Genetic variation in productivity of foundation riparian species at the edge of their distribution: implications for restoration and assisted migration in a warming climate

• Published in: Global change biology Vol. 17; no. 12; pp. 3724 - 3735
• Main Authors: Grady, Kevin C., Ferrier, Sharon M., Kolb, Thomas E., Hart, Stephen C., Allan, Gerard J., Whitham, Thomas G.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.12.2011; Wiley-Blackwell
• Subjects: aboveground net primary productivity; Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; assisted migration; Biological and medical sciences; Climate change; Conservation biology; Conservation, protection and management of environment and wildlife; cottonwood; Endangered & extinct species; Environmental degradation: ecosystems survey and restoration; Fundamental and applied biological sciences. Psychology; General aspects; Genetic diversity; Genotype & phenotype; heritability; local adaptation; provenance; riparian; Riparian ecology; Terrestrial ecosystems; willow; Warming; Climate; Primary productivity; Genetic variability; aboveground net primary productivity; cottonwood; Migration; Dynamical climatology; Climate change; local adaptation; willow; provenance; Riparian; Heritability; Ecological recovery; assisted migration; Adaptation
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/j.1365-2486.2011.02524.x

We examined the hypothesis that genotypic variation among populations of commonly co‐occurring phreatophytic trees (Populus fremontii, Salix gooddingii) and the shrub (Salix exigua) regulates aboveground net primary productivity (ANPP) at a hot site at the edge of the species’ distribution. We used a provenance trial in which replicated genotypes from populations varying in mean annual temperature were transplanted to a common garden adjacent to the Lower Colorado River in southeastern California. The garden environment represented an extreme maximum temperature for the study species. Four major findings emerged: (1) Genotypic variation in ANPP was significant for all species with broad‐sense heritability (H2) across populations of 0.11, 0.13, and 0.10 for P. fremontii, S. gooddingii, and S. exigua, respectively, and within‐population H2 ranging from 0.00 to 0.25, 0.00 to 0.44, and 0.02 to 0.21, respectively. (2) Population ANPP decreased linearly as mean annual maximum temperature (MAMT) transfer distance increased for both P. fremontii (r2 = 0.64) and S. gooddingii (r2 = 0.37), whereas it did not change for S. exigua; (3) Populations with similar MAMT to that of the common garden were 1.5 and 1.2 times more productive than populations with 5.0 °C MAMT transfer distances for P. fremontii and S. gooddingii, respectively; and (4) Variation in regression slopes among species for the relationship between ANPP and MAMT indicate species‐specific responses to temperature. As these plant species characterize a threatened habitat type and support a diverse community that includes endangered species, ecosystem restoration programs should consider using both local genotypes and productive genotypes from warmer environments to maximize productivity of riparian ecosystems in the face of global climate change.