岷江上游典型村落资源利用与影响动因分析

从耕地占有数量及利用效率、土地资源构成、村落农业生产技术以及村落布局4个方面,研究岷江上游4个典型村落农业资源利用变化特点,认为农业资源禀赋条件、科技进步程度、民族文化和历史因素、制度政策、市场因子以及生态环境状况是形成村落资源利用的基本动因。     

Volume and financial value of species traded in the medicinal plant markets of Gauteng,South Africa

The demand for traditional medicinal plants and products in South Africa has created an extensive cross-border industry involving thousands of harvesters and traders. The market values of individual taxa vary considerably. Pricing structures fluctuate between markets and over time as the cost of harvesting species varies depending on a gatherer's access to the resources and the proximity of markets to the harvesting sites. This paper estimates trade values, describes the prices paid for 22 plant resources, investigates pricing structures relative to the mass/volume sold and the factors that influence the market price for plants. There is an inverse and disproportionate relationship between the price per kilogram (R/kg) and mass of the product sold. The smaller the quantity sold, the higher the R/kg sale values are relative to sales of larger quantities. This relationship is evident in different plant part types (e.g. bark and bulbs), species and markets (shops and street markets). Given the high mass sold relative to the price, bulbs, like bark, have the lowest R/kg values compared to other products like roots, fruits and leaves. The prices paid for heavier/denser species is thus disproportionate to the mass sold. If the relative values are used as an indicator of plant vulnerability (assuming high values indicate greater vulnerability), then bias is created in favour of 'lighter' and less dense plant parts typically sold in small quantities because of the nature of the plant part and the manner in which it is marketed and required by customers.     

农户能源利用方式的选择与农村环境的变化:某贫困山村薪炭林利用案例研究

为了深入了解农户能源利用状况与农村环境的相互作用关系,对一个贫困山村进行了为期15天的实地考察。通过问卷调查,入户访谈等方式,收集了50余份问卷和大量原始数据、图片资料,发现当地农户在利用薪材能源作为燃料直接燃烧时并不会带来对当地森林资源的破坏,但能源利用效率不高;而在用薪材能源作为香菇培养基原料时显著地提高了能源利用效率,却也严重影响了当地森林资源的可持续利用。由此可见,能源利用方式的选择与农村环境的变化息息相关。为了保证农村能源的可持续利用,人们需要同时考虑农村环境的承载能力,这就决定了改善农户能源利用状况不能单纯以提高能源利用效率为目标。在结合当地客观条件,综合当地政府、当地农户的意见的基础上,提出了当地能源利用的最佳方向应该是:在不增加农民支出前提下,鼓励农民改善薪材能源的利用方式,力图达到提高能源利用效率和森林资源可持续利用的“双赢”目的。     

雷州半岛红树林资源及其效益

对雷州半岛红树林资源及其效益进行调查分析。初步查明，雷州半岛沿海自然环境优越，适宜红树林生长发育，红树林资源丰富；现有红树植物15科26种，面积12422．9hm^2，分别占全国的93．8％、83．9％和32％；该地区的红树林在抵御风浪灾害、生物多样性保护、淤积造陆、防治污染等方面的生态环境效益及社会经济效益十分显著。     

中国土壤资源特点与粮食安全问题

土壤资源是粮食生产的基础，也是粮食安全的核心。文章在研究我国土壤资源特点的基础上，系统阐述我国粮食安全正面临着耕地减少、粮食减产的挑战。提出要解决我国耕地土壤和粮食安全问题，必须实施“藏粮于土”的行动计划，全面提高我国土壤资源的综合生产能力，其主要内容是：稳定耕地面积和粮食播种面积，实施基本农田严格保护机制；开发土壤潜力，提高粮食综合生产能力；加强生态环境建设，建立有弹性有应变能力的种植制度；防治土壤污染，保障粮食安全；适度开荒复垦，充分利用非耕地资源。     

自然保护区生物多样性经济价值类型及其评估方法

在分析生物多样性经济价值类型的基础上探讨了自然保护区生物多样性经济价值的类型和内涵,并将其分为直接实物价值、直接非实物服务价值、生态功能间接价值和非使用类价值（包括存在价值、遗产价值和选择价值）,进而提出评估这些价值的方法。     

