Drought impact on forest growth and mortality in the southeast USA: an analysis using Forest Health and Monitoring data
Drought impact on forest growth and mortality in the southeast USA: an analysis using Forest Health and Monitoring data
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DOI：
10.1890/08-0330.1
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发表时间：
2009-04-01
影响因子：
5
通讯作者：
Rieck, James R.
中科院分区：
文献类型：
--
作者：
Klos, Ryan J.;Wang, G. Geoff;Rieck, James R.
据预测，在许多气候变化情景下，干旱的频率和强度都将增加。因此，必须了解森林对潜在气候变化的反应，以努力减轻不利影响。本研究旨在探讨不同干旱强度对树木生长和死亡的区域性影响。具体而言，我们调查了在不同的干旱和林分条件下，1991-2005年的森林健康和监测（FHM）从亚拉巴马，格鲁吉亚和弗吉尼亚州的地块数据在整个美国东南部的增长和死亡率的变化。干旱的影响进行了研究，为三个物种组（松树，橡树，中生植物物种）使用帕尔默干旱严重程度指数（PDSI）作为干旱严重程度的指标。林分变量，包括总断面积，总树密度，树种丰富度，坡度，和林分年龄，被用来解释不同的林分条件下的干旱效应。松树和中生植物物种表现出显着的增长率随着干旱的严重程度。然而，没有显着差异的增长速度内观察到的橡树种组。在非干旱类的平均死亡率显着低于其他三个干旱类，其中没有发现显着差异，松树和中生植物物种。平均死亡率并没有显着差异干旱类橡树。总断面积，总树密度，林分年龄呈负相关的增长和死亡率呈正相关，这表明，年龄较大，密度高的林分更容易受到干旱的影响。断面积对生长的影响随着干旱严重程度的橡树和中生植物物种组。树种丰富度呈负相关的死亡率为松和中生植物物种组，表明与更多的物种遭受较少的死亡率。坡度与中生植物物种组内的死亡率呈正相关，其影响随干旱严重程度的增加而增加，表明在严重干旱条件下，坡度较大的站点死亡率较高。我们的研究结果表明，松树和中生植物物种是敏感的干旱，而橡树是耐旱。所观察到的物种群之间的差异生长和死亡率可能会改变美国东南部的物种组成。S.如果气候变化导致干旱事件变得更加频繁和/或严重，森林也会受到影响。在我们的研究中观察到的林分条件对干旱响应的显着影响也表明，森林管理可以作为一种工具，以减轻干旱的影响。
Drought frequency and intensity has been predicted to increase under many climate change scenarios. It is therefore critical to understand the response of forests to potential climate change in an effort to mitigate adverse impacts. The purpose of this study was to explore the regional effects of different drought severities on tree growth and mortality. Specifically, we investigated changes in growth and mortality rates across the southeastern United States under various drought and stand conditions using 1991-2005 Forest Health and Monitoring (FHM) plot data from Alabama, Georgia, and Virginia. Drought effects were examined for three species groups (pines, oaks, and mesophytic species) using the Palmer drought severity index (PDSI) as an indicator of drought severity. Stand variables, including total basal area, total tree density, tree species richness, slope, and stand age, were used to account for drought effects under varying stand conditions. The pines and mesophytic species exhibited significant reductions in growth rate with increasing drought severity. However, no significant difference in growth rate was observed within the oak species group. Mean mortality rates within the no-drought class were significantly lower than those within the other three drought classes, among which no significant differences were found, for both pines and mesophytic species. Mean mortality rates were not significantly different among drought classes for oaks. Total basal area, total tree density, and stand age were negatively related to growth and positively related to mortality, which suggests that older and denser stands are more susceptible to drought damage. The effect of basal area on growth increased with drought severity for the oak and mesophytic species groups. Tree species richness was negatively related to mortality for the pine and mesophytic species groups, indicating that stands with more species suffer less mortality. Slope was positively related to mortality within the mesophytic species group, and its effect increased with drought severity, indicating a higher mortality on sites of greater slope during severe-drought conditions. Our findings indicate that pines and mesophytic species are sensitive to drought, while oaks are tolerant of drought. The observed differential growth and mortality rates among species groups may alter the species composition of southeastern U. S. forests if drought episodes become more frequent and/or intense due to climate change. The significant effects of stand conditions on drought responses observed in our study also suggest that forest management may be used as a tool to mitigate drought effects.