Impact of Site Conditions Changes on the Tree Ring Records Suitability as Climate Proxies in the Brazilian Amazon

Abstract

The increment zones width in the xylem of Swietenia macrophylla King was investigated by dendrochronological methods in an undisturbed and a strongly disturbed tropical site near Aripuanã, Mato Grosso, Brazil (10°09' S, 59°26'W). The study aimed to assess the impact of forest disturbance on the relationship between precipitation and the cambial growth of this species. Tree-ring width chronologies were developed for both sites from cross-dated increment curves. Simple correlations were computed between monthly precipitation records and the annual increment of Swietenia for the period between 1870 and 2000. Logging activities and altered land use caused a significant decrease of the water supply of the Swietenia trees grown in the disturbed area compared to trees grown in the undisturbed area. Consequently, the precipitation of almost the total growing season had a significant influence on the tree ring width of Swietenia grown in the disturbed area, while in the undisturbed forest area the significant correlation between monthly precipitation and the tree ring width of Swietenia was restricted to the beginning of the growing season (November to January). However, the reconstruction of monthly precipitation data from the tree ring width records was more precise using the chronology developed from tree ring width records of undisturbed trees compared to the chronology developed from tree ring widths from the disturbed area. It was concluded that the use of the tree ring widths of Swietenia as climate proxies is restricted to certain months of the year and requires tree ring width chronologies developed from trees grown in undisturbed or only slightly disturbed forest areas without severe anthropogenic changes in microclimate.

Dendrochronology and growth of Copaifera langsdorffii wood in the vegetation dynamics of the Pirapitinga Ecological Station, state of Minas Gerais, Brazil

“…According to Fritz (1976), in order to be considered sensitive to environmental conditions, trees of the population must have a mean sensitivity value equal to or higher than 0.40. Latorraca et al (2015) and Dünisch and Latorraca (2016), on their turn, argue that the formation of false growth rings is associated with the fact that these species are sensitive to environmental conditioning factors. Therefore, C. langsdorffii population of the PES confirmed to be influenced by environmental factors due to the presence of false growth rings, mentioned in the beginning of the discussion.…”

“…Dendrochronology is a science that studies the formation of growth rings in plant species. The formation of these rings can be influenced by climatic, physical, genetic and/or anthropic events, such as precipitation, temperature, frequency of floodings, prolonged drought, soil quality, species deciduousness, and types of forest management (WORBES et al, 2003;LISI, et al, 2008;SOUTHWORT et al, 2013;LATORRACA et al, 2015;MATTOS et al, 2015;LATORRACA, 2016;FIGUEIREDO FILHO et al, 2017). Thus, growth rings can provide information on past and present environmental conditions (SOUTHWORT et al, 2013;FIGUEIREDO FILHO et al, 2017).…”

“…Knowing the age of the trees and the information that can be inferred from the growth rings analysis is of utmost importance for the optimization of forest use (WORBES et al, 2003;LATORRACA, 2016). However, this will only be possible through the involvement of different forestry research areas.…”

“…However, this will only be possible through the involvement of different forestry research areas. Studying the past of the forests can provide indispensable information regarding how to use, manage and preserve this resource for the future (DÜNISCH, LATORRACA, 2016).…”