On the influence of tree size on the climate–growth relationship of New Zealand kauri (Agathis australis): insights from annual, monthly and daily growth patterns

Abstract

Many tree-ring-based climate reconstructions are based on the assumption that the climate reaction of trees is independent of their size. Here, we test this assumption for New Zealand kauri (Agathis australis), one of the longest tree ring-based proxies for the El Niño-Southern Oscillation (ENSO). The most recent kauri chronology contains a large amount of archaeological material, e.g. timber for which the original tree size is often unknown. We analyzed the climate-growth relationship of different-sized kauri in a pristine forest using different temporal scales, i.e. annually, monthly and daily data on tree growth and climate conditions. Trees of different life stages exhibited approximately the same seasonal growth peaks during austral spring (October and November). The dormancy period overlaps with the period where weekly air temperature maxima are below ca. 17-18°C, and where the corresponding daily minima are below ca. 8°C. However, both correlation functions between annual growth and seasonal climate as well as Kalman filter regressions between daily growth and climate conditions suggest an influence of tree size on the climate-growth relationship for kauri. Smaller trees (DBH \ 40 cm) contain weaker climate signals than larger trees. Therefore, the precautionary stripping of near-pith material (first 20 cm) from kauri chronologies may result in more uniform responses to climate forcing and thus enhance the reliability of long-term climate reconstructions. Keywords Seasonal growth characteristics Á Climate-growth relationship Á Dendroclimatology Á Dendrochronology Á Dendrometer bands Á Kalman filter regression Á Correlation functions Communicated by Y. Sano.

Size‐, species‐, and site‐specific tree growth responses to climate variability in old‐growth subalpine forests

“…On these sites, the benefits of warmer temperatures (longer growing seasons and increased photosynthetic rates) may disproportionately benefit large trees that are in more direct contact with the macroclimatic environment whereas smaller trees are buffered by cooler microclimates created by a forest canopy (De Frenne et al 2013, Harwood et al 2014). Regardless of the eco‐physiological causes, patterns in size‐dependent climate sensitivity documented in the literature are highly variable, and this topic remains an active area of tree‐ring research (Mérian and Lebourgeois 2011, Wunder et al 2013, Trouillier et al 2019).…”

Inexpensive throughfall exclusion experiment for single large trees

“…We focused on water and carbon cycles as two major forest functions that respond to drought (Anderegg et al., ). To quantify biomass (carbon), we used manual and point dendrometers (both show stem growth at different time scales [Wunder et al., ; Macinnis‐Ng et al., ]), and for water fluxes, we used sap flow sensors (to measure water use [Macinnis‐Ng et al., , ]) and point dendrometers (to measure water deficit in the stems [Kaplick et al., ]). In each tree, we installed one band dendrometer (UMS GmbH, Munich, Germany) at breast height (1.6 m above the ground on the higher side of sloping ground) and three point dendrometers (Radius dendrometer, Ecomatik, Dachau, Germany).…”

Raised in the wild south: a dendrochronological and dendrochemical profile of a far-southern stand of kauri (Agathis australis) on the Taieri Plain, Otago

“…This period of accelerated growth may obscure climatic signals and often coincides with high attrition rates as young trees compete for limited resources. Attrition within the stand often introduces micro-scale, non-climate variability to the ring-width record, lowering the coherent signal within the stand (Wunder et al 2013). 2) Microclimate: the DK kauri grow on a flat site in a sheltered environment, at the northern end of the Taieri Plain, that is subject to less severe weather than much of the surrounding region.…”