Abstract
Key messageGrowth sensitivity to climate varies with soil moisture regime in spruce–fir forests in central British Columbia. Stands growing at their dry edaphic limits displayed especially strong and unique climatic sensitivities.Soil moisture regime is an important influence of productivity, process, and structure in forested ecosystems. In western North America, projected warming trends may result in decreasing available soil moisture; however, the potential effects on forest growth remain unclear. This study aimed to determine the influence of stand-level soil moisture regime on the climatic sensitivity of mature hybrid white spruce (Picea glauca (Moensch) Voss x Picea engelmannii Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forests in central British Columbia, Canada. We collected and analyzed tree-ring data from 51 stands spanning a range of soil moisture regimes. Dendroecological analyses of climate–growth relationships indicated that warm summer temperatures and drought limit growth for both species across all soil moisture regimes; however, responses were strongest on the driest sites. Spruce populations across the gradient of soil moisture regimes displayed unique climate-growth relationships; growth in populations on wetter sites was more correlated with summer climate from the year prior to growth. Radial growth responses to prior summer temperatures strengthened over the past ca. 80 years in both species and across most sites, suggesting that climate–growth relationships are shifting in this region. This study presents evidence of the importance of considering site-level ecological factors such as soil moisture regime when studying forest growth responses to climate.
Highlights
The effects of climate change on forest productivity will not be uniform over space and time
In British Columbia (BC), Canada, the identification of soil moisture regime in forested ecosystems commonly uses two methods based on the provincial Biogeoclimatic Ecosystem Classification (BEC) system (Meidinger and Pojar 1991)
We evaluated the influence of soil moisture regime on tree size by developing linear regression models for each species with mean stand height and DBH as dependent variables, and soil moisture regime (AET/potential evapotranspiration (PET) ratio) and stand age as independent variables
Summary
The effects of climate change on forest productivity will not be uniform over space and time. The BEC system assigns a relative soil moisture regime class (RSMR) to sites within relatively homogenous areas of climate called biogeoclimatic (BGC) units (Meidinger and Pojar 1991). The actual soil moisture regime (ASMR) is an alternative method of characterizing site SMR and provides a method of comparing available soil moisture across BGC units. It is defined as the ratio of actual evapotranspiration (AET) and potential evapotranspiration (PET), and can be estimated using site-specific equations that consider climatic and geographic variables (Palutikof et al 1994; Lu et al 2005; Bormann 2011). A drought assessment tool has been developed for use in BC which calculates AET/PET using a modeling approach that considers climate and soil characteristics (Nitschke and Innes 2008; Nitschke et al 2012; DeLong et al 2019)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
