Foliar and ecosystem respiration in an old-growth tropical rain forest
Foliar and ecosystem respiration in an old-growth tropical rain forest
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DOI：
10.1111/j.1365-3040.2008.01775.x
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发表时间：
2008-04-01
影响因子：
7.3
通讯作者：
Ryan, Michael G.
中科院分区：
文献类型：
--
作者：
Cavaleri, Molly A.;Oberbauer, Steven F.;Ryan, Michael G.
叶片呼吸是生态系统呼吸的主要组成部分，但在热带森林中，由于叶面积指数(LAI)的间接估计，外推往往是不确定的。在哥斯达黎加的一片古老的热带雨林中，人们使用便携式仪器直接测量了52个垂直样带的叶面积指数和夜间叶呼吸。在这项研究中，我们(1)探讨了结构、功能和环境变量对叶片呼吸的影响；(2)外推生态系统的叶片呼吸；(3)估计生态系统的呼吸。叶片呼吸温度响应在植物功能群内是恒定的，叶片形态驱动了呼吸和叶片养分在冠层内的大部分变异。单位地面积的叶呼吸速率为3.5+/-0.2亩·m-2·S(-1)，生态系统呼吸速率为9.4+/-0·5亩·CO2m(-2)·S(-1)[土壤=41%；叶=37%；木本=14%；粗木质碎屑=7%]。当用厄尔尼诺南方涛动(ENSO)年的温度模拟时，叶片呼吸比用正常年的温度模拟时高9%，这在该森林的碳汇与碳源行为的范围内。我们从组分通量估计的生态系统呼吸比同一森林的夜间净生态系统交换高33%，这表明仅基于涡流通量测量报告热带雨林巨大碳汇的研究可能是错误的。
Foliar respiration is a major component of ecosystem respiration, yet extrapolations are often uncertain in tropical forests because of indirect estimates of leaf area index (LAI). A portable tower was used to directly measure LAI and night-time foliar respiration from 52 vertical transects throughout an old-growth tropical rain forest in Costa Rica. In this study, we (1) explored the effects of structural, functional and environmental variables on foliar respiration; (2) extrapolated foliar respiration to the ecosystem; and (3) estimated ecosystem respiration. Foliar respiration temperature response was constant within plant functional group, and foliar morphology drove much of the within-canopy variability in respiration and foliar nutrients. Foliar respiration per unit ground area was 3.5 +/- 0.2 mu mol CO2 m(-2) s(-1), and ecosystem respiration was 9.4 +/- 0.5 mu mol CO2 m(-2) s(-1) [soil = 41%; foliage = 37%; woody = 14%; coarse woody debris (CWD) = 7%]. When modelled with El Nino Southern Oscillation (ENSO) year temperatures, foliar respiration was 9% greater than when modelled with temperatures from a normal year, which is in the range of carbon sink versus source behaviour for this forest. Our ecosystem respiration estimate from component fluxes was 33% greater than night-time net ecosystem exchange for the same forest, suggesting that studies reporting a large carbon sink for tropical rain forests based solely on eddy flux measurements may be in error.