Foliage of each species was sampled at 26 paired locations in the San Francisco Bay area. Eucalyptus globulus had significantly higher concentrations of Mn, Ca and Na, but significantly lower concentrations of Cu, Fe, Zn, P, NO3‐N and Kjeldahl‐N than did Quercus agrifolia. Concentrations of K and Mg did not differ between species. The relative concentration series for the species were similar: N>Ca>K>Mg>Na>P>Mn>Fe for Q. agrifolia and Ca>N>K> Mg>Na>Mn>P>Fe for E. globulus. Correlations between species were statistically significant for concentrations of Fe and Ca only. Thus, for these elements analysis of one species could be used as an indicator of the other.  相似文献   
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