Advances in Research on the Relationship Between Climatic Change and Tree-Ring Width

Abstract

There are significant correlations between tree growth and environment. Growth of trees is strongly influenced by environment and climatic factors. Tree_ring widths are significantly correlated with some climatic factors, such as temperature, precipitation, solar radiation and increasing atmospheric CO 2. Temperature is found to be an important climatic factor for the growth of trees in arid and semiarid regions. The increment of the lowest temperature at the beginning of growing season can extend the growing period favoring tree growth, and significantly increase tree ring widths, while trees will have narrow rings at extreme high temperature even when accompanied with abundant precipitation in the growing season. High temperature accelerates evaporation and evapotranspiration, which can result in anomalous moisture stress for the growth of the trees. Temperature and tree ring width are inversely proportional i.e. higher the temperature, lower the tree ring width. Similarly, the precipitation in growing season also plays an important part in the growth of trees. Tree_ring widths also respond positively to precipitation at the beginning of the growing period. In contrast, they show adverse or neutral response to excessive rainfall because precipitation is no more the limiting factor to tree growth at that time. The significant relation between trees growth and climatic factors could be primarily attributed to the availability of soil moisture, which is determined by temperature and precipitation together. A favorable water balance seems to be decisive to the increment of tree_ring width. High solar radiation has a negative effect on the tree growth, because high solar radiation usually means both low rainfall and high temperature, which in turn often result in low soil moisture and hampers tree growth. Although the rainfall is abundant in the areas influenced by monsoon, it shows no evident effect on tree_ring widths through monsoon. Pre_monsoon weather conditions (e.g. temperature and precipitation) are important limiting parameters for tree growth. Up to now, there have been no consistent conclusions about the relationship between tree_ring width and the increasing atmospheric CO 2. It is confirmed that the increasing CO 2 level increase growth of some tree seedlings and some short_life plant in greenhouses or in limit field experiments. Some experimental evidences also show that CO 2 level can be an important limiting factor in the growth of plants in the high_altitude environment. However, there are some experiments having failed to give tree_ring evidence for a possible CO 2 fertilization effect under natural environmental condition. Recently, scientists have made considerable progress in this field. These achievements can greatly help not only probe into the impact of paleo_climate on forest vegetation but also predict the effect of global climate change on terrestrial ecosystem. This paper reviewed the advances, applications and methods in this field, which aimed to widen people's knowledge and accelerate the development of this field.