Wetland Cover Types and Plant Community Changes in Response to Cattail-Control Activities in the Palo Verde Marsh, Costa Rica

The Palo Verde marsh restoration was performed in Costa Rica to reduce invasive Typha domingensis stands. The invasion of this cattail in the 1980s decreased the habitat quality, and thousands of waterbirds that used this seasonal marsh were not returning. In 2002, the Organization for Tropical Studies decided to manage the marsh using a tractor with angle-iron-paddle wheels to crush cattail. We evaluated the land cover changes in response to the prescribed management activities through GIS and vegetation-assessment analysis. Crushing activities started in July 2002. We defined three management plots: A and B) with crushing activities for different lengths of time and C) the control plot with passive management. We evaluated wetland cover changes, richness, and dominance of plant species in the three plots. We found that owing to management activities 1) cattail cover area decreased from 35% to 9% (Plot A) and from 62% to 7% (Plot B), while in Plot C it remained almost constant (always greater than 60%); 2) the area of total live vegetation including cattail decreased, giving way to open water and bare ground; 3) plant species richness was higher in the crushed plots than in the control plot; 4) cattail dominance decreased and more species were sharing the marsh area in managed plots than in the control plot; and 5) cattail cover was negatively related to species richness. We recommend continuing the control of cattail by crushing in order to rehabilitate the marsh and conserve its biodiversity. Keywords: aquatic vegetation responses, cattail ( Typha domingensis ), Costa Rica, Palo Verde Marsh, restoration