农林复合经营对土壤化学性质的影响

本试验选取了拜泉县幼龄云杉纯林土壤、大豆土壤、落叶松—美国红云豆农林复合经营型土壤、杨树—水飞蓟和杨树—板蓝根林药复合经营型土壤等5种土壤类型作为研究对象,研究各种农林复合经营条件对土壤化学性质的影响。研究结果表明:实行农林复合经营对土壤化学性质有显著的影响,并因作物的品种而存在差异。总体来看,只要选择适宜的间作品种,一般对林地的土壤都有良好的改善作用。在本试验选择的3种农林复合经营类型中,杨树—板蓝根效果最好。     

Carbon and nutrient budgets of the Chagga home garden system in the Kilimanjaro highlands,Tanzania

Sustainable land management of smallholder farms is crucial for ensuring food security in sub-Saharan Africa. However, little is known about the nutrient dynamics of smallholder farming systems at the farm level based on primary data. In this study, carbon (C) and nutrient budgets of the home garden system in the Kilimanjaro highlands, where Andosols predominate, were quantified at the farmer's field. We evaluated (1) the soil C and nutrient flow in the main three land-use blocks (banana (Musa spp.) garden, maize (Zea mays L.) field and grassland) in one representative home garden and (2) the internal flow between farmland and livestock and the external nutrient flow across the inside and outside of the six home gardens. Intensive applications of livestock dung to the banana trees resulted in a positive C budget (7.2 Mg C ha⁻¹ year⁻¹) in the banana garden. Nitrogen loss through the harvesting of feed and crops was almost balanced with the livestock dung application, while nitrogen loss through leaching only accounted for 3% of that applied. Banana productivity has been maintained despite a negative potassium budget (−241 kg K ha⁻¹ year⁻¹), probably owing to the replenished exchangeable potassium from Andosols. In the maize field, the C budget was negative (−1.7 Mg C ha⁻¹ year⁻¹) owing to high organic matter decomposition. Carbon and nutrient budgets in the grassland were all negative. Our results revealed that the village average livestock density (4.4 TLU ha⁻¹: TLU means tropical livestock unit) was sufficient for P, Ca and Mg balance in the home garden, whereas it was not sufficient for N and K balance. Increasing livestock density improved the nutrient balance of the system. However, it is noteworthy that 33%–47% of the feed supplied as C and nutrients was collected from outside the home gardens, suggesting a high reliance on external inflow to fulfil feed demands. In conclusion, intensive livestock dung application to banana cultivation was fundamental for maintaining agricultural productivity to replenish the nutrients lost from the system. At the same time, this system was sustained not only by C and nutrient cycling within the system, but also by transporting resources from the external environment into the system.     

Influence of soil properties and land use on organic carbon storage in agricultural soils near hedges

In this context of climate change, agroforestry systems are acknowledged to have a good potential to increase carbon storage in agricultural areas. However, the carbon storage potential of agroforestry systems still needs to be quantified accurately, especially for hedges. The objectives of this study were to (1) add references to the existing literature on the potential for soil organic carbon (SOC) storage near hedges and (2) identify the main factors that influence the variability in this potential. To this end, we sampled soil in the adjacent fields of 25 hedges in France with mixed crop-livestock agriculture, with sampling on both sides for 20 hedges and sampling on only one side for five hedges, giving a total of 45 study sites. We measured SOC stocks to a depth of 90 cm at distances of 1, 2, 3 and 10 m from the hedge. The results showed that hedges have a strong potential to store carbon in soils, with a mean increase of 15% in SOC stock within 3 m of the hedge. This increase in SOC stock had high variability because of site characteristics. Additional SOC stocks were the largest in rotations of annual crops and grasslands with a permanent grass strip 1 m wide near the hedge, followed by rotations of annual crops, permanent grasslands and rotations of annual crops and grasslands. Large additional SOC stocks because of the hedge were also associated with soils that had a high C:N ratio. The contribution of this type of land management to soil carbon storage thus depends on the local context in which it is implemented.     

三峡库区坡耕地典型香榧套种模式土壤碳氮磷及其生态化学计量特征

为阐明三峡库区坡耕地典型香榧套种模式对土壤碳(C)、氮(N)、磷(P)含量及其生态化学计量特征的影响,在重庆市云阳县宝坪镇香榧种植基地内,选取香榧纯林(TG)、香榧-黄精(TGP)、香榧-大豆(TGG)3种套种模式为研究对象,分析不同模式及土层深度下土壤C、N、P含量及其生态化学计量特征。结果表明：不同模式的土壤C含量无显著差异,N、P含量均表现为TGG(0.80,0.53 g/kg)>TGP(0.71,0.40 g/kg)>TG(0.56,0.39 g/kg),且与TG相比,TGG的N、P含量分别显著提高42.9%,35.9%。土壤C、N主要富集在0—10 cm土层,而P主要集中在10—20 cm土层。3种模式的土壤C∶N、C∶P、N∶P分别为8.39～10.73,31.63～45.22,3.25～5.61,均低于全国平均值(14.4,136.0,9.3)。N∶P<10,表明N为研究区限制性养分。相关性分析结果表明,土壤pH、容重和总孔隙度也是影响土壤C、N、P含量及其生态化学计量的重要指标。香榧套种模式有利于土壤养分的积累,TGG的C、N、P含量高于TGP和TG,...     

