Wind Velocity Reduction of Coastal Shelterbelt System in Shanghai,East China

Wind velocity reduction of coastal shelterbelt system was monitored for 1 month in 3 weather stations in Nanhui,Shanghai,and the benefits of shelterbelt system and trunk shelterbelt forest were compared in this paper.The results showed the wind velocity at the first weather station(W1),which located in front of trunk shelterbelt forest by the seaside,was the biggest,with the average of 9.36 m/s;the wind velocity at the second weather station(W2) was lower than that at W1,with the range of 0 to 18.2 m/s and the average of 6.39 m/s,and the wind velocity at the third weather station(W3) was the lowest,with the average of 2.58 m/s.Both the ratio of W2 to W1 and the ratio of W3 to W1 ranged from 0 to 100%,but most of the ratio of W2 to W1(89.59%) was above 20%,and most of the ratio of W3 to W1(95.52%) was below 50%,which shows bigger wind velocity reduction in shelterbelts system than in trunk shelterbelt forest.With the wind scale increased from 1 to 8 scale at W2 and W3,the wind velocity increased.But the reduction in wind velocity decreased.

基于层次分析法的毛乌素榆林沙区防护林健康评价体系研究

研究和建立防护林健康质量标准和评价体系,掌握毛乌素榆林沙区防护林健康状况,合理评价防护林健康状态对科学保护防护林资源和制定防护林可持续经营管理措施具有指导意义。以毛乌素榆林沙区防护林不同立地类型为研究对象,采用层次分析法,构建毛乌素榆林沙区防护林健康状况评价体系。结果表明:1)毛乌素榆林沙区防护林健康等级划分为5个,分别为健康(0.70~1.00)、微度退化(0.60~<0.70)、轻度退化(0.50~<0.60)、中度退化(0.40~<0.50)、重度退化(0~<0.40);2)毛乌素榆林沙区防护林健康状态总体偏低,属于轻度退化到中度退化,与实际调查结果基本相符。应加强毛乌素榆林沙区防护林的人为管护,减少人畜对防护林的破坏,以实现毛乌素榆林沙区防护林可持续发展与利用。

Protection efficiency assessment and quality of coastal shelterbelt for Dongshan Island at the coastal section scale

The coastal shelter forest in China is under threat of destruction and degradation because of the impact of human activities. Protection efficiency assessment of the coastal shelterbelt is an important component of shelterforest remediation planning and sustainable management. In this study, a protection efficiency index （PEI） model was established using the projection pursuit method to assess the protective quality of the coastal shelter forest at the coastal section scale of Dongshan Island, China. Three criteria were used, including forest stand structure, forest belt structure, and windbreak effect; each criterion further comprised multiple factors. Based on survey data of 31 plots in the coastal shelter forest of Dongshan Island, we calculated PEI values using a projection of a pursuit model. The result showed 64.5 % of the PEIs fell at or below the middle level, which can indicate the status of the coastal shelterbelt is unsatisfactory. To further explore whether the different bays and land use types create significant differences in PEIs and evaluation indices, we used an ANOVA to test the influence of various bays and forms of land use on coastal shelterbelts. The results showed that PEI and most of the indices differed significantly by bay; mean tree height, mean DBH, mean crown width, stand density, vegetation coverage, and wind velocity reduction differed significantly by land use. Therefore, relevant measures for different locations, bays and surrounding land use can be proposed to improve the existing conditions of the coastal shelterbelt. The results of this study provide a theoretical and technical framework for future changes and sustainable management of coastal shelterbelt on Dongshan Island.

