Composition and structure of an urban woody plant community

Abstract

The numbers and size of trees, saplings and shrubs were determined on 316 lots in an older Milwaukee suburb and recorded by lot location and land use. Vegetation pattern, structure, biomass and productivity were examined. Structurally, Shorewood vegetation resembles a savanna dominated by American elm but now shifting toward dominance by ash, maple and elm. Woody vegetation is predominant on back and front yards as opposed to side yards and parkways and on lots with one and two family residences as opposed to other land uses. Size class distribution for most species indicates high levels of reproduction and planting. Tree density is 32 stems per ha, sapling density is 64 stems per ha, and woody plants cover 42% of the surface. Biomass was estimated to be 36.48 t/ha, 97% of it in trees, while productivity is estimated at 0.49 kg/m² per year, to which trees contributed 45% and lawns 53%. The diversity of species and partitioning of biomass and productivity among vegetation strata make this urban ecosystem distinct from natural savannas.