Stem CO2 fluxes in two Sahelian shrub species (Guiera senegalensis and Combretum micranthum)
Stem CO2 fluxes in two Sahelian shrub species (Guiera senegalensis and Combretum micranthum)
复制标题
DOI：
10.1046/j.1365-2435.1998.00156.x
复制
发表时间：
1998-02-01
影响因子：
5.2
通讯作者：
Jarvis, PG
中科院分区：
文献类型：
--
作者：
Levy, PE;Jarvis, PG
1. 本文介绍了西非萨赫勒地区两种灌木（Guiera senegalensis和Combretum microthum）木本茎的二氧化碳通量的测量结果。测量是在切除的茎和原位上进行的。一项实验表明。呼吸速率与茎表面积密切相关，而与茎体积关系不大，因此与形成层和韧皮部有关，而与边材无关。这与几项研究形成对比，其中边材体积似乎是主要成分，差异归因于这里研究的灌木茎直径相对较小。测定了茎部CO2通量对光合光子通量密度(Q)的响应，为茎部的皮质光合作用提供了证据。原位测定了茎呼吸对温度的响应。使用标准指数与温度关系的一种变量来分析数据，R = (R-om + R-og) exp(k T)，其中R为呼吸速率，R-om为0℃时的维持呼吸速率，R-og为0℃时的生长呼吸速率，k为温度系数和Tis温度。假设旱季的数据代表维持呼吸，并用于定义R-om和k。因此，R-og项量化了雨季超过基线水平的呼吸增加，可能归因于生长。4 .丰水期塞内加尔羊草和小红花的R值分别为0.054和0.074 μ mol m(-2) s(-1)，而R-og值在0.061 ~ 0.96 μ mol m(-2) s（-1）之间。在生态系统尺度上，茎呼吸占叶片光合作用的17%，而茎皮质光合作用最多占茎呼吸的11.1%。
1. Measurements are presented of CO2 flux from woody stems of two shrub species in the Sahelian zone of West Africa (Guiera senegalensis and Combretum micranthum). Measurements were made on excised stems and in situ.2. An experiment suggested. that the respiration rate was closely related to the stem surface area but showed little relationship with stem volume, and was therefore associated with the cambium and phloem rather than the sapwood. This contrasts with several studies in which sapwood volume appeared to be the dominant component and the difference is attributed to the comparatively small diameter of stems in the shrubs studied here.3. Measurements were made of the response of stem CO2 flux to photosynthetic photon flux density (Q) and gave evidence of corticular photosynthesis in the stems.4. The response of stem respiration to temperature was determined in situ. The data were analysed using a variant on the standard exponential relationship with temperature, R = (R-om + R-og) exp(k T), where R is respiration rate, R-om is maintenance respiration rate at 0 degrees C, R-og is growth respiration rate at 0 degrees C, k is a temperature coefficient and Tis temperature. Data from the dry season were assumed to represent maintenance respiration and used to define R-om and k. The R-og term thus quantifies the increase in respiration during the wet season beyond this baseline level, presumably attributable to growth. Values of R were 0.054 and 0.074 mu mol m(-2) s(-1) in G. senegalensis and C. micranthum, respectively, whilst R-og ranged between 0.061 and 0.96 mu mol m(-2) s(-1) during the wet season.5. At ecosystem scale On an annual basis, stem respiration represented 17% of leaf photosynthesis, whilst corticular photosynthesis was at most 11.1% of stem respiration.