Trends in natural resource use and prospects for sustainable resource management in Kenya's Arid and Semiarid Lands

This paper describes the environmental problems facing the development of Kenya's Arid and Semiarid lands (ASAL) today. The problems arise because of a rapidly declining resource base in the ASAL as a result of overexploitation and misuse, following basic land use conflicts. The extent of the overutilization or resource damage is not well known and varies a great deal from one agroecological zone to another and from resource to resource in the ASAL; those most affected include: soil, water, range, forest, livestock and wildlife. As a result of increased population growth in the ASAL, these resources are under stress. This paper argues that many of the environmental problems in the ASAL cannot be solved if the development programme does not address the needs of the people who live in the ASAL. There is a need to shift the objective of ASAL development from a preoccupation with economic growth and the idea that the ASAL should make a contribution to GNP through interregional trade and export to sustainable development that enables the communities in the ASAL to support themselves at as good a standard of living as possible. The last part of this paper outlines a strategy to promote such sustainable development.     

一种确定林业发展项目的有效工具(英文)

在云南省绿春县的有些村庄,由砍柴造成的森林破坏是造成环境退化的主要原因。在黑河流域的上游,不断加剧的水土流失和河床抬升对下游上百万的人们构成威胁。尽管人们对森林破坏和土地的可持续利用、社区可持续发展之间的关系不是不了解,但当生存压力存在的时候就会忽略由此造成的对未来的影响。对于村民来说,他们已经意识到了他们的生存状况,并讨论解决的有效途径,而不是单纯等待外界的援助和干预。问题的关键是如何将这些变化和影响以一种直观和形象的方式向村民解释,并且让包括文盲在内的所有人都能理解。从这方面考虑,图形的东西比文字和数字分析更有优势。本文采用MIGIS(移动交互式地理信息系统的英文缩写,它包括两部分的内容,即PLA-参与式学习和行动和GIS-地理信息系统)在云南省绿春县哈尼族村寨来协助进行村民自发的造林规划。图6表1参16。     

Exotic Pinus carbaea causes soil quality to deteriorate on former abandoned land compared to an indigenous Podocarpus plantation in the tropical forest area of southern China

Soil properties under an exotic plantation (Pinus caribaea) and an indigenous plantation (Podocarpus imbricatus) were compared with adjacent secondary forests and abandoned land in the tropical forest areas of Jianfengling National Nature Reserve in Hainan province, southern China. The surface soil (0–0.2 m) under Pi. caribaea has higher bulk density, lower soil organic carbon, total N, total K, available N, microbial biomass carbon, and smaller soil microbial communities (as indicated by soil Biolog profiles) than under Po. imbricatus. Both land use types showed negative cumulative soil deterioration index (DI) compared to secondary forests. However, compared to abandoned land (DI = –262), the soil quality of Po. imbricatus showed improvement (DI = –194) while that of Pi. caribaea showed deterioration (DI = –358). These results demonstrated that these exotic pine plantations can significantly and negatively influence soil properties. By contrast, our results showed that adoption of indigenous species in plantations, or natural regeneration, can improve soil quality.     

Effects of different land use types on infiltration capacity in a catchment in the highlands of Ethiopia

Infiltration capacity is an important variable for understanding and predicting a range of soil processes. This study investigated for different slope positions the effects of forest conversion to cultivation and grazing on soil infiltration capacity. Infiltration capacity was measured in the field in each land use type using a double‐ring infiltrometer. A total of 108 soil samples (3 slope positions × 3 land use types × 4 soil profiles × 3 soil depths) were collected to determine the variables that affect infiltration capacity viz. particle size distribution, organic carbon content, dry bulk density and soil moisture content. The results showed that in the cultivated and grazed land compared with forest, infiltration capacity and soil moisture content were 70 and 45% smaller respectively, and dry bulk density was 13–20% larger. Changes in soil structure caused by surface soil compaction because of tillage and animal trampling coupled with a smaller soil organic carbon content, are likely to be the principal factors causing the decline in infiltration capacity and soil moisture content after conversion of forest to cultivation and grazing.     

森林、造林、再造林和毁林的定义与碳计量问题

森林的定义与土地利用，土地利用变化和林业（LULUCF）碳吸收或排放的计量密切相关。同时也是造林，再造林和毁林（ARD）定义的基础；ARD的定义直接关系到《京都议定书》第三条第三款（3.3条款）ARD活动引起的汇清除的计量和大小。本文基于森林有关定义国际研讨会和IPCC有关LULUCF碳计量的方法学指南的研讨和交流。通过大量资料收集和信息查询，对主要国际公约，国际组织和各国森林和ARD的定义进行了调研。并分析讨论了不同定义及其对LULUCF碳计量的影响。提出了碳计量中需要关注的焦点问题。     

Extent and conservation of tropical dry forests in the Americas

This paper shows the results of an assessment on the current extent of Neotropical dry forests based on a supervised classification of MODIS surface reflectance imagery at 500-m resolution. Our findings show that tropical dry forests extend for 519,597 km² across North and South America. Mexico, Brazil and Bolivia harbor the largest and best-preserved dry forest fragments. Mexico contains the largest extent at 181,461 km² (38% of the total), although it remains poorly represented under protected areas. On the other hand, Brazil and Bolivia contain the largest proportion of protected tropical dry forests and the largest extent in continuous forest fragments. We found that five single ecoregions account for more than half of the tropical dry forests in the Americas (continental and insular) and these ecoregions are: the Chiquitano dry forests, located in Bolivia and Brazil (27.5%), the Atlantic dry forests (10.2%), the Sinaloan dry forests in Mexico (9.7%), the Cuban dry forests (7.1%) and the Bajio dry forests in Mexico (7%). Chiquitano dry forests alone contain 142,941 km² of dry forests. Of the approximately 23,000 km² of dry forest under legal protection, 15,000 km² are located in just two countries, Bolivia and Brazil. In fact, Bolivia protects 10,609 km² of dry forests, where 7600 km² are located within the Chiquitano dry forest ecoregion and protected by a single park. Low extent and high fragmentation of dry forests in countries like Guatemala, Nicaragua, Ecuador, Costa Rica and Peru means that these forests are at a higher risk from human disturbance and deforestation.     

