Decomposing decomposition: isolating direct effects of temperature from other drivers of detrital processing
Decomposing decomposition: isolating direct effects of temperature from other drivers of detrital processing
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分解分解：将温度的直接影响与碎屑加工的其他驱动因素隔离开来
DOI：
10.1002/ecy.3467
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发表时间：
2021
期刊：
影响因子：
4.8
通讯作者：
Benstead, Jonathan P.
中科院分区：
文献类型：
--
作者：
Wilmot, Oliver J.;Hood, James M.;Huryn, Alexander D.;Benstead, Jonathan P.
理解所观察到的分解的温度依赖性（即，其“表观”活化能）需要分离温度对消费者新陈代谢的直接影响（即，“固有的”活化能），从那些由间接的季节性模式在物候和生物量，并通过长期，气候驱动的变化，驯化，适应和社区集会。这种解析很重要，因为将温度与分解联系起来的研究通常涉及多季数据和/或长期变化的空间代理，因此将这些间接因素纳入其中。这些因素的各种影响可能掩盖碎屑处理的固有温度依赖性。将分解的固有温度依赖性与其他驱动因素分开对于准确预测碎屑源温室气体对气候变暖的贡献非常重要，并且需要新的数据收集和分析方法。在这里，我们展示了在粗网和细网垃圾袋（后者不包括大型无脊椎动物）中孵育的红枫垃圾的分解率，在一年内，沿着自然温度梯度（年平均温度：12.8°-16.4 ° C），沿着从北格鲁吉亚州到美国亚拉巴马州中部的九条溪流中，连续约一个月的增量。我们使用基于距离的冗余分析和广义加性混合模型分析了这些数据，以解析分解速率对温度，季节性和切碎大型无脊椎动物生物量的依赖性。细网眼袋中的微生物分解受到温度和季节性的显著影响。占季节性校正的分解率从0.25到0.08电子伏特的温度依赖性。粗网眼袋中的碎纸机组合结构与两个地点和季节的温度有关，从“冷”的石首鱼为主的社区转变为以蜗牛或小龙虾为主的“暖”社区。切碎机生物量不是粗筛或大型无脊椎动物介导的显著预测因子（即，粗筛孔减去细筛孔）的破碎率，这也受到温度和季节性的共同影响。然而，与细网眼袋不同，对于粗网眼（0.36 eV）或大型无脊椎动物介导的（0.13 eV）速率，具有和不具有季节性的模型之间的窝仔分解的温度依赖性没有差异。我们的结论是，间接（非热）的季节性和现场水平的影响发挥了可变的和潜在的强大的作用，在塑造明显的温度依赖性的碎屑分解。这些影响应纳入旨在估计缓慢生态过程固有的温度依赖性的研究。
Understanding the observed temperature dependence of decomposition (i.e., its "apparent" activation energy) requires separation of direct effects of temperature on consumer metabolism (i.e., the "inherent" activation energy) from those driven by indirect seasonal patterns in phenology and biomass, and by longer‐term, climate‐driven shifts in acclimation, adaptation, and community assembly. Such parsing is important because studies that relate temperature to decomposition usually involve multi‐season data and/or spatial proxies for long‐term shifts, and so incorporate these indirect factors. The various effects of such factors can obscure the inherent temperature dependence of detrital processing. Separating the inherent temperature dependence of decomposition from other drivers is important for accurate prediction of the contribution of detritus‐sourced greenhouse gases to climate warming and requires novel approaches to data collection and analysis. Here, we present breakdown rates of red maple litter incubated in coarse‐ and fine‐mesh litterbags (the latter excluding macroinvertebrates) for serial approximately one‐month increments over one year in nine streams along a natural temperature gradient (mean annual: 12.8°–16.4°C) from north Georgia to central Alabama, USA. We analyzed these data using distance‐based redundancy analysis and generalized additive mixed models to parse the dependence of decomposition rates on temperature, seasonality, and shredding macroinvertebrate biomass. Microbial decomposition in fine‐mesh bags was significantly influenced by both temperature and seasonality. Accounting for seasonality corrected the temperature dependence of decomposition rate from 0.25 to 0.08 eV. Shredder assemblage structure in coarse‐mesh bags was related to temperature across both sites and seasons, shifting from “cold” stonefly‐dominated communities to “warm” communities dominated by snails or crayfish. Shredder biomass was not a significant predictor of either coarse‐mesh or macroinvertebrate‐mediated (i.e., coarse‐ minus fine‐mesh) breakdown rates, which were also jointly influenced by temperature and seasonality. Unlike fine‐mesh bags, however, temperature dependence of litter breakdown did not differ between models with and without seasonality for either coarse‐mesh (0.36 eV) or macroinvertebrate‐mediated (0.13 eV) rates. We conclude that indirect (non‐thermal) seasonal and site‐level effects play a variable and potentially strong role in shaping the apparent temperature dependence of detrital breakdown. Such effects should be incorporated into studies designed to estimate inherent temperature dependence of slow ecological processes.