A case study of shelterbelt effect on potato (Solanum tuberosum) yield on the Atherton Tablelands in tropical north Australia

An experimental study was conducted on the Atherton Tablelands of tropical north Australia to quantify the shelterbelt benefit to the production of potato (Solanum tuberosum). Wind speed, wind direction and potato yield were measured at various distances from the leeward side of the shelterbelt. Non-linear modelling was used to describe the relationship between potato yield and distance from the shelterbelt. With the developed model, definite integral was used to calculate the net increase percentage of potato yield.Wind speed was greatly reduced by the shelterbelt. Potato yield was increased by 6.7% due to the shelterbelt.It appears that fitting non-linear models is a useful method to determine an accurate net increase of crops from shelterbelts, providing an accurate assessment of the average crop yield on the open areas is achieved.     

Effects of species and shelterbelt structure on wind speed reduction in shelter

Live shelterbelts are common elements in coastal land areas and play an important role in reducing wind speed and sand drift. A simple measured index, that well represents relationship between shelterbelt structure and wind speed reduction, is required by landowners to enable them in establishing more effective shelterbelts. A three-dimensional crown (3D) density is proposed, which can be easily identified through shelterbelt parameters including maximum height, shelterbelt width, vertical crown/stem area ratio, and horizontal crown/stem area ratio. The utility of the index was tested in 10-year-old Casuarina equisetifolia and in 7-year-old Acacia auriculiformis shelterbelts in north central Coast of Vietnam. There was a significant negative linear relationship (R ² = 0.64, p < 0.001) between 3D density and wind speed reduction efficiency, while there was no relationship between a two-dimensional crown density and wind speed reduction efficiency. Reduction efficiency was found to increase at higher wind speeds in shelterbelts of A. auriculiformis, but not C. equisetifolia. The A. auriculiformis shelterbelt was more efficient in reducing wind speed compared to C. equisetifolia shelterbelt. The former recovered 70 % wind speed at 130 m (16.5H) leeward, while it recovered 70 % at 85 m (8H) leeward in C. equisetifolia shelterbelt.     

东北平原农田防护林规格的研究

东北平原农田防护林已经形成了比较完整的林网体系。本研究分析了农田防护林网全方位的防风作用、防霜作用以及林网内的综合气候效益场。在林网内,全方位防风效能大于10%的区域为防护效益区。作物产量和质量分析表明,林网的防护范围为25倍树高。根据高生长分析确定了构成农田防护林主要杨树品种的成林高度。根据综合分析确定适宜农田防护林网的规格为400m×400m。图7表3参11。     

退化草牧场防护林土壤腐殖质碳组分特征及酶活性

[目的]探讨不同防护林结构的配置、不同林龄草牧场防护林对土壤腐殖质碳组分特征和酶活性的影响及其两者的关系,寻找最佳草牧场防护林结构的配置方式。[方法]采用对比分析的方法,对草牧场防护林和无林草牧场(对照)土壤腐殖质碳组分特征和土壤酶活性进行了研究。[结果]林龄为15年距林带0 m处,网格状草牧场防护林的胡敏酸和富里酸总碳量、胡敏酸碳组分、富里酸碳组分和胡敏素的含量以及过氧化氢酶、多酚氧化酶、脲酶、蛋白酶、磷酸酶的活性等测定指标均分别比对照显著提高70.26%、120.97%、73.76%、139.84%、51.80%、85.00%、42.17%、94.65%、53.77%、49.81%;与带状、疏林状草牧场防护林相比,网格状草牧场防护林除土壤有机质、富里酸碳组分、胡敏素、蔗糖酶、蛋白酶、磷酸酶的差异不显著外,以上10个测定指标中的其余指标差异均显著。对于网格状草牧场防护林,土壤富里酸碳组分、胡敏素、多酚氧化酶、脲酶等测定指标在林龄为1~5年时随其增大而增加,5~15年缓慢降低,15年后下降速度增大;距离林带50 m处土壤有机质含量、胡敏素、多酚氧化酶活性高于距离防护林0 m和100 m,且100 m处较0 m处低,其它测定指标基本上随距离林带距离的增加而减小。距离防护林带100 m处时,部分指标与对照差异不显著,土壤改良效益基本消失。胡敏酸和富里酸总碳量与过氧化氢酶、多酚氧化酶、脲酶、磷酸酶呈极显著正相关,胡敏酸与蛋白酶呈极显著正相关;富里酸与过氧化氢酶、蔗糖酶、脲酶、磷酸酶呈极显著正相关;胡敏素与蔗糖酶呈显著负相关。[结论]林龄为5年的网格状防护林土壤富里酸碳组分、胡敏素、多酚氧化酶和脲酶活性等最佳;对防护林及其多数土壤腐殖质碳组分和酶活性升高的分析表明,网格状防护林的带间距应小于200 m。     

