牛粗饲料品质评价指标研究进展

粗饲料是牛日粮的重要组成部分,其品质对牛生产性能和健康有极大影响,而实际生产中往往做不到对其品质准确评价甚至忽略,进而影响养殖的经济效益。现有粗饲料品质评价指标有单项指标和综合指标,单项指标主要包括常规营养成分、干物质随意采食量、消化率等,综合指标则包括粗饲料相对值、品质指数、粗饲料相对品质指数、粗饲料分级指数等。现综述国内外现有评价粗饲料品质指标的研究进展,以期为研究人员进行牛粗饲料评价提供参考。     

晋西多沙粗沙区坝系建设的相关问题

 坝系是以小流域为单元,为充分利用水沙资源,在沟道中修建的以滞洪、拦泥、淤地为目的的大中小型淤地坝工程体系。坝系建设,就是在一条小流域内合理布局大、中、小型淤地坝工程体系,做到遇洪能拦,遇旱能灌,淤地能种,水多能排,防洪保收。为总结晋西多沙粗沙区坝系建设的经验教训,指导今后沟道坝系建设,在对小流域典型坝系进行综合调查的基础上,对坝系建设的相关问题进行了探讨。认为合理确定坝控规模、建坝密度、建设时序和大中小型淤地坝的比例,是保证沟道工程安全,充分发挥坝系群体最佳效益的主要内容。     

黄土高原多沙粗沙区侵蚀产沙的临界问题

黄土高原多沙粗沙区高强度产沙是自然因素和人文因素综合作用的结果。该产沙过程对其影响要素存在着多个维度的临界响应。在对多沙粗沙区侵蚀产沙影响要素进行识别的基础上，比较系统地阐述了该地区侵蚀产沙存在的自然临界和社会经济临界问题及其产生的内在机理，以便为该地区的水土流失治理和生态环境建设提供一定的理论和调控依据。     

防治黄河下游粗泥沙淤积的新思路

黄河下游河床的淤积早已引起了有关部门和专家的关注,提出并采取了许多防治方案。但是,黄河下游的淤积并没有得到有效的控制。为此,笔者在前人工作的基础上,提出了一些新的防治思路。     

Isolation and characterization of resistance gene analogs (RGAs) from sorghum (Sorghum bicolor L. Moench)

Degenerate primers designed based on known resistant genes (R-genes) and resistance gene analogs (RGAs) were used in combinations to elucidate RGAs from Sorghum bicolor, cultivar M 35-1. Most of the previously tried primer combinations resulted in amplicons of expected 500–600 bp sizes in sorghum along with few novel combinations. Restriction analysis of PCR amplicons of expected size revealed a group of fragments present in a single band indicating the heterogeneous nature of the amplicon. Many of these were cloned and some were considered for analysis. The nucleotide sequence of different cloned fragments was done and their predicted amino acid sequences compared to each other and to the amino acid sequences of known R-genes revealed significant sequence similarity. A cluster analysis based on neighbor-joining (N-J) method was carried out using sorghum RGAs (SRGAs) together with several analogous known R-genes resulting in two major groups; cluster-I comprising only SRGAs and cluster-II comprised of known R-gene sequences along with three SRGAs. Further analysis clearly indicated similarity of SRGAs in overall sense with already known ones from other crop plants. These sequences can be used as guidelines to detect, map and eventually isolate numerous R-genes in sorghum.     

山西杂粮产业集群式发展的思考

农业产业集群具有抱团发展的优势,推进山西杂粮产业集群式发展是促进贫困地区经济发展、农民依靠产业脱贫的有效途径.文章基于产业集群视角对振兴山西杂粮产业进行分析、总结,系统探讨山西杂粮产业集群式发展的现实意义、基础条件、发展机遇、存在的短板,最后提出推进山西杂粮产业集群式发展的战略路径.山西杂粮的优品质、多品种、多功能为山...     

Stand development of Norway spruce dominated subalpine forests of the Swiss Alps

In densely populated regions, forests can help protect communities and infrastructures from natural hazards such as avalanches and rockfall. To promote the protective function, substantial efforts are made to actively manage forest stands. In 2009 alone the Swiss government invested more than 60 million sfr for the maintenance of protection forests. However, to date there has been no comprehensive evaluation of how the structural development of actively managed stands differs from that of passively managed stands in the Alps. Over the past century the structure of Norway-spruce dominated subalpine forests of the Swiss Alps has been changing and it is not clear how these changes affect the potential protective function of these forests, as well as other forest functions such as wildlife habitat. Furthermore, it is not clear how stand dynamics and structural changes differ between stands that are actively managed and those that are passively managed, and thus to what degree active efforts of forest management are contributing to stands that actually have a greater protective function than passively managed forests.In this study, we analyzed the dynamics of subalpine forests using time series of forest inventory data and examined the influence of active vs. passive management, exposition, distance to treeline, elevation and slope steepness on stand structure and dynamics. We analyzed data from 395 plots in dense, subalpine, spruce-dominated forests in the Swiss Alps. Data were collected during three distinct periods (1983-1985, 1993-1995 and 2004-2006) as part of the Swiss National Forest Inventory (NFI). Using regression trees and multivariate statistics, we investigated which factors have the most important influence on tree growth and stand development.Overall, forest density increased significantly over the last 20 years and the predominance of dense forests increased at higher elevations. However, forest density has not increased in actively managed forests over the past 10 years. In passively managed stands, density was higher on south-facing slopes than on north-facing slopes. The volume and density of dead wood has increased over the last 20 years in both actively managed and passively managed forests. Active management over the last 20 years has maintained forest conditions that adequately maintain stands’ protection functions in the Swiss Alps. However, stand development, especially increasing density, in the passively managed stands of the Swiss Alps suggests that the majority of passively managed stands also provide adequate protective functions against rock and avalanche hazards without the high costs of active management.     

The effects of windthrow on forest insect communities: a literature review

This paper reviews the effects that windstorm-induced drastic changes (micro-climate, soil, vegetation, and ground structural heterogeneity) have on forest insect communities. In the current context of shady and CWD-deprived managed forests, windthrow gaps act as regional biodiversity hotspots by maintaining habitat continuity in a mosaic landscape, and by facilitating the breeding and population growth of clearing specialists and saproxylic species. Windthrow gaps are dead-wood islands where forest protection and habitat conservation goals may stand against each other. Besides the quantitative effect of dead wood on bark beetle outbreaks and saproxylic diversity, the latter is favoured by key dead-wood micro-habitats such as large logs, snags and sun-exposed coarse woody debris. The role of natural enemies and sanitation operations in regulating pest outbreaks is discussed. Heterogeneous openings provide many micro-habitats favouring flower-visiting insects, phytophages on saplings, on fallen tree crowns, and on diverse understory flora, as well as ground insects on specific micro-sites.