Dray Matthew W, Crowther Thomas W, Thomas Stephen M, A'Bear A Donald, Godbold Douglas L, Ormerod Steve J, Hartley Susan E, Jones T Hefin
Cardiff School of Biosciences, Cardiff University, Cardiff, United Kingdom.
Cardiff School of Biosciences, Cardiff University, Cardiff, United Kingdom ; School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, United States of America.
PLoS One. 2014 Jan 22;9(1):e86246. doi: 10.1371/journal.pone.0086246. eCollection 2014.
Elevated atmospheric CO2 can change foliar tissue chemistry. This alters leaf litter palatability to macroinvertebrate detritivores with consequences for decomposition, nutrient turnover, and food-web structure. Currently there is no consensus on the link between CO2 enrichment, litter chemistry, and macroinvertebrate-mediated leaf decomposition. To identify any unifying mechanisms, we presented eight invertebrate species from aquatic and terrestrial ecosystems with litter from Alnus glutinosa (common alder) or Betula pendula (silver birch) trees propagated under ambient (380 ppm) or elevated (ambient +200 ppm) CO2 concentrations. Alder litter was largely unaffected by CO2 enrichment, but birch litter from leaves grown under elevated CO2 had reduced nitrogen concentrations and greater C/N ratios. Invertebrates were provided individually with either (i) two litter discs, one of each CO2 treatment ('choice'), or (ii) one litter disc of each CO2 treatment alone ('no-choice'). Consumption was recorded. Only Odontocerum albicorne showed a feeding preference in the choice test, consuming more ambient- than elevated-CO2 birch litter. Species' responses to alder were highly idiosyncratic in the no-choice test: Gammarus pulex and O. albicorne consumed more elevated-CO2 than ambient-CO2 litter, indicating compensatory feeding, while Oniscus asellus consumed more of the ambient-CO2 litter. No species responded to CO2 treatment when fed birch litter. Overall, these results show how elevated atmospheric CO2 can alter litter chemistry, affecting invertebrate feeding behaviour in species-specific ways. The data highlight the need for greater species-level information when predicting changes to detrital processing-a key ecosystem function-under atmospheric change.
大气中二氧化碳浓度升高会改变叶片组织化学性质。这会改变落叶对大型无脊椎动物分解者的适口性，进而影响分解过程、养分周转和食物网结构。目前，关于二氧化碳浓度升高、凋落物化学性质与大型无脊椎动物介导的叶片分解之间的联系尚无定论。为了确定任何统一的机制，我们为来自水生和陆地生态系统的8种无脊椎动物提供了来自在环境二氧化碳浓度（380 ppm）或升高的二氧化碳浓度（环境浓度 +200 ppm）下生长的欧洲桤木（普通桤木）或垂枝桦（银桦）树的落叶。桤木落叶在很大程度上不受二氧化碳浓度升高的影响，但在高二氧化碳浓度下生长的桦树落叶氮浓度降低，碳氮比更高。分别为无脊椎动物提供以下两种情况之一：（i）两个落叶圆盘，每种二氧化碳处理各一个（“选择”），或（ii）仅每种二氧化碳处理的一个落叶圆盘（“无选择”）。记录消耗量。在选择试验中，只有白角齿角石表现出取食偏好，消耗的环境二氧化碳浓度下的桦树落叶比高二氧化碳浓度下的更多。在无选择试验中，物种对桤木的反应高度特异：蚤状钩虾和白角齿角石消耗的高二氧化碳浓度下的落叶比环境二氧化碳浓度下的更多，表明存在补偿性取食，而鼠妇消耗的环境二氧化碳浓度下的落叶更多。喂食桦树落叶时，没有物种对二氧化碳处理有反应。总体而言，这些结果表明大气中二氧化碳浓度升高如何改变落叶化学性质，以物种特异性方式影响无脊椎动物的取食行为。数据突出表明，在预测大气变化下碎屑处理（一项关键的生态系统功能）的变化时，需要更多物种层面的信息。