沙地草牧场防护林对土壤水分变化的影响

通过白音花沙地草牧场防护林下的土壤水分变化分析得出：草牧场防护林保护下的土壤水分随季节变化呈现明显的周期变化,距林带不同距离及不同土壤深度的土壤水分变化也不同。研究表明：草牧场防护林不仅提高了其防护范围内的土壤水分,改善了土壤水分供应状况,而且可有效调控沙地土壤水分,提高沙地生产力。     

民勤绿洲枣树、杨树防护林经济效益对比分析

对民勤绿洲枣树林带、杨树林带及其防护下的作物进行经济效益对比分析 ,结果表明 :枣树林带防护下小麦的产量比杨树下的高 7.9% ,玉米的产量比杨树下的高 4 .2 % ;枣树林带胁地范围比杨树林带小 3～ 6m ;枣树林带的年均净收入是 6 584 .2 3元 / (hm2 林网 ) ,投入产出比是 9.2 8,分别是杨树林带的 16 .7倍和 3.78倍。枣树林带相对杨树林带经济效益明显。近林带 30m的范围内作物的产量曲线呈“S”型 ,可分为强烈减产带、平稳过渡带和产量恢复带。适宜在民勤地区大力推广经济型枣树防护林     

Effects of shelterbelts on snow distribution and sublimation

On the Canadian Prairies and the northern US Great Plains, snow is an important component of annual precipitation, sometimes constituting over 40% of the total, although there is much annual and regional variability. Much of this snow is transported by wind, causing substantial sublimation losses, which are reduced by obstacles and topographic features on the landscape that reduce snow transport and trap snow. Agroforestry configurations trap snow and reduce the amount and distance of snow movement and, because of this, reduce the amount of moisture lost to sublimation. The planning of agroforestry measures should therefore take into account their effects on snow hydrology. In this study, the effects of shelterbelts on snow quantity and distribution are shown over multiple years, including a number of locations in Manitoba and Saskatchewan. Results show that snow transport reached equilibrium in 400?m or less (i.e., that sublimation rates were at their maximum beyond 400?m leeward of a shelterbelt). Also, in a paired landscape inventory, the landscape with shelterbelts had 29% more snow water equivalent (SWE) than the unsheltered landscape. Site-specific meteorological data was used in the Prairie Blowing Snow Model, now a component of the Cold Regions Hydrological Model, to calculate the effects of agroforestry configurations on snow water conservation. Modeled snow distribution agreed well with measured snow at Conquest, Saskatchewan, in the winter of 2009/2010. Using actual weather data for the same location for the period 1996–2011, the model calculated the annual sublimation from 200?m wide fields protected by shelterbelts to be up to 12.5?mm less than similar unsheltered fields.     

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.     

Recognition of shelterbelt continuity using remote sensing and waveform recognition

Shelterbelt systems play an important and long-term role in ecological stability and food security. Today, shelterbelts are threatened by anthropogenic destruction, plant diseases, and insect pests. Determining the continuity of shelterbelts is essential for the management and maintenance of complete and stable shelterbelt systems. In this paper, we acquired SPOT 5 images with a 10 m × 10 m spatial resolution, and, based on a GIS method, we generated belt waveforms using a waveform data collector. We then developed a waveform recognition model for belt continuity based on waveform recognition theory. Finally, we identified a minimum threshold value for the identification of belt gaps, and conducted belt continuity recognition in the study area. The results were compared with data calculated from aerial images with a 0.5 m × 0.5 m spatial resolution. When belt gaps were <10 m, recognition was poor, but when belt gaps were between 10 and 20 m, the mean absolute error was 3.8 %, and when belt gaps were >20 m, the mean absolute error was 2.7 %. We propose that this method provides a powerful new tool for the investigation and management of shelterbelt systems.     

草牧场防护林对积雪厚度的影响

前苏联在60年代就进行了农田、牧场防护林对积雪影响的研究[1],认为通风结构林带附近积雪较为均匀,11H(H=树高)处积雪比其它结构林带的要厚,即有效积雪距离长;营造3～5行,行距为2.5～2.7m,带间宽度为300～400m,疏透度为0.5～0.6的林带,不仅积雪厚度最大,而且在网格里呈均匀分布[2]。中亚林业研究所曾经在克日鲁马地区观测了草牧场防护林带的防护作用,认为透风系数为0.20～0.45的草牧场防护林带,对积雪分布的作用最好[1]。1978～1983年,库尔斯克州水土保持试验站还观测了幼龄杨树(Populussp.)林带的积雪作用。认为2～3年生的幼龄杨树林带对…     

