Continental-scale climatic drivers of growth ring variability in an Australian conifer

Abstract

Callitris is Australia's most successful and drought tolerant conifer genus. Callitris species are distributed across a huge geographical range from rainforest to arid zones, and hence they provide a rare opportunity to view plant growth trends across the continent. Here, we make a continental-scale examination of how climate influences basal diameter growth in Callitris. We sampled a total of five species but focused effort (23 of 28 samples) on the most widespread species, C. columellaris. Cores from a total of 23 trees were sampled from 15 sites that spanned a gradient in mean annual rainfall from 225 to 2117 mm and mean annual temperature from 11.5 to 28.2°C. Ring production is not annual across much of the distribution of the genus, so 14 C-AMS dating was used to establish the frequency of ring production for each core. Ring width, tracheid lumen diameter and number of tracheids per ring were also measured on each core. Ring production was close to annual at mesic sites with reliable alternation of rainfall or temperature regimes but was more erratic elsewhere. For C. columellaris, ring width significantly increased with mean annual rainfall (r 2 = 0.49) as a result of wider and more tracheids per ring. For this species tracheid lumen diameter was correlated with annual rainfall (r 2 = 0.61), with a threefold increase from the driest to the wettest sites, lending support to the hypothesis that conifers growing at drier sites will have narrow lumen diameters to maximise mechanical strength of the xylem.

Variation in stem radial growth of the Australian conifer, Callitris columellaris, across the world’s driest and least fertile vegetated continent

“…Mean ring widths of C. columellaris were similar in the temperate and arid zones; however, site productivity would be substantially higher in the temperate zone than in the arid zone because there were more and taller C. columellaris trees as well as more trees of other species (Table 1; Prior et al 2011). Furthermore, radiocarbon dating suggests that growth events may also be slightly more frequent in the temperate zone (mean 1.6 compared with 1.4 per year; Bowman et al 2011). …”

“…Furthermore, dendrochronologists generally focus on climatically sensitive sites and species that typically produce annual growth rings. Unfortunately, this approach cannot be applied in large expanses of the world, especially in arid climates with erratic rainfall (La Marche et al 1979;Pearson et al 2011;Bowman et al 2011). Consequently, there is a pressing need to extract ecologically meaningful tree growth data from systems where crossdating, and thus development of annually resolved chronologies, is highly problematic Grierson 2007, 2009).…”

“…Earlier work based on several Callitris species has established that growth is constrained annually by seasonal drought in the tropics, and by low winter temperatures only in the coldest parts of the continent ). However, growth rings of Callitris in many regions may not be annual because growth may occur opportunistically in response to irregular rainfall in parts of its range, or be subject to very few climatic constraints (Pearson et al 2011;Bowman et al 2011). These recent studies, based on 14 C-AMS dating, have been limited to a handful of sites but have highlighted that tree rings of Callitris (and likely Where sampling sites were very close together, symbols are superimposed.…”

Ageing culturally significant relic trees in southeast Queensland to support bushfire management strategies

“…Establishing the age of old cultural custodian trees within forest communities in fire‐prone environments can be a useful indicator of past use of controlled fire, low‐intensity fire, fire exclusion or fire control. However, because tree age determination using growth rings is unreliable in tropical and subtropical forests (Bowman et al 2011; Prior et al 2012), and the use of periodic tree growth rates is unverified, radiocarbon dating was used. The aim of this study was to provide age estimates as evidence of potential survival and longevity of trees growing under low‐intensity bushfire management strategies and to obtain tree age data to calibrate an alternative non‐destructive low‐cost tree‐growth‐rate‐based method for ageing trees.…”

Diferencias en el hábito de crecimiento como variable explicativa de la influencia climática en Prosopis flexuosa en el Desierto del Monte Central (Argentina).

“…Piraino et al (2015) desarrollaron cronologías de ancho de anillos incluyendo ambas categorías morfológicas, mientras que Giantomasi et al (2013) sugieren descartar los individuos multi-fustales, ante la posibilidad de que sean consecuencia de disturbios, y por consiguiente, aporten efectos de variabilidad sobre el crecimiento radial que no están vinculados al clima. Aún cuando se discute respecto de incluir información derivada de individuos multi-fustales en estudios locales, el tema alcanza a otras investigaciones donde individuos multi-fustales han sido evitados en análisis dendroclimatológicos (Wang et al, 2005;Gareca et al, 2010;Bowman et al, 2011). Por lo previamente expuesto, cabe preguntarse entonces: ¿los algarrobos que difieren por sus características morfológicas presentan variaciones intra-especificas en la relación entre el ancho de los anillos y clima?…”