Plant, invertebrate, and avian community responses to physical and hydrological manipulations in Puerto Rico wetlands

Wetlands in Puerto Rico have been greatly reduced in area and quality. The Puerto Rico Department of Natural and Environmental Resources began implementing wetland management at Humacao Nature Reserve (HNR) in 2000. However, information on effects of hydrological and mechanical manipulations in HNR wetlands on plant, invertebrate, and bird communities was lacking. Therefore, I investigated the effects of disking and hydrological manipulations on these resources in 3 moist-soil impoundments at HNR in 2001--2002.; I designated impoundments as blocks and 0.5-ha square treated and untreated plots as experimental units (n = 22). I collected vegetation, invertebrate, water depth, and salinity data from plots monthly and conducted weekly surveys of bird. I drained and disked impoundments during summer and flooded impoundments in fall-winter.; I detected 51 plant species, 53 invertebrate families, and 67 bird species in the impoundments. Plant species diversity and above-ground standing crop were greater in untreated than disked plots and varied monthly. Plant species richness was not influenced by treatment but varied monthly. Vegetative cover exhibited a treatment by month interaction. Neither salinity nor water depth influenced plant species diversity, richness, above-ground standing crop, or cover.; Invertebrate familial diversity, richness, and density and bird species diversity, richness, and abundance were not influenced by treatment or month. Invertebrate diversity, richness, and density and bird species diversity, richness, and abundance increased with increasing water depth. Increased salinity decreased invertebrate diversity, richness, and density but not bird species diversity, richness, and abundance. Vegetative cover did not affect diversity, richness, and density of invertebrates or bird abundance, but it decreased bird species diversity and richness.; If impoundments had not been constructed at HNR, most birds would not have occurred on the area. Management of moist-soil habitats represents an alternative to improve wetlands in Puerto Rico. I recommend disking during late summer to retard vegetation growth. Water depth should be kept within 10--20 cm range, and salinity level should be kept below 15 ppt to avoid impacting plants and invertebrates. Ridges within impoundments should be leveled to flood all possible areas.