Stem Circadian Phenology of Four Pine Species in Naturally Contrasting Climates from Sky-Island Forests of the Western USA

Forests

Emanuele Ziaco¹  Franco Biondi¹ 

[1] DendroLab, Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV 89557, USA;

关键词: arid environments;    tree water deficit;    point dendrometers;    hydroclimate;    north American monsoon;    stem water dynamics;    Pinus longaeva;    Pinus flexilis;    Pinus ponderosa;    Pinus monophylla;   

DOI  :  10.3390/f9070396

来源: DOAJ

【 摘 要 】

We identified intra-annual climatic drivers of stem water relationships and growth in foundation conifers at a subalpine site in the Great Basin Desert and at a montane site in the Mojave Desert (Nevada, USA). Sites were instrumented to represent naturally different levels of heat and drought stress as part of NevCAN (the Nevada Climate and ecohydrological Assessment Network). We analyzed three years (2013–2015) of sub-hourly dendrometer records for limber (Pinus flexilis) and bristlecone pine (Pinus longaeva) at the subalpine site, and for ponderosa (Pinus ponderosa) and pinyon pine (Pinus monophylla) at the montane site. Multiple logistic regression was used to identify relationships with environmental variables measured in-situ. At both sites, stem expansion occurred during the early morning and late afternoon, and irreversible stem increment was concentrated in the early morning hours. In subalpine species, stem growth started in late spring and continued until August, while at the montane site stem growth was episodic, peaking during summer monsoonal rainstorms. Circadian maximum and minimum stem size during the growing season were reversed during the dormant season at the colder/wetter subalpine site but not at the warmer/drier montane one. Knowledge of intra-annual tree-water relationships and stem growth helps understand how sky island forests grow under highly diverse climatic conditions, including severe drought and heat stress.

【 授权许可】

Unknown