Wood CO2 efflux in a primary tropical rain forest
Wood CO2 efflux in a primary tropical rain forest
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DOI：
10.1111/j.1365-2486.2006.01269.x
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发表时间：
2006-12-01
影响因子：
11.6
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.
热带森林光合作用和植物呼吸作用之间的平衡可能会对全球碳循环产生重大影响。木质组织CO2流出是植物呼吸总量的主要组成部分，但由于在上层冠层和景观中的采样不佳，生态系统尺度速率的估计是不确定的。为了克服这些问题，我们使用了一个便携式脚手架塔来测量木本组织CO2从地面到冠层顶部的流出量在一个主要的热带雨林在哥斯达黎加不同的坡度和土壤磷含量的网站范围。本研究的目的是：（1）确定是否使用表面积，体积，或生物量建模和外推木材CO2排放，（2）确定木材CO2排放量是否随季节变化，（3）确定木材CO2排放量是否随功能组，冠层高度，土壤肥力或坡度变化，（4）外推木材CO2排放到森林。小直径木质组织（< 10 cm）的CO2排放量与表面积有关，而> 10 cm茎的CO2排放量与表面积和体积均有关。木材CO2排放量在2年内没有季节性的证据。在25度（F-A）每单位木材表面积的CO2排放量最高的固氮优势树种五针草macroloba，其次是其他树种，藤本植物，然后棕榈树。小直径F-A随高度的增加而急剧增加，大直径F-A随直径的增加而增加。土壤磷素和坡度对F-A的影响较小，但较为复杂。每单位地面面积的木材CO2排放量为1.34 +/- 0.36 μ mol m（-2）s（-1），或508 +/- 135 g C m（-2）yr（-1）。小直径的木材，只有15%的总木质生物量，占70%的总木质组织CO2流出的森林，而藤本植物，只有3%的总木质生物量，贡献了四分之一的总木材CO2流出。
The balance between photosynthesis and plant respiration in tropical forests may substantially affect the global carbon cycle. Woody tissue CO2 efflux is a major component of total plant respiration, but estimates of ecosystem-scale rates are uncertain because of poor sampling in the upper canopy and across landscapes. To overcome these problems, we used a portable scaffolding tower to measure woody tissue CO2 efflux from ground level to the canopy top across a range of sites of varying slope and soil phosphorus content in a primary tropical rain forest in Costa Rica. The objectives of this study were to: (1) determine whether to use surface area, volume, or biomass for modeling and extrapolating wood CO2 efflux, (2) determine if wood CO2 efflux varied seasonally, (3) identify if wood CO2 efflux varied by functional group, height in canopy, soil fertility, or slope, and (4) extrapolate wood CO2 efflux to the forest. CO2 efflux from small diameter woody tissue (< 10 cm) was related to surface area, while CO2 efflux from stems > 10 cm was related to both surface area and volume. Wood CO2 efflux showed no evidence of seasonality over 2 years. CO2 efflux per unit wood surface area at 25 degrees (F-A) was highest for the N-fixing dominant tree species Pentaclethra macroloba, followed by other tree species, lianas, then palms. Small diameter F-A increased steeply with increasing height, and large diameter F-A increased with diameter. Soil phosphorus and slope had slight, but complex effects on F-A. Wood CO2 efflux per unit ground area was 1.34 +/- 0.36 mu mol m(-2) s(-1), or 508 +/- 135 g C m(-2) yr(-1). Small diameter wood, only 15% of total woody biomass, accounted for 70% of total woody tissue CO2 efflux from the forest; while lianas, only 3% of total woody biomass, contributed one-fourth of the total wood CO2 efflux.