山西北部农田防护林的防风功能及结构研究

山西北部地区处于毛乌素沙漠前沿,是暖温带落叶阔叶林向温带干旱草原的过渡带。20世纪50-60年代当地营造了大面积的小叶杨(Populus simonii)人工林,形成了以林网为主体的农田防护林体系,对防治农田土壤风蚀起到了重要的作用。近年来,在旧林带更新改造中,对林带结构、树种配置缺乏技术,表现出在营造林带中有较大盲目性。为了对防护林今后的发展提供科学依据和方法,1996-2001年作者在山西北部的朔州、大同等地设置了定位调查观测点,使用轻便式风速风向仪、通风干湿球温度计、地温计、玻璃皿对小叶杨不同结构林带的防风功能进行了调查研究。提出了农田防护林的设计应以树木展叶期的防风能力为指标,以疏透结构为最佳配置,初植株行距为2 m3 m,4-6行配置,5年后可形成疏透结构林带。表4参13。     

Effects of stand structure on wind speed reduction in a Metasequoia glyptostroboides shelterbelt

In a Metasequoia glyptostroboides coastal forest shelterbelt near Shanghai, China, we studied relationships between stand structure and wind shelter effect. We located 16 plots at intervals of 500 m along the shelterbelt and characterized both horizontal and vertical structure of each plot. Wind speed was measured within each plot and at different distances windward and leeward. We found that wind shelter effects were closely related to stand structure of the studied M. glyptostroboides shelterbelt. Stands with high basal area but intermediate crown index and intermediate proportion of large trees (LT) produced the best shelter effects, with significantly longer shelter distance (d70, shelter distance which the wind speed U does not exceed 70 % of U ₀) and slightly lower minimum relative wind speed (U _m /U ₀). Simple structural indices that can be easily measured in the field were good predictors of the shelter effect. LT was the best predictor of d70, while basal area at ground level was the best predictor of U _m/U ₀. The relationships between stand structure and shelter effect provides a practical guideline to the design, construction and management of forest shelterbelts. In order to provide the best shelter effects, high basal area of >50 m² ha^?1 at ground level or >33 m² ha^?1 at breast height coupled with an intermediate LT value of about 60 % should be maintained for the studied M. glyptostroboides shelterbelt.     

Remote estimation of shelterbelt width from SPOT5 imagery

Width is one of the key parameters of a shelterbelt. Traditional methods to acquire this width are mainly based on field measurement, which is impractical for monitoring shelterbelts at regional scale. There are many studies analyzing linear objects, but they are not directly applicable to width detection of such objects. In this paper, we analyzed relationships among vegetation fractions retrieved from SPOT5 remote sensing imagery with 10 m × 10 m spatial resolution, shelterbelt area, and shelterbelt width in one pixel. Based on this analysis, we developed a method for recognizing shelterbelt width from a remote sensing image of central western Jilin Province, China. The result was validated by field measurement data and measurement from an aerial image of 0.5 m × 0.5 m spatial resolution. Mean absolute error was 2.40 and 2.73 m respectively, suggesting that the proposed method is feasible and its accuracy is acceptable. The study provides a valuable method for monitoring shelterbelt width across large spatial scales and an accurate input parameter for the recognition of shelterbelt porosity from remote sensing data in future research.     

Characterizing pork producer demand for shelterbelts to mitigate odor: an Iowa case study

Shelterbelts have been shown to mitigate livestock odors incrementally through complex physical and social dynamics. By surveying Iowa hog producers, we assessed the current degree of shelterbelt usage by pork producers, examined producers’ beliefs and concerns regarding shelterbelt usage for odor mitigation and estimated both their willingness to pay and their overall demand for shelterbelts. Overall, Iowa hog producers display strong beliefs that shelterbelts help, social-psychologically, to mitigate odors and generally believe that shelterbelts physically reduce odors. Seventy-five percent of producers expressed a mean willingness to pay $0.18 per pig produced annually. Sixty percent are willing to pay within a range of estimated costs, and 13% are willing to pay more. Overall, younger (<mean) producers are the most probable users of this technology, and they tend to meet four criteria: they plan to be at the same site for over 10 years; they are located in regions with high pig populations; they are at higher risk of affecting neighbors with odors, due to their proximity; they appreciate the more intangible perceived benefits of using shelterbelts (e.g., those associated with social-psychological responses). Overall, the younger producers perceived excessive cost/labor requirements as their main concerns. This information is critical to guide future extension programming that addresses all key concerns of current and potential users of shelterbelts.     

