Landscape patterns and agriculture: modelling the long-term effects of human practices on Pinus sylvestris spatial dynamics (Causse Mejean, France)

This paper focuses on understanding human impact on landscape. Both ecological and human practices are analysed as interacting processes. An agent-based model integrating biological and historical knowledge is used to analyse the pattern of Scots Pine encroachment in a French Mediterranean upland. In the STIPA model, pine trees are autonomous agents and a cellular automaton simulates land-use. We test the effects of shifting cultivation on tree establishment at the landscape scale. This allows us to understand how agropastoral practices patterned this area from the 17th to 19th century: simulations show the importance of shifting cultivation in limiting woodland progression. Fallow duration linked to environmental heterogeneity is a significant factor for explaining pine dynamics and landscape patterning at the scale of the study region. We put this result in perspective with current rangeland management policies that often consider grazing as the most relevant tool for open landscape maintenance. Our results also show the importance of taking into account time-scale effects when linking landscape patterns to agricultural systems.     

Linking Land-use, Water Body Type and Water Quality in Southern New Zealand

Land-use and vegetation cover have been linked to the nutrient levels (nitrogen, phosphorus) of surface waters in several countries. However, the links generally relate to streams and rivers, or to specific types of standing water, for example shallow lakes in a geologically defined region. We measured physical variables and nutrient chemistry of 45 water bodies representative of the wide range of lentic wetland environments (swamps, riverine wetlands, estuaries, reservoirs, shallow lakes, deep lakes) in Otago, New Zealand, and related these to catchment variables and land-use in order to assess the potential influence of catchment modification on water quality of these diverse wetlands. Catchment boundaries and land cover were derived from maps using ArcView GIS software. Our predictions that concentrations of nutrients and other components of water quality would correlate positively with the nature and intensity of catchment modification were confirmed in multivariate analyses. Physical and chemical measures were positively related to the extent of modification in the catchment (percentage of the catchment in pasture, planted forest, scrub and urban areas), and negatively related to lack of catchment modification (more of the catchment in bare ground, tussock grassland and indigenous forest). The strong negative correlations between nutrient concentrations, suspended sediment, water colour and the percentage of tussock cover in the catchment imply that increased conversion of the␣native tussock grassland to pastoral farming in␣Otago will increase nutrient concentrations and␣reduce water quality of the diverse lentic ecosystems.     

Using the VS‐Fast methodology for soil degradation assessment: a case study from Senegal

Soil degradation threatens sustainable food production and accelerates global warming. Poorer countries, whose agricultural sectors are highly dependent on their natural resource bases, are hit particularly hard by declining soil productivity. Calls for soil‐quality monitoring are therefore, justified and this could inform decision‐makers on the preparation of appropriate interventions. However, the provision of monitoring methodologies is not an easy task. Soil degradation affects several soil characteristics that at larger scales cannot be evaluated with models or remote‐sensing techniques. Therefore, this study focuses on investigating the use of field‐based soil assessment methodologies to differentiate degrees of soil degradation. Specifically, we test the Visual Soil Field Assessment Tool (VS‐Fast) for detecting and monitoring soil degradation using a cross‐section of 71 sites in Senegal, the soil quality of which were classed by local experts. We found low correlation between VS‐Fast classes and expert assessments. By using an ordered logit model to quantify class boundaries, we show that experts categorized areas as ‘degraded’ for a wider range and higher VS‐Fast scores than the corresponding VS‐Fast class. Yet, from general linear models and analysis of variance procedures we found that areas classed by experts as ‘degraded’ had statistically significant lower VS‐Fast scores compared to those that were judged as ‘normal’ and ‘good’, while differences of the VS‐Fast scores between the latter two were negligible. It is remarkable that the visual assessment, the cheaper component of the VS‐Fast score, performs better in differentiating degradation status than its measured counterpart. The results support the need to investigate the applicability of other VSA methodologies that only use field observations and tactile methods.     

清末呼兰地区移民与农业开发

呼兰是清政府在东北最早开禁的地区。1860～1903年，清朝先后开放了蒙古尔山、通肯等地区，关内移民开始大量涌入呼兰地区．土地开发规模迅速扩大，粮食产量大幅度提高，农产品加工业崛起，农产商品率迅速提高，促进了农业的近代化。     

贵州省农业产业结构研究

运用产业结构相似系数、产业结构变化系数和描述产业结构稳定性的熵来对贵州省农业产业结构现状进行分析与评价,其研究成果对确定贵州省农业产业结构调整方向和发展贵州省农业农村经济有一定的参考价值。     

金代农业科学发展探讨

从耕作技术、水利兴修和农田灌溉3方面介绍了金代农业科学的成就，为人们了解金代农业生产方式提供参考。     

河北太行山区县域农业可持续发展能力系统评价与分析

【研究目的】为了研究河北省太行山区25个县(市、区)的农业可持续发展能力及趋势;【方法】笔者通过文献对比分析和专家调查法,确定了评价山区农业可持续发展能力的指标体系,涵括了人口、经济、社会、资源和环境五个层次,共计31个指标,以此对河北省太行山区25个县(市、区)农业可持续发展能力的评价分析;【结果】分析结果显示,该区农业发展趋势整体是可持续的,但25个县(市、区)的发展能力和发展速度表现各异,其总体评价值年增长率变化有强有弱,多年平均在0￣12%之间。农业可持续发展能力高的地区评价值年平均增长率为8%￣12%、发展能力中等地区评价值年平均增长率为4%￣8%、发展能力低下的地区评价值年平均增长率为0￣4%。【结论】发展能力高的地区,虽然对资源利用和环境的压力较大,但其社会、人口、经济的发展基本与生态环境协调共进;可持续发展能力低的地区,其社会、人口、经济的发展与资源环境发展不协调,而且对资源的利用效率低,对生态环境的破坏也比较大。     

论朱元璋对传统农本思想的继承和创新

农本思想在我国传统经济思想中占有主导地位。朱元璋在治国过程中继承传统农本思想,重视农业生产,制定了许多兴农恤农政策,并在继承传统农本思想的基础上有所创新,提出了重农不轻商的新理念。     

农业信息化多媒体Web数据库构建——以三峡库区为例

三峡库区农业信息化平台的核心是农业信息化多媒体数据库系统的架构。通过对农业信息化平台的需求分析,提出在.NET平台下多媒体数据库的设计思想,阐述了多媒体数据库中主要表的设计和多媒体数据关联。实现了农业信息化平台中表的关联和多媒体Web数据库中数据的查询。     

论基层农业科技单位的科技创新与成果转化

通过对科技创新和成果转化状况的分析,认为基层农业科技单位是中国农业科技创新和科技成果转化的重要力量;但基层农业科技单位面临规模小负担重,资金不足人才匮乏,竞争能力不强等诸多问题。面对这一现状,基层农业科技单位唯有积极探索机制改革,强化科技创新,加速成果转化才能得以生存、发展和壮大。