Potential Vegetation and Carbon Redistribution in Northern North America from Climate Change

Abstract

There are strong relationships between climate and ecosystems. With the prospect of anthropogenic forcing accelerating climate change, there is a need to understand how terrestrial vegetation responds to this change as it influences the carbon balance. Previous studies have primarily addressed this question using empirically based models relating the observed pattern of vegetation and climate, together with scenarios of potential future climate change, to predict how vegetation may redistribute. Unlike previous studies, here we use an advanced mechanistic, individually based, ecosystem model to predict the terrestrial vegetation response from future climate change. The use of such a model opens up opportunities to test with remote sensing data, and the possibility of simulating the transient response to climate change over large domains. The model was first run with a current climatology at half-degree resolution and compared to remote sensing data on dominant plant functional types for northern North America for validation. Future climate data were then used as inputs to predict the equilibrium response of vegetation in terms of dominant plant functional type and carbon redistribution. At the domain scale, total forest cover changed by~2% and total carbon storage increased by~8% in response to climate change. These domain level changes were the result of much larger gross changes within the domain. Evergreen forest cover decreased 48% and deciduous forest cover increased 77%. The dominant plant functional type changed on 58% of the sites, while total carbon in deciduous vegetation increased 107% and evergreen vegetation decreased 31%. The percent of terrestrial carbon from deciduous and evergreen plant functional types changed from 27%/73% under current climate conditions, to 54%/46% under future climate conditions. These large predicted changes in vegetation and carbon in response to future climate change are comparable to previous empirically based estimates, and motivate the need for future development with this mechanistic model to estimate the transient response to future climate changes.

Quantifying carbon and species dynamics under different fire regimes in a southeastern U.S. pineland

“…Of the southern pine species, longleaf pine is the most resistant to frequent surface fires, prolonged drought, disease, insects, and hurricane damage, particularly while prescribed fire regimes are in place (Wahlenberg 1946). Climate change can alter disturbance rates (Dolan et al 2017), create environmental conditions that favor different dominant species (Flanagan et al 2016), and alter prescribed fire activities by limiting prescription windows (Mitchell et al 2014). This study highlights the vulnerability of emissions due to high severity wildfires at multiple frequencies in southeastern U.S. forests and supports the application of frequent prescribed burning to mitigate long-term carbon emissions and maintain ecosystem stability.…”

“…LANDIS-II and LANDIS-PRO were found to have slightly different times to maximum potential AGB (Xiao et al 2017) which would alter the length of the suppression period needed before prescribed fire is not carbon beneficial with respect to emissions from a potential future wildfire. Climate change can alter disturbance rates (Dolan et al 2017), create environmental conditions that favor different dominant species (Flanagan et al 2016), and alter prescribed fire activities by limiting prescription windows (Mitchell et al 2014). These scenarios present many avenues for future research on the complex relationships between longleaf pine, hardwoods, and fire frequency.…”

Atmospheric change as a driver of change in the Canadian boreal zone1

“…Largely similar to present-day levels, and some regions are slightly wetter (Hope et al 2016) Drier in the Boreal Plains and Boreal Cordillera, wetter in the Atlantic Maritime, and limited changes in other ecozones (Jeong et al 2014;Wang et al 2014) Drier in many parts of the boreal, except for the Taiga A mixture of adaptive forest management measures undertaken to enhance forest productivity and (or) resilience to natural disturbances in the western boreal (see Gauthier et al 2014;Park et al 2014); more nonconiferous species intentionally introduced to reduce fire risks (Terrier et al 2013;Girardin and Terrier 2015;Astrup et al 2018); novel climate-adaptive management of protected areas in the boreal implemented to better maintain ecosystem productivity and biological diversity (see Powers et al 2013b;Murray et al 2015;Batllori et al 2017) Increased conifer mortality in the drier Boreal Plains; higher tree productivity in the northeastern and the wetter parts of southern boreal and Atlantic Maritime (Hember et al 2017); more homogeneous pattern of vegetation productivity in undisturbed forests west of Hudson Bay (Nelson et al 2014); pace of northward expansion of many trees at least 50% slower than the spatial velocity of climate change (Sittaro et al 2017) Western boreal forests dominated by young stands of non-conifers and earlysuccessional conifers (Flanagan et al 2016;Searle and Chen 2017); substantially reduced tree biomass in western and central boreal due to multiple natural (Wotton et al 2010;Dhital et al 2015;Boulanger et al 2017a)…”

Potential Transient Response of Terrestrial Vegetation and Carbon in Northern North America from Climate Change

“…Plants in ED are represented by PFTs, which group vegetation into classes dependent on physiognomy, leaf form, photosynthetic pathway, and other characteristics, and are adjusted for the region of study. Following Hurtt et al [32], trees in North America are represented by two dominant types, cold deciduous and evergreen, with the modifications made by Flanagan et al [33]. That research used advanced remote sensing to calibrate ED for the proper PFT distribution under contemporary climate, and then simulated a climate change scenario to determine the equilibrium response.…”

“…Two climate data sets were used. A current climate data set established contemporary carbon and PFT distribution as supported by remote sensing data [33], and a future climate data set established the predicted equilibrium responses and was used for the transient response scenarios. The current climate data set was from the Multi-Scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) conducted by the North America Carbon Program (NACP) [45,46].…”