Characterization of the herbaceous layer in woody thickets of Geoffroea decorticans in central Pampean grasslands

RAUBER, R.B; DEMARÍA, M; ARROYO, D; CIPRIOTTI, P.A

PHYTOCOENOLOGIA

GEBRUDER BORNTRAEGER

Lugar: Stuttgart; Año: 2020

0340-269X

diversity of species, productivity, carbon storage and cycling, water dynamics, among others. In Argentina?ssemiarid grasslands, an increase in the range of distribution and the density of the woody species Geoffroeadecorticans has been observed since the last decades. The aims of this research were: a) to classify the woodythickets dominated by Geoffroea decorticans, b) to relate the floristic and functional composition of the herbaceouslayer to environmental characteristics, and c) to compare the functional composition between thicketsand grassland vegetation. Study area: The study was conducted in the grasslands of the semiarid western extremeof the Pampas phytogeographical region. Methods: Seventy three woody thickets were surveyed recordingthe cover of all herbaceous species, light interception under tree canopies and the environmental contextsurrounding (i.e. natural grassland, pastures and annual crops). A cluster analysis was carried out to classify thethickets, and the composition of major functional groups was compared among cluster groups. To order thesampling sites along a gradient, and to evaluate the environmental context as constraint external variables aCanonical Correspondence Analysis was carried out. Finally, richness, diversity, exotic and annual species´richness, and shared species was compared between woody thickets and grassland vegetation based on bibliographicrecords. Results: The cluster analysis classified woody thickets into four groups. The environmentalcontext surrounding the woody thickets and light interception explain 83.7% of the observed floristic compositionvariability. Palatable species had a significantly higher cover than non-palatable ones. Woody thickets hadmore richness and diversity, mainly by a higher number of annual and exotic species. Conclusions: The increasein woody cover would increase the heterogeneity, richness and diversity of natural vegetation. But, at the sametime, it would favour the entrance of exotics and annuals.