Knowledge Resource Center for Ecological Environment in Arid Area
| 干旱区绿洲农田防护林景观格局及其增产效应 | |
| 其他题名 | Landscape Pattern and its Yield-improving Effects of Farmland Windbreaks of Oasis in Arid Regions |
| 杨书雅 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 李小玉 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 防护林是陆地景观的重要组成部分，农田防护林能够抵御自然灾害，改善农田小气候，增加作物产量，同时农田林带对林带边缘作物也具有负效应，对农业生产造成了一定的影响。因此，基于遥感与GIS技术，在流域尺度上分析农田防护林的景观格局，量化农田防护林对作物产量的防护效应具有实际意义。本文选择玛纳斯河流域绿洲区域，借助遥感数据及统计资料数据，开展绿洲农田主要作物产量研究，分析干旱区绿洲农田防护林网的景观格局及其对作物的增产效应。得到如下研究结果：（1）玛纳斯县、沙湾县和团场的防护林网带斑比的相对误差分别为0.7240、0.7374和0.7579，连接度的相对误差分别为0.5307、0.5629和0.6863，环度值的相对误差分别为0.6577、0.6380和0.4945。各景观指标的相对误差均大于0.15，说明玛纳斯河流域绿洲农田防护林网尚且达不到优质标准，团场防护林网带斑比和连续相对较差，环度相对较好，这可能与绿洲的开发历史和管理方式有关。防护林景观格局存在林带面积不足、缺带断带、林网分布不均匀等情况，需要在空间上补齐缺失的林带，在数量上加大林带密度，更加科学合理的实现农田的可持续发展。（2）以landsat8遥感影像为数据源，得到玛纳斯河流域棉花分布面积为398249.62ha，占流域总面积的61.13%，利用统计局公布的数据进行验证，其解译精度为94.42%。流域内棉花平均产量为2049.27kg/ha，利用统计局公布的县市棉花单产数据进行验证，其估算精度小于4%。流域内绿洲中心区域棉花产量相对较高，一般以2100~2400kg/ha分布较多，而绿洲边缘靠近荒漠区域以及邻近居民地区域，棉花产量略低，部分产量甚至在1800kg/ha以下。（3）建立防护林评价体系，评价农田防护林网对棉花产量的影响。当防护效应达到70%之前，棉花单产呈明显的上升趋势，当达到70%时，棉花增产率为8.07%。当达到70%以后，基本处于稳定状态。这也说明了当防护林的防护效应达到一定阈值时，对作物的增产作用减弱，甚至会导致减产。防护林通过改变风速、温度等小气候达到增产作用，当防护林网规模扩大到一定程度时，将不会继续增加产量。由于林带与棉花竞争土壤水分和养分以及光照，防护林反而会对农田产生胁地效应，从而影响防护林网附近棉花的产量。因此，该研究中评价结果可以在区域尺度上为防护林对农田的增产效应提供科学依据，为农田防护林的经营与管理提供理论基础。 |
| 英文摘要 | Shelterbelt is an important part of terrestrial landscape, farmland windbreak can resist natural disasters, improve farmland microclimate, increase crop yield. However, farmland shelterbelt also has a negative effect on the yield of the forest edge crops. Therefore, it has practical significance to analysis the landscape pattern of farmland windbreak, and research the protective benefit on crop yield of farmland windbreak in the large scale. In this study, high resolution remote sensing images and statistical data were employed to analysis the landscape pattern and its yield-improving effects of farmland windbreak in the Manas River Basin oasis. The results shows that:(1)For the farmland windbreaks in Manas County, Shawan County, and the Farm, the relative errors of their landscape metrics are: 0.7240, 0.7374 and 0.7579 for the ratio of belt to patch, 0.5307, 0.5629 and 0.6863 for the connectivity, and 0.6577, 0.6380 and 0.4945 for the ring value, respectively. The relative errors of each landscape metric is greater than 0.15, which indicates the farmland windbreaks in the Manas River Basin oasis cannot meet the good quality standard. The ratio of belt to patch and connectivity of the Farm shelterbelt is relatively poor, the ring is relatively good, which may relates to the development of oasis history and management style. The prominent problems include the limited windbreak area, uneven windbreak distribution, little closed grid, and bad forming conditions. In order to achieve the sustainability of the farmlands, the missing windbreak needs to be developed and the density of windbreak should also be increased.(2) Based on the landsat8 remote sensing image data, extract the distribution information of cotton in research area. The result shows that the distribution area of cotton in Manas River Basin is 398249.62ha, accouting for 61.13% of the total area of the basin, verification by the data from the Bureau of Statistics, the precision of interpretation is 94.42%. Secondly, based on the light energy utilization model, and combined with the CASA model, to estimate the biomass of cotton in growing season of 2013. Using of the harvest index to estimate the yield of cotton in the Manas River Basin. In the River Basin, the average yield of cotton was 2049.27kg/ha, and verification by using the data of cotton yield per county from the Bureau of Statistics, the estimated accuracy is less than 4%. In the River Basin, the cotton yield was relatively high in the central area of oasis, and generally 2100~2400kg/ha. While the oasis near the edge of desert area and adjacent residential area, the cotton yield slightly lower and even under 1800kg/ha.(3) Using the Normalization index of farmland forest boom period to classify the level of farmland shelterbelt, and establish the windbreak evaluation system, to evaluate the effects of farmland shelterbelt on cotton yield. When the protective effect was under 70%, the cotton yield showed a significant upward trend. When the cotton yield reached 70%, the yield of cotton was increased by 8.07%. When reach up to 70%, the cotton yield in a stable state basically. It shows that when the protective effect of the windbreaks reaches a certain threshold, the positive effect of the yield of crops trend to weak, and even reduce the yield. The windbreaks change the wind speed and temperature to increase the yield of crops. While the scale of windbreak network reaches to a certain extent, it will not continue to increase production. Due to competition for soil moisture、nutrients and light between cotton and windbreak, the windbreak will have group effect on the farmland, and affect the yield of cotton near the windbreak. Therefore, the results of this study can provide a scientific basis for the windbreak to increase the yield of farmland, and provide a theoretical basis for the operation and management of farmland windbreak. |
| 中文关键词 | 农田防护林 ; 景观格局 ; 景观指标 ; 绿洲 ; 防护水平 ; 增产效应 |
| 英文关键词 | farmland windbreaks landscape pattern landscape metrics oasis protection level yield-improving effects. |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 测绘工程 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287981 |
| 推荐引用方式 GB/T 7714 | 杨书雅. 干旱区绿洲农田防护林景观格局及其增产效应[D]. 中国科学院大学,2017. |
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