Dalva Maria da Silva Matos

Variation in aboveground biomass and necromass of two invasive species in the Atlantic rainforest, southeast Brazil

Este trabalho descreve a variacao da biomassa e necromassa aerea, e da producao primaria liquida (NAGPP) de duas especies invasoras Panicum maximum Jacquin (Poaceae) e Pteridium arachnoideum (Kaulf.) Maxon. (Dennstaedtiaceae) em duas areas da Reserva Biologica de Poco das Antas, no sudeste brasileiro. As duas especies eram mono-dominantes nestas areas, ambas localizadas na matriz entre fragmentos florestais. A materia orgânica foi amostrada mensalmente durante dois anos, separada em biomassa e necromassa e a producao aerea primaria liquida (NAGPP) foi calculada. Houve variacao intra-sazonal bem marcada, para ambas as especies; Pa. maximum geralmente apresentou os maiores valores para biomassa, necromassa, massa total e NAGPP (NAGPP, Pa. maximum = 3953 g m-2 ano-1, Pt. arachnoideum = 2667 g m-2 ano-1). A NAGPP nao variou entre as duas estacoes de crescimento para Pa. maximum, porem estas diferencas foram acentuadas para Pt. arachnoideum (2% comparados aos 44% de variacao em relacao a media). A segunda estacao de crescimento foi mais seca e Pa. maximum produziu maior quantidade de necromassa do que na primeira estacao de crescimento; Pteridium mostrou pouca variacao sazonal de biomassa, mas uma maior produtividade na segunda estacao de crescimento. Pteridium arachnoideum e aparentemente mais sensivel ao clima, especialmente em relacao a pluviosidade.

Feeding visit time of fruit-eating birds in Cerrado plants: revisiting the predation risk model

Fruiting plants that attract frequent visits by fruit-eating birds tend to be predictable patches for a predator. Consequently, the risk of a predator attack increases the longer a bird stays on a fruiting plant. We tested whether large and cryptic species of fruit-eating birds spend more time per feeding visit than smaller and conspicuous ones in fruiting plants of the Brazilian Cerrado. Data were obtained from the literature for eight fruiting plant species and from field observations of birds feeding on fruits of Zanthoxylum rhoifolium (Rutaceae). We searched for a positive linear relationship between the mean visit time and the total length of the species, considering bird color as a covariate. Feeding visits of the large and cryptic bird species lasted longer than feeding visits of small and conspicuous species. Large birds may be safer from predators because large predators are less common. Cryptic birds may be difficult to be detected by predators and, consequently, may be less likely to be attacked by predators than conspicuous birds. Thus, our results provide support to the hypothesis that vulnerable bird species spend less time foraging in fruiting plants.

Germination and allometry of the native palm tree Euterpe edulis compared to the introduced E. oleracea and their hybrids in Atlantic rainforest

Palms are distinctive plants of tropics and have peculiar allometric relations. Understanding such relations is useful in the case of introduced species because their ability to establish and invade must be clarified in terms of their responses in the new site. Our purpose was to assess the survival and invasive capacity of an introduced palm species in the Atlantic rainforest, Euterpe oleracea Mart., compared to the native Euterpe edulis Mart. and to the hybrids produced between the two species. Considering this, we compared the allometry in different ontogenetic stages, the germination rates, and aspects of the initial development. The ontogenetic stages proposed for both Euterpe illustrated the growth patterns described for palm trees. E. oleracea and hybrids adjusted to the geometric similarity allometric model, while E. edulis presented a slope greater than would be expected considering this model, indicating a greater height for a given diameter. E. oleracea showed the same amount of pulp per fruit as E. edulis and a similar initial development of seedlings. The main differences observed were a lower germination rate and a faster height gain of E. oleracea seedlings. We conclude that E. oleracea, which is similar to E. edulis in aspects of allometry, development, seed and seedling morphology, may be an important competitor of this native palm tree in the Atlantic Forest.

The role of Pteridium arachnoideum(Kaulf) on the seed bank of the endangered Brazilian Cerrado

The native bracken (Pteridium arachnoideum) often occurs in mono-specific stands in the Brazilian Cerrado, and this dominance can impact on both the above-ground vegetation and soil seed bank. This study investigated how invasion by this species over a 20-year period changed the seed bank and the relationship between the seed bank and litter mass. We extracted soil samples from three replicated invaded and uninvaded sites, and followed seedling emergence for six months. We collected the above-ground biomass and litter of P. arachnoideum in ten 1m2 plots from three invaded sites. There was no difference between invaded and uninvaded areas in seed bank richness, diversity or overall abundance. The most abundant family was the Melastomataceae, followed by the Poaceae. The Melastomataceae was more abundant in uninvaded sites, but the most common species of this family (Tibouchinastenocarpa) was not affected. The grasses were more common in invaded sites in the rainy season and were affected by heterogeneity in the litter layer. The seed bank could play a role in the recovery of these invaded areas, but the presence of weeds and invasive grasses could constrain their use as a management strategy.

