Wood CO(2) efflux and foliar respiration for Eucalyptus in Hawaii and Brazil.
Wood CO(2) efflux and foliar respiration for Eucalyptus in Hawaii and Brazil.
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DOI：
10.1093/treephys/tpp059
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发表时间：
2009-10
期刊：
影响因子：
4
通讯作者：
M. G. Ryan;M. Cavaleri;A. Almeida;R. Penchel;R. Senock;José Luiz Stape
中科院分区：
文献类型：
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作者：
M. G. Ryan;M. Cavaleri;A. Almeida;R. Penchel;R. Senock;José Luiz Stape
我们对夏威夷桉树木材的CO（2）排放量进行了7年的测量，并将这些测量结果与巴西3年和4年半的桉树进行了比较。在夏威夷，从2年到5年，每单位生物量木材的CO（2）排放量下降了约10倍，是树木生长下降的两倍。巴西树木的CO（2）排放量比生长速度相似的夏威夷树木低8- 10倍。从夏威夷木材CO（2）排放量计算的生长和维持呼吸系数随树龄和大小而下降（生长系数从1年生的0.4molC流出molC（-1）木材生长下降到6年生的0.1molC流出molC（-1）木材生长;保持系数为0.006至0.001微摩尔C（摩尔C生物量）（-1）s（-1），在20 ℃下相同时间段）。这些结果表明，干扰CO（2）通过树皮流出，抑制CO（2）从呼吸流出。我们还比较了夏威夷3年和7年生树木地上木质部分的生物量分数和木材CO（2）流出量，以估计地面附近的集中测量可能会使木材CO（2）流出量的林分水平估计值产生偏差。夏威夷3年生桉树比7年生桉树具有更高的直径< 0.5 cm的树枝比例和更低的树干生物量比例。生物量特定的CO（2）外推到树在1.4米处测得的流出量可能会使树水平的估计偏差约50%，假设没有树皮光合作用的再固定。然而，两个树的大小的偏差没有差异。在巴西和夏威夷的可比处理中，每单位氮的叶片呼吸是相同的（20 ℃时为4.2微摩尔C mol N（-1）s（-1））。
We measured CO(2) efflux from wood for Eucalyptus in Hawaii for 7 years and compared these measurements with those on three- and four-and-a-half-year-old Eucalyptus in Brazil. In Hawaii, CO(2) efflux from wood per unit biomass declined approximately 10x from age two to age five, twice as much as the decline in tree growth. The CO(2) efflux from wood in Brazil was 8-10x lower than that for comparable Hawaii trees with similar growth rates. Growth and maintenance respiration coefficients calculated from Hawaii wood CO(2) efflux declined with tree age and size (the growth coefficient declined from 0.4 mol C efflux mol C(-1) wood growth at age one to 0.1 mol C efflux mol C(-1) wood growth at age six; the maintenance coefficient from 0.006 to 0.001 micromol C (mol C biomass)(-1) s(-1) at 20 degrees C over the same time period). These results suggest interference with CO(2) efflux through bark that decouples CO(2) efflux from respiration. We also compared the biomass fractions and wood CO(2) efflux for the aboveground woody parts for 3- and 7-year-old trees in Hawaii to estimate how focusing measurements near the ground might bias the stand-level estimates of wood CO(2) efflux. Three-year-old Eucalyptus in Hawaii had a higher proportion of branches < 0.5 cm in diameter and a lower proportion of stem biomass than did 7-year-old trees. Biomass-specific CO(2) efflux measured at 1.4 m extrapolated to the tree could bias tree level estimates by approximately 50%, assuming no refixation from bark photosynthesis. However, the bias did not differ for the two tree sizes. Foliar respiration was identical per unit nitrogen for comparable treatments in Brazil and Hawaii (4.2 micromol C mol N(-1) s(-1) at 20 degrees C).