A vegetação das nascentes do Rio Tibagi e sua relação com o regime hídrico dos solos

Abstract

The influence of soil water retention on vegetation patterns was studied in a grassland community under Histosols in the adjacency of Ponta Grossa and Palmeira-PR (25° 16' 25" S e 49° 49' 29" W), an area well-known for its soil water retention, soil carbon sink and biotic variability. This study was carried out to characterize the Tibagi River spring with pedologic and vegetation patterns, as well as the soil erosion effects on biotic and abiotic processes. Six transects around the gully erosion were made, in both stream sides, including three similar areas among them, but different soil conditions and vegetation types. The soil temperature, water table response, chemical and physical properties, floristic composition, structure of vegetation and aboveground biomass were recorded for these areas. The difference in chemical composition of soils was not so marked, but considerable differences in physical properties of the soil and vegetation characteristics were found between areas. It was observed that the gully erosion dissecated the field around it by decreasing depth of water table, decreasing pore space and water retention. Due to the better drainage of soils near gully erosion, the establishment of mesophilic vegetation over hydrophilic vegetation has been verified in addition to high percentage of bare soil, which promote high soil temperatures and make vegetation establishment difficult. Among changes in biomass, structure and floristic composition that were observed influenced by the gully erosion, were invasion of alien species and mesophilic species. The Sphagnum spp. required areas were there was high water table levels. Rare species and a new occurrence of Asteraceae in the South of Brazil were sampled. The wet grasslands conservation were related to water Histosol content, which highlights its importance. Changes in management practice are required to improve environmental quality.

The influence of soil water retention on vegetation patterns was studied in a grassland community under Histosols in the adjacency of Ponta Grossa and Palmeira-PR (25° 16' 25" S e 49° 49' 29" W), an area well-known for its soil water retention, soil carbon sink and biotic variability. This study was carried out to characterize the Tibagi River spring with pedologic and vegetation patterns, as well as the soil erosion effects on biotic and abiotic processes. Six transects around the gully erosion were made, in both stream sides, including three similar areas among them, but different soil conditions and vegetation types. The soil temperature, water table response, chemical and physical properties, floristic composition, structure of vegetation and aboveground biomass were recorded for these areas. The difference in chemical composition of soils was not so marked, but considerable differences in physical properties of the soil and vegetation characteristics were found between areas. It was observed that the gully erosion dissecated the field around it by decreasing depth of water table, decreasing pore space and water retention. Due to the better drainage of soils near gully erosion, the establishment of mesophilic vegetation over hydrophilic vegetation has been verified in addition to high percentage of bare soil, which promote high soil temperatures and make vegetation establishment difficult. Among changes in biomass, structure and floristic composition that were observed influenced by the gully erosion, were invasion of alien species and mesophilic species. The Sphagnum spp. required areas were there was high water table levels. Rare species and a new occurrence of Asteraceae in the South of Brazil were sampled. The wet grasslands conservation were related to water Histosol content, which highlights its importance. Changes in management practice are required to improve environmental quality.