PARENT SESSION
Organized Oral Session 33: Restoring and designing ecosystems for a crowded planet: Provision of ecosystem services or mere window dressing?
Organizer(s): ML Martinez and M Palmer
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 510a, Level 5, Palais des congrès de Montréal

Restoration of biodiversity in stream ecosystems: Beyond the aesthetic endpoint.

Swan, Christopher^*,1, Palmer, Margaret¹, ¹ University of Maryland, Baltimore County, College Park, MD

ABSTRACT- Increasingly, complex interactions between human and natural systems will be centered on the concept of restoration of ecosystems at various scales and across diverse spaces. As human impact on natural systems has increased, there has been a parallel increase in the need and interest to restore ecosystems. Of paramount importance has been the restoration of biodiversity to match levels of native, pre-disturbed species assemblages. However, there has been recent interest in how restoration of biodiversity for aesthetic reasons can also improve the quality of ecosystem processes. Humans rely on critical ecosystem services provided by streams and rivers, yet human activities have led to degradation of these ecosystems worldwide. Re-planting of streamside vegetation is a common practice to restore these ecosystems, since riparian trees can reduce nutrient runoff, stabilize banks and moderate extremes in water temperature. But does biodiversity of these tree communities matter? Important ecosystem processes within streams, including organic matter decomposition and nutrient cycling, can be impacted by the input of material from replanted streamside vegetation. There exists strong evidence that in-stream consumers, which constitute the prey base for some fish species, rely heavily on senesced leaf material from riparian trees. Given interspecific variability in leaf chemistry, it has been shown that consumers do respond to biodiversity of leaf litter, and this has consequences for ecosystem services such as leaf decomposition. We performed a field experiment where we manipulated the species composition of leaf litter in the stream and followed the decomposition of speciose leaf litter assemblages in the presence and absence of consumers. We found that consumers can alter how diverse leaf litter decomposes. Since in-stream resources for these consumers, in the form of speciose leaf litter, reflect streamside biodiversity of tree species, our results suggest restoration of biodiversity in such critical habitats can be linked to ecosystem services. Furthermore, the extent to which efforts to restore biodiversity of streamside vegetation may reach beyond in-stream consumers to higher trophic levels (e.g., fish). The procurement of clean water delivered by pristine streams and rivers is crucial to human health and well-being. Implementation of restoration plans for our waterways may benefit from careful consideration of desired patterns in species richness in order to sustain critical, in-stream ecosystem processes.

Key words: restoration, ecosystem services, cultural benefits, streams