A new model to simulate climate‐change impacts on forest succession for local land management

Abstract

We developed a new climate-sensitive vegetation state-and-transition simulation model (CV-STSM) to simulate future vegetation at a fine spatial grain commensurate with the scales of human land-use decisions, and under the joint influences of changing climate, site productivity, and disturbance. CV-STSM integrates outputs from four different modeling systems. Successional changes in tree species composition and stand structure were represented as transition probabilities and organized into a state-and-transition simulation model. States were characterized based on assessments of both current vegetation and of projected future vegetation from a dynamic global vegetation model (DGVM). State definitions included sufficient detail to support the integration of CV-STSM with an agent-based model of land-use decisions and a mechanistic model of fire behavior and spread. Transition probabilities were parameterized using output from a stand biometric model run across a wide range of site productivities. Biogeographic and biogeochemical projections from the DGVM were used to adjust the transition probabilities to account for the impacts of climate change on site productivity and potential vegetation type. We conducted experimental simulations in the Willamette Valley, Oregon, USA. Our simulation landscape incorporated detailed new assessments of critically imperiled Oregon white oak (Quercus garryana) savanna and prairie habitats among the suite of existing and future vegetation types. The experimental design fully crossed four future climate scenarios with three disturbance scenarios. CV-STSM showed strong interactions between climate and disturbance scenarios. All disturbance scenarios increased the abundance of oak savanna habitat, but an interaction between the most intense disturbance and climate-change scenarios also increased the abundance of subtropical tree species. Even so, subtropical tree species were far less abundant at the end of simulations in CV-STSM than in the dynamic global vegetation model simulations. Our results indicate that dynamic global vegetation models may overestimate future rates of vegetation change, especially in the absence of stand-replacing disturbances. Modeling tools such as CV-STSM that simulate rates and direction of vegetation change affected by interactions and feedbacks between climate and land-use change can help policy makers, land managers, and society as a whole develop effective plans to adapt to rapidly changing climate.

Global change and terrestrial plant community dynamics

“…For instance, vegetation states and their transitions are defined in terms of existing species assemblages, but patterns of species coexistence and vegetation change may not remain the same under novel climate and biogeochemical conditions in the future (12,13). Coupling with mechanistic models may, however, circumvent these shortcomings (125).…”

Daily temperature records from a mesonet in the foothills of the Canadian Rocky Mountains, 2005–2010

“…Temperature variability across the landscape also needs to be understood to support the growing demand to model climate change impacts on Earth systems (e.g., Thomas et al, 2006;Deutsch et al, 2008;Clarke et al, 2015;Zuliani et al, 2015;Yospin et al, 2015;Franklin et al, 2016). General circulation models that are used for climate change scenarios or global climate reanalyses typically operate on scales of tens to hundreds of kilometres (e.g., Dee et al, 2011;Taylor et al, 2012;Murakami et al, 2016).…”

Projecting the CO2 and Climatic Change Effects on the Net Primary Productivity of the Urban Ecosystems in Phoenix, AZ in the 21st Century under Multiple RCP (Representative Concentration Pathway) Scenarios

“…Increased NPP would not necessarily means improved ecosystem sustainability. Rapid climate changes may benefit some plant species more than others ( Figure 4) and trigger ecosystem succession [83][84][85]. Since the desert cities like Phoenix are hotspot of climate changes, it is possible that some native species will be at a disadvantage in face of the competition from alien species which can take full advantage of the elevated CO 2 in the future [86][87][88][89][90].…”