Unthinned slow-growing ponderosa pine (Pinus ponderosa) trees contain muted isotopic signals in tree rings as compared to thinned trees
Unthinned slow-growing ponderosa pine (Pinus ponderosa) trees contain muted isotopic signals in tree rings as compared to thinned trees
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与间伐的树木相比，未间伐的生长缓慢的美国黄松 (Pinus ponderosa) 树轮中的同位素信号较弱
DOI：
10.1007/s00468-014-1016-z
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
McDowell
中科院分区：
文献类型：
--
作者：
Brooks;Bauhus;Kohler;McDowell
为了研究间伐后高生长速率的生理过程，我们分析了12株美国黄松木材中的氧同位素值（δ 18 Ow（美国黄松）树木从控制，中度和重度间伐林分，并将其与木材为基础的估计碳同位素歧视（13C），断面积增量（BAI），和气体交换。我们发现，（重）变薄导致的转变和增加的年际变化的稳定碳和氧同位素比值相对于控制在整个第一个后变薄十年。敏感性分析结果表明，在重度间伐林分中，气孔导度（gs）的增加和水源水的差异是δ18Owshift的可能原因。我们利用环境和生理数据模拟了所有处理的δ18Owof树木的年际变化，发现与对照林分相比，间伐林分中树木δ 18Owof年际方差的显著增加与δ 18Owof对环境条件变化的更大响应有关。基于模型的结果，木材同位素在生长缓慢的控制树木的气候反应更温和的可能是减少碳汇强度的结果，导致更高程度的混合以前存储和新鲜的同化物相比，快速增长的树木在变薄的立场。另外，δ 18 Ow对对照林分树木气候变化的微弱响应可能是由于对照林分中已知影响δ 18 Ow的生理过程（光合作用、蒸腾作用）变化很小。
Key messageThe muted wood isotopic signal in slow-growing trees of unthinned stands indicates lower responsiveness to changing environmental conditions compared to fast-growing trees in thinned stands.AbstractTo examine the physiological processes associated with higher growth rates after thinning, we analyzed the oxygen isotopic values in wood (δ18Ow) of 12 ponderosa pine (Pinus ponderosa) trees from control, moderately, and heavily thinned stands and compared them with wood-based estimates of carbon isotope discrimination (∆13C), basal area increment (BAI), and gas exchange. We found that (heavy) thinning led to shifts and increased inter-annual variability of both stable carbon and oxygen isotope ratios relative to the control throughout the first post-thinning decade. Results of a sensitivity analysis suggested that both an increase in stomatal conductance (gs) and differences in source water among treatments are equally probable causes of the δ18Owshift in heavily thinned stands. We modeled inter-annual changes in δ18Owof trees from all treatments using environmental and physiological data and found that the significant increase in δ18Owinter-annual variance was related to greater δ18Owresponsiveness to changing environmental conditions for trees in thinned stands when compared to control stands. Based on model results, the more muted climatic response of wood isotopes in slow-growing control trees is likely to be the consequence of reduced carbon sink strength causing a higher degree of mixing of previously stored and fresh assimilates when compared to faster-growing trees in thinned stands. Alternatively, the muted response of δ18Owto climatic variation of trees in the control stand may result from little variation in the control stand in physiological processes (photosynthesis, transpiration) that are known to affect δ18Ow.
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影响因子：
2.7
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影响因子：
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