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Post-fire resilience of restored coastal sage scrub and grassland communities

Citation

dela Cruz, Michelle L. et al. (2022), Post-fire resilience of restored coastal sage scrub and grassland communities, Dryad, Dataset, https://doi.org/10.7280/D1D40D

Abstract

California coastal sage scrub (CSS) and native grassland systems are experiencing increased fire frequencies and extreme droughts due to climate change. These stressors, in addition to historical and ongoing disturbances, make native-dominated communities vulnerable to vegetation-type conversion to communities of non-native grassland. The challenge is to restore resilient native plant communities under these shifting conditions. Our study site, Bee Flat Canyon in the Santa Ana mountains, contains CSS, grasslands, and other plant communities degraded by historic agricultural and rangeland use. The area was restored by the Irvine Ranch Conservancy (IRC) over 10 years and burned shortly after project completion in the 2020 Silverado fire, presenting a unique opportunity to assess restoration resilience to fire. We studied how restored CSS communities recovered compared to unrestored degraded and intact areas post-fire, whether physiological traits influence post-fire cover of CSS species, and how restored grassland changed over time in relation to temperature, precipitation, and fire. We found no significant difference between restored and intact CSS sites for abundance and survivorship of crown sprouting shrubs and cover of native/non-native forb seedlings, indicating that restored sites were as resilient as intact sites. Degraded sites remained in a degraded state post-fire and contained almost zero native shrubs. There were differences in CSS plant community composition amongst degraded, intact, and restored CSS sites such that restored sites contained some native species that were seeded but absent from intact sites and vice versa. Plant physiological traits did not correlate with cover of CSS species, indicating that traits were not predictors of fire response. In restored grassland, cover did not significantly correlate with temperature and precipitation. Forbs and non-native grasses recovered post-fire, but the native grass Stipa pulchra continued to decline, possibly due to competition. Grassland plant community composition shifted significantly toward a higher dominance of non-native grasses in the second year post-fire compared to previous years, indicating a need for non-native control measures after fire. From these assessments, we recommend the IRC to (1) continue monitoring and managing weeds in CSS and grasslands, (2) enhance the diversity of their restoration seed mixes with additional native species, and (3) develop a post-fire recovery plan to limit the reestablishment of non-native species and support resilience of native species.

Methods

DATASET OVERVIEW

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Please see the README for a specific study for detailed dataset file overviews.

Dataset 1: CSS Shrub Recovery

- Short Description: Analysis of abundance, survivorship, and shrub size data of crown sprouting shrubs in restored, intact, and degraded areas of CSS in 2021.

Dataset 2: CSS Seedling Recruit

- Short Description: Analysis of functional group cover and species composition from quadrat point-intercept and species list data in restored, intact, and degraded areas of CSS in 2021 and 2022.

Dataset 3: CSS Functional Traits

- Short Description: Analysis of CSS species response to fire, water, and nitrogen from functional trait data in 2013 and 2015 and pre- and post-fire abundance data in 2020 and 2022.

Dataset 4: Grassland Monitoring

- Short Description: Analysis of functional group cover and species composition from transect point-intercept, temperature, and precipitation data in grasslands from 2011 to 2022.

Dataset 5: Plant Species Information

- Short Description: Reference data that contains six-letter codes, scientific names, native status, and functional group information of plant species that are in Orange County, in restoration seed mixes, and observed in the capstone project.

 

Dataset 6: GIS Files

- Short Description: Map files for the Post-Fire Resilience of Restored Coastal Sage Scrub and Grassland Communities Project.



DATA AND FILE OVERVIEW

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Please see the README for a specific study for detailed dataset file overviews.

File 1: BCBR_DatasetDirectory.csv

         - Short Description: Dataset containing a list of all data and analyses in the Bee Flat Canyon Post-fire Resilience Project.

         - File format: Comma separated values (.csv)

         - Date Created: May 18, 2022

 

SHARING AND ACCESSING INFORMATION

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Licenses or restrictions placed on the data: no licenses or restrictions are placed on this data.

Usage Notes

The Bee Flat Canyon Post-fire Resilience Project contains five datasets: (1) CSS Shrub Recovery, (2) CSS Seedling Recruitment, (3) CSS Functional Traits, (4) Grassland Monitoring, (5) Plant Species Information.

Please see README_BCBR_DatasetDirectory for a full orientation of the datasets in this project.

Funding

NA