Alley cropping and analog forests for soil conservation in the dry uplands of Sri Lanka

The use of contour hedgerows of woody legumes to control soil erosion has been promoted amongst smallholders in the Upper Mahaweli catchment of Sri Lanka since 1988. The success of this program depends greatly on the properties of the different production systems occupying the alleys created by these hedgerows such as: profitability, time taken for profit to be realized, labour requirements, seasonal distribution of labour, environmental and economic stability, biophysical sustainability, the contribution of the system to the domestic needs of the farm family, adoptability of the system and successful management of the hedgerows. These properties were used to evaluate seven desktop farm models with different combinations of: seasonal crops, coffee-pepper intercrop, fodder-dairy, woodlot, and analog forest established in the alleys. The analog forest is a perennial polyculture which, like the traditional forest garden, is structurally and functionally analogous to the natural forest. It was found that a model with 40% seasonal crops, 20% perennial crops (coffee-pepper) and 40% analog forest made the best compromise between the properties under consideration. It is recognized that the socio-economic conditions that determine the appropriateness of this model in the Sri Lankan context are not universal and the extension of the analog forest concept into other tropical uplands is discussed.     

Effects of trees on paddy bund on soil fertility and rice growth in Northeast Thailand

A study was conducted in Northeast Thailand on six rice paddy fields on a farm with similar soil (Aquic Quartzipsamments) and with a single tree on the paddy bund. There were 4 tree species: Parinarium anamense, Dipterocarpus obtusifolius, D. intricatus, and Samanea saman. Samples of soil (0–10 cm depth) and rice were collected at 3 positions (1, 5–7, and 9–11 m) away from the tree base in 3 replicated tree-soil trasects in each paddy field. Significantly higher pH, organic matter, and nutrients (N, P, K, Ca, and Mg) were found in paddy fields with S. saman (a legume tree) but grain yield and biomass of rice were significantly lower. Higher soil fertility was found in the positions closer to tree base while grain yields, biomass, and number of tillers were lower, and rice was taller and had more unfilled grain. Shading was deduced to be the key factor responsible for the depressed rice yields and growth at positions closer to tree base especially in the highly shading S. saman.     

浅议沙棘在水土保持生态建设中的作用和发展对策

沙棘以其独特的生物学特性和显著的生态功能,成为水土保持生物措施建设的先锋树种和关键树种.我国沙棘资源开发利用历史悠久,取得了显著成效.加快沙棘资源开发利用的对策是提高认识,项目带动,创新机制,强化管理,产业化开发等.     

Evaluating trap cropping strategies for insect pest control through simulation models

Trap cropping is a habitat management strategy where the aim is to reduce damage to the crop of interest by mixing it with other plants that are highly attractive to insect pests. However, despite its potential, the application of this strategy has been limited mainly due to a lack of consistent effectiveness. Here, we developed an individual-based spatially explicit model that accounts for reproduction, movement and mortality of insects within a mixed crop system. This model was used to evaluate the effects of varying trap crop spatial configurations (border, stripes and patches), cover (2, 4 and 10 %) and supplemental management strategies (early harvest and pesticide application) to gain insight into the best control options offered by trap cropping. As a case study, we considered Liriomyza huidobrensis, a world known leafminer pest. Our results showed a maximum reduction of about 34 % in the pest population of the main crop when using trap plants. The supplemental management strategy had a stronger effect than other factors, with pesticide use being the best option. A sensitivity analysis showed that demographic parameters were more relevant than the behavioral ones in determining the success of the method. Our model suggests that trap cropping is only suitable for controlling L. huidobrensis if a pesticide application is added to the trap crop. Individual-based models, which are cheaper and less laborious than direct field testing, might provide an important tool to help define management schemes for the control of herbivorous pests.     

工程绿化中公路建设土壤保护的研究

公路建设作为我国国民经济的基础设施建设,在促进经济增长的同时,也造成了许多生态负效应,其中土壤扰动是公路建设产生的各种负效应中最普遍也是破坏范围和程度较大的一种。随着我国国民经济水平与人民生活质量的进一步提高,公路绿化日益得到重视,并成为公路建设的一个重要组成部分,而路域土壤则是公路绿化重要的限制因子之一。为了更好地促进路域土壤的保护,在全面分析公路建设对土壤造成影响的基础上,指出了路域土壤保护在理论研究和实践等方面存在的不足,为进一步开展相关研究提供依据。     

The household economics of rubber intercropping during the immature period in Northeast Thailand

