Assessment of tree response to drought: validation of a methodology to identify and test proxies for monitoring past environmental changes in trees

Abstract

A thinning experiment stand at Avoca, Ballinvalley, on the east coast of the Republic of Ireland was used to test a developed methodology aimed at monitoring drought stress, based on the analysis of growth rings obtained by coring. The stand incorporated six plots representing three thinning regimes (light, moderate and heavy) and was planted in the spring of 1943 on a brown earth soil. Radial growth (early- and latewood) was measured for the purpose of this study. A multidisciplinary approach was used to assess historic tree response to climate: specifically, the application of statistical tools such as principal component and canonical correlation analysis to dendrochronology, stable isotopes, ring density proxy, blue reflectance and forest biometrics. Results showed that radial growth was a good proxy for monitoring changes to moisture deficit, while maximum density and blue reflectance were appropriate for assessing changes in accumulated temperature for the growing season. Rainfall also influenced radial growth changes but not significantly, and was a major factor in stable carbon and oxygen discrimination, mostly in the latewood formation phase. Stable oxygen isotope analysis was more accurate than radial growth analysis in drought detection, as it helped detect drought signals in both early- and latewood while radial growth analysis only detected the drought signal in earlywood. Many studies have shown that tree rings provide vital information for marking past climatic events. This work provides a methodology to better identify and understand how commonly measured tree proxies relate to environmental parameters, and can best be used to characterize and pinpoint drought events (variously described using parameters such as like moisture deficit, accumulated temperature, rainfall and potential evaporation).

Geographic and temporal patterns in white spruce climate–growth relationships in Yukon, Canada

“…Correlation and response functions indicate that drought limits spruce growth in lower-elevation stands across the southern half of Yukon, which supports other studies of white spruce in southern Yukon (Hogg and Wein, 2005;Zalatan and Gajewski, 2005;Johnstone et al, 2010). Precipitation summed from the prior July to current June was the most common variable influencing growth, and this variable may reflect an integrated measure of (a) the effects of soil moisture from the previous growing season on carbohydrate reserves, and (b) the effects of soil moisture during the early portion of the current year's growing season and earlywood formation (Tene et al, 2011). Future droughts may impact white spruce productivity and health in southern Yukon.…”

Scientific Merits and Analytical Challenges of Tree‐Ring Densitometry

“…Despite limitations, maximum BI has featured in a number of climate response and reconstruction studies (primarily summer temperature) that have been partly (or entirely) derived from this parameter, covering many regions, including northern (Björklund et al, ; Fuentes et al, ; Linderholm et al, ; McCarroll et al, ), northwest (Rydval, Gunnarson, et al, , Rydval, Loader, et al, ; Tene et al, ; Wilson et al, ), western (Trachsel et al, ), and eastern Europe (Kaczka et al, , ; Rydval et al, ), North America (Wilson et al, ; Wilson, D'Arrigo, et al, ), and the Caucasus (Dolgova, ). The parameter has also been included in large‐scale (hemispheric) reconstructions of temperature (Anchukaitis et al, ; Wilson et al, ) and the development of a temperature reconstruction in the tropics (Buckley et al, ).…”

Considering evolutionary processes in adaptive forestry

“…The relation between the measured trait and the actual function is generally indirect and requires careful interpretation, e.g. carbon isotope discrimination or ring density used as proxies of the response to drought (Osório and Pereira 1994;Tene et al 2011). It is probably worth reminding that splitting an integrated phenotypic trait into simpler functional components does not resolve the complexity, e.g.…”