University of Queensland, School of Biological Sciences, Queensland 4072 Australia.
Ecol Appl. 2010 Oct;20(7):1838-50. doi: 10.1890/09-1690.1.
Opportunities for dual restoration and carbon benefits from naturally regenerating woody ecosystems in agricultural landscapes have been highlighted recently. The restoration capacity of woody ecosystems depends on the magnitude and duration of ecosystem modification, i.e., the "agricultural legacy." However, this legacy may not influence carbon sequestration in the same way as restoration because carbon potential depends primarily on biomass accumulation, with little consideration of other attributes and functions of the ecosystem. Our present study simultaneously assesses the restoration and carbon potential of Acacia harpophylla regrowth, an extensive regrowth ecosystem in northeastern Australia. We used a landscape-scale survey of A. harpophylla regrowth to test the following hypotheses: (1) management history, in combination with climatic and edaphic factors, has long-term effects on stem densities, and (2) higher-density stands have lower restoration and carbon potential, which is also influenced by climatic and edaphic factors. We focused on the restoration of forest structure, which was characterized using stem density, aboveground biomass, stem heights, and stem diameters. Data were analyzed using multilevel models within the hierarchical Bayesian model (HBM) framework. We found strong support for both hypotheses. Repeated attempts at clearing Brigalow (A. harpophylla ecosystem) regrowth increases stem densities, and these densities remain high over the long term, particularly in high-rainfall areas and on gilgaied, high-clay soils (hypothesis 1). In models testing hypothesis 2, interactions between stem density and stand age indicate that higher-density stands have slower biomass accumulation and structural development in the long term. After accounting for stem density and stand age, annual rainfall had a positive effect on biomass accumulation and structural development. Other climate and soil variables were retained in the various models but had weaker effects. Spatial extrapolations of the HBMs indicated that the central and eastern parts of the study region are most suitable for biomass accumulation; however, these may not correspond to the areas that historically supported the highest biomass Brigalow forests. We conclude that carbon and restoration goals are largely congruent within areas of similar climate. At the regional scale, however, spatial prioritization of restoration and carbon projects may only be aligned where carbon benefits will be high.
最近，人们强调了在农业景观中从自然再生木本生态系统中获得双重恢复和碳效益的机会。木本生态系统的恢复能力取决于生态系统改造的程度和持续时间，即“农业遗产”。然而，这种遗产可能不会以同样的方式影响碳封存，因为碳潜力主要取决于生物量积累，而很少考虑生态系统的其他属性和功能。本研究同时评估了澳大利亚东北部广泛再生的金合欢属植物再生的恢复和碳潜力。我们使用金合欢属植物再生的景观尺度调查来检验以下假设：（1）管理历史，加上气候和土壤因素，对茎密度有长期影响，（2）密度较高的林分具有较低的恢复和碳潜力，这也受到气候和土壤因素的影响。我们专注于森林结构的恢复，其特征是用茎密度、地上生物量、茎高和茎径来表示。使用多层次模型在分层贝叶斯模型（HBM）框架内分析数据。我们发现这两个假设都得到了强有力的支持。反复试图清除金合欢属（金合欢属生态系统）再生林增加了茎密度，并且这些密度在很长一段时间内保持较高，特别是在高降雨量地区和在吉盖尔德、高粘土壤上（假设 1）。在检验假设 2 的模型中，茎密度和林龄之间的相互作用表明，在长期内，密度较高的林分的生物量积累和结构发育速度较慢。在考虑茎密度和林龄后，年降雨量对生物量积累和结构发育有积极影响。其他气候和土壤变量保留在各种模型中，但影响较弱。HBM 的空间外推表明，研究区域的中部和东部最适合生物量积累；然而，这些可能与历史上支持最高生物量金合欢属森林的地区不一致。我们得出结论，在类似气候的地区，碳和恢复目标在很大程度上是一致的。然而，在区域尺度上，只有在碳效益高的地方，恢复和碳项目的空间优先排序才可能一致。
