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首页> 外文期刊>British Journal of Environment and Climate Change >Topographic Effects on Vegetation Biomass inSemiarid Mixed Grassland under ClimateChange Using AVHRR NDVI Data
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Topographic Effects on Vegetation Biomass inSemiarid Mixed Grassland under ClimateChange Using AVHRR NDVI Data

机译：利用AVHRR NDVI数据研究气候变化对半裸混交草地植被生物量的地形影响

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The topography effects on vegetation biomass under climate change impact have been ignored in prairie regions as it is not as significant as in mountain areas. This paper aims to investigate the topographic effects on vegetation biomass under climate change in semiarid Canadian mixed grass prairie. The study site is Grasslands National Park (GNP) and the study period is from 1985 to 2007. Data used include dry green biomass data sampled from June to July of 2003 to 2005, 10-day Advanced Very High Resolution Radiometer (AVHRR) 1km Normalized Difference Vegetation Index (NDVI) composites of 1985 to 2007, and Global Digital Elevation Model derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM) data with 90 m resolution. To achieve the objective, the applicability of AVHRR NDVI data being a proxy of vegetation biomass was investigated. Then, the range and standard deviation (SD) of each individual vegetation patch in both valley and upland grasslands were calculated. In addition, the variation trend of valley and upland vegetation was analyzed respectively using the Mann-Kendall (M-K) test and the Sen’s slope. The results indicate that the inter-annual variation of vegetation biomass at GNP can be fairly well represented by AVHRR 1 km NDVI data. Although some patches in valley grassland have similar NDVI range and SD values as those in upland grassland, the others have much smaller range and SD values than the highest range (0.154) and SD (0.045) of upland grassland. The M-K test and Sen’s slope analyses indicate that NDVI had an increase trend with a larger slope (0.0005) in upland and a smaller slope (0.0002) in valley grassland. It is concluded that climatic variation has more effects on upland grassland than valley grassland in GNP. Topography effects in prairie regions should not be ignored.
机译：在草原地区，气候变化影响下地形对植被生物量的影响已被忽略，因为它不像山区那样重要。本文旨在研究地形变化对加拿大半干旱混合草草原气候变化对植被生物量的影响。研究地点是草地国家公园（GNP），研究期间为1985年至2007年。使用的数据包括2003年6月至7月至2005年采样的干燥绿色生物量数据，为期10天的超高分辨率高分辨率辐射计（AVHRR）1公里1985年至2007年的植被差异指数（NDVI）复合材料，以及从90 m分辨率的先进星载热发射和反射辐射计（ASTER GDEM）数据获得的全球数字高程模型。为了达到这个目的，研究了AVHRR NDVI数据作为植被生物量的替代指标的适用性。然后，计算了山谷和高地草原中每个植被斑块的范围和标准差（SD）。此外，分别使用Mann-Kendall（M-K）检验和Sen坡度分析了山谷和高地植被的变化趋势。结果表明，AVHRR 1 km NDVI数据可以很好地表示GNP植被生物量的年际变化。尽管山谷草原中的某些斑块的NDVI范围和SD值与旱地草原的相似，但其他斑块的范围和SD值却比陆地草原的最高范围（0.154）和SD（0.045）小得多。 M-K测试和Sen的坡度分析表明，NDVI呈上升趋势，其中高地坡度（0.0005）和谷地草原坡度（0.0002）较小。结论是，在GNP中，气候变化对高地草原的影响大于对山谷草原的影响。草原地区的地形影响不容忽视。

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