Deforestation and extant distributions of Mexican endemic mammals

Deforestation threatens biodiversity conservation worldwide, but little quantitative information is available on how it affects individual species’ distributions. We modeled potential distributions of 85 continental endemic Mexican mammal species using ecological niche modeling, and produced testable predictions of species’ extant distributions by limiting ecological niches to remnant untransformed habitat based on the Inventario Nacional Forestal 2000. We included point occurrence data for all endemics only from collecting localities prior to 1970, before wide areas of habitat transformation occurred nationwide. Most endemics (61 of 85, 72%) showed a high proportion of transformed habitat (34.5%) at the national level. More than one-fourth of the endemics (23 out of 85, 27%) lost more than 50% of untransformed habitat within their potential distributions; two showed drastic areal loss of more than 90%; another two showed a loss of more than 80%. Only 34 of the endemics are listed as endangered or threatened in the Mexican Norma Oficial Mexicana (NOM). No significant association existed between proportional loss and conservation status as assigned in the NOM, nor are correlations significant between original distributional area and area of remnant untransformed habitat. Both findings suggest that geographic location determines extinction risks rather than area per se. Endemics in the state of Veracruz and in the Transvolcanic Belt suffered the most drastic niche reductions and thus appear to be at high extinction risk from further deforestation.     

Lowland rainforest avifauna and human disturbance: persistence of primary forest birds in selectively logged forests and mixed-rural habitats of southern Peninsular Malaysia

We compared the composition and structure of primary forest avifauna among primary forests, selectively logged forests and mixed-rural areas (e.g. villages and agricultural areas) of Peninsular Malaysia. We found that forests that were selectively logged at least 30 years ago contained only 73-75% of the 159 species of extant primary forest birds, with an increased proportion of dominant species. We estimated that only 28-32% of the primary forest species utilized the mixed-rural habitat, and that the number of species that bred in the agricultural landscapes might be even lower. The microhabitat of different species most affected their vulnerability to disturbance. Most small, arboreal frugivores and omnivores, and insectivores that fed from tree trunks, showed greater persistence in the mixed-rural habitat than ground dwelling bird species, which were affected most by disturbance. Resource abundance and variables that were closely related to forest disturbance such as the density of large trees, density of dead trees, canopy cover density and shrub volume influenced the distribution of the primary forest birds. Large primary forest reserves and a revision of short-cycle logging regimes (ca. 30 years) are needed if we are to conserve the lowland rainforest avifauna of Peninsular Malaysia and other parts of Southeast Asia.     

森林采伐的环境约束

阐述了人类与森林相互作用的发展过程及近代出现的与森林减少有关的大环境问题，并根据许多发达国家在森要采伐与森林环境方面的研究成果，就采伐作业对森林环境产生的直接和间接作用进行了综合分析和阐述。指出，森林的锐减和人口的猛增是造成当代环境危机的主要原因之一。采伐作业对森林产生的不利影响是客观存在的，但只要采伐规划合理和作业技术应用适宜，这种影响不会对森林的良性发展产生实质性的负作用。     

Determinants of Agricultural Intensity Index “Scores” in a Frontier Region: An Analysis of Data from Northern Guatemala

Data on farming systems in Petén, Guatemala, were used to develop an agricultural intensity index. The index can be used to assign an intensity “score” to a given farming system based on the array of practices used by the farmer, each practice’s contribution to production intensity, and the scale at which these practices are used. The scores assigned to 118 farmers in three study areas in Petén were analyzed through analysis of variance (ANOVA) to identify the factors that account for the variation in intensity levels, as measured through the index. The analyses reveal that the factors influencing agricultural intensity in Petén vary greatly from one study area to the next. This is due to differences in livelihood opportunities and strategies that, in turn, affect how agriculture fits into the local economy and how and why intensification is pursued. Variation in intensity levels can best be understood by considering the factors at the household and sub-regional scales that influence (a) whether farmers feel a need to intensify, (b) whether they see some benefit in doing so, and (c) whether they have the resources required to intensify production through particular strategies. Close attention must be paid to these factors by conservation and development organizations seeking to influence land use patterns and conserve forest in Petén. Avrum J. Shriar is an Assistant Professor at Virginia Commonwealth University where he specializes in Environmental Geography, Rural Development and Land Use, Farming Systems, and Latin America and the Caribbean. He holds a BA in Geography from Bishop’s University in Lennoxville, Quebec, a Master of Environmental Studies (MES) from Dalhousie University in Halifax, Nova Scotia; and a PhD in Geography from the University of Florida in Gainesville. Some of his recent articles have appeared in Food Policy, Geoforum, Human Ecology, Agroforestry Systems, and the Delaware Review of Latin American Studies.