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四川盆地浅丘陵区农林复合系统内部天空散射辐射分布特性理论分析 总被引：1，自引：0，他引：1
根据四川盆地浅丘区农林复合系统特点,从理论上分析了该系统内天空散射辐射令布特征。提出了在林带和地形(坡度变化)的双重影响下的林带间平均相对辐照成分布特征,为农林复合系统的设计提供了依据;除林带本身产生“光胁地”外,地形变化即坡度的增加,叶“光胁地”效应有增强作用,对其范围有扩大作用。 相似文献
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本文对川中浅丘农区坡地林农复合系统的价值流进行了研究。结果表明：复合系统与对应的对服农地系统相比，前者具有明显的价值积累效应和罗高价值积累速率，其纯收益、劳动力产值分别增加２４．４６－３７．１１％和２１．０８－２９．００％。 相似文献
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系统地研究了农林复合系统对自然资源利用率的影响,结果表明：农林复合系统具有提高资源利用率的功能,但系统内不同模式之间光能利用率差异较大,梨粮复合模式光能利用率比周边种植模式高１０．３％,系统内光能利用率则比旷野平均提高了２５．０％。农林复合系统水分利用率一般可比旷野农田高１０．３％～１５．２％。农林复合模式热量利用效率比一般旷野农田高１１％～１３％。农林复合系统不仅能改善农田生境与提高资源利用效率,还能增加农民的经济收入,可在我国北方平原农区大力推广。 相似文献
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本文探讨了农林复合经营的意义,分析了德州平原农区林业发展的历史和现状,认为在以生产粮、棉为主的平原农区发展林业,实行农林复合经营是必然趋势;目前已经营造起来的综合防护林体系,是典型的农林复合经营形式。笔者还认为农林复合经营将是地少人多的平原农区农林生产发展的主要方向。 相似文献
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农林间作可充分利用自然资源,发挥经济、社会、生态三大效益,是实现平原农区农林可持续发展的最佳模式;因地制宜,大搞农林间作,实现平原农区农林可持续发展。 相似文献
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总结阐述了研究子专题的来源，取得的成果与成果特色。子专题来源于“九五”国家重点科技攻关项目－“生态林业工程技术研究与开发”。该报告介绍了攻关期间完成的硬件与软件任务：取得“衡阳县防护林体系结构优化与林种、树种、林分结构调整”；“英南试验示范区农林复合经营系统结构优化布局”；“防蚀保土型农林复合经营系统的防蚀保土技术”；“防蚀保土型农林复合经营模式营建技术”；“农林复合模式施肥配方与施肥技术”；“生物保土地埂营造技术”；“香椿地埂栽培技术”等技术成果，以及“林分有利于作物生长最适闭度”；“无植被恢复时坡耕梯土的土壤侵蚀模数”；“植被覆盖比例带来的水土流失减少量”；“生物地埂类型及其保土功能”；“植覆盖率、生物量与输沙率、土壤侵蚀量的相关关系”；“树冠大 作物产量关系”；“不同郁闭条件下作物气象资源利用的新颖”、“ 相似文献
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攀枝花市生物多样性与生物资源可持续性分析 总被引：4，自引：1，他引：4
攀枝花市地处川西南山地，地形、地貌十分复杂，气候、土壤条件多样，为生物的生存提供了丰富多样的适宜条件，研究表明：（1）生物物种丰富多样，植物区系地理成分复杂，且植物的旱生性明显。（2）在森林中各类型多样性指数较大的从大到小依次是云南松、云南松与阔叶林混交林、栓皮栎和柞栎林、多变石栎和硬斗石栎林、桤木林等；草地的多样性指数表明，山地疏林草地、山地灌木草地多样性较大。（3）景观镶嵌体结构发生很大变化：自然植被面积减少，次生植被扩展；干热河谷稀树灌草丛类型上升100米－200米；森林面积不断减小，结构日趋简单化；草地也因过牧不断退化；栖息地发生重大改变后，动物资源也大受影响，分布区减少，种群数量减少。森林的多样性指数最大，其次依次为草地和栽培植物种群；景观的碎裂化程度不断增高。（4）以森林资源、草地资源、珍稀生物资源（主要讨论珍稀植物资源）和栽培植物种群为生物资源包含的主要内容，以景观的稳定性、多样性、碎裂化程度和各景观元素的优势度为生物资源可持续性的评价指标，评价结果表明，一是森林资源和草地资源的持续利用程度均较差，二是多样性和破裂化对生物资源可持续性的影响尤为显著，景观的碎裂化问题相当严重。因此，应加强生态环境建设，重点保护好现有森林资源，推进生态公益林建设，积极开展植被恢复和生态重建，提高森林覆盖率和稳定性；同时合理规划自然保护区，促进生物多样性的保护，对充分发挥森林的涵养水源、保持水土、储存基因、繁衍珍稀动植物资源等功能都具有十分重要的意义。 相似文献
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我省川中浅丘农区,地少人多,一般25度以上的坡地都开垦种粮,成片的造林地很少。大于30亩以上的宜林地不到5％〔1〕,森林复被率仅1—3％,用材和烧柴缺乏,水土流失严重。过去人们认为,川中浅丘农区农业用地人平只有一亩左右,那有更多地可以造林。为了解川中农区土地利用情况,究竞有多少土地可以造林,和怎样造林的问题。我们选择了位于川中腹地的资阳县太平公社进行调查,现将结果整理如下: 相似文献
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In tropical regions where agricultural activities are limited, agroforestry is an alternative for both economic development and for the management and conservation of biodiversity. The potential role of different types of land use as reservoirs of dung beetle diversity in the wet tropical forest of the Pacific lowlands of Colombia is evaluated in three agroforestry systems that differ in canopy cover and the sowing density of Borojoa patinoi crops associated with timber forest. Although total species richness was similar among land use types, differences related to the decrease in the abundance and biomass of the species were remarkable, and reflected in turn by the diversity and structure of the guilds. The general pattern observed was one in which the structure of the dung beetle assemblage of B. patinoi growing below a diversified and permanent tree cover was similar to that of the primary and secondary forest. Beetle diversity in management systems with less tree cover or a high sowing density of B. patinoi was lower and very similar to that of abandoned agricultural fields. This suggests that B. patinoi agroforestry systems can be viewed as valuable instruments for biodiversity management and conservation in the wet tropical forests of the Pacific lowlands and not just as substitutes for forest, though we must be aware that structural changes in the beetle community may in turn affect the ecological processes regulated by these insects in the agrosystems under study. 相似文献
