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21.
论述了农林复合经营的概念及内涵,现代农林复合经营崛起的历史必然性,并通过对农林复合经营在农林牧相互促进、协调发展方面,实现经济、社会、生态三大效益统一的论述,充分揭示了其在农村可持续发展中的重要地位和作用。  相似文献   
22.
植物篱种植模式综合效益研究   总被引:2,自引:0,他引:2  
祝其丽  孙辉  何道文  马睿  唐学芳 《四川环境》2007,26(3):41-45,54
植物篱种植模式是一种有效的山区水土保持、土壤改良以及多种经营的耕作模式。该模式自20世纪70年代以来在热带非洲和东南亚等地区进行了试验、示范和较为系统的研究,作为坡耕地水土保持和土壤改良的生物措施受到广泛重视。20世纪80年代以来该模式在我国很多地区也进行了研究、示范和推广,并取得显著成效。本文在国内外已有研究基础上,采用层次分析法对四川省宁南县马桑坪的等高固氮植物篱种植模式的生态效益、经济效益、社会效益及综合效益进行了较为系统的分析和评价。评价结果表明,植物篱种植模式的生态效益、经济效益、社会效益及综合效益均大于顺坡耕作模式,种植新银合欢植物篱比种植山毛豆植物篱的综合效益高;在种植相同植物篱树种的前提下,施磷肥比不施磷肥的效果好。同时,针对该技术目前在研究和应用方面存在的问题提出了一些建议。  相似文献   
23.
    
Epiphytes, air plants that are structurally dependent on trees, are a keystone group in tropical forests; they support the food and habitat needs of animals and influence water and nutrient cycles. They reach peak diversity in humid montane forests. Climate predictions for Central American mountains include increased temperatures, altered precipitation seasonality, and increased cloud base heights, all of which may challenge epiphytes. Although remaining montane forests are highly fragmented, many tropical agricultural systems include trees that host epiphytes, allowing epiphyte communities to persist even in landscapes with lower forest connectivity. I used structural equations models to test the relative effects of climate, land use, tree characteristics, and biotic interactions on vascular epiphyte diversity with data from 31 shade coffee farms and 2 protected forests in northern Nicaragua. I also tested substrate preferences of common species with randomization tests. Tree size, tree diversity, and climate all affected epiphyte richness, but the effect of climate was almost entirely mediated by bryophyte cover. Bryophytes showed strong sensitivity to mean annual temperature and insolation. Many ferns and some orchids were positively associated with bryophyte mats, whereas bromeliads tended to establish among lichen or on bare bark. The tight relationships between bryophytes and climate and between bryophytes and vascular epiphytes indicated that relatively small climate changes could result in rapid, cascading losses of montane epiphyte communities. Currently, shade coffee farms can support high bryophyte cover and diverse vascular epiphyte assemblages when larger, older trees are present. Agroforests serve as valuable reservoirs for epiphyte biodiversity and may be important early-warning systems as the climate changes.  相似文献   
24.
Activities involving land use, land-use change,forestry, and agriculture (LUCF) can help reducegreenhouse gas (GHG) concentrations in the atmosphereby increasing biotic carbon storage, by decreasing GHGemissions, and by producing biomass as a substitutefor fossil fuels. Potential activities includereducing rates of deforestation, increasing landdevoted to forest plantations, regenerating secondaryforest, agroforestry, improving the management offorests and agricultural areas; and producing energycrops.Policymakers debating the inclusion of a variety ofLUCF activities in the Clean Development Mechanism(CDM) of the Kyoto Protocol need to consider themagnitude of the carbon contribution these activitiescould make. Existing estimates of the cumulative GHGoffset potential of LUCF activities often take aglobal or regional approach. In contrast, land-usedecisions are usually made at the local level anddepend on many factors including productive capacityof the land, financial considerations of thelandowner, and environmental concerns. Estimates ofGHG offset potential made at a local, or at mostcountry, level that incorporate these factors may belower, as well as more useful for policy analyses,than global or large regional estimates. Whilecountry-level estimates exist for forestry activities,similar estimates utilizing local information need tobe generated for agricultural activities and biofuels,as well as for the cumulative potential of all LUCFactivities in a particular location.  相似文献   
25.
IntroductionSincethe 195 0s ,manyforestshavebeenplantedintheplainareasofChinafortheimprovementoftheenvironmentalqualityandensuringthesupplyofwoodandnon timberforestproducts.Forestrydevelopmenthasplayedanimportantroleinadjustingtheruraleconomicstructure ,i…  相似文献   
26.
  总被引:1,自引:0,他引:1       下载免费PDF全文
Nitrogen,phosphorusandpotasiumrecyclinginanagroforestryecosystemofHuanghuaihaiPlain:withPaulowniaelongataintercroppedwheatand...  相似文献   
27.