A DECIDUIDADE FOLIAR INDICA A VULNERABILIDADE DE ESPÉCIES LENHOSAS AO FOGO

Studies demonstrated that the occurrence of fires may cause phenological behaviours that diverge from commonly described patterns. The aim of this study was to evaluate whether the vulnerability of woody species to fire can be indicated by leaf deciduousness. The activity index and the intensity index of different phenophases were compared between burned and unburned individuals of woody species with different levels of leaf deciduousness (deciduous, semideciduous and evergreen). For the deciduous species, the vegetative phenophases were similar between burned and unburned individuals. For the semideciduous species, burned individuals showed higher intensity and activity of the vegetative phenophases. For the evergreen species, the stimulus for production of new leaves and retardation of expanded and senescent leaves was recorded in burned individuals. In terms of reproductive phenology, in burned individuals, lower intensity and activity of unripe and ripe fruits were recorded for deciduous and semideciduous species, whereas the stimulus for flowering and fruiting was recorded for evergreen species. The periodicity of the phenophases can be modulated by the occurrence of fire even after an interval of two years. The effect of the fire was gradually more pronounced from deciduous to evergreen species, indicating the higher vulnerability of evergreen woody species to this type of disturbance.

Efeito da inundação lateral sobre a distribuição da vegetação ripária em um trecho do rio Cuiabá, MT

Hydrological and phytosociological studies were conducted in a 550 m topographic profile installed perpendicularly to the Cuiaba River, in the municipality of Rosario Oeste, MT, Brazil, in order to analyze the influence of flooding on riparian vegetation distribution. A backwater hydrological model under a subcritical regime was fitted allowing the establishment of a hydrological series in the study area. From this series, the recurrence intervals for the area were obtained. The results suggested that the banks of the main channel, the secondary channel and its lateral dike, the flood plain, and the terrace are flooded at every ∼1 - 1.7 years, ∼1.77 - 2.8 years, ∼3 years, and from ∼3.25 to ∼39 years, respectively. The species Combretum leprosum Mart. (Combretaceae) presented the greatest VI in the bank of the main channel; Callisthene fasciculata (Spr.) Mart. (Vochysiaceae) presented the greatest VI in the bank of the main channel and in the terrace; and Licania parvifolia Huber (Chrysobalanaceae), Cariniana estrellensis (Raddi) Kuntze. (Lecythidaceae), and Vochysia divergens Pohl. (Vochysiaceae) in the flood plain. The results indicated that flooding frequency and especially the flooding time are the main determinative ecological factors of plant species distribution along the topographic profile.

First record of herbivory of the invasive macrophyte Hedychium coronarium J. König (Zingiberaceae)

Invasive species can cause structural and functional changes in their non-native habitats, such as changes in the trophic chain. We describe ramet herbivory of butterfly ginger, an aggressive aquatic weed in Brazil, by capybaras in a floodplain area of a Cerrado reserve. This is the first record of herbivory of H. coronarium in invaded areas. Capybaras could be using the butterfly ginger as habitat and as a food resource, which could cause changes in apparent competition between these invasive and native macrophytes.

From individuals to communities: How singleton invasive pine saplings lead to biodiversity change in the Brazilian Cerrado hotspot

This work was funded by the Brazilian Ciencia sem Fronteiras/Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) (1091/13-1), European Research Council (AdG BioTIME 250189and PoC BioCHANGE 727440), the Royal Society and the Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico/CNPq (307839/2014-1).

The risks of introduction of the Amazonian palm Euterpe oleracea in the Atlantic rainforest

The introduction of a species may alter ecological processes of native populations, such as pollination and dispersal patterns, leading to changes in population structure. When the introduced and the native species are congeners, interference in pollination can also lead to hybridization. We aimed to understand the ecological aspects of Euterpe oleracea introduction in the Atlantic forest and the possible consequences for the conservation of the native congener Euterpe edulis. We analysed the population structure of palm populations, including hybrids, and observed the interaction with frugivorous birds of both palm species after E. oleracea introduction. We observed that E. edulis had significantly lower density and a smaller number of seedlings when occurring with E. oleracea. Native and introduced Euterpe species shared nine frugivorous bird species. E. oleracea and hybrids had dispersed outside the original planting area. Consequently, the risks of introduction of E. oleracea may mostly be related to the disruption of interactions between E. edulis and frugivorous birds and the spontaneous production of hybrids. Finally, the cultivation of E. oleracea and hybrids in Atlantic rainforest could affect the conservation of the already endangered E. edulis.