Inter-annual variation in the response of leaf-out onset to soil moisture increase in a teak plantation in northern Thailand
Inter-annual variation in the response of leaf-out onset to soil moisture increase in a teak plantation in northern Thailand
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DOI：
10.1007/s00484-013-0784-2
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发表时间：
2014-01
影响因子：
3.2
通讯作者：
N. Yoshifuji;Yasunori Igarashi;N. Tanaka;Katsunori Tanaka;Takanori Sato;C. Tantasirin;Masakazu Suzuki
中科院分区：
文献类型：
--
作者：
N. Yoshifuji;Yasunori Igarashi;N. Tanaka;Katsunori Tanaka;Takanori Sato;C. Tantasirin;Masakazu Suzuki
为了了解年际气候变化对植被-大气质量和能量交换的影响，有必要探索叶落叶开始时间的变化以响应气候波动。我们基于12年的叶面积指数和树液流量测量，研究了泰国北部一个柚木种植园的叶脱落和蒸腾开始日期对土壤水分的响应。叶片脱落和蒸腾开始的时间在不同年份之间差异最大可达40天，并取决于0-0.6m土层相对可提取水(Θ)大于0.2时的初始日期，这与我们以前的结果一致。我们的新发现是，相对于Θ&> 0.2时的初始日期，叶片脱落和蒸腾开始的延迟与Θ&> 0.2时的初始日期成线性增加。在Θ>； 0.2出现在3月份(旱季后期)的年份中，延迟时间大约为2000万天--由于季风前的强降雨，这比往常要早得多--而Θ>； 0.2在5月出现的年份几乎不会延迟。这一延迟表明了其他因素对叶片脱落开始的影响，这控制了叶片脱落对土壤水分增加的反应延迟。这些结果增加了我们对热带地区年际气候变化所发生的叶片物候变化的模式和程度的了解，特别是在热带地区，这种研究是必要的。
To understand the impact of inter-annual climate change on vegetation-atmosphere mass and energy exchanges, it has become necessary to explore changes in leaf-out onset in response to climatic fluctuations. We examined the response of leaf-out and transpiration onset dates to soil moisture in a teak plantation in northern Thailand based on a 12-year leaf area index and sap flow measurements. The date of leaf-out and transpiration onset varied between years by up to 40 days, and depended on the initial date when the relative extractable water in a soil layer of 0–0.6 m (Θ) was greater than 0.2 being consistent with our previous results. Our new finding is that the delay in leaf-out and transpiration onset relative to the initial date whenΘ> 0.2 increases linearly as the initial date on whichΘ> 0.2 becomes earlier. The delay spans about 20 days in years whenΘ> 0.2 occurs in March (the late dry season)—much earlier than usual because of heavy pre-monsoon rainfalls—while there is little delay in years whenΘ> 0.2 occurs in May. This delay indicates the influence of additional factors on leaf-out onset, which controls the delay in the response of leaf-out to soil moisture increase. The results increased our knowledge about the pattern and extent of the changes in leaf phenology that occur in response to the inter-annual climate variation in tropical regions, where, in particular, such research is needed.