TY - JOUR
T1 - Importance of considering soils in seed transfer zone development
T2 - evidence from a study of the native Bromus marginatus
AU - Gibson, Alexis
AU - Nelson, Cara R.
AU - Rinehart, Susan
AU - Archer, Vince
AU - Eramian, Aram
N1 - Publisher Copyright:
© 2019 by the Ecological Society of America
PY - 2019/3
Y1 - 2019/3
N2 - Seed transfer zones, which define the geographical relationship between adaptive traits and environmental factors, are increasingly used to determine the source populations that can be combined in restoration and revegetation. Climatic variables have been the most commonly used environmental data in transfer zone development, even though soils are also a primary selective force on plants. We assessed the importance of including soils in seed transfer zones using Bromus marginatus, a native grass used for restoration and revegetation in the western United States, as an example. Seeds were collected from 64 populations across Montana and Idaho and grown in a common garden for two years. We assessed among-population variation based on 11 traits related to germination rate, plant size, vigor, inflorescence number, survival, and carbon isotope discrimination (∆13), and used this variation to develop seed transfer zone maps using two approaches: (1) a conventional approach, using only climatic variables (climate only) and (2) an expanded approach that included soils and climatic variables (soils + climate). The most influential drivers of trait variation were factors related to soil water availability: soil order, available water content (AWC), and organic carbon levels. Populations from areas with andic soils, which have high soil AWC and soil organic carbon, had low germination, limited first-year survival, low ∆13, and small seeds. Growing season length and winter temperatures were also predictive of trait variation. In comparison to climate-only models, soils + climate models explained 11% more variance (120% relative increase) for ∆13 and an average of 4.5% more (27% relative increase) for growth traits and survival. The transfer zone map developed using soils + climate differed from the climate-only map in both spatial pattern of ecotypic variation and number of transfer zones; the soils + climate map had more zones and a higher proportion of small (<4 km2) transfer zone patches, while the climate-only map had more large patches >37 km2. Including soils in transfer zone development may identify adaptive trait variation that is obscured by large-scale differences in climate and could improve plant materials used for ecosystem management.
AB - Seed transfer zones, which define the geographical relationship between adaptive traits and environmental factors, are increasingly used to determine the source populations that can be combined in restoration and revegetation. Climatic variables have been the most commonly used environmental data in transfer zone development, even though soils are also a primary selective force on plants. We assessed the importance of including soils in seed transfer zones using Bromus marginatus, a native grass used for restoration and revegetation in the western United States, as an example. Seeds were collected from 64 populations across Montana and Idaho and grown in a common garden for two years. We assessed among-population variation based on 11 traits related to germination rate, plant size, vigor, inflorescence number, survival, and carbon isotope discrimination (∆13), and used this variation to develop seed transfer zone maps using two approaches: (1) a conventional approach, using only climatic variables (climate only) and (2) an expanded approach that included soils and climatic variables (soils + climate). The most influential drivers of trait variation were factors related to soil water availability: soil order, available water content (AWC), and organic carbon levels. Populations from areas with andic soils, which have high soil AWC and soil organic carbon, had low germination, limited first-year survival, low ∆13, and small seeds. Growing season length and winter temperatures were also predictive of trait variation. In comparison to climate-only models, soils + climate models explained 11% more variance (120% relative increase) for ∆13 and an average of 4.5% more (27% relative increase) for growth traits and survival. The transfer zone map developed using soils + climate differed from the climate-only map in both spatial pattern of ecotypic variation and number of transfer zones; the soils + climate map had more zones and a higher proportion of small (<4 km2) transfer zone patches, while the climate-only map had more large patches >37 km2. Including soils in transfer zone development may identify adaptive trait variation that is obscured by large-scale differences in climate and could improve plant materials used for ecosystem management.
KW - Andisols
KW - genecology
KW - mountain brome
KW - restoration
KW - seed transfer zones
KW - soils
KW - water use efficiency
UR - http://www.scopus.com/inward/record.url?scp=85062258717&partnerID=8YFLogxK
U2 - 10.1002/eap.1835
DO - 10.1002/eap.1835
M3 - Article
C2 - 30644139
AN - SCOPUS:85062258717
SN - 1051-0761
VL - 29
JO - Ecological Applications
JF - Ecological Applications
IS - 2
M1 - e01835
ER -