Dendroclimatic analysis of teak (Tectona grandis L. f.) from central India to evaluate the potential for climate reconstruction

Abstract

Paleoclimatology is the study of climate prior to the instrumental record. Instrumental records are available for a period nearly 100-150 years, which is inadequate for explaining the climate variability and climate change in past millennial time scale. Paleoclimatic data helps in testing the hypothesis about the causes of climate change. When the past climate fluctuations are understood, the climate variations in the future could possibly be anticipated. The science of reconstruction past climate by using tree rings is known as Dendroclimatology.

In the present dendroclimatic study, 96 teak core samples have been used from Allapalli (Ggadchiroli, 26 cores), Nagzira (Bhandra, 26 cores) of Maharashtra and Edugurapalli (Bhandrachalam, 18 cores), and Thatibanda (Visakapattanam, 26 cores) of Andhra Pradesh by IITM. Samples were precisely cross dated and ring width was measured using stereo microscope and measurement setup along with the software ‘TROPMET RINGS’, after proper mounting, sanding, polishing and skeleton plotting. COFECHA program was used for checking the quality of corssdating and measurement accuracy. Standardization of the tree ring series is an important aspect of dendroclimatology for removing the non-climate signals from tree ring series and to improve the climate signals. The computer program ARSTAN was used for this specific purpose. Common period statistics produced by ARSTAN show moderately high values of common variance and signal to noise ratio for each chronology, which suggests a high dendroclimatic potential of the chonologies.

Climate of site is very important to understood tree-growth climate relationship. Monthly, seasonal and annual climatic conditions over the sampling sites were analyzed by calculating climatology of stations using the data collected from nearby IMD stations. CRU TS (time-series) 3.20 data (0.5-0.5 degree resolution) of monthly gridded temperature and rainfall over a period of 1901-2011 was also used along with IMD data for analyzing the growth climate relationship, since the data showed good correlation with station data. Masulipatnam and Hanamkonda climate is influenced by both Southwest and Northeast monsoon whereas Chandrapur and Nagpur climate is influenced overall warming for all stations. Seasonal rainfall does not have a common trend for all stations.

The various response function analyses carried out over study sited in central India clearly indicate the crucial role played by the summer climate in tree growth. All the four cases, for which the relationships between tree growth and climate have been studied, show more or less similar behavior of the growth responses to summer climate (pre-monsoon). The significant negative response of summer temperature associated with the positive response of summer precipitation is mainly related to the availability of moisture which is a function of both temperature and precipitation. The study highlights the importance of moisture availability during beginning of tree growth and the potential of teak for the reconstruction of summer climate.