Niedertscheider Maria, Tasser Erich, Patek Monika, Rüdisser Johannes, Tappeiner Ulrike, Erb Karl-Heinz
1Institute of Social Ecology Vienna, Alpen-Adria Universitaet, Schottenfeldgasse 29, 1070 Vienna, Austria.
2Institute for Alpine Environment, European Academy Bozen/Bolzano, Bolzano/Bozen, Italy.
Ecosystems. 2017;20(8):1391-1406. doi: 10.1007/s10021-017-0120-5. Epub 2017 Mar 10.
The role of ecosystems as carbon (C) sinks or sources is intrinsically related to land-use intensity, which determines the land required for biomass production. Here, we systematically investigate the role of different land-use types including their land-use intensities on vegetation C-stocks (SC) in the Stubai valley, located in the Austrian central Alps. After a period of high land-use impacts until 1954, indicated by massive C-depletion, land-use shifted to completely new courses. Polarization into high-intensity low-land areas and extensification at higher altitudes allowed for a tripling of SC until 2003. The most important land-use change was the intensification of the livestock sector accompanied by abandonment of extensive grasslands and reduced harvest pressure on forests after WWII. Market integration, abundance of fossil energy carriers, as well as structural change of the economy were important underlying socio-economic drivers of these trends. However, despite this remarkable SC increase, SC amounted to only 62% of the potential carbon stocks (SC) in 2003. Although conversion of forests to agriculture clearly contributed the lion's share to this SC-gap, forest management explains roughly one quarter of the SC-difference. We found that time-lags between land-use shifts and the establishment of a new C-climax had fundamental repercussions on recent C-dynamics in the study region. Apparently, the land system is still net-accumulating C, although land-use changes have peaked decades earlier. Our findings are crucial for the understanding of C-dynamics, including the role of land management and time-lags in mountainous regions, which are regarded key areas for terrestrial C-sequestration.
生态系统作为碳汇或碳源的作用与土地利用强度有着内在联系，而土地利用强度决定了生物质生产所需的土地面积。在此，我们系统地研究了奥地利中部阿尔卑斯山施图拜山谷不同土地利用类型及其利用强度对植被碳储量（SC）的作用。在1954年之前，土地利用受到高强度影响，大量碳损耗表明了这一点，之后土地利用转向全新的模式。到2003年，高强度低地地区和高海拔地区的粗放化形成两极分化，使得碳储量增加了两倍。最重要的土地利用变化是畜牧业的集约化，同时伴随着二战后粗放型草地的废弃以及森林采伐压力的降低。市场整合、化石能源载体的丰富以及经济结构变化是这些趋势的重要社会经济驱动因素。然而，尽管碳储量显著增加，但2003年的碳储量仅占潜在碳储量（SC）的62%。虽然森林向农业的转变显然是造成这一碳储量差距的主要原因，但森林管理大约解释了四分之一的碳储量差异。我们发现，土地利用转变与新的碳平衡建立之间的时间滞后对研究区域近期的碳动态产生了根本性影响。显然，尽管土地利用变化在几十年前就已达到峰值，但土地系统仍在净积累碳。我们的研究结果对于理解碳动态至关重要，包括山地地区土地管理和时间滞后的作用，而山地地区被视为陆地碳固存的关键区域。