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Biologically mediated soil processes rely on soil biota to provide vital ecosystem services in natural and managed ecosystems. However, land use changes continue to impact on assemblages of soil biota and the ecosystem services they provide. The objective of the present study was to assess the effect of land use intensification on the distribution and abundance of soil invertebrate communities in the Nilgiri, a human-dominated biosphere reserve of international importance. Soil invertebrates were sampled in 15 land use practices ranging from simple and intensively managed annual crop fields and monoculture tree plantations through less intensively managed agroforestry and pristine forest ecosystems. The lowest taxonomic richness was found in annual crops and coconut monoculture plantations, while the highest was in moist-deciduous and semi-evergreen forests. With 21 ant species, agroforestry systems had the highest diversity of ants followed by forest ecosystems (12 species). Earthworms and millipedes were significantly more abundant in agroforestry systems, plantations and forest ecosystems than in annual crop fields. Ants, termites, beetles, centipedes, crickets and spiders were more abundant in forest ecosystems than in other ecosystems. It is concluded that annual cropping systems have lower diversity and abundance of soil invertebrates than agroforestry and natural forest ecosystems. These results and the literature from other regions highlight the potential role that agroforestry practices can play in biodiversity conservation in an era of ever-increasing land use intensification and habitat loss. 相似文献
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The role of different agroforestry systems in the conservation of plant diversity and forest structure has not been directly
compared in many agricultural dominated landscapes. In this study, we investigated tree diversity and forest structure in
a complex agroforestry landscape traditionally grown for cocoa and mixed food crops and compared these to the natural forest
in southeastern Ghana. The study was carried out using 36 25 m × 25 m plots. There was significant difference [95% Confidence
Interval (95% CI)] in the native forest/non-crop tree species richness between the natural forest and the agroforest farmlands
but species richness was similar between the cocoa and mixed food crops agroforests. The density of native forest/non-crop
trees was significantly higher (P < 0.05) in the natural forest but similar between cocoa and mixed food crops agroforest. Similarly, the basal area of native
forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but comparable between cocoa and food crops agroforest. Of the 20 most abundant native forest/non-crop
trees recorded, 12 of them showed significant responses (P < 0.05) to land use change with nine of the species significantly abundant in the natural forest relative to the agroforest
systems. Eighteen native forest/non-crop trees species in the agroforestry systems were commonly recorded as being used; 100%
of them being used as fuel wood with 83.3 and 77.8%, respectively, used as medicines and materials. The findings of this study
suggests that although complex agroforestry systems are a poor substitute for the natural forest the heterogeneous mosaic
landscape in which complex agroforestry forms part can be strategically managed to maximize the benefits of both sustainable
