Cattail Growth Research Articles

Water and soil parameters affecting growth of cattails.

Water and soil parameters affecting growth of cattails.

Cattail invasion of sedge meadows following hydrologic disturbance in the Cowles Bog Wetland Complex, Indiana Dunes National Lakeshore

The vegetation of the 80.7 hectare Cowles Bog Wetland. Complex has been altered from its historic mixed sedge-grass domination (Carexstricta,Calamagrostiscanadensis) in lower areas and woody growth in slightly elevated areas, as based on archival aerial photographs from 1938–1982 and recent field data. Cattails (Typha spp.) were present in 1938 and made minor gains in cover through 1970. However, the major invasion of cattails appears to be associated with stabilized, increased water levels caused by seepage from diked ponds constructed upgradient from the wetland in the early 1970s. The water level increases are assumed to have been of a magnitude which adversely affected the sedge-grass community but did not preclude cattail growth. The cattail vegetation type increased in cover from 2.0 ha in 1938 to 9.7 ha in 1970 to 37.5 ha in 1982. The sedge-grass vegetation type correspondingly decreased from 56.4 ha to 43.0 ha to 5.7 ha. Cattail invasion appears to have occurred through establishment of disjunct colonies by seed reproduction, followed by vegetative expansion and merging of the colonies.

Breeding Sex Ratios, Territoriality, and Reproductive Success in the Red‐Winged Blackbird (Agelaius Phoeniceus)

Data on sex rations, territoriality, and reproductive success were obtained from a breeding population of Red—winged Blackbirds, and were used to examine the adaptive significance of polygyny and nest—site selection. All the territorial males on the study area were adults, and the sex ratio of the population was 3.0 females per male in 1966 and 2.7 females per male in 1967, with the range being 0—6 females per male in both years. The number of young fledged per male and per female increased with increasing harem size. Harem size was related to the type and density of the vegetation in a territory and not to the size of the territory or the food supply on it. Harems were larger in cattail than in bulrush territories and larger in areas with scattered cattails than in those with denser cattail growth. Cattail territories fledged more young per female than bulrush territories in 1967, but not in 1966. Nests placed in cattails had a higher fledging success both years than nests in bulrushes, and nests in sparse cattail cover fledged more young per nest than nests in denser growth. Concealment from predators and, to a lesser extent, shelter from wind and rain probably account for the preference for cattails as a nest—site. Nests built in cattails suffered less predation than bulrush nests, and in 1966 nestling starvation was lower in cattails. Nests were generally placed higher above water in cattails than in bulrushes, and predation decreased with increasing nest height.