Spatial and topographic trends in forest expansion and biomass change, from regional to local scales
Spatial and topographic trends in forest expansion and biomass change, from regional to local scales
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DOI：
10.1111/gcb.12915
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发表时间：
2015-09-01
影响因子：
11.6
通讯作者：
Barrett, Tara M.
中科院分区：
文献类型：
--
作者：
Buma, Brian;Barrett, Tara M.
天然林的生长和扩张是全球重要的固碳过程。气候变化可能会通过二氧化碳施肥、温度升高和降水量改变来增加某些地区的森林生长;然而，干扰机制的改变和气候压力（如干旱）也会减少森林的碳储存。对森林变化中碳储量的观测有助于确定森林密度（例如Mg ha（-1））和空间（范围和位置）方面的森林碳储量的当前趋势。监测自然（未管理）地区的变化特别有用，因为虽然植树造林和从历史土地使用中恢复是目前的大型碳汇，但这些碳汇的长期可行性取决于其特定地点的气候变化和扰动动态。我们利用一个大型的、无人管理的生物群落（>135 000 km（2）），跨越广泛的纬度梯度，以探索位置的变化如何影响森林密度和空间格局：阿拉斯加的北美温带雨林森林，其生物量和土壤中储存了>2.8 Pg C，相当于美国相邻森林中C的>8%。我们表明，区域生物群落正在发生变化，收益超过损失，并位于不同的空间地形背景。森林收益集中在北部，低海拔和高纬度地区，特别是在庇护地区，而损失则偏向南部和低纬度地区。重复样地规模生物量数据（n = 759）表明，在缓坡和高纬度地区，森林内生物量的增加超过损失（直径>12.7厘米的活树，986千兆克/年）。这项工作表明，虽然温带雨林动态发生在精细的空间尺度（
Natural forest growth and expansion are important carbon sequestration processes globally. Climate change is likely to increase forest growth in some regions via CO2 fertilization, increased temperatures, and altered precipitation; however, altered disturbance regimes and climate stress (e.g. drought) will act to reduce carbon stocks in forests as well. Observations of asynchrony in forest change is useful in determining current trends in forest carbon stocks, both in terms of forest density (e.g. Mg ha(-1)) and spatially (extent and location). Monitoring change in natural (unmanaged) areas is particularly useful, as while afforestation and recovery from historic land use are currently large carbon sinks, the long-term viability of those sinks depends on climate change and disturbance dynamics at their particular location. We utilize a large, unmanaged biome (>135 000 km(2)) which spans a broad latitudinal gradient to explore how variation in location affects forest density and spatial patterning: the forests of the North American temperate rainforests in Alaska, which store >2.8 Pg C in biomass and soil, equivalent to >8% of the C in contiguous US forests. We demonstrate that the regional biome is shifting; gains exceed losses and are located in different spatio-topographic contexts. Forest gains are concentrated on northerly aspects, lower elevations, and higher latitudes, especially in sheltered areas, whereas loss is skewed toward southerly aspects and lower latitudes. Repeat plot-scale biomass data (n = 759) indicate that within-forest biomass gains outpace losses (live trees >12.7 cm diameter, 986 Gg yr(-1)) on gentler slopes and in higher latitudes. This work demonstrates that while temperate rainforest dynamics occur at fine spatial scales (