Predicting maize and soybean production in a sheltered field in the Cornbelt region of North Central USA

Shelterbelts (field windbreaks) are an important tool for farming in semi-arid areas but are not commonly used. An obstacle to the adoption of shelterbelts is the lack of site-specific information about the benefits and costs associated with establishing and maintaining them. A group of researchers has been developing a modeling system that will estimate site-specific effects, benefits, and costs for sheltered fields that produce maize or corn (Zea maize) and soybean (Glycine max) in the U.S. Corn Belt region. Akey component of the modeling system is the use of the CROPGRO-Soybean and CERES-Maize models to simulate yield response to microclimatic changes acrossa sheltered field. In this work, we tested the ability of both models to simulate yield in a sheltered field, evaluated the potential yield increase of shelterbelts based on long-term simulations, and compared the influence of shelter induced changes in temperature and windrun on yield. Both models simulated yield increases due to shelter. The soybean model was more responsive to microclimatic differences than the maize model. Long-term simulations generally showed a field level increase in yield due to shelter for maize and soybeans with an average increase of 4.1 and 3.3, respectively. Change in windrun due to shelter is more important in increasing yield than changes in temperature. The CERES-Maize model seems to be more sensitive to changes in windrun than the CROPGRO-Soybean model.     

庄园式沙地防护林网的防护效益分析

以泰来县的庄园式沙地防护林网为试验基点 ,结合国家“九·五”攻关课题“嫩江沙地治理与示范” ,对防护林网内的主要作物玉米的产量 ,防护林网的增产效果及防护面积等进行了研究 ,结果表明 ,在沙地防护林网内以系统聚类法分成的高产区、增产区和平产区 ,玉米的茎高、穗长和底径的差异极显著 ,高产区可增产 310 .5 % ,增产区可增产 14 2 % ,防护作用明显。为增加防护面积 ,达到防护面积 90 %以上的防护目标 ,应在网格内增设复合林带 ,在樟子松林带内栽植杨树大苗 ,以进一步提高防护效益     

Mitigating swine odor with strategically designed shelterbelt systems: a review

Recent reports clearly indicate that odor emitted from concentrated livestock production facilities in the Midwest of the US is a significant social problem that negatively impacts rural and state economies, human health, and the quality of rural life. A potential incremental approach to dealing with livestock odor is the use of shelterbelts arranged in strategic designs near and within livestock facilities. This review outlines the various ways that shelterbelts can be effective technology which bio-physically mitigates odor thereby reducing social conflict from odor nuisance. The biophysical potential of shelterbelts to mitigate livestock odor arises from the tree/shrub impacts on the central characteristics and physical behavior of livestock odor. As the majority of odors generated in animal facilities that are detectable at appreciable distances travel as particulates, there is compelling evidence that shelterbelts can ameliorate livestock odor by impeding the movement of these particulates. Because the odor source is near the ground and the tendency of livestock odor is to travel along the ground, shelterbelts of modest heights (i.e. 20–30 ft) may be ideal for odor interception, disruption, and dilution. Shelterbelts can be adapted to fit almost any production situation. Depending on shelterbelt health, these trees can provide long term, year round odor interception, with increasing effectiveness over time. Additionally, more is becoming known about how landscape aesthetics affect how people might perceive livestock odor, suggesting that landscape elements such as shelterbelts can lead to aesthetic improvements and perhaps more positive opinions of livestock odor and the farm systems that create them.     

京郊农田防护林景观生态评价--以北京大兴县北藏乡为例

Based on theories of protective forests and landscape ecology, the reasonableness of structures and patterns of shelterbelt system at Beizang Town, Daxing County, Beijing were analyzed and assessed from the two scales of forest belts and networks, by integrating uses of field investigation, GIS and RS techniques. Results showed that the existent main belt (3-12 m in width) was too narrow, while the assistant belt (3-27.1 m in width) was too wide; the species composition of the existent shelterbelts was single, and the structures and patterns of the shelterbelt system were unreasonable. It is suggested that the structure of the main and the assistant belts should be changed, such as increasing the width of main belts, decreasing the width of assistant belt, and planting more mixed species, and the pattern with arbores in the middle and shrubs in the sides of belts could be taken into account. For the landscape structure of forest network after regenerating or reconstruction, the grid number of closed network should be 13 per km2 and the minimum number of belts should be 34 per km2, This study also testified that integrating GIS and remote technique with landscape ecology could provide an effective method for reasonable reconstruction of the structures and patterns of shelterbelts system.     

农田防护林系统的小尺度气候效应

本文采用农业气候统计的方法,通过历史和同期的比较,对苏北平原不同农田防护林营造规模的7个邻近县的10项气候要素进行了分析,指出较大规模的农田防护林对于当地县级的地面气候具有良性影响,特别表现在致冷作用和增湿作用上,有利于粮食作物的稳产丰收。在林木覆盖率不超过20％的情况下,营造防护林的规模大小,不能影响大气候的变化背景。     

防护林健康评价研究进展

防护林是防御自然灾害、维护基础设施和维持生态平衡的重要森林群落。文中通过分析森林健康的概念、内涵,并结合防护林的特点,归纳得出防护林健康的内涵;从防护林健康的评价指标和评价方法出发,详细阐述了防护林健康评价已取得的成果,并提出当前研究所面临的挑战以及今后的研究趋势。