Hirschel G, Körner C, Arnone Iii J A
Department of Botany, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland, , , , , , CH.
Oecologia. 1997 Apr;110(3):387-392. doi: 10.1007/s004420050173.
Though field data for naturally senesced leaf litter are rare, it is commonly assumed that rising atmospheric CO concentrations will reduce leaf litter quality and decomposition rates in terrestrial ecosystems and that this will lead to decreased rates of nutrient cycling and increased carbon sequestration in native ecosystems. We generally found that the quality of␣naturally senesced leaf litter (i.e. concentrations of C, N and lignin; C:N, lignin:N) of a variety of native plant species produced in alpine, temperate and tropical communities maintained at elevated CO (600-680 μl l) was not significantly different from that produced in similar communities maintained at current ambient CO concentrations (340-355 μl l). When this litter was allowed to decompose in situ in a humid tropical forest in Panama (Cecropia peltata, Elettaria cardamomum, and Ficus benjamina, 130 days exposure) and in a lowland temperate calcareous grassland in Switzerland (Carex flacca and a graminoid species mixture; 261 days exposure), decomposition rates of litter produced under ambient and elevated CO did not differ significantly. The one exception to this pattern occurred in the high alpine sedge, Carex curvula, growing in the Swiss Alps. Decomposition of litter produced in situ under elevated CO was significantly slower than that of litter produced under ambient CO (14% vs. 21% of the initial litter mass had decomposed over a 61-day exposure period, respectively). Overall, our results indicate that relatively little or no change in leaf litter quality can be expected in plant communities growing under soil fertilities common in many native ecosystems as atmospheric CO concentrations continue to rise. Even in situations where small reductions in litter quality do occur, these may not necessarily lead to significantly slower rates of decomposition. Hence in many native species in situ litter decomposition rates, and the time course of decomposition, may remain relatively unaffected by rising CO.
虽然关于自然衰老落叶的实地数据很少见，但人们普遍认为，大气中二氧化碳浓度上升会降低陆地生态系统中落叶的质量和分解速率，进而导致养分循环速率下降，原生生态系统中的碳固存增加。我们普遍发现，在二氧化碳浓度升高（600 - 680 μl l）条件下，在高山、温带和热带群落中生长的多种原生植物物种的自然衰老落叶质量（即碳、氮和木质素浓度；碳氮比、木质素氮比），与在当前环境二氧化碳浓度（340 - 355 μl l）下生长的类似群落中产生的落叶质量没有显著差异。当这些落叶在巴拿马的潮湿热带森林（赛氏榕、小豆蔻和垂叶榕，暴露130天）以及瑞士的低地温带钙质草原（苔草和禾本科植物混合种；暴露261天）中就地分解时，在环境二氧化碳浓度和升高的二氧化碳浓度条件下产生的落叶分解速率没有显著差异。这种模式的一个例外发生在生长于瑞士阿尔卑斯山的高山莎草——弯叶苔草上。在二氧化碳浓度升高条件下就地产生的落叶分解速度明显慢于在环境二氧化碳浓度下产生的落叶（在61天的暴露期内，分别有14%和21%的初始落叶质量分解）。总体而言，我们的结果表明，随着大气二氧化碳浓度持续上升，在许多原生生态系统常见的土壤肥力条件下生长的植物群落中，落叶质量预计相对变化很小或没有变化。即使在落叶质量确实出现小幅下降的情况下，这些下降也不一定会导致分解速率显著减慢。因此，对于许多原生物种来说，就地落叶分解速率以及分解的时间进程可能相对不受二氧化碳上升的影响。
