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Engelhardt , K.A.M. and M.E. Ritchie. 2001. Effects of macrophyte species richness on wetland ecosystem functioning and services. Nature 411:687-689. In a Nutshell: Problem - A critical question in environmental biology is whether macrophyte diversity in wetlands determines the effectiveness of the well-known services of wetlands to society. Recent work in grasslands suggests that greater plant species richness leads to more efficient uptake of nutrients and greater productivity. However local environments in wetlands are typically dominated by a single vascular plant species. Thus, vascular plant diversity in wetlands may not affect ecosystem functioning positively, or even by the same mechanisms as in grassland systems, and biodiversity therefore may not ubiquitously positively affect ecosystem functioning. What - Species richness of rooted, submerged aquatic plant (macrophyte) communities was manipulated in experimental wetland mesocosms. Findings - Algal and total plant (algal + macrophyte) biomass was higher and system phosphorus loss was lower in mesocosms with greater macrophyte species richness. Greater plant biomass resulted from a sampling effect, i.e., the increased chance in species mixtures that algal production would be facilitated by the presence of a less competitive species. Lower system phosphorus losses resulted from the greater chance in species mixtures of a high algal biomass and the presence of Sago pondweed, which physically filter particulate phosphorus from the water. Potential Applications - The indirect and direct effects of macrophyte species richness on algal production, total plant biomass, and phosphorus loss suggest that management practices to maintain macrophyte diversity may enhance wetland ecosystem functioning and associated services. |
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