Temporal variability in aboveground plant biomass decreases as spatial variability increases

Area of Science:

• Ecology
• Ecosystem Science
• Landscape Ecology

Background:

• Ecological theory posits that increased biodiversity stabilizes ecosystem functions.
• The relationship between spatial heterogeneity and temporal variability in ecosystem functions remains an active area of research.
• Understanding how landscape-scale processes influence ecosystem stability is crucial for conservation and management.

Purpose of the Study:

• To test the hypothesis that spatial variability, generated by a mosaic of disturbance-treated patches, reduces temporal variability in aboveground plant biomass at the landscape scale.
• To investigate the role of the portfolio effect and metacommunity variability theory in explaining the observed patterns.
• To assess how interacting disturbances (fire and grazing) shape landscape heterogeneity and influence ecosystem function variability.

Main Methods:

• Utilized multi-year data from seven experimentally managed tallgrass prairie landscapes.
• Manipulated spatial variability by creating landscapes with one to eight patches subjected to different fire and grazing regimes.
• Quantified temporal variability in aboveground plant biomass and analyzed relationships with spatial variability, functional group synchrony, and disturbance patterns.

Main Results:

• Increased spatial variability, driven by patchy fire and herbivory, significantly reduced temporal variability in aboveground plant biomass.
• Statistical evidence supported the portfolio effect, indicating that a diverse spatial arrangement of resources buffers against temporal fluctuations.
• A positive relationship was found between temporal variability and functional group synchrony, aligning with metacommunity variability theory.

Conclusions:

• Spatially heterogeneous disturbance regimes, such as those created by fire and grazing mosaics, can dampen temporal variability in ecosystem functions like aboveground plant biomass.
• Landscape-scale spatial heterogeneity contributes to a portfolio of ecosystem services, including wildlife habitat, fuel, and forage availability.
• The interplay between disturbance patterns and spatial arrangement of patches is a key driver of variability within and among ecological landscapes.