Masting is shaped by tree-level attributes and stand structure, more than climate, in a Rocky Mountain conifer species
Data files
Jan 23, 2023 version files 58.29 MB
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AET.tif
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cb_2018_us_state_20m.dbf
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cb_2018_us_state_20m.prj
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cb_2018_us_state_20m.shp
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cb_2018_us_state_20m.shx
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clim_df_FULL_min.csv
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CWD.tif
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full_cones_3.csv
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PIPO_1km.tif
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ponderosa_sites_10_27.dbf
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ponderosa_sites_10_27.prj
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ponderosa_sites_10_27.shp
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ponderosa_sites_10_27.shx
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README.txt
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tree_age.csv
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Abstract
Many tree species mast, meaning seed production is highly variable from year to year and synchronous within a stand, but this phenomenon remains poorly understood. To better understand how a changing climate, altered disturbance regimes, or novel management strategies might affect future seed production, we quantified the joint influence of both biotic (tree size, age, and neighborhood competition) and abiotic factors (climate and weather) on seed production in a widespread conifer species, Rocky Mountain ponderosa pine (Pinus ponderosa var. scopulorum). We reconstructed individual-level annual cone production across a large portion of this species' range using the cone abscission scar method, and mixed models were used to test hypotheses related to the causes and drivers of masting in this species. Our results suggest that masting in ponderosa pine is a process shaped at the individual-level, and this leads to high, local-scale variation in annual cone production. The effects of weather were strongest at climatically marginal sites, but overall, the joint effects of weather and climate only weakly described individual-level patterns of annual cone production in ponderosa pine (R2m = 1.6%, R2c = 30.1%). Rather, we found that masting was strongly influenced by tree- and stand-level factors such as diameter, age, and local neighborhood density, all of which were associated with the mean, interannual variability, and between-tree synchrony of cone production at the individual-level. Larger and older trees produced more cones, more frequently, and with less synchrony than smaller and younger trees. Open-grown trees experiencing lower levels of neighborhood competition also produced more cones with less interannual variability, but with higher between-tree synchrony. Because tree- and stand-level traits appear to regulate seed production more strongly than climate or weather in this species, management interventions targeting these factors could be powerful tools to manage future tree recruitment. Thus, current efforts to reduce stand density and conserve large trees in some ponderosa pine forests may enhance tree-level seed production and reduce variability in seed crops among years.