Conservation value of dispersed tree cover threatened by pasture management

Trees dispersed in pastures are a prominent feature of many Central American landscapes, particularly in cattle producing regions where farmers retain trees to serve as shade, fodder, timber and firewood. The presence of dispersed trees in pastures is often considered as important for the conservation of biodiversity by providing habitat and enhancing landscape connectivity. However, despite their critical productive and environmental roles, little is known about tree distribution within pastures or how farmers’ management decisions influence the trees themselves and their impact on farm productivity and biodiversity conservation. Here, we present a synthesis of (a) the abundance, composition, and size of dispersed trees in four important cattle producing regions of Costa Rica (Caňas and Río Frío) and Nicaragua (Rivas and Matiguás), based on inventory of 18,669 trees on 1492 ha of pasture, (b) the local knowledge, management and use of trees by cattle farmers, and (c) opportunities for ensuring sustainable management of dispersed trees in pasture-dominated landscapes. Dispersed trees were common in all four landscapes, with mean frequency ranging from 8.0 trees ha⁻¹ in Caňas to 33.4 trees ha⁻¹ in Matiguás. A total of 255 tree species were found in pastures across the four landscapes. The total number of tree species per landscape varied from 72 in Rivas to 101 in Caňas and Rio Frio, with mean species richness per farm ranging from 22.9 in Rio Frio to 45.9 in Matiguás. In all four landscapes, a handful of tree species dominated the pastures, with the ten most abundant species in each landscape accounting for >70% of all trees recorded. Most of these common tree species provide fruits or foliage eaten by cattle, or are important timber or firewood species, and are deliberately retained by farmers for these uses. In all four landscapes, farmers had a detailed knowledge of tree attributes affecting pasture and animal productivity, and influenced tree cover through pasture management activities and occasional tree cutting. Current farm management practices are gradually decreasing the diversity of trees in pastures, and in some cases also tree density, reducing their contribution to farm productivity and biodiversity conservation. To reverse this trend, incentives are required to encourage cattle farmers to retain and enhance tree cover in pastures, through the adoption of pasture management practices that favor the regeneration and persistence of a diverse range of tree species.     

Comparisons of Mayan forest management, restoration, and conservation

Numerous communities associated with at least five distinct ethnic Mayan groups in southern Mexico and Central America continue to rely upon forested areas as integral components of their agricultural systems. They carefully manage these areas so that forests provide food, raw materials, and animals. Management practices include removing and planting of woody and herbaceous species, apiculture, and seed harvest. Mayan agroforestry systems in geographically and ecologically distinct areas of Mesoamerica were evaluated to better understand traditional agroforestry system components and how indigenous Mayan agroforestry could be a part of regional forest conservation and restoration. Systems were within Mexican land grant areas (ejidos) or on contested land. Although these systems rely upon different woody species and management techniques, common among them are: (1) the use of multi-stage and successional pathways with forest as a part of the larger system, (2) species that are believed by traditional ecological knowledge (TEK) to accelerate forest regeneration - more than 30 tree species are recognized and managed as potential facilitators of forest regeneration and (3) direct human consumption of forest products at all stages of regeneration.     

Distribution pattern and conservation of threatened medicinal and aromatic plants of Central Himalaya,India

A study was conducted to examine the distribution pattern of four rhizomatous medicinal and aromatic plant species (MAPs) viz., Angelica glauca, Pleurospermum angelicoides, Rheum emodi and Arne- bia benthamii in different forest stands in Central Himalaya. Results show that A. glauca and P. angelicoides had a higher (50%) frequency at Chipkoan, Garpak and Phagati forest, R. emodi had a higher (60%) frequency at Rishikund, Suki and Himtoli, and A. benthamii had a higher (70%) frequency at Suki and Khambdhar The densities of A. glauca (0.6 plants·m -2 ) and P. angelicoides (0.5 plants·m -2 ) were higher at Chipkoan and Garpak sites than at other micro-sites, while densities of R. emodi (0.8 plants·m -2 ) and A. benthamii (1.0 plants·m -2 ) were higher at Suki and Khambdhar sites. A. glauca had highest total basal covers (TBC) (1.2 cm 2 ·m -2 ) at Chipkoan, P. angelicoides had highest TBC (0.92 cm 2 ·m -2) at Lati kharak site, A. benthamii had the highest TBC (6.48 cm 2 ·m -2 ) atKhambdhar, and R. emodi had highest TBC (4.53 cm 2 ·m -2 ) at Rishikund. For the four studied species, A. glauca showed a contagious distribution, P. angelicoides and R. emodi showed the random and A. benthamii showed the regular type of distribution.     

