Growth response of conifers is species-specific and depends on site and climate conditions. Studies on daily radial stem growth use different analytical approaches to determine species reactions to environmental conditions. These results contribute to improve forecasts of tree growth under a changing climate. During 2013 and 2014, radial stem growth of 33 mature Cedrus libani individuals growing under different climatic conditions in Turkey and Germany was monitored hourly using high precision point dendrometers. Stem radius increments (SRI) were extracted from dendrometer readings. The annual course of SRI showed site-specific patterns with mean daily values ranging between 9.9 and 29.3 lm over the growing season. Correlation and principal component analyses indicated that humidity and low temperatures during the growing season favored SRI. Multiple regression analyses demonstrated that precipitation and relative air humidity were the most important factors influencing daily SRI. Climate-growth relationships were further evaluated using the regression tree method. Precipitation was the most significant factor on daily SRI for all sites. The close coupling of SRI to relative air humidity and precipitation underlines the importance of stem water status for radial stem growth of C. libani which is native to regions with summer drought. It further explains the superior growth of C. libani in Germany.
Aim of study: The main purpose of the present study is to model present and future potential distribution areas of the Crimean juniper (Juniperus excelsa M. BIEB.) under climate change. Area of study: The study was carried out in the Lakes District that covers Burdur, Isparta and Antalya provinces in the west of the Mediterranean region. Material and methods: During the study, the inventory data of 40 productive juniper stands in the region were collected. The future projections for the study area were made for the year 2070 with all Representative Concentration Pathways (RCPs) scenarios and 19 bioclimatic predictors from HadGEM2-ES. Modeling process was performed by using the Maximum Entropy (MaxEnt) method. Main results: The AUC value of the model was determined as 0.966 ± 0.028. The model identified that Precipitation of Driest Month, Temperature Seasonality, Precipitation of Coldest Quarter, Max Temperature of Warmest Month, Mean Diurnal Range were the major variables influencing the current and future distributions of the species. According to the models, there will be a dramatic decrease in the potential distribution of the Crimean juniper. Consequently, the results from all these studies will be able to create an effective base for the biodiversity and ecosystem planning studies to be realized according to the climate change scenarios. Highlights: Understanding how climate change will affect the distribution of plant species in the future is an important topic in ecological researches. Climate change scenarios are the most preferred parameters to remove this uncertainty. It is predicted that the Crimean juniper will be affected by climate change and its distribution will decrease dramatically.
Potential distribution models (PDM) can be defined as equations derived to estimate the appropriate alternative distribution areas in nature using the actual environmental variables in the natural distribution areas of species [1-7]. On one hand one can determine the habitat characteristics of the species through PDM while on the other hand ecology-based information needed for basic concepts such as sustainability, conservation, restoration, and biodiversity can be collected [8-12]. In particular,
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