In order to alleviate poverty in Northeast Thailand, the Thai government has promoted rubber farming, which has expanded at the expense of annual crops. Because of a long immature period, planting rubber represents a loss of income for poor farmers in the very first years. This paper analyzed how rubber intercropping during the immature period helps farmers to compensate for this loss of income. Economic performances of the most widespread rubber farming systems were analyzed using information collected from a questionnaire addressed to 35 farmers in Buriram province. A sub-sample of 22 farmers was further interviewed to estimate the contribution of rubber intercropping in the formation of the total annual income during the immature period. The results showed that interest in rubber intercropping has grown, with cassava and rice as the main associated crops. With additional costs of about 14,169 ?/ha/year over monospecific rubber plantations, rubber-cassava intercropping systems generated a gross margin estimated at 11,340 ?/ha/year for a 3-year period. Compared to a monospecific rubber plantation, rubber-cassava intercropping systems reduced management costs by 59% over the 6-year period of rubber immaturity. The cash-income drawn from intercropping ranged from 0 to 26.8% of the household’s total annual income, which can be of considerable importance for low-income farmers.     

Crop production under different rainfall and management conditions in agroforestry parkland systems in Burkina Faso: observations and simulation with WaNuLCAS model

Traditional agroforestry parkland systems in Burkina Faso are under threat due to human pressure and climate variability and change, requiring a better understanding for planning of adaptation. Field experiments were conducted in three climatic zones to assess Sorghum bicolor (L.) Moench (Sorghum) biomass, grain yield and harvest index in parklands under different rainfall pattern and compared to simulations of sorghum biomass and grain yield with the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model for calibration and parametrisation. For planning adaptation, the model was then used to evaluate the effects of different management options under current and future climates on sorghum biomass and grain yield. Management options studied included tree densities, tree leaf pruning, mulching and changes in tree root patterns affecting hydraulic redistribution. The results revealed that sorghum biomass and grain yield was more negatively affected by Parkia biglobosa (Jacq.) Benth. (néré) compared to Vitellaria paradoxa C. F Gaertn (karité) and Adansonia digitata L. (baobab), the three main tree species of the agroforestry parkland system. Sorghum biomass and grain yield in different influence zones (sub-canopy, outside edge of canopy, open field) was affected by the amount of precipitation but also by tree canopy density, the latter depending itself on the ecological zone. The harvest index (grain as part of total biomass) was highest under the tree canopy and in the zone furthest from the tree, an effect that according to the model reflects relative absence of stress factors in the later part of the growing season. While simulating the effects of different management options under current and future climates still requires further empirical corroboration and model improvement, the options of tree canopy pruning to reduce shading while maintaining tree root functions probably is key to parkland adaptation to a changing climate.     

Benefit measurement of the soil and water conservation for ecological forestry engineering

IntroductionThelossofwaterandsoilhasbeentheglobatprobIem.Itstotalareais25millionkm'.or16.8%ofgIobalIandarea.ThefertileSurfacesoilof6obiIIiontflowsintoriverseachyeaIBecauseofsoiIcorrosionthelandof21obillionhm2hasIostfertiIityand...,otbeusedasagricuIturalIand.HumanrecognizestheseverityofIossofwaterandsoilwhileheusesjandresources.Thediff6rentmeasuresarebeingtakeninordertoincreasesoilandwaterconservation.Sev-eralecoIogicaIforestryengineeringshavebeencar-riedoutInChinaforenvironmentconserva…     

海南岛尖峰岭野生兰科植物资源分布与保护对策

对海南岛尖峰岭野生兰科植物资源进行了系统调查,结果表明:海南岛尖峰岭野生兰科植物种类十分丰富,具有53属114种,其中附生兰84种,地生兰30种;60%以上的兰科植物分布于海拔700~1 200 m热带山地雨林中。由于过度无序开发,尖峰岭林区的野生兰科植物资源保存现状不容乐观,因此建议通过健全管理机制、加大宣传力度、加强人工培育研究以及依托旅游发展兰花产业等措施进行有效保护。     

丘陵缓坡梯土不同植被覆盖条件下土壤保土能力研究

通过对湘中丘陵缓坡梯土的定位研究，对６个试验迳流小区和一个对比迳流小区的迳流系数、输沙率在未间种作物时进行探讨，揭示了７个迳流小区的保土保水能力，对林下间种的花生、油菜覆盖度与输沙率的关系进行了深入研究，找出了花生与油菜的覆盖度的动态变化对输送率的影响。并对时间模式与年迳流量、泥沙量的关系进行了探讨。     

Assessing opportunity costs of conservation: Ingredients for protected area management in the Kakamega Forest,Western Kenya

