An evaluation of agroforestry systems as a rural development option for the Brazilian Amazon

In the Brazilian Amazon mass deforestation has resulted from a sequenceof road building, extractive logging, and pasture development during the pastthree decades. Ranchers have consolidated small agricultural holdings, pushingfarmers to move to forest frontiers or urban fringes, prompting furtherdeforestation and social instability. In response to this conversion ofAmazonian forests, the authors sought to identify both economically viable andmore sustainable development alternatives within the Brazilian state ofPará. There, local farmers of Japanese descent have developed a varietyof agroforestry systems in which 10 to 20 hectare (ha) fields yieldincomes comparable to 400 to 1,200 ha pastures. In addition, suchcrop fields generate substantially more rural employment per hathan do pastures. Ongoing forest conversion to pasture is clearly not a productof sound economic decision making. Improved land zoning and public policiescould favor agroforestry over further pasture expansion, stabilizing ruralpopulations while helping to conserve the Amazon's remaining forests. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth and yield of some indigenous trees in an Amazonian agroforestry system: a rural-history-based analysis

Over the years farmers of Japanese descent in the Brazilian Amazon have planted indigenous trees that yield various products and services: fruit, seeds,bark, latex, oil, and shade and wind breaks for understory crop plants. Production of timber is often the intended end use of such planted trees. Long-term growth performance of these trees nevertheless has not been well documented. The authors constructed 65-year growth curves for nine indigenous tree species based on measurements of diameter at breast height (dbh), height, and tree age data provided by farmers in the Brazilian State of Pará. An index of wood prices used to calculate state stumpage taxes was then applied to mean stem wood growth curves to produce price curves. These price curves estimate both present value of standing timber, and the value added from annual growth of standing timber in the agroforestry systems studied. The results of this study provide local farmers with a tool to estimate potential annual income from the growth of their trees, and a basis for planning timber harvest rotations. This study's approach may be applicable in other parts of the tropics, where growth information about indigenous trees commonly used in agroforestry is lacking.This revised version was published online in November 2005 with corrections to the Cover Date.     

基于Maxent模型的丹霞山国家级自然保护区极小种群植物丹霞梧桐的潜在生境评价

【目的】基于Maxent模型评价丹霞梧桐的潜在生境,为该种的就地保护和迁地保护提供科学依据。【方法】采用无人机获取丹霞梧桐黄叶期186个空间分布数据,结合6个环境变量,利用Maxent模型预测丹霞梧桐的潜在适生区,并分析主要环境变量对其分布的影响。【结果】Maxent模型评价效果达到优秀水平,训练集和验证集的AUC值分别为0.947和0.906;刀切法验证结果表明,高程、坡度和坡向是影响丹霞梧桐潜在分布的主要环境变量,其贡献率分别为51.2%、30.3%和7.8%;在3个主要环境变量的共同作用下,丹霞梧桐的潜在适生区主要分布在丹霞山高程150~530m、坡度20°~60°的阳坡;以自然断点法将丹霞梧桐的潜在适生区分为高适生区、中适生区、低适生区和非适生区4个等级,高、中适生区面积为30.27km^2,仅占丹霞山总面积的10.41%;低适生区面积为41.01km^2,非适生区面积为219.5km^2,共占丹霞山总面积的89.59%;野外实地调查数据验证结果表明,92.1%的丹霞梧桐实地分布点落入高、中适生区,Kappa系数为0.958,说明Maxent模型的预测精度较高。【结论】Maxent模型可较准确预测出丹霞梧桐在丹霞山的潜在适生区,并揭示影响其分布的3个主要环境变量,该模型对小尺度区域预测亦有较好效果。对丹霞梧桐保护提出2点建议:1)就地保护方面,要严格限制其高、中适生区的旅游设施建设,并建立长期的无人机遥感监测系统跟踪其种群动态变化;2)迁地保护方面,根据其适生条件,选择适合区域开展野外回归试验扩大其种群分布。本研究结果可验证低空无人机遥感在物种识别和种群调查中的优势和可行性,并揭示该方法在丹霞地貌这种特殊生境监测与评价中的潜力和应用价值。     

The Organization and Management System of Closing Hillside for Forest as a Regeneration Project (CHFRP)

By investigation, the thesis analyses and summarizes the forming and developing of CHFRP In Xupu county. We select the Mayandong stock cooperation forest farm as object, adopt the methods such as semi-structure interview, analysing second data and surveying sample plots, analyse and study the process to clarify the property right, the profits allocated forms and the management forms. The results show that CHFRP can tentatively resolve the contradiction between the forestland using right scattered to every household and proper scale management demanded by forestry production. CHFRP can enhance economic result and stabilize the production form in countryside. The ecological result, economic result and social result of CHFRP are sufficient.