Changes in and evaluation of surface soil quality in Populus×xiaohei shelterbelts in midwestern Heilongjiang province,China

To examine changes in surface soil quality over time in Populus×xiaohei shelterbelts,we collected soil samples from five shelterbelts of different ages and also from former cropland left fallow for 25 years.Twenty-one surface soil(0–20 cm)properties were measured,and variation in soil quality was assessed using one-way ANOVAs and multiple comparison tests.Based on this analysis,16 soil indexes were used in a model evaluating soil quality,with each index given weight as determined by the correlation coefficient.Compared with the control,the postmature forest had greater soil moisture content but lower bulk density(P<0.05).The mature forest also had higher soil pH,total organic carbon,alkali-hydrolyzed nitrogen,available phosphorus,and biomass nitrogen content,but reduced nitrate-nitrogen and total phosphorus content than the control(P<0.05).Total porosity was highly positively correlated with aeration,nitrate-nitrogen,alkali-hydrolyzed nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen.Soil total organic carbon,ammonium nitrogen,nitrate-nitrogen,alkali-hydrolyzed nitrogen,total nitrogen,available phosphorus,microbial biomass carbon and microbial biomass nitrogen were all strongly correlated.In the soil quality evaluation model,total organic carbon was assigned the highest weight and total potassium content the lowest.The soil quality index was lowest in the near-mature forest and greatest in the postmature forest.Generally,soil quality in P opulus×xiaohei shelterbelts varied with age and was higher in the 10–20 cm versus 0–10 cm soil layer.After a single forest generation,surface soil quality was significantly improved.

An overview of the “Three-North” Shelterbelt project in China

The ＂Three-North＂ Shelterbelt is the largest and most distinctive artificial ecological engineering project in China. It has been conducted since November 25, 1978 in the ＂Three-North＂ （i.e., Northeast China, North China and Northwest China） regions. In this study, the background and the essential benefits of the ＂Three-North＂ Shelterbelt project are summarized. The basic status and future development of the ＂Three-North＂ Shelterbelt project are also studied. As well, we tried to discuss the problems existing in the current shelterbelt system and the strategies to conduct this ecological project rationally.

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.

Assessment of the effects of the shelterbelt on the soil temperature at regional scale based on MODIS data

At present, the most researches on the protected effect of shelterbelt are on the basis of the two scales of forest belts and networks. However, with the further research on the global environmental change, more attention was paid to the regional climate effect of shelterbelt. In present study, we analyzed the temperature effect of the shelterbelt at regional scale by using the land surface temperature （LST） data from the moderate resolution imaging spectroradiometer （MODIS） at Yushu, Nong＇an, Dehui, and Fuyu in Jilin Province of China from March to October in 2008. Results show that the shelterbelt can increase the soil temperature of the protected farmland as compared with no shelterbelt zone, with the increment of 0.57oC per day in fine shelterbelt and 0.38oC per day in the normal shelterbelt. Moreover, the correlation analysis of the air temperature, precipitation and the soil type and the shelterbelt effect shows that the air temperature and precipitation are negatively correlated with the shelterbelt effects, that is, the more the temperature and precipitation are, the less the effect produced. While the impact of the soil types on the shelterbelt＇s effect is not very obvious as a whole. This paper draws significance in terms of analyzing the effects of the shelterbelt on the soil temperature at regional scale utilizing the remotely sensed data and GIS technique.

A retrieval and validation method for shelterbelt vegetation fraction

Shelterbelts are important in defending against natural disaster and maintaining ecological balances in farmland. Understanding of the shelterbelt vegetation fraction is fundamental to regional research of shelterbelts using remote sensing. We used SPOT5 imagery with 10×10m spatial resolution in combination with knowledge of the characteristics of shelterbelts to develop a method for retrieval of the vegetation fraction of shelterbelts by the pixel un-mixing model. We then used the method to retrieve values for shelterbelts in study area. By combining the parameters of photographic images with characteristics of shelterbelts, we developed a method for measuring the vegetation fraction of shelterbelts based on an advanced photographic method. We then measured the actual values to validate the retrieval result. The multiple correlation coefficients between the retrieved and measured values were 0.715. Our retrieval and measuring methods presented in this paper accurately reflect field conditions. We suggest that this method is useful to describe shelterbelt structure using remote sensing.

