Abstract
Dendroclimatology has focused mainly on the tree growth response to atmospheric variables. However, the roots of trees directly sense the “underground climate,” which can be expected to be no less important to tree growth. Data from two meteorological stations approximately 140 km apart in southern Siberia were applied to characterize the spatiotemporal dynamics of soil temperature and the statistical relationships of soil temperature to the aboveground climate and tree-ring width (TRW) chronologies of Larix sibirica Ledeb. from three forest–steppe stands. Correlation analysis revealed a depth-dependent delay in the maximum correlation of TRW with soil temperature. Temperatures of both the air and soil (depths 20–80 cm) were shown to have strong and temporally stable correlations between stations. The maximum air temperature is inferred to have the most substantial impact during July–September (R = −0.46–−0.64) and early winter (R = 0.39–0.52). Tree-ring indices reached a maximum correlation with soil temperature at a depth of 40 cm (R = −0.49–−0.59 at 40 cm) during April–August. High correlations are favored by similar soil characteristics at meteorological stations and tree-ring sites. Cluster analysis of climate correlations for individual trees based on the K-means revealed groupings of trees driven by microsite conditions, competition, and age. The results support a possible advantage of soil temperature over air temperature for dendroclimatic analysis of larch growth in semiarid conditions during specific seasons.
Highlights
The influence of climate on the growth and vitality of vegetation is extremely important and widely studied, but usually only in relation to aboveground climatic conditions [1,2]
Soil temperature series from meteorological stations as far as 100 km from the tree-ring sites have been found suitable for dendroclimatic studies of the dependence of larch tree growth on soil temperature in south central Siberia
The maximum correlation of soil temperature with tree-ring width (TRW) indices was found to occur at depths of 20–80 cm, coinciding with the depth of the main root zone of larch
Summary
The influence of climate on the growth and vitality of vegetation is extremely important and widely studied, but usually only in relation to aboveground climatic conditions [1,2]. The root system, albeit shielded by the soil from the direct impact of weather, plays a vital role in plants’ intake of water and mineral resources [3]. It is reasonable to expect that seasonal moisture and temperature fluctuations in the root-inhabited layer of soil will have no less effect than atmospheric weather on the plant organism. Low soil temperature suppresses the functioning of roots [4], and the water content of the root-inhabited layer of the soil is a more direct measure than precipitation of the moisture available to the plant [5]. Investigating the interactions between vegetation and the “underground climate” should be of great importance and practical relevance.
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