Vegetation dynamics on mosaics of Camposand Araucaria forest between 1974 and 1999 in Southern Brazil

Abstract

A mosaic of Campos grassland and)H=K?=HE= forest characterizes the vegetation of the Southern Brazilian highland plateau. Palaeoecological evidence indicates that forest expansion over grassland initiated after the mid Holocene, when climate changed towards present day cool and moist conditions. In this paper, we discuss landscape level changes that occurred on vegetation patterns after grazing and fire exclusion in a mosaic of Campos and)H=K?=HE= forest in Southern Brazil. The analysis of aerial photographs from 1974 and 1999 showed alterations on grassland communities under grazing and fire exclusion, especially pronounced shrub establishment near the edge of the forest. Considering the change in the cover of vegetation classes relative to the total altered cover in all classes from 1974 to 1999, the most prominent alterations were: 48% from grassland with tussock grasses dominance (GRA) to grassland with shrubs (GSR), 24% from GRA to grassland with tall shrubs (GTS), 16% from GSR to GTS and 9% from GTS to forest (FOR). Considering the alteration relatively to the vegetation cover in 1974, the most relevant changes were: 44% from GSR to GTS and 94% from GTS to FOR. These observations support a directional forest expansion over grassland under grazing and fire exclusion.

Dinâmica espaço-temporal (1962-2006) das fitofisionomias em unidade de conservação do Cerrado no sudeste do Brasil

“…Além das fi sionomias mencionadas, que puderam ser enquadradas na classifi cação de Ribeiro & Walter (1998) 1, tabela 1). Outras pesquisas sobre dinâmica da cobertura vegetal com dados de sensoriamento remoto, em zonas de interface entre fl orestas e savanas ou campos, mostram resultados semelhantes aos obtidos neste estudo (Archer et al 1988, Carmel & Kadmon 1999, Bowman et al 2001, Oliveira & Pillar 2004, Pinheiro 2006, Durigan & Ratter 2006e Marimon et al 2006. Nessas pesquisas há um consenso de que o avanço das fi sionomias fl orestais sobre formações campestres é explicado pela situação climática favorável às primeiras, e que a eliminação do pastejo e queimadas são fatores importantes para a expansão de formações fl orestais.…”

Gall-inducing insects of an Araucaria Forest in southern Brazil

“…PM has no cattle grazing or burning practices since 1994, a singular situation in the region, but still commonly practiced in the nearby farms. Hence, forests have been regenerating in the former (Oliveira & Pillar 2004) while management practices are still adopted constantly in the latter farms. The regional climate is classified according to Köppen as Cfb (Moreno 1961), which is a subtropical rainy climate, with a uniformly dis- tributed precipitation throughout the year, and warm summers.…”

“…We focused on sampling the existing forests in the landscape (forest types), distinguishing between a large forested area, here called 'continuous forest', and smaller 'natural forest patches' inserted in the grasslands. This was performed in order to account for possible differences since forest patches exhibit their own dynamics of expansion over grasslands (Oliveira & Pillar 2004). Sampling was carried out in five occasions cumulatively: December 2010, and April, May, June and September 2011; given the absence of seasonality for the gallers of this region (Dalbem & Mendonça 2006) and the sampling of both forest types in each occasion, gall seasonality is not expected to affect the results.…”

“…As with all Atlantic forests, plant and animal richness is high, with the biogeographic value of the vegetation residing in its defining canopy species Araucaria angustifolia, a conifer that dominates the landscape and gives a temperate character to a mainly tropical biota (Oliveira-Filho & Fontes 2000). At higher altitudes there is a marked presence of Campos grasslands forming mosaics with Araucaria forests, with forests tending to expand over grasslands under conditions of fire and grazing exclusion (Oliveira & Pillar 2004). We report for the first time the diversity of galling insects in an Araucaria Forest site, addressing gall morphological characteristics, host plant and inducer identification, investigating the occurrence of galls within both continuous stands of Araucaria forest and smaller natural forest patches surrounded by grasslands.…”

Nest site selection by Hypsiboas faber(Anura, Hylidae) in Southern Brazil

“…This study was conducted at Center of Research and Nature Conservation Pró-Mata, São Francisco de Paula municipality -Rio Grande do Sul, Brazil, an area covered by a vegetation mosaic formed by Araucaria Forest, Atlantic Rainforest and Brazilian Upland grasslands (Oliveira & Pillar, 2004). Pró-Mata (29°26'17" to 29°43'42"S and 50°08'14" to 50°14'18"W, 600 to 1,000 m a.s.l.)…”