Characterizing Growing Season Length of Subtropical Coniferous Forests with a Phenological Model
Characterizing Growing Season Length of Subtropical Coniferous Forests with a Phenological Model
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DOI：
10.3390/f12010095
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发表时间：
2021-01
期刊：
影响因子：
2.9
通讯作者：
Yuan-Bo Gong;C. Staudhammer;S. Wiesner;G. Starr;Yinlong Zhang
中科院分区：
文献类型：
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作者：
Yuan-Bo Gong;C. Staudhammer;S. Wiesner;G. Starr;Yinlong Zhang
在全球气候变化的背景下，了解植物物候变化是人们非常关注的问题。物候模型可以帮助理解和预测生长季节的变化，并可以用涡度协方差(EC)技术估计的总初级生产力(GPP)进行参数化。这项研究使用了美国东南部三个土壤持水能力不同的成熟亚热带长叶松林九年来来自EC的GPP数据，并结合特定地点的微气象数据对基于光合作用的物候模型进行了参数化。我们评估了天气条件和规定的火如何导致生态系统物候过程的变化。结果表明，土壤水分有效性对植物物候有一定的影响，土壤水分有效性越大，生长季越长。我们还观察到，规定火是该地区一种常见的森林管理活动，对物候过程的影响有限。休眠季节火灾对不同地点的物候过程没有显著影响，但我们观察到火灾和非火灾年份在生长季开始(SOS)方面的差异。火烧使SOS延迟10d±5d(SE)，土壤水分有效性越高，这种影响越明显，平均延长SOS 18d。火也与春季物候对辐射和气温的敏感性增加有关。我们发现，年际气候变化和周期性天气异常(洪水、短期干旱和长期干旱)对年度生态系统物候过程的控制比规定的火灾更大。当短期夏季干旱后可用水增加时，生长季就延长了。随着未来气候变化，美国东南部亚热带地区预计将经历更频繁的短期干旱，这可能会缩短该地区的生长季，并导致长叶松生态系统的固碳能力下降。
Understanding plant phenological change is of great concern in the context of global climate change. Phenological models can aid in understanding and predicting growing season changes and can be parameterized with gross primary production (GPP) estimated using the eddy covariance (EC) technique. This study used nine years of EC-derived GPP data from three mature subtropical longleaf pine forests in the southeastern United States with differing soil water holding capacity in combination with site-specific micrometeorological data to parameterize a photosynthesis-based phenological model. We evaluated how weather conditions and prescribed fire led to variation in the ecosystem phenological processes. The results suggest that soil water availability had an effect on phenology, and greater soil water availability was associated with a longer growing season (LOS). We also observed that prescribed fire, a common forest management activity in the region, had a limited impact on phenological processes. Dormant season fire had no significant effect on phenological processes by site, but we observed differences in the start of the growing season (SOS) between fire and non-fire years. Fire delayed SOS by 10 d ± 5 d (SE), and this effect was greater with higher soil water availability, extending SOS by 18 d on average. Fire was also associated with increased sensitivity of spring phenology to radiation and air temperature. We found that interannual climate change and periodic weather anomalies (flood, short-term drought, and long-term drought), controlled annual ecosystem phenological processes more than prescribed fire. When water availability increased following short-term summer drought, the growing season was extended. With future climate change, subtropical areas of the Southeastern US are expected to experience more frequent short-term droughts, which could shorten the region’s growing season and lead to a reduction in the longleaf pine ecosystem’s carbon sequestration capacity.