河西走廊荒漠化土壤资源及生物改土培肥的效应

论述了河西走廊灰漠土、灰棕漠土、棕漠土的地理分布、成土条件、理化性质和主要亚类。在灰棕漠土上进行了紫花苜蓿 (Medicagosativa)对荒漠化土壤改土培肥效应的研究 ,结果表明 :栽植 3a紫花苜蓿鲜草产量 5 5 2t·hm-2 ,折干草 2 4 8t·hm-2 ;与对照比较 ,0～ 2 0cm土层中自然含水量增加 90 .6 5 g·kg-1 ,>0 .2 5mm团粒结构增加 1 7.2 3 % ,孔隙度增加 7.93 % ,容重降低 0 .2 1g·cm-3,pH由 8.4 5降至 8.2 0 ;全盐含量降低 4 .6 3 g·kg-1 ,脱盐率达 70 .3 6 % ;有机质、速效N、速效P、速效K亦随之增加。     

天津市农村能源建设与可持续发展战略探讨

本文针对天津市农村能源建设与可持续发展的关系及能源建设方向等问题,分析了天津市农村能源的现状与特征,从而提出能源与经济,环境协调发展,调整能源结构提高农村能源利用的新举措。     

辽宁省农用地质量空间分布格局及影响因素研究

采用GIS技术、地统计学分析和景观生态学方法对辽宁省农用地质量的空间分布规律及其多样性、均匀度、集中度、优势度等进行研究,结果表明：辽宁省农用地质量的区域分异明显,等别表现出由辽西低山丘陵区和辽东山地丘陵区向中部平原区的递增规律。探讨农用地质量空间格局的影响因素,发现农用地自然质量空间分布格局主要受到地带性因素与大尺度的非地带性因素的控制,农用地利用质量和经济质量空间分布格局受到人类活动的影响显著。     

Predicting the spatial distribution of mangroves in a South African estuary in response to sea level rise,substrate elevation change and a sea storm event

The spatial distribution of mangroves in the Mngazana Estuary under sea level rise induced by climate change, together with different substrate elevation change scenarios was predicted for 2020, 2050 and 2100. The present inundation frequency tolerance range was from 0.8 to 31.2 %, equivalent to substrate elevation thresholds of 1.1 and 1.7 m amsl. These thresholds were measured by field surveys and analysis of a gauge station situated near the mouth of the estuary. The predictions were based on the assumption that the inundation frequency tolerance range of mangrove stands remains constant in the future. Through the use of a digital elevation model an initial increase of 2.10 ha year^?1 was found in mangrove area between present and 2020 (from 122.6 to 143.6 ha). This was due to habitat becoming available that is currently too compacted for seedling establishment to occur. This compaction resulted from human and cattle traffic for grazing. Thereafter there would be a mean loss of 0.66 ha year^?1 from 2020 through 2100. Landward migration of mangroves would not take place due to the elevation limit of adjacent non-mangrove areas. In addition, the loss rate would increase to 1.01 ha year^?1 under insufficient sediment accretion, but would decrease to 0.18 ha year^?1 under thriving mangroves condition. The analysis of sea storm event in September 2008 showed that local water level increased by 28 cm and maximum affected area was 87.0 ha (about 71 % of mangrove stands). The inundation continued over 5 days. The results indicated that the combination impact of sea level rise, substrate elevation change and sea storm would possibly be a threat to tropical African estuaries with large flat intertidal areas and mangroves.     

黄河水量统一调度实施前后河口三角洲生态环境变化研究

全流域水量统一调度是缓解黄河断流,维护流域生态环境的重要举措。水量调度效果如何,河口生态环境变化状况是非常重要的衡量指标。文章提出了评价水量调度效果的河口生态环境对比指标,并尝试运用遥感技术、水文数据和调查资料,对比分析了水量调度前后河口三角洲生态环境变化情况。结果表明,黄河水量统一调度后,河口三角洲最小河道生态基流在非汛期基本得到满足,断流现象不再发生,径流入海率和输沙入海量有所增加,淡水湿地面积逐渐增多,物种多样性明显得到改善。这反映出黄河流域水量统一调度后,河口三角洲生态环境正逐步恢复。     

我国自然保护区生态旅游资源价值实现方式研究

从我国自然保护区所面临的经费困难和开展生态旅游的现状入手 ,概述了生态旅游资源的价值评估法和加拿大国家公园使用者收费情况 ,并探讨了我国自然保护区生态旅游资源价值实现的若干方式     

江南丘陵红壤区的农业水资源特征与调控利用——以江西省余江县为例

农业水资源按分布空间分为大气降水、地表水、土壤水和地下水。江南丘陵红壤区的各类水资源特征是:大气降水丰沛而时空分配不均;地表水多而径流、蒸发量大;红壤贮水库容小、深层水多而有效性差;地下潜水较多而承压水少。针对上述特征,应因地制宜通过工程、生物、农艺措施进行水资源调控,针对“四水”进行人工降雨,地表水集蓄,增加土壤深层水、有效水利用和潜水开发等,以蓄丰补欠、趋利避害,提高水资源的利用率。     

Cooperative breeding and immunity: a comparative study of PHA response in African birds

