Grazing and solar irradiance drive patterns of change in two grassland plant communities in southern British Columbia

Cumming, W. F. Preston; Newman, Reg F.; Bradfield, Gary E.; Kržić, Maja; Thompson, Donald

doi:10.1016/j.jaridenv.2016.06.001

Cited by 6 publications

(1 citation statement)

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“…To maintain grassland resilience, light grazing combined with periodic low‐severity prescribed burning may be the optimal management practices for maintaining native bunchgrass cover while preventing encroachment of conifers and reducing excessive fuel accumulation. Light grazing regimes that leave adequate living plant material and litter cover are important for growth and recovery of native bunchgrasses in the grasslands of Interior BC (Bradfield et al, 2021; Cumming et al, 2016; McLean & Wikeem, 1985). In this study, we found that restoration activities including low‐severity prescribed fire disturbances and mechanical removal of dense stands of trees on historical grasslands are important practices for maintaining grassland resilience.…”

Section: Discussionmentioning

confidence: 99%

Wildfire disturbance reveals evidence of ecosystem resilience and precariousness in a forest–grassland mosaic

Hamilton

Burton

2023

Ecosphere

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Forest and grassland ecosystems are sometimes located adjacently within the same climate. In Interior British Columbia, Canada, there are complex forest–grassland mosaics within the Interior Douglas‐fir biogeoclimatic zone. Historically, both grassland and forest ecosystems experienced high‐frequency, low‐severity fire regimes. Since European settlement and introduction of livestock grazing and fire exclusion, trees have encroached on grasslands, and tree densities in forests have increased. In this study, we characterize plant communities and near‐surface soil moisture in forest and grassland sites, and in historical grassland sites affected by tree encroachment. We hypothesized that spatial and temporal patterns of near‐surface soil moisture are reflected in aboveground plant community composition and structure. After initial sampling of soil moisture and plant communities, the study area was burned in a wildfire. Applying a multifactorial approach to comparing adjacent grassland and forest sites, we treated the wildfire event as a natural experiment, sampling post‐wildfire plant species composition and soil moisture, and measuring the severity and spatial heterogeneity of surface burn conditions. Evidence supports the concept of mutually exclusive fire‐reinforced bistable grassland and forest states, with greater spatial heterogeneity of soil moisture and burn severity in forests, and highly uniform patterns of soil moisture, vegetation, and burn severity in grasslands. Areas of forest encroachment on grasslands had understory plant communities dominated by exotic species, while restored grasslands had native bunchgrass cover like typical grasslands of the region. Additionally, there was post‐wildfire divergence of forest‐ and grassland‐associated plant communities. Viewed through a resilience theory conceptual framework, we suggest that ecosystem legacies are reinforcing post‐wildfire ecosystem identity and associated native plant communities. External factors—particularly past heavy livestock grazing and fire suppression—have caused ecosystem precariousness that can be addressed with management actions.

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Section: Discussionmentioning

confidence: 99%