Boreal-forest soil chemistry drives soil organic carbon bioreactivity along a 314-year fire chronosequence
Boreal-forest soil chemistry drives soil organic carbon bioreactivity along a 314-year fire chronosequence
复制标题
北方森林土壤化学沿着 314 年的火灾时间顺序驱动土壤有机碳生物反应性
作者：
B. Andrieux;D. Paré;J. Beguin;P. Grondin;Y. Bergeron
抽象的。在野火之后，有机碳（C）积累在
北方森林土壤长期积累模式以及
负责持续土壤碳稳定或封存的机制
鲜为人知。我们评估了火灾后C储备的功能变化，
水库（生物活性和柠檬酸盐）使用的比例C
在长期的实验室培养中，
C耐酸水解的比例。我们发现所有的土壤
C池随火灾后时间的延长而线性增加。生物活性和
酸不溶性土壤碳库分别以0.02和0.12 MgC ha−1 yr−1的速率增加，
它们相对于土壤总碳储量的比例保持不变，
火灾后的时间（分别为8%和46%）。我们直接量化了
变量和C生物活性之间的间接因果关系，
理清气候、苔藓优势、土壤
颗粒大小分布和土壤化学性质（pH值，交换性
锰和铝，和金属氧化物）的变化结构在体外
土壤C生物活性。我们的分析表明，
研究区的灰化土壤是最好的预测因子，
土壤C生物活性对于O层，pH和交换性锰
最重要的（模型平均估计值均为0.34）因子
与土壤有机碳生物活性直接相关，其次是自
火（0.24），苔藓优势（0.08），气候和纹理（0两者）。为
矿质土壤中，交换性铝是最重要的影响因素
（模型平均估计值为-0.32），其次是金属氧化物（-0.27），pH值
（-0.25），火灾发生后的时间（0.05），气候和纹理（0.05），
两者）。在这项研究中检查的四个气候因素中（即，年平均
温度，5摄氏度以上的生长度日数，年平均
降水和水平衡），只有那些与水的可用性-
而不是温度-有一个间接的影响（O层）或边际间接
矿质土壤对土壤碳生物活性的影响。鉴于预测的
气候变化对土壤碳平衡的影响与土壤的大小密切相关
和土壤碳库的生物活性，我们的研究强调，
包括土壤化学的直接影响和
气候和土壤质地对土壤有机质分解的影响
系统模型来预测北方土壤对全球变暖的反应。
Abstract. Following a wildfire, organic carbon (C) accumulates in
boreal-forest soils. The long-term patterns of accumulation as well as the
mechanisms responsible for continuous soil C stabilization or sequestration
are poorly known. We evaluated post-fire C stock changes in functional
reservoirs (bioreactive and recalcitrant) using the proportion of C
mineralized in CO2 by microbes in a long-term lab incubation, as well
as the proportion of C resistant to acid hydrolysis. We found that all soil
C pools increased linearly with the time since fire. The bioreactive and
acid-insoluble soil C pools increased at a rate of 0.02 and 0.12 MgC ha−1 yr−1, respectively,
and their proportions relative to total soil C stock remained constant with
the time since fire (8 % and 46 %, respectively). We quantified direct and
indirect causal relationships among variables and C bioreactivity to
disentangle the relative contribution of climate, moss dominance, soil
particle size distribution and soil chemical properties (pH, exchangeable
manganese and aluminum, and metal oxides) to the variation structure of in vitro
soil C bioreactivity. Our analyses showed that the chemical properties of
podzolic soils that characterize the study area were the best predictors of
soil C bioreactivity. For the O layer, pH and exchangeable manganese were
the most important (model-averaged estimator for both of 0.34) factors
directly related to soil organic C bioreactivity, followed by the time since
fire (0.24), moss dominance (0.08), and climate and texture (0 for both). For
the mineral soil, exchangeable aluminum was the most important factor
(model-averaged estimator of −0.32), followed by metal oxide (−0.27), pH
(−0.25), the time since fire (0.05), climate and texture (∼0 for
both). Of the four climate factors examined in this study (i.e., mean annual
temperature, growing degree-days above 5 ∘C, mean annual
precipitation and water balance) only those related to water availability –
and not to temperature – had an indirect effect (O layer) or a marginal indirect
effect (mineral soil) on soil C bioreactivity. Given that predictions of the
impact of climate change on soil C balance are strongly linked to the size
and the bioreactivity of soil C pools, our study stresses the need to
include the direct effects of soil chemistry and the indirect effects of
climate and soil texture on soil organic matter decomposition in Earth
system models to forecast the response of boreal soils to global warming.