Physiognomic and physiologic changes in mountain grasslands in response to environmental and anthropogenic factors
Physiognomic and physiologic changes in mountain grasslands in response to environmental and anthropogenic factors
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DOI：
10.1016/j.apgeog.2015.11.007
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发表时间：
2016-01-01
影响因子：
4.9
通讯作者：
Alados, Concepcion L.
中科院分区：
文献类型：
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作者：
Gartzia, Maite;Perez-Cabello, Fernando;Alados, Concepcion L.
山地草原为可持续发展和人类福祉提供了宝贵的生态系统服务。这些生境经历了与其地貌（生物量）和生理（绿度）特性相关的重要变化。其中一些变化引起了人们的极大关注，如木材侵蚀，而其他变化，如未经历木材侵蚀的草地的生物量和绿化率的变化几乎是未知的。利用Landsat-5专题制图器的归一化植被指数（NDVI）和归一化红外指数（NDII）计算了未受林地侵蚀影响的茂密草原的地貌和生理特征。利用多时相向量分析了20世纪80年代末和21世纪初在西班牙比利牛斯山脉拍摄的图像，以检测生物量和绿色度的增加或减少。为了了解这些变化的来源，我们用人为因素（土地利用，即放牧、滑雪场和相关基础设施）和环境因素（地形、岩性和气候）对它们进行了建模。草地生物量和绿度的减少与人为因素的相关性最强，呈现出局域斑块的退化格局。尽管如此，环境因素与这两个指数的正相关最为强烈，在生物量和绿度的增加中发现了一个连续的模式。在牲畜载畜率高的地区，草地生物量和绿度减少，而在牲畜载畜率低的地区，生物量和绿度增加。在低海拔地区，生物量和绿化率下降的草地要么是在平缓的山坡上，主要受人类活动的影响，要么是在陡峭的山坡上，受到滑雪胜地的局部影响。在受人为因素干扰的地区，初夏降雨的增加触发了侵蚀过程，增强了人为压力对草地绿度和生物量的负面影响。相比之下，高海拔、陡坡、北向或西向、酸性岩性、大陆性较少、降雨较多的草地，生物量和绿化率增加最多。这些结果表明，除了树木侵蚀之外，山地草原的变化正在深刻地改变其生理和地貌，指出与当前管理实践和气候趋势的直接关系。(C) 2015年作者。Elsevier Ltd.出版。
Mountain grasslands provide valuable ecosystem services for sustainable development and human wellbeing. These habitats have suffered important changes related with their physiognomic (biomass) and physiologic (greenness) properties. Some of these changes received significant attention i.e. woody encroachment, while others, like the changes in biomass and greenness of those grasslands that have not experienced woody encroachment are almost unknown. We calculated physiognomic and physiologic properties for dense grasslands not affected by woody encroachment through the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Infrared Index (NDII) from Landsat-5 Thematic Mapper. Imagery taken in the late-1980s and late-2000s in the Spanish Pyrenees were analyzed with multi-temporal vectors to detect increases or decreases of biomass and greenness. To understand the source of these changes, we modeled them with anthropogenic (land use, i.e. grazing, ski resorts, and related infrastructures) and environmental factors (topographic, lithologic and climatic). Anthropogenic factors were most strongly correlated with decrease in the biomass and greenness, showing degradation patterns of the grasslands at localized patches. Nonetheless, environmental factors were most strongly correlated with positive changes in both indices, detecting a continuous pattern in the increase in biomass and greenness. In areas that had high livestock stocking rates, grasslands biomass and greenness decrease, while in areas that had low stocking rates, biomass and greenness increases. Grasslands at low elevation showing decrease in biomass and greenness were either on gentle slopes and largely affected by human activities, or on steep slopes locally affected by ski resorts. In areas that have been disturbed by anthropogenic factors, the increase of rain in early summer trigger erosion processes, enhancing the negative effect of anthropic pressure on grassland greenness and biomass. In contrast, grasslands at high elevations, on steep slopes, and those that had north or west aspects and that had an acidic lithology, with less continentality, and that received more rain, had the most increase in biomass and greenness. Those results suggest that changes in mountain grasslands, apart from woody encroachment, are deeply altering their physiology and physiognomy, pointing out direct relationships with current management practices and climate trends. (C) 2015 The Authors. Published by Elsevier Ltd.