Abstract:  The occurrence of fauna in commercial plantations is often associated with structural complexity. Through a meta-analysis, we tested whether the structural complexity of plantations could enhance bird species assemblages and whether bird assemblages respond differently depending on taxonomic affiliation, body size, and diet. Our analyses included 167 case studies in 31 countries in which bird assemblages in forests and plantations were compared and 42 case studies in 14 countries in which bird assemblages in plantations of different structural complexity were compared. Species richness, but not abundance, was higher in forests than in plantations. Both species richness and abundance were significantly higher in complex than in structurally simple plantations. Taxonomic representation and body size did not differ between forest and plantations, except that there were fewer insectivorous birds in plantations than in forests. In the comparison of simple versus complex plantations, abundance of all taxonomic and dietary groups was higher in complex plantations. Body size did not affect bird species richness or abundance. Independent of the type of plantation, bird richness and abundance were greater in structurally complex plantations. Enhancing the structural complexity of plantations may mitigate their impact and offer habitat for some native species.  相似文献   
28.
Abstract:  Many tropical forests have been converted for agri- or silviculture or a combination of both (agroforestry). Conservation at a landscape scale requires an understanding of the distribution and abundance of native biodiversity in these converted natural ecosystems, of which the knowledge is especially poor for African agroecosystems. We compared species density and species composition of four plant groups (trees and shrubs, epiphytic vascular plants, mosses, and liverworts) among three arboreal land-use types in southwestern Ethiopia (montane rainforest fragments, shade-tree coffee home gardens, and exotic tree plantations). Species density was significantly higher in forests than in coffee home gardens for all plant groups and in exotic tree plantations for all groups except mosses. Home gardens had more vascular epiphytic species than plantations, whereas the reverse was true for mosses and liverworts. The species composition of the forest plots was sometimes more similar to home-garden plots than plantation plots and sometimes vice versa. Fifteen forest plots had, however, cumulatively more species than a random selection of 15 nonforest (coffee home garden and plantation) plots, even if the 2 plot types complemented each other in terms of habitats for forest plants. Tree plantations dominated by Eucalyptus had many small trees and shrubs in common with forests, whereas plantations with Cupressus were important substrates for forests mosses and liverworts. Our results illustrate the importance of undisturbed forests habitats for conservation of species at a landscape scale and that different human-made land-use types may complement each other in their capacity as additional habitats for forest species.  相似文献   
29.
Designing agroecosystems that are compatible with the conservation of biodiversity is a top conservation priority. However, the social variables that drive native biodiversity conservation in these systems are poorly understood. We devised a new approach to identify social–ecological linkages that affect conservation outcomes in agroecosystems and in social‐ecological systems more broadly. We focused on coastal agroforests in Fiji, which, like agroforests across other small Pacific Islands, are critical to food security, contain much of the country's remaining lowland forests, and have rapidly declining levels of native biodiversity. We tested the relationships among social variables and native tree species richness in agroforests with structural equation models. The models were built with data from ecological and social surveys in 100 agroforests and associated households. The agroforests hosted 95 native tree species of which almost one‐third were endemic. Fifty‐eight percent of farms had at least one species considered threatened at the national or international level. The best‐fit structural equation model (R2 = 47.8%) showed that social variables important for community resilience—local ecological knowledge, social network connectivity, and livelihood diversity—had direct and indirect positive effects on native tree species richness. Cash‐crop intensification, a driver of biodiversity loss elsewhere, did not negatively affect native tree richness within parcels. Joining efforts to build community resilience, specifically by increasing livelihood diversity, local ecological knowledge, and social network connectivity, may help conservation agencies conserve the rapidly declining biodiversity in the region.  相似文献   
30.
SUMMARY

Biodiversity of a protected area of West Himalaya (Askot Wildlife Sanctuary) was studied and analysed for landscape, faunal and floral diversity. The forest and pasture land, ideal habitats for the flora and fauna, covered nearly 52% and 12%, respectively, of total reported area. Among the fauna Himalayan musk deer (Moschus chrysogaster), thar (Himitragus jemlahicus), snow leopard (Panthera uncia), koklas (Pucrassia macrolophas), monal (Lophophorus impejanus) and snow cock (Tetragalus tibetanus) are threatened species. Plant diversity is represented by 1262 species of vascular plants (Angiosperm 1112, Gymnosperm 7, Pteridophytes 143 taxa). Diversity of the species within families, genera, habitats, communities and along vertical gradient zone was analysed. Maximum diversity existed in the family Orchidaceae (120 taxa), genera Polystichum (13 taxa), altitude zone (1001–2000 m; 860 taxa), habitat (forest; 623 taxa) and community (Banj oak: 92 taxa). Seventy-one families were found to be monotypic. Species were further analysed for ethnobotanical use (medicine: 70, edible: 55, fodder: 115, fuel: 31, house building: 13 etc.), domesticated diversity (crops: 19, vegetables: 26, fruits: 16), agroforestry or marginal, threatened and endemic diversity. Similarity in species composition within the habitats indicated maximum similarity in areas of shrubberies and alpine meadows/ slopes (71.65%) and exposed open/grassy slopes and shady moist places (47.32%). 432 (34.2%) taxa are native to Indian Himalaya of which 24 are endemic and 235 are near endemics. 65.8% of taxa are represented in the neighbouring areas and other regions of the globe. Ten taxa occurring in the Sanctuary have been already recorded in the Red Data Book of Indian Plants. Conservation and management of species is focused.  相似文献   
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