Effects of contemporary land-use and land-cover change on the carbon balance of terrestrial ecosystems in the United States
Effects of contemporary land-use and land-cover change on the carbon balance of terrestrial ecosystems in the United States
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DOI：
10.1088/1748-9326/aab540
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发表时间：
2018-03
影响因子：
6.7
通讯作者：
B. Sleeter;Jinxun Liu;C. Daniel;B. Rayfield;J. Sherba;T. Hawbaker;Zhiliang Zhu;P. Selmants;T. Loveland
中科院分区：
文献类型：
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作者：
B. Sleeter;Jinxun Liu;C. Daniel;B. Rayfield;J. Sherba;T. Hawbaker;Zhiliang Zhu;P. Selmants;T. Loveland
土地利用和土地覆盖的变化可以对陆地碳动态产生深远的影响，但其对全球碳收支的影响仍不确定。虽然土地变化对生态系统碳动态的影响一直是众多研究的重点，但很少有人基于长期范围内大范围地理区域内多种生态系统类型的观测数据。在这项研究中，我们使用各种天气尺度的遥感数据来估计1973-2010年间与城市化、农业扩张和收缩、森林采伐和野火相关的土地利用变化对美国毗邻地区(即不包括阿拉斯加和夏威夷)陆地生态系统(森林、草原、灌木和农业)碳平衡的影响。我们估计农业和森林面积将出现较大幅度的净下降，而草原和灌丛面积的增幅相对较小。在所有类别中，净变化最大的是估计增加的已开发土地114865平方公里，年平均增长率为3282平方公里−1。平均而言，美国生态系统每年以254Tg C yr−1的速率封存碳。在研究期间，林地的净汇下降了35%，这主要是土地利用遗留、干扰增加以及土地利用转换导致的森林面积减少的结果。土地利用、土地利用的变化变化数据的不确定性导致1985年之前的年度碳汇估计误差约为16%(约±40Tg C yr−1)。1980年代中期开始改进的LULC和干扰图将这种不确定性在1985年后减少了约50%。我们的结论是，LULC的变化是理解生态系统碳动态的关键组成部分，在变化的检测、量化和归因方面的持续改进有可能显著减少当前的不确定性。
Changes in land use and land cover (LULC) can have profound effects on terrestrial carbon dynamics, yet their effects on the global carbon budget remain uncertain. While land change impacts on ecosystem carbon dynamics have been the focus of numerous studies, few efforts have been based on observational data incorporating multiple ecosystem types spanning large geographic areas over long time horizons. In this study we use a variety of synoptic-scale remote sensing data to estimate the effect of LULC changes associated with urbanization, agricultural expansion and contraction, forest harvest, and wildfire on the carbon balance of terrestrial ecosystems (forest, grasslands, shrublands, and agriculture) in the conterminous United States (i.e. excluding Alaska and Hawaii) between 1973 and 2010. We estimate large net declines in the area of agriculture and forest, along with relatively small increases in grasslands and shrublands. The largest net change in any class was an estimated gain of 114 865 km2 of developed lands, an average rate of 3282 km2 yr−1. On average, US ecosystems sequestered carbon at an annual rate of 254 Tg C yr−1. In forest lands, the net sink declined by 35% over the study period, largely a result of land-use legacy, increasing disturbances, and reductions in forest area due to land use conversion. Uncertainty in LULC change data contributed to a ~16% margin of error in the annual carbon sink estimate prior to 1985 (approximately ±40 Tg C yr−1). Improvements in LULC and disturbance mapping starting in the mid-1980s reduced this uncertainty by ~50% after 1985. We conclude that changes in LULC are a critical component to understanding ecosystem carbon dynamics, and continued improvements in detection, quantification, and attribution of change have the potential to significantly reduce current uncertainties.