Study on specifications of farmland shelterbelt net in Northeastern Plain of China

s: The farmland shelterbelts in Northeastern Plain of China have formed relatively complete net system. The func-tions of shelterbelt net in omnibearing wind check and prevention of frostbite as well as the field of integrated climate effect within shelterbelt net were analyzed, through located observation of meteorological factors. Within the shelterbelt net, the area with more than 10% efficiency of omnibearing wind check was determined as benefited area. The analysis of yield and quality of crops indicated that the sheltering range of shelterbelt net was 25 times tree height. The mature heights of the various varieties of poplar composed the shelterbelts were determined according to their height growth. Based on the comprehensive analysis above, the suitable size of farmland shelterbelt net in Northeastern Plain of China was decided to be 400 m×400 m.

A Method for Spatial Heterogeneity Evaluation on Landscape Pattern of Farmland Shelterbelt Networks:A Case Study in Midwest of Jilin Province,China

On the basis of landscape ecology, combining the Spot 5 high resolution satellite imagery with GIS, a method evaluating the spatial heterogeneity of shelterbelts distribution at landscape scale is put forward in this paper. The distance coefficients of reasonable and existing landscape indexes of farmland shelterbelt networks were com-puted, and then through the classification of the distance coefficients, and the establishment of evaluation rules, the spatial heterogeneity of farmland shelterbelts was evaluated. The method can improve the evaluating system of previ-ous studies on shelterbelts distribution, resolve the disadvantages of lacking spatiality of overall evaluation, and make the evaluation results have more directive significance for shelterbelt management. Based on this method, spatial het-erogeneity of shelterbelt networks was evaluated in the midwest of Jilin Province, China. The results show that the re-gions with fewer shelterbelts and no closed network account for 34.7% of the total area, but only 4.9% of the area has relative reasonable pattern of shelterbelt networks. Many problems exist in the distribution pattern of shelterbelts, therefore, much attention should be paid to construct farmland shelterbelts in the study area.

Effect of farmland shelterbelts on gully erosion in the black soil region of Northeast China

The black soil region of northeast China is one of the most important grain-producing areas in China. Increasingly severe gully erosion in this region has destroyed much farmland and reduced grain production. We analyzed SPOT5 imagery from 2007 and TM imagery from 2008 to describe the distributions of gullies and farmland shelterbelts in Kedong County and to assess the effect of farmland shelterbelts on gully erosion. The ima- gery revealed 2311 gullies with average density of 418.51 m km-2, indicating very serious gully erosion. With increasing slope gradient there was an inverse trend between gully density and shelterbelt density, indicating that farmland shelterbelts can prevent gully erosion. The defense effect of farmland shelterbelts against gullyerosion varied with distance： for distances 〈120 m, the defense effect was consistent and very strong; for distances of 120-240 m, a weak linear decrease was found in the defense effect; and for distances 〉240 m, the defense effect of the shelterbelts was significantly weaker. We recommend an optimal planting density of farmland shel- terbelts for the prevention of gully erosion at 1100-1300 m km-2.

基于RS和GIS的农田防护林对作物产量影响的评价方法

在区域尺度评价农田防护林对作物产量的影响对于农田防护林建设和经营管理具有重要意义。该文提出了一种基于遥感(remote sensing,RS)和地理信息系统(geographic information system,GIS)技术的农田防护林对作物产量影响的评价方法。首先利用多时相遥感影像识别农田防护林的经营阶段和和生长状态,建立农田防护林防护效应的综合判定模式;其次采用机制法,通过光、温、水、土逐级衰减,计算作物生产潜力,并基于遥感影像和光能利用率模型估算作物单产;最后构建农田防护林对作物产量影响的评价方法体系。基于该方法,在吉林省长春市北部的农田防护林重点建设区选择样区,评价了该区2009年农田防护林对玉米产量的影响。结果表明,农田防护林在一定程度上将会促进玉米增产。尤其在自然条件较差的低产区,农田防护林的增产作用更加显著,增产率达到8.85%;而在高产区,增产率约为2.4%,但是由于胁地效应的影响,在部分地区可能造成减产。因此,在农田防护林的规划建设中,应根据不同的立地条件,因地制宜,在占地面积最小的情况下,达到稳产增产的作用,实现农田防护林的最大防护效应。该研究丰富了在区域尺度研究农田防护林防护效应的技术方法,可以更加科学合理的评价区域尺度上农田防护林的增产效益,并为农田防护林的经营管理提供科学依据。

黄淮海平原地区防护林网冬小麦生产力模拟的初步研究

防护林对农田生产力的影响是一个复杂的过程,需要对多种网格进行综合监测。遥感技术为多网格、同步定量评价防护林体系对作物产量的影响提供了有力支持。本研究以黄淮海平原为例,使用增强型遥感图像时空融合方法(ESTARFM)融合多源遥感影像,通过基于遥感的光能利用效率模型,模拟黄淮海防护林网内农田总初级生产力(gross primary producivity,GPP)。结果表明:(1)冬小麦GPP实测值与模拟值具有显著的线性相关性,平均相对误差为15.62%,决定系数(R2)达0.8596。可见,建立的GPP模型具有较高的模拟精度;(2)从遥感获取的10个网格冬小麦GPP情况来看,网格间农田生产力存在较大的空间变异性。本研究初步揭示了基于遥感影像融合方法,定量估算防护林网内农田GPP的可行性,为进一步探讨防护林对农田生产力的影响提供了重要手段。