agriculture production and conservation of plant diversity by acting as buffer between protected areas and intensively managed
areas. 相似文献
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四川盆地丘陵区主要森林群落结构特征研究 总被引：7，自引：3，他引：7
本文对四川盆地丘陵区主要森林群落--人工柏木纯林、次生栎柏混交林和桤柏混交林的群落结构特征进行了研究.结果表明：在群落的物种组成、生活型、层片结构以及Shannon-Wiener多样性指数、Pielou均匀度指数和Simpson生态优势度指数表征的群落综合特征上,次生混交林与人工林具有很大差异.人工柏木纯林物种数量少,乔、灌、草层的物种多样性和均匀度较低,生态优势度较高;次生栎柏混交林和桤柏混交林物种数量较多,乔、灌、草层有较高的物种多样性和均匀度,较低的生态优势度. 相似文献
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Syed Ajijur Rahman Terry Sunderland James M. Roshetko Imam Basuki John R. Healey 《Small-Scale Forestry》2016,15(4):433-442
This paper investigates the types of agroforestry system that exist in Gunung Salak Valley, West Java, Indonesia in order to characterize the differences in their basic structure and associated crop plant diversity. Data were collected through rapid rural appraisal, field observation and focus groups, followed by household survey of a sample of 20 agroforestry farmers. Five main agroforestry systems (homegardens, fruit tree system, timber tree system, mixed fruit–timber system, and cropping in the forest understory) exist in the study area, and all of them exhibit a noticeable diversity in terms of both species composition and utilization. Products from farming accounted for an average 24 % of household income. They comprised agroforestry products which contributed IDR 3.25 million/year and other agricultural products contributing IDR 1.66 million/year. The observed agroforestry systems include not only a form of forest dominated by ‘cultivated trees’, but also an anthropogenic vegetation formation derived from agricultural antecedents. In land-use classifications agroforestry systems are not recognized as forestry, but like forests they provide tree products and services. Classification will always be disfunctional if a binary system is applied, thus a more sophisticated approach should be adopted that incorporates the economic and environmental characteristics of a wider range of systems. 相似文献
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Analysis of existing agroforestry practices in Madhupur Sal forest: an assessment based on ecological and economic perspectives 总被引：1，自引：0，他引：1
A study was conducted in Madhupur sal forest of Tangail, Bangladesh to identify the suitable agroforestry practices of the
area. Considering the ecological aspects of different agroforestry practices 10 sample plots (10 m × 10 m) from each land
uses were taken, including natural forest to get a comparative scenario. The study showed that among the different agroforestry
practices, Margalef and Shannon-Weiner index values are the maximum for pineapple agroforestry and lower for banana agroforestry,
and Evenness index value is the maximum for lemon agroforestry. Determination of tree biomass in different land uses revealed
that it is highest (3 078.6 kg/100 m2) in natural forest followed by pineapple agroforestry, lemon agroforestry and banana agroforestry. Soil pH, moisture content,
organic matter, organic carbon, phosphorus and total nitrogen showed statistically significant variation while bulk density,
particle density, sulphur and potassium did not show any statistically significant variation among the land uses. Soil fertility
status showed that pineapple agroforestry is more fertile than rest of other land uses. The Net Present Value (NPV) indicated
that banana agroforestry is financially more profitable than other two systems, while the Benefit-Cost ratio (BCR) is higher
in pineapple agroforestry (4.21 in participatory agroforestry and 3.35 in privately managed land). Even though banana agroforestry