早稻施氮对连作晚稻产量和氮肥利用率及土壤有效氮含量的影响

于20022～005年,在湖南长沙采用连续定位试验,研究了早稻施氮对连作晚稻产量、氮肥利用率、土壤有效氮含量的影响。试验设早稻施氮/晚稻不施氮、早稻施氮/晚稻施氮、早稻不施氮/晚稻不施氮、早稻不施氮/晚稻施氮4个处理。结果表明,在连续4年早季施氮的条件下,连作晚稻施氮处理的平均产量为6.45.t/hm2,地上部干物质重12.13.t/hm2,氮素吸收量183.6.kg/hm2,分别比连作晚稻不施氮处理增加28.4%、35.1%和103.5%,均达到显著水平;在连续4年早季不施氮的条件下,连作晚稻施氮处理的平均产量为6.61.t/hm2,地上部干物质重12.14.t/hm2,氮素吸收量165.6.kg/hm2,分别比不施氮处理增加33.4%、37.6%和95.6%,均亦达到显著水平。连作晚稻在早季不施氮和早季施氮两种情况下氮肥利用率不同,前者的氮肥生理利用率显著高于后者,增幅为37.8%,两者的氮肥农学利用效率、吸收利用率差异不显著,但前者4年氮肥农学利用效率平均值比后者高18.1%,吸收利用率低6.8个百分点。早晚两季均不施氮小区土壤碱解氮含量均明显低于其他施氮小区,但没有出现随试验年度加长而连续下降的趋势;当早稻或晚稻其中有一季施用了氮肥,或者两季均施用了氮肥的小区,土壤碱解氮含量差异不显著。说明连作晚稻产量主要受当季施氮量的影响,而受早季施氮量的影响较小;早季不施氮小区的连作晚稻氮肥的农学利用效率、生理利用率比早季施氮小区高;在一定程度上降低稻田氮肥用量不会导致土壤背景氮含量的下降。     

A Suitable Site for in situ (On-farm) Management of Plant Diversity in Traditional Agroecosystems of Western Himalaya in Uttaranchal State: A Case Study

There is a growing realisation world over that the introduction of modern agriculture has to be supplemented with measures to conserve biodiversity in situ if yield gains are to be stabilized. Hence, there is a growing interest from agricultural development specialists and conservation biologists for understanding the socioeconomic factors determining the conservation of biodiversity in situ. The present study was conducted with the objective of understanding the in situ (on-farm) conservation of agrobiodiversity in traditional agroecosystems taking the Urgam valley in north-western Himalaya of India, as a case study. An inventory was made of traditional crops and wild economic species for subsistence, and the structure of forest resource base, traditional knowledge related to resource management and use. Institutional and scientific challenges for in situ (on-farm) management of crop diversity were studied and are discussed in this paper. Complementarity of in situ (on-farm) conservation with ex situ conservation together with crop improvement in such marginal areas are suggested.     

Crossing the thresholds: human ecology and historical patterns of landscape degradation

In discussions of landscape sensitivity, human activities have generally been regarded as external forces contributing to landscape change, with a focus on the impacts of cultivation methods, fertiliser practices, grazing pressures and atmospheric pollution. However, there has been comparatively little study undertaken that integrates physical and social systems in a historic context to explain the basis of human activity in sensitive landscapes. Where such attempts have been made, the manner of common land management has figured prominently, with ‘tragedy of the commons’ concepts used to explain land degradation and to provide a foundation for policy response. This has also been the case in Southern Iceland and in this paper we assess the extent to which common land domestic grazing pressures were the primary external force causing soil erosion and land degradation during the period of occupation from ca. 874 AD. We first provide field observation of soil erosion, temporally defined by tephrochronology, to highlight the extent of land degradation during this period. The ‘tragedy of the commons’ explanation of degradation is then assessed by evaluating historic documentary sources, and by environmental reconstruction and modeling of historic grazing pressures. These analyses indicate that regulatory mechanisms were in place to prevent overgrazing from at least the 1200s AD and suggest that there was sufficient biomass to support the numbers of domestic livestock indicated from historic sources. We suggest that failure to remove domestic livestock before the end of the growing season and an absence of shepherding were more likely to contribute to land degradation than absolute numbers. Lack of appropriate regulation of domestic livestock on common grazing areas can be attributed to limited cultural knowledge of changing and rapidly fluctuating environmental conditions.     

Traditional soil and land appraisal on fadama lands in northeast Nigeria

Abstract. As part of a study of recession farming on the 'fadama' lands on a segment of the Komadugu-Yobe floodplain, a survey was carried out to investigate the local farmers' perception of soil types and management practices. The farmers are clearly aware of the differences in soil type on the fadama and they possess unique skills in managing their farm lands. The farmers classify fadama soils for recession farming by assessing soil texture and soil drainage conditions by feel and observation. Integrating such local knowledge into soil surveys will lead to better practical definition of mapping units and give soil names that have more meaning for the farmers.     

农村中学图书馆路在何方?

本文从农村文化素质来看乡镇中学图书馆建设的重要性，探索乡镇中学图书馆的发展之路，并提出了乡镇中学图书馆建设几点建议。     

试论面向知识经济的高校内部审计

知识经济意味着一个双向的社会运动:知识的经济化和经济的知识化。知识经济时代的来临，提高了高校在社会中的地位。知识经济更需要审计监督。知识经济的信息化、数字化、虚拟化和网络化要求使得高校审计工作的目标、方式和内容产生重大变化。高校内部审计需要创新。