Effects of Spatial Density of Farmland Shelterbelts on NDVI on the Northern Slope of Tianshan Mountains

[Objectives]To explore the effects of spatial density of farmland shelterbelts on NDVI on the northern slope of Tianshan Mountains.[Methods]Taking the economic belt of the northern slope of the Tianshan Mountains as the research area and using the grid method,the spatial density distribution of farmland shelterbelts can be known.Combining the grid method with NDVI data,the average value of normalized difference vegetation index(NDVI)during the growing period of crops can be obtained.In addition,the protection benefits of the shelterbelts on crops were analyzed through comparing the growth of crops within the protection zone with and without protection.[Results]The grids with shelterbelt distribution were better than the grids without shelterbelt distribution,and the shelterbelt played a great role in promoting crop growth.In the middle stage of crop growth,the protection benefit of shelterbelt was significant.The spatial density of shelterbelts was unevenly distributed in the range of 0.6 to 0.8,and the protection benefits were poor.[Conclusions]It is expected to explore the effects of shelterbelts on crop growth at a larger regional scale,so as to provide a basis for the management and design of shelterbelts in the future,and to provide a theoretical basis for studying the protective effect of farmland shelterbelts on crops.

Evaluating the Role of Shelterbelt in Vegetation Development in a Semi Arid Zone of Yobe State, Nigeria

This study evaluates the role of shelterbelts on the development and dynamics of vegetation in relation to livelihoods in the study area using geo-information techniques. The study covered the period between 1972 and 2007. The results show that in 1972 vegetation cover in the study area extended over an area of 6955 hectares (i.e.?shrubs, grasses and trees) which represents 65% of the area;however there was a decrease in 1986 to an area of 5779 hectares (54%). Despite the establishment of shelterbelt in the area in 1987, the trend did not change. This is obvious in the reduction of vegetation cover between 1986 and 2000 to a total area of 3893 hectares (37%). The vegetation cover further decreased to 2791 hectares (26%) in 2005 and 1659 hectares (16%) in 2007 respectively. The study concludes that the establishment of shelterbelts alone cannot guarantee the success of vegetation cover development in the area without a sustainable plan which recognizes the local communities as critical stakeholders. Thus, variables like population growth and GDP have a role to play in vegetation cover depletion. The study recommends that efforts geared towards enlightenment of the local communities on the need for conservation should be encouraged by Government and Non-Governmental Organisations.

"3Ns" Shelterbelt Network Project

In China’s three northern regions of the Northwest, North and Northeast (3Ns), there are 1.33 million sq km of desert and sand land, forming a 5,000-km-long wind-sand belt. In 1978, the Chinese government decided to build the "3Ns" shelterbelt network. The project covers 13 provinces, autonomous regions and cities including Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi, Inner Mongolia, Shanxi, Hebei, Beijing, Tianjin, Liaoning, Jilin and Heilongjiang, eovering an area of 4.06 million sq km, 42％ of the country’s total land. It plans to complete the project in 73 years, in three phases: the first phase

烟台沿海防护林体系盐桦两年生苗造林试验初探

通过在沿海防护林体系设置4种立地条件进行盐桦造林试验,研究盐桦在不同立地条件下的适应生长规律,评估土壤、海风、强降雨等因素对盐桦的影响,以确定两年生盐桦适合生长的立地环境,为盐桦应用于烟台沿海防护林体系造林提供必要的理论及技术支撑。结果显示,盐桦两年生苗可以应用于沿海防护林体系,包括平原农林间作区、丘陵区、低山区,存活率均在75%以上,但在沿海基干林沙区造林效果较差。盐桦2年生苗更适合于生长在土质优良的沙壤土。盐桦受海风侵蚀容易出现不同程度枯稍现象,同时不耐长期水淹环境。

沙漠化土地整治过程中防护林体系优化配置的研究

文章对内蒙古鄂尔多斯市达拉特旗五股地沙漠化土地整治过程中防护林体系的优化配置做了研究。结果表明:在沙漠化土地整治和防护林体系配置过程中,应建造控制面积大于6.67 hm^(2)的防护林网,初期在格内设置高立式死沙柳沙障;所选用的树种其生态效益无明显差异,但抗性以新疆杨表现最佳。

