Conservation and restoration projects often involve starting new populations by introducing individuals into portions of their native or projected range. Such efforts can help meet many related goals, including habitat creation, ecosystem service provisioning, assisted migration, and the reintroduction of imperiled species following local extirpation. The outcomes of reintroduction efforts, however, are highly variable, with results ranging from local extinction to dramatic population growth; reasons for this variation remain unclear. Here, we ask whether population growth following plant reintroductions is governed by variation at two scales: the scale of individual habitat patches to which individuals are reintroduced, and larger among-landscape scales in which similar patches may be situated in landscapes that differ in matrix type, soil conditions, and other factors. Quantifying demographic variation at these two scales will help prioritize locations for introduction and, once introductions take place, forecast population growth. This work took place within a large-scale habitat fragmentation experiment, where individuals of two perennial forb species were reintroduced into eight replicate ~50 ha landscapes, each containing a set of five ~1 ha patches that varied in their degree of isolation (connected by habitat corridors or unconnected) and edge-to-area ratio. Using data on individual growth, survival, reproductive output, and recruitment collected one to two years after reintroduction, we developed models to forecast population growth, then compared forecasts to observed population sizes, three and six years later. Both the type of patch (connected and unconnected) and identity of the landscape to which individuals were reintroduced had effects on forecasted population growth rates, but only variation associated with landscape identity was an accurate predictor of subsequently observed population growth rates. Models that did not include landscape identity had minimal forecasting ability, revealing the key importance of variation at this scale for accurate prediction. Of the five demographic rates used to model population dynamics, seed production was the most important source of forecast error in population growth rates. Our results point to the importance of accounting for landscape-scale variation in demographic models and demonstrate how such models might assist with prioritizing particular landscapes for species reintroduction projects.
Annual_growth
These data represent growth measurements of transplanted individuals of two native forb species from September 2008-September 2009. The Growth column represents the difference in log-volume (log(cm3) length x width x height) between 2008 and 2009. The Log_size column represents the volume of plants in 2008 as log(cm3). The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
Annual_survival
These data represent survival measurements of transplanted individuals of two native forb species from September 2008-September 2009. The Survival column represents survival between 2008 and 2009, coded as 1 for live plants and 0 for dead plants. The Log_size column represents the volume of plants in 2008 as log(cm3). The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
Seed_production
These data represent developed seeds per inflorescence on transplanted individuals of two native forb species. Inflorescences were collected in September-October 2009. The Seeds column represents counts of seeds on individual stalks. The Log_size column represents the volume of parent plants in 2008 as log(cm3). The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
Stalk_production
These data represent the total number of flowering heads (inflorescences) on transplanted individuals of two native forb species during the 2009 flowering season (September-October). The Stalks column represents counts of flowering heads per plant. The Log_size column represents the volume of plants in 2008 as log(cm3). The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
First-year_growth
These data represent first-year growth of offspring of founder plants in September 2009, reflecting one season of individual growth post-germination. The Log_size column represents the size of plants as the log of volume (in cm3, length x width x height) . The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
Seedling_establishment
These data represent data on number of new germinants in September 2010 (the first September after seeds were added).
The Germinants column represents the number of seedlings observed in September (excluding seedlings that germinated
and died before September). The column titled Total_seeds is a constant that represents the number of seeds added to each plot. The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. The Landscape column represents the identity of eight landscape units, each containing four patches.
Observed_abundance
These data represent the observed abundance in 32 reintroduced populations of two native forb species. The column Abundance2009 represents counts of each species in plots in 2009, Abundance2012 represents counts of each species in plots in 2012, and Abundance2015 represents counts of each species in plots in 2015.The Species column includes codes that represent Carphephorus bellidifolius (CB) and Liatris earlei (LE). The Patch column represents the identity of patches where populations were located, with possible values including B,C,D, and E. The Landscape column represents the identity of eight landscape units, each containing four patches. Together, the Patch and Landscape columns represent unique populations. The Patch_type column represents the experimental treatment of patches in the experiment, including Connected, Winged, and Rectangular patches. Lambda9_12 represents the annualized population growth rate between 2009 and 2012, while Lambda9_15 represents the annualized population growth rate between 2009 and 2015.
National Science Foundation, Award: SBE-1415297, DEB-0613701, DEB-0613975, DEB-0614333, DEB-1354101, and DEB-1354085