Cooperatively breeding birds might be expected to suffer from higher costs of parasitism than pair-breeding species because of two aspects of their ecology which should facilitate horizontal transmission and possibly select for higher parasite virulence: first, they interact regularly with more individuals than pair-breeding species, and second, these individuals are commonly close relatives that could share similar resistance alleles. This hypothesis predicts that cooperative breeders should invest relatively more in immune defence than closely related species which breed in pairs. I tested this prediction comparatively in African birds by examining the response of the immune system to the mitogenic lectin, phytoahemagglutinin (PHA response) in relation to cooperative breeding. Among 66 species, of which 18 breed cooperatively, PHA response was significantly higher in cooperatively breeding species. This association appeared not to be confounded by body size, clutch size, nest position, coloniality or similarity owing to common phylogenetic descent. These results suggest that cooperatively breeding birds may have been selected to invest more than pair-breeders in defences against parasites. If so, then additional costs of philopatry and helping behaviour might be imposed on breeders, helpers and offspring.     

How resources and encounters affect the distribution of foraging activity in a seed-harvesting ant

We examined how the foraging ecology of the seed-harvesting ant Messor andrei depends upon the distribution of resources and the presence of conspecifics. Bait experiments showed that colonies can recruit to high-density patches of seeds. However, at the seasonal scale, natural resource distribution did not affect the distribution of foraging activity. We conducted the study in years of high rainfall and thus seed availability may not have been a limiting factor. Colonies always preferred to forage in areas closer to their nest, which may reduce travel time between the nest and foraging sites. On a day-to-day scale, encounters between neighboring colonies at a site increased the probability that colonies would return to forage at that site; this was true both for natural and experimental encounters. In the summer, this resulted in colonies foraging at the sites of intraspecific encounters on more days than in areas where no encounter had occurred. Encounters between colonies included fighting, and there was little overlap between the foraging areas of neighboring colonies: both results suggest that one function of encounters is to defend foraging space. The high probability of return to the site of an encounter between colonies suggests that encounters may have a second function: to indicate the presence of resources. Received: 28 June 1999 / Received in revised form: 12 October 1999 / Accepted: 16 October 1999     

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH₂OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl₂ extractable fraction. A large proportion of Cu was bound to the acidic H₂O₂ extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier’s procedure, and the order of mobility was Zn > Cd > Cu  > Pb.     

Seasonal distribution and speciation of mercury in a gold mining area,north-west province,South Africa

The seasonal speciation of mercury (Hg) was determined in water, soil, and sediments from watersheds located in the North-West province of South Africa. The study area is known to have a long history of mining activities which also include the recovery of gold from old tailings. Both inorganic (IHg) and methyl mercury (MHg) were detected at high concentrations (up to 8480 μg IHg kg^?1 and 13 μg MHg kg^?1) in surface sediments during dry season. A considerable remobilization of Hg from bottom sediments was observed in water from dry to wet season as well as the migration of Hg away from pollution sources due to seasonal influences. Hg in sediments mostly has been speciated as Hg⁰. Enhancement of Hg methylation occurred mainly in deeper sediments at regions corresponding to the lowest redox potential, higher pH, and enrichment of IHg. Hg values in borehole waters were very high (up to 3310 ng L^?1) suggesting a serious contamination of the site groundwater which needs to be addressed urgently in order to minimize further impact that affects the Vaal River and other water systems located nearby.     

Joint protected area management: a proposal for the management of Sanctuaries and National Parks in India

SUMMARY

With the aim of evaluating the biotic pressure on a protected area, Kuldiha Sanctuary in Orissa, India was taken as a case study. In the 19 villages lying within a 1 km radius of the Sanctuary, there are 9814 people with 19% literacy. Tribals constitute 73.3% of the population. Some 7507 head loaders collect firewood from the Sanctuary every day. In addition, 37 297 cattle enter the forest for grazing. Consequently alienating the people depending on the Sanctuary in the management and conservation of wild flora and fauna is not only futile but also detrimental to the socio-cultural-economic fabric of the ecosystem of the people. In this study, involvement of the local community in the protection and management of the Sanctuary and National Park is proposed and methods of implementation, funding and a legal framework are discussed.     

Evaluation of carrying capacity with particular reference to firewood and fodder resources in Central Himalaya: a case study of Baliya catchment

SUMMARY

The dwindling forests of the Central Himalaya are suffering from serious losses, threatening the subsistence population of the region. This study analyses the rate of consumption of fodder and firewood in a Central Himalayan catchment and estimates the carrying capacity of the catchment for these resources. Estimates indicate that the carrying capacity of the natural ecosystems and agroecosystems, in terms of availability of fodder and fuelwood resources, has already been exceeded.