Comparison Growth Situation of Tree-Ring Width between Poplars and Betula at the Floodplain Irtysh River, Altai, China

Since the effect of soil moisture comparison of growth situation between Populus and Betula trees have not been studied, we choose it as our main objective. Tree-ring width chronology of Poplars and Betula was investigated on the Irtysh river floodplain, Altai Prefecture at an altitude of 500 m a.s.l. and climatic factors influencing the tree-ring width were examined. Why does soil moisture in different layers have unique relationships with our 3 sampling sites, when the conditions and altitude have slightly differences? Altai has a cold semi-arid climate, the sum annual rainfall is 202 mm and annual mean is 4.5°C. Mean expressed population signal in all 3 sampling sites was significant at 0.89. Three parameters of monthly climatic data [mean temperature, total of precipitation and soil moisture <>] were used for the analysis. Later formation rings of Betula platyphylla are related to soil moisture (0.495 at p<0.01) and precipitation (0.397 at p<0.01). Populus canescens growth was significantly influenced by July precipitation (0.337 at p<0.01). Populus euphratica is affected highly by soil moisture, which shows significant positive correlation from prior November to this May (0.485 at p<0.01) suggesting that tree rings integrate the state of the climate in the soil moisture. The results of this observation shows that better than regional hydroclimatic variability especially with soil moisture, Poplar gives way to Betula, because of stable and significant correlation, so Popular euphratica confirms that it is the best floodplains forest species for dendrochronological study