gives higher NPV, capital required for this practice is much higher. The findings suggest that pineapple agroforestry has
a tendency towards becoming ecologically and economically more sound than other two practices as it has better ecological
attributes and required comparatively low investment. 相似文献
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竹林区竹类种质保育需要建立避免人为干扰的竹类自然生态系统,但现有的竹林粗放遍及各处的经营策略则直接威胁到竹类种质栖息地的保护。通过对蜀南竹海人工经营和未经营下楠竹林群落环境与种群结构的对比分析,认为保护区内楠竹林经营强度改变了植物群落结构,导致植物物种多样性的丧失,地表灌木、草本和凋落物的盖度降低,生物量减少;考虑天然楠竹林结构演替,楠竹的人工经营(纯林经营)是维持楠竹林生产力和楠竹林的必然途径。基于现代林业理论,提出了县域楠竹林适度经营与保护的空间分工性、集约化策略,以期获得保护区长期的生态经济社会效益与生态安全屏障的优化格局。 相似文献
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《林业研究》2017,(5)
Tree diversity in West Africa is threatened by intensified land uses and salinization,and farmers' role in conservation of tree species is unclear.We hypothesized that farmers contribute to conservation of tree diversity through protection of trees in their agroforestry landscapes and compared the diversity and structure of the tree vegetation across landscape classes.Inventories were carried out in three villages in the Groundnut Basin in Senegal,assessing tree diversity,density and crown cover.Tree diversity as assessed by species accumulation curves was high in forests,but cultivated landscapes had comparable or almost comparable diversity,especially in the cases where the forest was planted or was affected by charcoal production.However,the occurrence of exotic species was higher in cultivated parts of the landscape,and although many species were in common,ordination plots indicated that forests and cultivated landscapes to some degree had different species composition.Salinity had a strong influence on vegetation,not only in the tans(salt marshes) but also across the other landscape classes.In conclusion,agroforestry landscapes in the three villages harbor considerable tree diversity,but insufficient to fully conserve the tree species.We argue that informing and including farmers in tree management in the region will contribute to overall conservation of tree genetic resources. 相似文献
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We tested the economic value of ecological knowledge in a midwestern USA alley-cropping system where row crops are planted in alleys between fine hardwood trees grown for veneer. Economic models were constructed to compare among agroforestry designs as well as to compare agroforestry with traditional forest plantation culture and row crop monoculture and rotational management. The general modeling approach was to quantify production inputs and outputs, estimate costs and revenues, simulate tree growth and crop productivity in agroforestry configurations, and estimate discounted cash flows. We incorporated scenarios that controlled both above- and below-ground competition through appropriate management as found in our previous research. This research showed the importance of below-ground competition in determining crop yields and the period of time that crop income could be expected from the agroforestry interplanting. Net present values and internal rates of return showed that agroforestry systems were generally more favorable investments than traditional agriculture and forestry. More importantly, the use of simple management techniques targeted at reducing below-ground competition allowed longer cultivation of row crops, greatly increasing returns to the landowner. Thus, the economic benefit of understanding the ecological interactions within agroforestry plantings dictates that accurate assessment of agroforestry alternatives will require the modeling of agroforestry as an integrated, interactive system.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献