道路农田防护林系统水分关系研究

道路农田防护林系统水分关系研究任勇，王佑民（北京林业大学，１０００８３）（西北林学院，陕西杨陵７１２１００）ＷａｔｃｒＲｅｌａｔｉｏｎｓｉｎＦａｒｍｌａｎｄＳｈｅｌｔｅｒｂｅｌｔＳｙｓｔｅｍｂｙｔｈｅＲｏａｄｓ．ＲｅｎＹｏｎｇ￥（ＢｅｉｊｉｎｉｇＦｏｒｅｓｌｒｙＵｚｉｕｅｒｓｉｔｙ，１０００８３），ＷａｎｇＹｏｕｍｉｎ（ＮｏｒｔｈｗｅｓｔｅｒｎＣｏｌｌｅｇｅｏｆＦｏｒｅｓｔｒｙ，Ｙａｎｇｌｉｎｇ，Ｓｈａａｎｘｉ，７１２１００）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ，１９９３，１２（４）：ｌ－６．ＩｎｔｈｅｒｅｇｉｏｎｆｒｏｍｌｏｅｓｓｐｌａｔｅａｕｔｏＮｏｒｔｈＷｅｉＲｉｖｅｒ，２０－１００ｃｍｓｏｉｌｌａｖｅｒｉｓｔｈｅｍａｉｎｌａｖｅｒｆｒｏｍｗｈｉｃｈｔｈｅｒｏｏｔｓｙｓｔｅｍｏｆＰ．×ｄａｋｕａｎｅｎｓｉｓＨｓｕａｂｓｏｒｂｓｗａｔｅｒ，ａｎｄ０－０．１ＨｉｓｔｈｅｒａｎｇｅｉｎｗｈｉｃｈＰ．×ｄａｋｕａ－ｎｅｎｓｉｓｂｙｔｈｅｒｏａｄｓｓｔｒｏｎｇｌｙａｆｆｄｃｔｓｂｙｔｈｅｒｏａｄｓｓｔｒｏｎｇｌｙａｆｆｅｃｔｓｍｏｉｓｔｕｒｅｃｏｎｄｉｔｉｏｎｏｆｆａｒｍｌａｎｄ．

浅谈陕北毛乌素沙地大规模喷灌农田防护林体系的建设

毛乌素沙地是我国风沙较为严重的地方之一,营建农田防护林体系不仅能阻挡风沙进入毛乌素沙地,还发展当地绿色产业,并带动陕北地区现代农业发展,极大改善了陕北区域的经济环境。本文根据陕北毛乌素沙地当地的气候、土壤等条件,总结出适合毛乌素沙地大规模喷灌农田防护林的林带结构、宽度、疏透度、间距和树种等。为陕北毛乌素沙地农田防护林体系建设的进一步完善,提供理论参考。

张掖绿洲农田防护林可持续经营评价指标体系研究

以可持续发展理论为指导 ,结合森林可持续经营的思想 ,从森林生态学和森林经理学的角度出发 ,在张掖绿洲农田防护林的基本特征和经营状况的基础上 ,进行了系统的阐述和分析 ,提出了张掖绿洲农田防护林可持续经营的思想内涵。并运用数学方法 ,从社会发展指标、经济发展指标、生态功能指标、政策、技术保障功能指标等 6个方面构建了张掖绿洲农田防护林可持续发展的指标体系 ,计算结果表明 ,张掖绿洲农田防护林可持续发展力指数为 0 .4 780 ,为基本不可持续发展。

基于高分辨率卫星影像的农田防护林林带保存率遥感识别

农田防护林林带保存率反映了林带结构的完整性,对林带防护效应的发挥有重要影响。传统的基于野外调查获取的林带保存率数据准确,但无法满足快速、大面积监测的需求。利用遥感手段获取农田防护林保存率信息,有利于农田防护林结构和功能的相关研究,并可为农田防护林精准经营和管理提供依据。本文基于我国吉林一号高分辨率多光谱遥感影像,利用遥感信息提取方法获取农田防护林矢量和植被覆盖度数据,并将每条农田防护林林带视为二维矩阵,有序提取林带走向和林带宽度方向的植被覆盖度值,通过分析林带波形特征确定林带边界,并通过阈值方法提取边界内部林带像元,完成林带保存率的遥感识别,最后按林带走向和不同保存率范围共获取160个验证点的参考数据对遥感识别结果进行验证。结果显示:(1)林带保存率遥感识别结果与参考数据的相关性较强(R^(2)=0.936),平均绝对误差为5.4%,总体精度较高;(2)林带保存率在不同林带走向的识别效果均较好,相对而言,南北走向的相关性相对低,其可能是受到林带阴影的影响;(3)林带保存率遥感识别的绝对误差随保存率的增加呈现出先增加后减小的趋势,即对高保存率林带(>80%)和低保存率林带(<20%)的绝对误差最小,监测精度最高,在保存率处于中间状态,尤其是在50%~60%区间内的绝对误差最大,其可能与该部分林带较为破碎、林隙小而多有关。基于高分辨率多光谱卫星影像能够较为准确地识别农田防护林林带保存率,该方法提高了农田防护林结构的遥感监测能力,并可为农田防护林结构与功能的准确监测和评价提供技术支撑。

瓜州县农田防护林健康评价体系构建及应用

干旱荒漠绿洲区农田防护林健康与否,直接关系到绿洲农作物抵御风沙灾害与干热风的能力。文中以瓜州县农田防护林为研究对象,通过生态学调查和等级评分方法,构建了群落结构、健康风险、防护功能和外界干扰4个一级指标、22个二级指标的农田防护林健康评价指标体系,制定了农田防护林健康评价指标优劣等级表,采用专家打分法和AHP层次分析法确定各指标权重,并利用生态系统健康综合指数模型计算了农田防护林健康指数。结果表明:瓜州县农田防护林整体综合健康指数为0.6462,处于亚健康状态;农田防护林处于健康状态、亚健康状态和不健康状态的占比分别为30.56%、48.65%和21.62%;建议加快补植并完善农田防护林网。