Estimating Biomass in California's Chaparral and Coastal Sage Scrub Shrublands

Bohlman, Gabrielle N.; Underwood, Emma C.; Safford, Hugh D.

doi:10.3120/0024-9637-65.1.28

Cited by 21 publications

(33 citation statements)

References 38 publications

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“…In addition, by adjusting the time-dependent predictors in our model it can be applied consistently across different years, yielding a temporal stack of biomass estimates that can be used to assess recovery after disturbance. Our estimates by age class and vegetation type are generally consistent with field estimates from the literature [17], (Table 4), particularly among the older (> 10 years) age classes.…”

Section: Discussionsupporting

confidence: 88%

“…In addition to comparisons made with the remote sensing-based datasets described above , we also wanted to compare the WWETAC-UCD AGLBM estimates to field estimates published in the literature. To do this we cross-referenced our estimates with biomass estimates compiled by Bohlman et al (2018) [17], hereafter referred to as Bohlman, based on a literature review of 37 research studies spanning 72 years in California shrublands. The review summarizes field studies by three CWHR shrubland classes -mixed chaparral, chamise-redshank chaparral, and coastal sage scrub -and age class (time since fire disturbance).…”

Section: Comparison Of Wwetac-ucd Estimates With Field Estimated Biomassmentioning

confidence: 99%

“…Table 4. Above ground live biomass (AGLBM) and mean annual biomass increment (growth) values estimated by the WWETAC-UCD model for the three CWHR vegetation types and two age classes presented in Bohlman [17]. WWETAC-UCD values were extracted from the Station (2009) and Pechanga (2000) fires.…”

Section: Comparison Of Wwetac-ucd Estimates With Field Measured Biomassmentioning

confidence: 99%

“…WWETAC-UCD values were extracted from the Station (2009) and Pechanga (2000) fires. Bohlman [17] summarized AGLBM and increment data from a literature search of 37 studies spanning 72 years.…”

Section: Comparison Of Wwetac-ucd Estimates With Field Measured Biomassmentioning

confidence: 99%

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New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

Schrader-Patton¹,

Underwood²

2021

Preprint

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Chaparral shrublands are the dominant wildland vegetation type in southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrub-lands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict above ground live biomass in southern California using remote sensing data (Landsat NDVI) and a suite of geophysical variables. By substituting the NDVI and precipi-tation predictors for any given year we were able to apply the model to each year from 2000-2019. Using a total of 980 field plots, our model had a k-fold cross validation R2 of 0.51 and a RMSE of 3.9. Validation by vegetation type ranged from R2 = 0.17 (RMSE=9.7) for Sierran mixed conifer to R2 = 0.91 (RMSE = 2.3) for sagebrush. Our estimates showed an improvement in accuracy over a two other biomass estimates that included shrublands, with an R2 = 0.82 (RMSE = 4.7) compared to R2 = 0.068 (RMSE = 6.7) for a global biomass estimate and R2 = 0.29 (RMSE = 5.9) for a regional biomass estimate. Given the importance of accurate biomass estimates for resource managers we calculated the mean year 2010 shrubland biomass for the four national forests which ranged from 3.5 kg/m2 (Los Padres) to 2.3 kg/m2 (Angeles and Cleveland). Finally, we compared our estimates to field-measured biomass from the literature summarized by shrubland vegetation type and age class. Our model provides a transparent and repeatable method to generate biomass measure-ments in any year, thereby providing data to track biomass recovery after management actions or disturbances such as fire.

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Section: Discussionsupporting

confidence: 88%

Section: Comparison Of Wwetac-ucd Estimates With Field Estimated Biomassmentioning

confidence: 99%

Section: Comparison Of Wwetac-ucd Estimates With Field Measured Biomassmentioning

confidence: 99%

Section: Comparison Of Wwetac-ucd Estimates With Field Measured Biomassmentioning

confidence: 99%

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New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

Schrader-Patton¹,

Underwood²

2021

Preprint

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“…Recently, Bohlman et al. () summarized the extant sources of biomass/carbon data for chaparral, but the data are scarce and additional, larger efforts to estimate chaparral carbon are imperative. Furthermore, monitoring biomass in shrublands over time will contribute to understanding post‐disturbance biomass recovery and how carbon storage on public lands is affected by management actions.…”

Section: Future Research Priorities To Address Vulnerability In Chapamentioning

confidence: 99%

Global Change and the Vulnerability of Chaparral Ecosystems

Underwood

Franklin

Molinari

et al. 2018

Bulletin Ecologic Soc America

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Vegetation‐type conversion of evergreen chaparral shrublands to savannahs dominated by exotic annual herbs: causes and consequences for ecosystem function

Pratt

2021

American J of Botany

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Woody, evergreen shrublands are the archetypal community in mediterranean‐type ecosystems, and these communities are profoundly changed when they undergo vegetation‐type conversion (VTC) to become annual, herb‐dominated communities. Recently, VTC has occurred throughout southern California chaparral shrublands, likely with changes in important ecosystem functions. The mechanisms that lead to VTC and subsequent changes to ecosystem processes are important to understand as they have regional and global implications for ecosystem services, climate change, land management, and policy. The main drivers of VTC are altered fire regimes, aridity, and anthropogenic disturbance. Some changes to ecosystem function are certain to occur with VTC, but their magnitudes are unclear, whereas other changes are unpredictable. I present two hypotheses: (1) VTC leads to warming that creates a positive feedback promoting additional VTC, and (2) altered nitrogen dynamics create negative feedbacks and promote an alternative stable state in which communities are dominated by herbs. The patterns described for California are mostly relevant to the other mediterranean‐type shrublands of the globe, which are biodiversity hotspots and threatened by VTC. This review examines the extent and causes of VTC, ecosystem effects, and future research priorities.

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Estimating Biomass in California's Chaparral and Coastal Sage Scrub Shrublands

Cited by 21 publications

References 38 publications

New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

Global Change and the Vulnerability of Chaparral Ecosystems

Vegetation‐type conversion of evergreen chaparral shrublands to savannahs dominated by exotic annual herbs: causes and consequences for ecosystem function

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