Edaphic stresses such as salt or heavy metal toxicity, nutrient deficiency, or poor physical properties challenge restoration practitioners. I examined constitutive or plastic variation within and among plant species in response to edaphic stresses and restoration-related soil amendments.
Theory predicts constitutive responses to constant stress and plastic responses to variable stress. I demonstrated that greater plasticity in one salt tolerance response may be physiologically linked to lesser plasticity in others using 20 saltgrass (Distichlis spicata) genotypes in a greenhouse study. Genotypes with greater foliar Na plasticity and lesser foliar K:Na and Na turnover rate plasticity substituted more Na for K, increasing salinity tolerance under constant salinity stress. Although I observed gender segregation with salinity in the planted Owens Lake Playa (Inyo County, CA, USA) population, I did not observe gender differences in salinity tolerance in the greenhouse.
Effects of serpentine soil variation on plant community variation are poorly understood. To identify growth-limiting factors on barren relative to adjacent, densely-vegetated soils in the New Idria serpentine formation (San Benito County, CA, USA), I analyzed field-collected soils and foliage from barren and vegetated areas and grew Bromus madritensis ssp. rubens (invasive annual grass), Achillea millefolium (native perennial forb), and Ceanothus cuneatus (native evergreen shrub) in these soils amended factorially with N, K, and Ca. Large barren-vegetated biomass differences under well-watered conditions implicated soil chemistry. The factors maintaining the New Idria barren-vegetated pattern varied with plant species or functional type. High soil heavy metal concentrations more strongly reduced herbaceous species growth while nutrient interactions (Ca:Mg) were more important for woody species.
Revegetation of disturbed serpentine soils is needed, and organic soil amendments may reduce edaphic stresses. I examined benefits of compost amendment for native (Achillea, Ceanothus) and invasive (Bromus) plant growth on disturbed New Idria serpentine soils. I measured plant and soil properties in control and compost-amended barren and vegetated soils. Compost did not improve soil water holding properties or decrease plant heavy metal uptake, but it increased available Ca and K, Ca:Mg, and CEC. It provided species-specific benefits to both native and invasive species.
|Advisor:||Richards, James H.|
|Commitee:||Claassen, Victor P., Eviner, Valerie T.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 71/12, Dissertation Abstracts International|
|Subjects:||Ecology, Soil sciences, Plant biology|
|Keywords:||Heavy metal toxicity, Owens Lake playa, Salinity, Serpentine, Sex-linked traits|
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