The Kakamega Forest is the only remaining tropical rainforest fragment in Western Kenya and hosts large numbers of endemic animal and plant species. Protected areas were established decades ago in order to preserve the forest's unique biodiversity from being converted into agricultural land by the regions large number of small-scale farmers. Nonetheless, recent research shows that degradation continues at alarming rates. In this paper we address an important challenge faced by protected area management, namely, the design of a cost-effective incentive scheme that balances local demand for subsistence non-timber forest products against conservation interests. Using primary data collected from 369 randomly selected farm-households we combine a farm-household classification with mathematical programming in order to estimate the opportunity costs of conserving the Kakamega Forest and restricting access to non-timber forest product resources. We validate our model and analyze the impact of changes in major economic frame conditions on our results before we derive recommendations for an improved protected area management in the study region. Our findings suggest that a more flexible approach to determining the price of recently established forest product extraction permits would greatly enhance management efficiency without significantly compromising local wellbeing.     

Agronomic and economic appraisal of alley cropping with Leucaena diversifolia on an acid soil in the highlands of Burundi

Although alley cropping has been shown elsewhere to permit continuous cropping, it has not been widely tested in the highlands of east and central Africa where it has the additional potential of controlling soil erosion. The effect of four rates (0, 30, 60 and 90 kg N ha^–1) of inorganic N on the performance of alley cropping using Leucaena diversifolia as the hedgerow species was studied in the central highlands of Burundi. Significant increase in maize yield (average of 26%) due to alley cropping was only first realised in 1992, three years after the commencement of the trial. In 1993, the average yield advantage of the alley cropping plots was 21%. The prunings augmented the response of maize yield to inorganic N in 1992 and 1993. Compared with the control, economic benefits over the five-year period for all the treatments were negative.     

石阡县林木种质资源调查及其利用研究

采用踏查、线路调查和样方调查方法对石阡县林木种质资源进行调查,发现石阡有林木种子植物179科717属1 884种,其中裸子植物8科16属25种,被子植物171科701属1 859种;对野生资源进行区系分析,表明世界分布48科、热带分布73科、温带分布45科,表现出该县野生种子植物区系具有明显的热带亲缘关系特点;按照主要用途和目标价值将林木种子植物资源进行分类、研究。根据资源现状和保存利用情况,提出了进一步挖掘、利用林木种质资源的建议措施。     

Comparison of minirhizotron and soil core methods for quantifying root biomass in a temperate alley cropping system

A study was carried out in southern Indiana, USA with the objective of comparing soil core sampling and the minirhizotron technique in quantifying fine root biomass and root distribution patterns in an alley cropping system with black walnut (Juglans nigra L.), northern red oak (Quercus rubra L.) and maize (Zea mays L.). Spatial variation in tree rooting pattern was investigated prior to planting maize. Tree fine root biomass was quantified at distances of 0, 1.1, 2.3, 3.5, and 4.3 m where 0 m represents the tree row and 4.3 m represents the middle of the alley. Root samples were collected to a depth of 90 cm using a hydraulic auger. Maize rooting pattern was determined 65 days after planting to the same depth. Using plexiglass access tubes installed near the actual soil core locations and a minirhizotron camera root images were recorded on a VHS tape. These images were later analyzed using a raster based GIS software (ERDAS-IMAGINE). Regression analysis revealed significant relationships between root surface area measurements from minirhizotron observations and fine root biomass data from soil coring for all species. Predicted fine root biomass data were also in close agreement with actual fine root biomass for all species examined. Maize root biomass was slightly, but not significantly, underestimated by the minirhizotron technique in the top 30 cm soil layer. No significant underestimation or overestimation of root biomass in surface or deeper soil layers was observed for the tree species. The results indicate that minirhizotron can be used in quantifying fine root biomass if site and species specific predictive models can be developed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Agroforestry for soil and water conservation in the western Himalayan Valley Region of India 1. Runoff, soil and nutrient losses

