Climate change drives a northward expansion of C4 grasses in North America by the end of the century
Abstract
C4 grasses currently cover 18% of the earth's surface and are critically important as food sources, and account for roughly 25% of terrestrial productivity. Yet in the future these patterns will change as a result of the opposing impacts of atmospheric CO2 and climate on C3 and C4 physiologies. Here, we use the carbon isotope ratio (d13C) of modern and fossil bison and mammoth tissues as a proxy for the abundance of C3 and C4 vegetation across North American habitats. We then combine stable isotope data with CMIP5 climate model simulations, and used eight different climatic predictor variables and advanced statistical techniques to model the spatial distributions of C3 and C4 grasses from today through the year 2100 for two fossil-fuel emissions scenarios. For both scenarios, our vegetation model predicts increases in C4 grass abundance of up to 50% in the northern Great Plains and moderate decreases in C4 grass abundance in the central and southern Great Plains. The overall effect of these C3/C4 distribution changes will be a decreases in the magnitude of the north-south grass gradient in the Great Plains ecoregion with the loss of the highest abundance of C4 ecosystems in the panhandles of Texas, Oklahoma and western Kansas. These results have important implications for future changes in animal and plant biodiversity, agricultural productivity, and C4 grass invasions in North America. Our study suggests that changing climates will likely start to favor C4 crops over C3 crops in the northern Great Plains, potentially influencing the nature of different grain food supplies. Additionally, changes in C3 and C4 grass distributions, including decreases in the abundance of C3 grasses in native grasslands in the northern Great Plains, could have negative effects on the fauna that feed preferentially on those C3 grasses, and may also reduce also the number of unique habitats that currently maintain high biodiversity.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC13I..06C
- Keywords:
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- 0410 Biodiversity;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 1640 Remote sensing;
- GLOBAL CHANGE