Effect of weather-climatic conditions on intraannual stem radial increment in Quercus pubescens (Fagaceae) and Juniperus excelsa (Cupressaceae)

Abstract

The aim of the work was to determine the most important environmental factors affecting the intra­annual radial growth of the native dominant species trees Quercus pubescens Willd and Juniperus excelsa M. Bieb., co-occurring in the semi-arid climate of the Southern coast of the Crimea. The analysis a 4-year high-resolution automatic point dendrometers dataset (2016-2019), which were non-invasively fixed to the tree stems at a height of 1.3 m. During the studied period, characterized by contrasting weather conditions, differences between tree species were revealed, both in the patterns of seasonal and daily stem radial growth and in the response plants to the effects of environmental conditions. Data analysis showed that on the Southern coast of the Crimea cambium activity in Q. pubescens is limited to one season with a period of intensive stem radial increment in May-June. In seasonal dynamics of stem radial increment in J. excelsa two peaks: in April-May and in September-October was revealed. The effect of precipitation on stem growth in total was higher than air temperatures, which confirms the assumption that on the Southern coast of the Crimea the main factor limiting the stem radial growth of Q. pubescens and J. excelsa is the moisture availability to the trees. It was found that the most significant to the stem radial increment in Q. pubescens were precipitation in May-June and in J. excelsa - precipitation in June and September-October. Higher plastic of intra-annual dynamics cambial activity in J. excelsa increases the adaptability of plants to drought and may provide them with an additional competitive advantage against co-occurring Q. pubescens in thermoaridization climatic conditions predicted for the Southern coast of the Crimea.