Forest tree growth response to hydroclimate variability in the southern Appalachians

Abstract

Climate change will affect tree species growth and distribution; however, under the same climatic conditions species may differ in their response according to site conditions. We evaluated the climate-driven patterns of growth for six dominant deciduous tree species in the southern Appalachians. We categorized species into two functional groups based on their stomatal regulation and xylem architecture: isohydric, diffuse porous and anisohydric, ring porous. We hypothesized that within the same climatic regime: (i) species-specific differences in growth will be conditional on topographically mediated soil moisture availability; (ii) in extreme drought years, functional groups will have markedly different growth responses; and (iii) multiple hydroclimate variables will have direct and indirect effects on growth for each functional group. We used standardized tree-ring chronologies to examine growth of diffuse-porous (Acer, Liriodendron, and Betula) and ring-porous (Quercus) species vs. on-site climatic data from 1935 to 2003. Quercus species growing on upslope sites had higher basal area increment (BAI) than Quercus species growing on mesic, cove sites; whereas, Acer and Liriodendron had lower BAI on upslope compared to cove sites. Diffuse-porous species were more sensitive to climate than ring porous, especially during extreme drought years. Across functional groups, radial growth was more sensitive to precipitation distribution, such as small storms and dry spell length (DSL), rather than the total amount of precipitation. Based on structural equation modeling, diffuse-porous species on upslope sites were the most sensitive to multiple hydroclimate variables (r(2) = 0.46), while ring-porous species on upslope sites were the least sensitive (r(2) = 0.32). Spring precipitation, vapor pressure deficit, and summer storms had direct effects on summer AET/P, and summer AET/P, growing season small storms and DSL partially explained growth. Decreasing numbers of small storms and extending the days between rainfall events will result in significant growth reduction, even in regions with relatively high total annual rainfall.

Relationships between Tree Age and Climate Sensitivity of Radial Growth in Different Drought Conditions of Qilian Mountains, Northwestern China

“…The prediction of forest dynamics and policy-making about forest management and protection are often based on the analysis of radial growth-climate relationships [1,2]. The responses of radial growth to climate varied with the regional variability in moisture conditions [3].…”

Climate Change Sensitivity of Multi-Species Afforestation in Semi-Arid Benin

“…Although climate-growth relationships have been quantified for mature trees of several tropical and temperate species [9,29,68], much remains unknown regarding the sensitivity of tree growth during the early stages of development in semi-arid areas. In this study, we used a generic approach of climate sensitivity assessment that combines field experiments and modelling as an alternative to the traditional dendrochronology technique.…”

“…Although trees are central to many climate change adaptation and mitigation strategies, they are vulnerable (particularly in their early growth), to variation in solar radiation, rainfall, and temperature as determinants of potential evapotranspiration (ET 0 ). Changes in these climatic variables, particularly temperature increases and precipitation shortages leading to higher frequencies of extreme weather events (i.e., severe drought and intense rainfall), are expected to affect tree growth and challenge the sustainable management of forests and tree plantations [8][9][10].…”

“…Dendrochronology has been successfully used to analyze temporal and spatial climate-growth relationships for tree and shrub species in tropical and temperate forests [9,23,27,28]. However, dendrochronological applications may be inappropriate for young trees and compromised by problematic anatomical features such as missing, vague, discontinuous and false rings common in tropical species [29,30], thereby also restricting the use of biomass increments derived from tree-ring series [31,32].…”

Drought response of upland oak (Quercus L.) species in Appalachian hardwood forests of the southeastern USA

“…In a recent study, Elliott et al (2015) analyzed the variability of drought response of six prominent Appalachian hardwood species and observed the individual tree drought-growth relationships varied according to xylem architecture, with diffuse porous species (e.g., yellow-poplar (Liriodendron tulipifera L.), red maple (Acer rubrum L.), sweet birch (Betula lenta L.)) more susceptible to reduced growth than ring-porous oak (Quercus L.) species. Similarly, utilizing US Forest Inventory and Analysis data, Brzostek et al (2014) reported that mesophytic species such as the yellow-poplar and sugar maple (Acer saccharum Marsh.…”