三北防护林体系区域环境效应的数值模拟(Ⅰ) 区域环境模式简介和检验

研究工作以中尺度模式 MM5为基本框架 ,在模式的下边界详细考虑了植被的动力、热力作用 ,以全球谱模式 T1 0 6同化资料作为驱动场 ,延长积分时间形成了一个包含植被效应的区域环境模式。进一步以1 998年 5月为例对植物生长季节模式区域环境进行了数值模拟 ,并从区域月平均状况和逐日变化等方面将模拟结果和观测进行了对比分析。分析表明 ,区域环境模式能比较准确地模拟区域环境状态及其变化 。

三北防护林体系建设工程的生态经济评价——以固原市原州区和辽宁省朝阳县为例

根据工程的特点建立三北工程社会影响评价指标体系,通过深入调查研究取得评价的基础材料,以原州区和朝阳县为例,用定性定量相结合的方法从生态、社会和经济效益3方面对三北工程产生的影响进行系统分析与评价。在探明实施中制约工程有效性和持续性的社会变量的基础上,提出工程可持续发展的若干对策。

沿海防护林体系热效应的遥感分析

沿海防护林体系热效应的遥感分析王述礼，金昌杰，关德新（中国科学院沈阳应用生态研究所１１００１５）ＲｅｍｏｔｅＳｅｎｓｉｎｇＡｎａｌｙｓｉｓｏｎｔｈｅＨｅａｔＥｆｆｅｃｔｓｏｆＣｏａｓｔａｌＳｈｅｌｔｅｒｂｅｌｔＳｙｓｔｅｍ．￥ＷａｎｇＳｈｕｌｉ；Ｊｉ...

泥质海岸防护林综合效益评价指标体系研究

北方泥质海岸地区是我国生态脆弱地带,泥质海岸防护林建设所发挥的生态、经济、社会效益对改善这一地区的生态环境尤为重要。采用频度分析法、理论分析法、专家咨询法相结合的方法来选择评价指标,用AHP层次分析法来确定指标权重。研究最终选取了26个具体指标,构建了4个指标层次,建立了适用于泥质海岸综合效益的评价指标体系,确定了指标的权重,其中生态效益占68.33%,经济效益占22.55%,社会效益占10.07%。泥质海岸防护林工程重点改善沿海地区的生态效益,同时兼顾经济和社会效益的发展,所建立的综合评价指标体系以及所确定的指标权重科学合理,适用于泥质海岸防护林综合效益评价。

区域防护林体系总体热效应的遥感分析

本文利用NOAA/AVHRR卫星资料分析了章古台地区不同生境的反射率及地表温度,并研究了防护林体系对辐射平衡和表面温度的影响。结果表明,固沙造林可使辐射平衡由占总辐射的46％提高到57％,白天地面有效辐射由占总辐射的35％减小到29％,表面温度日较差由13.0—14.0℃减小到2.0—3.5℃。

临港新城沿海防护林体系建设现状、问题及对策

从防护林构成和建设过程等方面,分析了上海临港新城沿海防护林建设现状,总结了临港新城沿海防护林存在的问题,针对各类防护林建设面积、树种选择、林分结构优化和低效林改造技术,探讨了临港新城沿海防护林建设对策,为长三角地区海岸带防护林生产实践提供借鉴。

宁夏盐池沙区生态经济型防护林体系林种树种优化比例研究

运用层次分析方法对盐池沙区林业建设的现状进行了分析,建立了盐池县生态经济型防护林体系的优化模型,提出了盐池县风沙区生态经济型防护林体系林种、树种的最优比例。林地面积由原来的6.894万hm2增加到10.905万hm2,固沙林、饲料林、草原防护林、农田防护林、经济林、薪炭林、特用林分别占25.68%、20.39%、14.09%、12.09%、10.59%、8.78%、8.39%。