Stable carbon isotopes in tree rings indicate improved water use efficiency and drought responses of a tropical dry forest tree species
Stable carbon isotopes in tree rings indicate improved water use efficiency and drought responses of a tropical dry forest tree species
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DOI：
10.1007/s00468-010-0474-1
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发表时间：
2011-02-01
影响因子：
2.3
通讯作者：
Hietz, Peter
中科院分区：
文献类型：
--
作者：
Brienen, Roel J. W.;Wanek, Wolfgang;Hietz, Peter
了解热带树木对增加[CO2]和气候变化的响应非常重要，因为热带森林在碳和水文循环中发挥着重要作用。利用树木年轮的稳定碳同位素（δ C-13）研究了墨西哥南部热带干燥森林树种含水含水树（Mimosa acantholoba）对大气CO2变化和气候变化的生理响应。基于树木年轮δ c -13的年记录，我们计算了内在水分利用效率（W (i)）和胞间[CO2] （c (i)）。我们的研究结果表明，在过去40年里，树木对大气[CO2]的增加反应强烈；W (i)急剧增加了40%，而c (i)基本保持不变。维持恒定的c (i)表明，光合速率不太可能因更高的[CO2]而增加，而W (i)的改善可能是由于气孔导度的降低。这可能对水文循环产生重大影响。c (i)的年际变化与年总降雨量密切相关（r = 0.70），不受温度、太阳辐射或云量的影响。我们的研究结果表明，热带干燥森林树木年轮中的δ C-13可能是评估树木对增加[CO2]和气候变化的长期响应的有力工具。
Understanding the responses of tropical trees to increasing [CO2] and climate change is important as tropical forests play an important role in carbon and hydrological cycles. We used stable carbon isotopes (delta C-13) in tree rings to study the physiological responses of a tropical dry forest tree species in southern Mexico, Mimosa acantholoba to changes in atmospheric [CO2] and variation in climate. Based on annual records of tree ring delta C-13, we calculated intrinsic water use efficiency (W (i)) and intercellular [CO2] (c (i)). Our results showed that trees responded strongly to the increase in atmospheric [CO2] over the last four decades; W (i) increased dramatically by 40%, while c (i) remained largely constant. The maintenance of a constant c (i) indicates that photosynthetic rates are unlikely to have increased in response to higher [CO2], and that improvements in W (i) are probably due to a reduction in stomatal conductance. This may have large consequences for the hydrological cycle. Inter-annual variation in c (i) was strongly correlated with total annual rainfall (r = 0.70), and not influenced by temperature, solar radiation or cloud cover. Our results show that delta C-13 in tree rings of tropical dry forest trees may be a powerful tool to evaluate long-term responses of trees to increasing [CO2] and to variation in climate.