Erosion losses were investigated in a field experiment, from 90 × 15 m erosion plots at 4% slope in the western Himalayan valley region of India. The plots were planted with Leucaena leucocephala and Eucalyptus hybrid, either as block plantation or in alley farming with maize (Zea mays), Chrysopogon fulvus grass or turmeric (Curcuma longa). The treatments also included contour planting of sole maize, sole Chrysopogon fulvus grass and a clean weeded cultivated fallow. During the nine year study period, the average annual monsoon rainfall was about 1000 mm and it caused 347 mm runoff and 39 Mg ha^-1 soil loss per year from fallow plots. The runoff and soil loss were reduced by 27% and 45% by contour cultivation of maize. Contour tree-rows or leucaena hedges reduced the runoff and soil loss by 40% and 48%, respectively, over the maize plot, reducing soil loss to about 12.5 Mg ha^-1. This reduction in erosion was primarily due to the barrier effect of tree or hedgerows and micro-terraces formed through sediment deposition along the contour barriers. Such vegetative measures, that are productive while being protective, offer viable alternative for erosion control in areas with gentile slopes of the valley region. High density block plantations of eucalyptus and leucaena almost completely controlled erosional losses and can be recommended for steeper slopes that are vulnerable to heavy erosion. This revised version was published online in June 2006 with corrections to the Cover Date.     

柏木水土保持林凋落量的研究

通过定位观测,对柏木水土保持林凋落物的数量、组成、养分含量及养分归还量进行了系统的研究,并分析了柏木凋落物的月变化规律,建立了凋落物量预测模型,论证了柏木水土保持林凋落物对改良土壤、涵养水源、保持水土具有重要作用。     

公路边坡水土保持草种引种试验研究

为使高速公路边坡防护选择适宜草种，适宜季节，进行了一系列对比实验，并对实验结果每月观察记录，进行分析比较，得出结论－－白三叶，高羊茅，狗牙根，百喜草，马蹄金，弯叶画眉草，波斯菊等草种选择适宜的播种时间播种，能达到很好的生态防护效益和美观效果，具有外观美，造价低，工程费用及维护费用低，效果长期等特点。     

石灰岩山地水土保持林的树种选择

在石灰岩山地水土保持立地类型划分的基础上 ,参照相关研究成果 ,通过标准地调查和主要牧草的播种试验 ,以生长量和生物量为指标 ,确定了水土保持林不同立地类型适宜的树 (草 )种     

攸县3种不同水土保持林土壤抗侵蚀性能

为了研究湖南省攸县境内的不同水土保持林对土壤抗侵蚀性能的影响,本文从林地土壤的物理性状、土壤抗蚀性能和土壤抗冲性能3个方面来进行对比研究。测定其林地0~20 cm层土壤的容重、孔隙度、水稳定指数、渗透系数、土壤团聚体占土样百分比和抗冲指数几个指标,进而分析不同林分类型之间的林地土壤抗侵蚀性能的差异。结果表明:从土壤的物理性状来看,楠+桤木+枫香混交林的容重和孔隙度均比其他两种林分要好;从土壤的抗蚀性能来看,3种不同林分的水稳性指数大小按照大小顺序为楠+桤木+枫香混交林枫香+栾树+桤木混交林杉木+柏木+马尾松混交林,楠+桤木+枫香混交林的渗透性能优于杉木+柏木+马尾松混交林和枫香+栾树+桤木混交林,且3种林分的水稳性指数与渗透系数均大于荒坡地;从土壤抗冲性能来看,土壤总团聚体占土样百分比和土壤抗冲指数按照楠+桤木+枫香混交林枫香+栾树+桤木混交林杉木+柏木+马尾松混交林的大小排列顺序,且指标均大于荒坡地。     

典型黑土区水土保持林土壤结构性特征的对比研究(英文)

以典型黑土区水曲柳林、落叶松林、樟子松林、云杉林及撂荒地为对象,通过对土壤容重、非毛管孔隙/毛管孔隙(NCP/CP)、广义土壤结构指数(GSSI)的测定、计算与对比分析,研究了不同类型人工水土保持林对土壤结构性特征的影响。结果表明:在所研究的0-30cm土层范围内,水曲柳林和落叶松林在降低土壤容重方面略好于樟子松林和云杉林,降低幅度为8.04%-1 1.01%,落叶松林与云杉林和樟子松林之间差异均达显著水平(p0.05),而水曲柳林仅与云杉林差异显著(p0.05);林地土壤的平均NCP/CP值均显著高于撂荒地(p0.05),增加幅度范围为59.75%～128.82%,土壤透气性、透水性能力提高,并以落叶松林提高幅度最大;各林地的平均GSSI值均显著高于撂荒地(p0.05),增加幅度范围为2.98%-4.36%,说明林分可以有效改善土壤结构,使其能够更加接近旱地土壤理想结构,以水曲柳林和云杉林改良效果相对较强,但实现趋近理想土壤结构的途径、即相态的变化方式有所不同。研究结果可为科学评价典型黑土区植被恢复对土壤质量的影响和深入系统研究水土保持林构建提供理论依据。图3表2参17。