Growth Assessment of Native Tree Species from the Southwestern Brazilian Amazonia by Post-AD 1950 14C Analysis: Implications for Tropical Dendroclimatology Studies and Atmospheric 14C Reconstructions

Guaciara M Santos,Mário Tomazello-Filho,Gabriel Assis-Pereira,Daigard Ricardo Ortega Rodriguez,Fidel A Roig,Ana Carolina Barbosa,Nathan De Oliveira Barreto

doi:10.3390/f12091177

Abstract

Tree-ring width chronologies of cedro (Cedrela fissilis Vell.) (1875 to 2018), jatobá (Hymenaea courbaril L.) (1840 to 2018) and roxinho Peltogyne paniculata Benth.) (1910 to 2018) were developed by dendrochronological techniques in the southern Amazon Basin. Acceptable statistics for the tree-ring chronologies were obtained, and annual calendar dates were assigned. Due to the lack of long-term chronologies for use in paleoclimate reconstructions in degraded forest areas, dendrochronological dating was validated by 14C analysis. Tree-rings selected for analysis corresponded to 1957, 1958, 1962, 1963, 1965, 1971, and 1972. Those are critical calendar years in which atmospheric 14C changes were the highest, and therefore their tree-ring cellulose extracts 14C signatures when in alignment with existing post-AD 1950 atmospheric 14C atmospheric curves would indicate annual periodicity. Throughout our correlated calendar years and post-AD 1950 14C signatures, we indicate that H. courbaril shows an erratic sequence of wood ages. The other two tree species, C. fissilis and P. paniculata, are annual in nature and can be used successfully as paleoclimate proxies. Moreover, due to the sampling site’s strategic location in relation to the Tropical Low-Pressure Belt over South America, these trees can be used to enhance the limited amount of observational data in Southern Hemisphere atmospheric 14C calibration curves.

Highlights

IntroductionTree rings are an important source of high-resolution data for the long-term assessment of events occurring prior to instrumental data that characterize climate variability [1,2], and can be applied to calibrating and simulating climate, ecological, and physiological forecasting of forest ecosystems [3,4,5,6]
Chronology statistical parameters are generally commonly acceptable to determine chronology fitness among dendrochronologists, these parameters can still miss the mark when dealing with new tree species in the tropics
We used post-AD 1950 14 C measurements of selected tree rings and determined that while the H. courbaril tree species from Jamari National Forest (JNF) is unsuited to moving forward within dendrochronology applications due to indistinguishable features, C. fissilis and P. paniculata tree species are annual in nature, and their chronologies align perfectly with expected values

Summary

Introduction

Tree rings are an important source of high-resolution data for the long-term assessment of events occurring prior to instrumental data that characterize climate variability [1,2], and can be applied to calibrating and simulating climate, ecological, and physiological forecasting of forest ecosystems [3,4,5,6]. It is paramount that tree growth increments be continuous and their pattern well known so that climate indicators can be properly derived [7,8,9]. Calibration curves are needed for converting 14 C dates to cal- 4.0/). The majority of tree-ring chronologies (see [17]) with reliable cross-dating control of radial growth have been from ecoregions with well-defined seasons: e.g., the extratropics [18]. Recent efforts and important methodological advances [19]

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Conclusion