COMPOSITION AND STRUCTURE OF A MIXED-HARDWOOD BOTTOMLAND FOREST IN THE WEST CROSS TIMBERS OFNORTH-CENTRAL TEXAS

摘要

We analyzed composition and structure of a bottomland forest in north-central Texas that was a form of the sugarberry-cedar elm-pecan (Celtis laevigata variety laevigata-Ulmus crassifolia-Carya illinoinensis) forest, which is widespread in south-central North America. The forest had three layers: upper canopy of dominant trees, under canopy of shorter trees and shrubs, and herbaceous zone of native C_3 grasses with annual and perennial forbs. Sugarberry and cedar elm were dominant trees with greatestdensity and regeneration in advanced successional stages, whereas pecan was established in earlier serai stages and persisted as a dominant with largest individual trees and less regeneration. Other important native species of trees included red mulberry (Morus rubra) and bois d'arc (Madura pomífera). Canada wildrye (Elymus canadensis) and broadleaf woodoats (Chasmanthium latifolium) were dominants of the herbaceous layer. The most common forbs were giant ragweed (Ambrosia trífida variety texana) andpigeonberry (Rivina humilis). Peak standing crop of herbage was 1,597 kg/ha.