Adaptive strategy biases in engineered ecosystems: implications for plant community dynamics and the provisioning of ecosystem services to people.
Abstract
Plant communities in green stormwater infrastructure (GSI) such as biofilters play an integral role in ecosystem services provisioning, such that many design manuals now feature plant lists that guide vegetation selection. This study looks at the implications of those lists for biofilter plant communities and their services, focusing on (1) how plants are selected across US climate zones, (2) whether selected plants exhibit adaptive strategy biases (i.e. towards competitive, stress tolerant or ruderal strategies that might impact ecosystem services provisioning) and (3) whether human-induced selection or natural climatic processes underly any biases revealed. Our results suggest that biofilter plant strategies are significantly biased towards stress tolerance or competitiveness (depending on the climate zone) and away from ruderalness relative to the broader pool of native and wetland-adapted native species. Competitive bias was evident in humid-continental climates and stress-tolerant bias in hot coastal/arid climates, with some degree of anti-ruderal bias present across all zones. These biases are correlated with human concerns related to water availability and climate (water conservation; p < 0.05, irrigation; p < 0.1, climate extremes; p < 0.1). They do not appear to reflect strict climatological limits (i.e. limits that are independent of preferences or design constraints imposed by people) because they are not also evident for native plants. The benefits and costs of relaxing these biases are discussed, focusing on the implications for water quality, hydrologic, and cultural services provisioning and the dynamicity of GSI ecosystems, particularly their capacity to self-repair, a prerequisite for the development of self-sustaining GSI.