Warm summer nights and the growth decline of shore pine in Southeast Alaska

Shore pine, which is a subspecies of lodgepole pine, was a widespread and dominant tree species in Southeast Alaska during the early Holocene. At present, the distribution of shore pine in Alaska is restricted to coastal bogs and fens, likely by competition with Sitka spruce and Western hemlock. Monitoring of permanent plots as part of the United States Forest Service Forest Inventory and Analysis program identified a recent loss of shore pine biomass in Southeast Alaska. The apparent loss of shore pine is concerning, because its presence adds a vertical dimension to coastal wetlands, which are the richest plant communities of the coastal temperate rainforest in Alaska. In this study, we examined the shore pine tree-ring record from a newly established plot network throughout Southeast Alaska and explored climate-growth relationships. We found a steep decline in shore pine growth from the early 1960s to the present. Random Forest regression revealed a strong correlation between the decline in shore pine growth and the rise in growing season diurnal minimum air temperature. Warm summer nights, cool daytime temperatures and a reduced diurnal temperature range are associated with greater cloud cover in Southeast Alaska. This suite of conditions could lead to unfavorable tree carbon budgets (reduced daytime photosynthesis and greater nighttime respiration) and/or favor infection by foliar pathogens, such as Dothistroma needle blight, which has recently caused widespread tree mortality on lodgepole pine plantations in British Columbia. Further field study that includes experimental manipulation (e.g., fungicide application) will be necessary to identify the proximal cause(s) of the growth decline. In the meantime, we anticipate continuation of the shore pine growth decline in Southeast Alaska

Biology · Geography · Pinus contorta · Shore · Environmental Science · Fire effects on ecosystems · Plant Water Relations and Carbon Dynamics · Tree-ring climate responses · Ecology · Forestry · Geology · Oceanography

• Cluster analysis and topoclimate modeling to examine bristlecone pine tree-ring growth signals in the Great Basin, USA

  Open Access•Tyler Tran, Tyler J Tran et al.•Environmental Research Letters•2017

  Añadir item

• Topoclimate effects on growing season length and montane conifer growth in complex terrain

  Open Access•David M Barnard, Holly Barnard et al.•Environmental Research Letters•2017

  Añadir item

• Updated high‐resolution grids of monthly climatic observations – the CRU TS3 .10 Dataset

  Open Access•Ian Harris, P D Jones et al.•International Journal of…•2014

  Añadir item

• Processes and impacts of Arctic amplification

  Open Access•Mark C Serreze, Roger G Barry•Global and Planetary Change•2011

  Añadir item