Discrimination and characterization of management systems in semi-arid rangelands of South Africa using RapidEye time series
Discrimination and characterization of management systems in semi-arid rangelands of South Africa using RapidEye time series
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DOI：
10.1080/01431161.2014.882028
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发表时间：
2014-03-04
影响因子：
3.4
通讯作者：
Ewert, Frank
中科院分区：
文献类型：
--
作者：
Brueser, Katharina;Feilhauer, Hannes;Ewert, Frank
在南非草原，牧场管理与土地保有权密切相关。据报道，与商业农场相比，公共农场的牲畜植被条件较差。高空间和时间分辨率图像的时间序列可能有助于改进对这些牧场的评估，因为它们提供的空间尺度与现场评估的典型尺度相似，因此可以克服现场测量的有限时空代表性。使用一个生长季节（2010-2011）期间 13 张 RapidEye 图像的时间序列来探索两种管理系统（商业与公共）之间和内部的光谱差异。等位图排序用于绘制样本图的连续光谱差异。使用同时自回归模型（SAR）进行回归，差异随后与植物和土壤的生态变量相关，包括放牧效应指标。最大的差异出现在公共农场和商业农场的样地之间。植被属性与生长季节和休眠期反射率的差异显着相关。然而，这些关系并不表明公共农场的植被退化。他们进一步表明，夏季月份与管理相关的放牧干扰模式导致了农场之间的光谱差异，但可能损害了与植被组成差异相关的光谱差异的详细表征。
In South African grasslands, rangeland management is strongly related to land tenure. Communal farms are reported to exhibit less desirable vegetation conditions for livestock than commercial farms. Time series of high spatial and temporal resolution imagery may be useful for improved evaluation of these rangelands as they provide information at a spatial scale similar to the typical scale of field assessments and may thus overcome the limited spatio-temporal representativeness of field measurements. A time series of 13 RapidEye images over one growing season (2010-2011) was used to explore spectral differences between and within two management systems (commercial vs. communal). Isomap ordination was applied to map continuous spectral dissimilarities of sample plots. Using regression with simultaneous autoregressive models (SAR), dissimilarities were subsequently related to ecological variables of plant and soil, including indicators for grazing effects. The largest differences were found between sample plots of communal and commercial farms. Vegetation attributes were significantly related to dissimilarities in reflectance, both from the growing season and the dormant period. However, these relationships did not suggest vegetation degradation on communal farms. They further suggest that a management-related pattern of grazing disturbance in the summer months led to spectral differences between farms but could have impaired the detailed characterization of spectral dissimilarities related to differences in vegetation composition.