植树造林对土壤性质和菌根形成的影响

A study was conducted on Cambisols in Northern Germany to analyze the effect of fast growing trees （Salix and Populus spp.） used in agroforestry on soil chemical and physical properties and also on endo- and ectomycorrhizal colonization of the fine roots. Representative plots of three trials, Giilzow （GUL）, Vipperow （VIP） and Rostock （ROS）, were used to measure the topsoil inventories at the very beginning and after six （GUL）, seven （VIP） and ten （ROS） years of afforestation with fast growing trees. The effect on soil organic carbon, plant available nutrients, reaction, bulk density, porosity and water conditions was analyzed, Arable soils without tree coppice were used as controls. Additionally, the endoand ectomycorrhizal colonization of two Salix and two Populus clones were investigated at one site （GUL） in 2002. The amounts of organic carbon in the topsoil increased significantly （P 〈 0.01） presumably induced by leaf and root litter and also by the lack of tillage. The soil bulk density significantly decreased and the porosity of the soil increased significantly （both P 〈 0.01）. The proportion of medium pores in the soil also rose significantly （P 〈 0.05 and 0.01）. Generally, afforestation of arable soils improved soil water retention. Ectomycorrhizas dominated the mycorrhizal formation of the Salix and Populus clones, with the accumulation of organic matter in the topsoil suspected of supporting the ectomycorrhizal formation. Thus, agroforestry with Salix and Populus spp. conspicuously affected chemical and additionally physical properties of the top layer of Cambisols within a period of six years.     

Microclimate modifications,growth and yield of intercrops under Hardwickia binata Roxb. based agroforestry system

An experiment was conducted by planting Hardwickia binata Roxb. at 200, 400 and 800 trees ha^???1, intercrops viz., Brassica campestris (mustard) and Glycine max (soybean) were sown from the second year onwards in winter and summer respectively at the National Research Centre for Agroforestry, Jhansi, U.P., India with the objectives of evaluating agrosilvicultural potential of the system and to study the effect of tree densities on ecophysiology of understorey crops. Tree growth was affected by both density and intercrop in the initial years of growth. Photosynthetic photon flux density (PPFD) available to the intercrops reduced with increasing densities. Transpiration rate and stomatal conductance in intercrops decreased due to the presence of trees. No significant changes in leaf temperature were observed till the fifth year of the growing season. Yield was significantly higher in pure crop in comparison with all the densities in mustard. Soybean yield under 200 trees ha^???1 was comparable to that of the pure crop. Trees at the density of 200 trees ha^???1 provided a conducive microenvironment to the intercrops.     

Silvopastoral Practices and the Condor Bioreserve,Ecuador

Abstract

The Condor Bioreserve initiative has the potential to serve as a model of integrated watershed management for developing countries. Within the region, landowners and settlers, government agencies and multiple non-governmental organizations face the challenge to modify land uses to best serve the tripartite goals of managing water resources, preserving critical habitat for biological conservation, and maintaining livelihoods. Livestock, especially cattle, are a valued commodity for people in the region. At the same time, increased tree cover on private land can provide many benefits such as increased income diversity, soil retention, and improved conditions for biological conservation. Silvopastoral systems can accommodate the desires of local landowners for livestock while addressing conservation goals of increased tree cover. A review of such systems and related conditions in the Bioreserve region and Ecuador is followed by reviews of other examples from the Andes region and other mountainous parts of the world. Suggestions include promoting forestry systems with fuller canopies through a rating system in park connector areas and buffer zones, local value-added timber processing, consideration of timber certification, and continuing current successes, such as extensionists promoting tree-related projects, markets for forestry products derived from private lands, community tree nurseries, and improved pastures incorporating trees.     

杨树农林复合经营研究进展

摘要：杨树农林复合经营是杨树产业的一个重要发展方向,在全球范围逐步受到重视。本文整理了杨树农林复合经营模式、并综述了农林复合经营效益、胁地效应及他感作用等方面的研究进展。在此基础上分析了杨树农林复合经营研究中存在的问题及展望。     

基于参与性调查农户对农林复合系统的认知与响应——以川中丘陵区为例

农林复合系统作为可持续的农业系统,对生态、经济和社会的和谐发展具有重要的影响。以川中丘陵区为例,采用参与性农户评估方法(PRA)对比分析了农户对农林复合系统的意愿及其影响因素。结果表明:农林复合种植模式的示范推广明显增加了农户对农林复合系统的认知和了解,提高了农户对农林系统的意愿,但仍然有一定比例的农户表示不愿意采用。此外,所有调查农户的环境保护的意识仍然不高。通过Logistic回归分析得出,农户对农林复合系统的认知、与外界的交流学习、经济收入状况、受教育程度以及耕地面积是决定农户决策意愿的主要影响因素。建议加强对宣传教育和示范力度,提高农户的环保意识;加大对农户的扶持力度;提高经济产品销售通道。     

豫东平原杨农复合系统物质生产与碳截存

农林复合系统由于林分、农作物和土壤之间的相互作用而对储藏和固定碳具有巨大的潜力.其已经成为减少大气CO2浓度、解决全球气候变暖问题的重要土地利用方式之一,将会对陆地生物圈中通量的输入和碳的长期贮藏产生重要的影响.对豫东平原农区5,9,11和13年4个不同林龄的杨农间作复合系统的生物量、生产力和碳截存量进行测定和研究,结果表明:豫东平原农区5,9,11和13年4个不同年龄段的杨农间作复合系统的总生物量分别为33.03,103.06,124.30和154.60 t·hm-2.4个年龄的杨农间作复合系统平均净生产力分别为19.95,29.30,33.24和56.94t·hm-2a-1.豫东平原农区5,9,11和13年4个年龄的杨农间作复合系统总碳截存量分别达到了19.86,52.42,62.45和76.44 t·hm-2.