The response of boreal peatland community composition and NDVI to hydrologic change, warming, and elevated carbon dioxide
The response of boreal peatland community composition and NDVI to hydrologic change, warming, and elevated carbon dioxide
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DOI：
10.1111/gcb.14465
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发表时间：
2019-01-01
影响因子：
11.6
通讯作者：
Montgomery, Rebecca A.
中科院分区：
文献类型：
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作者：
McPartland, Mara Y.;Kane, Evan S.;Montgomery, Rebecca A.
卫星平台捕捉到的北极和北方归一化植被指数(NDVI)值的广泛变化表明，北方生态系统正在经历快速的生态变化，以应对气候变暖。气温上升和水文变化正在推动生态系统生物物理性质的变化，卫星观测到的变化表现为区域归一化植被指数的长期变化。为了研究这些变化的潜在生态驱动因素，我们在操纵水文、温度和二氧化碳(CO2)水平的实验中，使用田间尺度的NDVI遥感来跟踪泥炭地植被。除了NDVI外，我们还测量了物种覆盖率和叶面积指数(LAI)。我们监测了两种广泛代表北方地区的泥炭地类型。其中一个地点是阿拉斯加泥炭地实验(APEX)中位于阿拉斯加费尔班克斯附近的一片肥沃的沼泽，第二个地点是位于明尼苏达州北部的云杉和泥炭地变化环境下的反应(云杉)实验中的一个营养贫乏的沼泽。我们发现，NDVI随着APEX点土壤水分的长期减少而减少，这与光合叶面积和莎草的相对丰度的减少是一致的。我们观察到，随着云杉地温度的升高，NDVI增加，与灌木相对丰富度的增加和叉树盖度的减少有关。云杉地的升温处理也导致灌木层的叶面积指数增加。我们没有发现二氧化碳浓度升高对群落组成的强烈影响。我们的发现支持了最近的研究，即从卫星平台观测到的NDVI的变化可能是群落组成和生态系统结构因应气候变暖而发生变化的结果。
Widespread changes in arctic and boreal Normalized Difference Vegetation Index (NDVI) values captured by satellite platforms indicate that northern ecosystems are experiencing rapid ecological change in response to climate warming. Increasing temperatures and altered hydrology are driving shifts in ecosystem biophysical properties that, observed by satellites, manifest as long-term changes in regional NDVI. In an effort to examine the underlying ecological drivers of these changes, we used field-scale remote sensing of NDVI to track peatland vegetation in experiments that manipulated hydrology, temperature, and carbon dioxide (CO2) levels. In addition to NDVI, we measured percent cover by species and leaf area index (LAI). We monitored two peatland types broadly representative of the boreal region. One site was a rich fen located near Fairbanks, Alaska, at the Alaska Peatland Experiment (APEX), and the second site was a nutrient-poor bog located in Northern Minnesota within the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. We found that NDVI decreased with long-term reductions in soil moisture at the APEX site, coincident with a decrease in photosynthetic leaf area and the relative abundance of sedges. We observed increasing NDVI with elevated temperature at the SPRUCE site, associated with an increase in the relative abundance of shrubs and a decrease in forb cover. Warming treatments at the SPRUCE site also led to increases in the LAI of the shrub layer. We found no strong effects of elevated CO2 on community composition. Our findings support recent studies suggesting that changes in NDVI observed from satellite platforms may be the result of changes in community composition and ecosystem structure in response to climate warming.