Fernando Roberto Martins

Distribution and abundance of arboreal species in the atlantic ombrophilous dense forest in Southeastern Brazil

The relative densities of arboreal species of 17 surveys carried out in the Atlantic Ombrophilous Dense Forest of São Paulo state, SE Brazil, were compared by means of multivariate analysis (cluster, TWINSPAN, PCA, DCA and CCA) to assess floristic and structural variation. The arboreal flora of this vegetation formation is heterogeneous: out of the 771 specific binomials cited, 478 were recorded only once. As the results were similar whether these 478 species were included or not, they were therefore excluded from subsequent analyses. The cluster analysis and TWINSPAN recognised two floristic-structural groups: Coastal Province and Atlantic Plateau. The DCA resulted in a gradient related to distance from the sea, from the Coastal Province towards the Atlantic Plateau (λ1=0.6944). The CCA confirmed this separation on the first axis (λ1=0.6944; 12.7% of total variance; p<0.01) and showed this gradient to be associated with altitude and latitude on one hand and temperature and precipitation on the other. The influence of latitude and longitude was weak. Although surveys used different criteria, only the minimum individual size adopted in sampling showed a weak influence on the second axis on the CCA (λ2=0.4437; 8% of total variance), and sampling method showed no influence. A positive relationship between geographical distance and floristic-structural dissimilarity was detected by the Mantel test (Zobs=0.320; Zave=0.300; p<0.001). The predominance of arboreal species of restricted distribution and the great spatial variation of abundance would appear to indicate narrow niches. The occurrence of complex and non-linear gradients suggests the importance of several other abiotic features in the spatial distribution and abundance of arboreal species in the Atlantic Ombrophilous Dense Forest in the state of São Paulo.

Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)

The cerrado, a savanna-like formation, is the second-most widespread vegetation type in Brazil. Its core region occupies the Brazilian Central Plateau, with a seasonal climate, including wet summer and dry winter. We studied the reproductive phenological patterns of the cerrado plant community in Emas National Park (central Brazil). Monthly field trips revealed 601 species, classified, according to their dispersal syndromes, into anemo-, auto-, or zoochorous species, when they were dispersed by wind, explosion or gravity, or animals, respectively. We analysed the flowering and fruiting patterns of the community in relation to dispersal syndromes, comparing the herbaceous and the woody components. The herbaceous component was characterised by a majority of autochorous species, and the woody component, by a majority of zoochorous species. There was a striking seasonality in the community-wide pattern of flowering and fruiting, although this was different between the herbaceous and the woody components. Woody species flowered mainly during late dry and early wet seasons, whereas herbaceous species flowered especially during late wet season. In the dry season, when their diaspores can be dispersed more efficiently, the proportions of anemo- and autochorous fruiting species were higher. During the rainy season, when their fruits can be kept attractive for longer time, the number of fruiting zoochorous species reached its peak.

Composição florística de uma floresta estacional semidecidual montana no município de Viçosa-MG

This study aims to investigate the floristic composition of the Silvicultura forest (20o45`S and 42o55´W) by comparing it to other forest compositions. Thus, the cluster analysis method of unweighted pair-group using arithmetic averages (UPGMA) was used, applying the Sorensen binary similarity index found among compared forests. A list of 154 species of 47 families was recorded. The Silvicultura forest is more similar to the montane semideciduous forests of Lavras and Atibaia, but less similar to submontane and coastal forests. These results show that temperature plays an important role in the floristic differentiation of the southern and southeastern Brazilian forest types.

Climate, soil and tree flora relationships in forests in the state of São Paulo, southeastern Brasil

ABSTRACT - (Climate, soil and tree flora relationships in forests in the state of Sao Paulo, southteastern Brasil). With the aim of verifying possible influences of abiotic features on the spatial distribution of forest tree species and families, thirteen surveys in the state of Sao Paulo were selected, representing different conditions (localization at the extreme coordenates and altitudes, succesional stages, surveying methods). By applying Jaccards Index to the binary matrices of 806 synonymized specific binomina and 79 families (Cronquists system) phenograms were constructed using the method of the unweighted pair grouping by mathematical average (UPGMA). The species formed two floristic blocks: hygrophyllous (yearly rainfall greater than 2000 mm without dry season) and mesophyllous (yearly rainfall about 1400 mm with variable dry season). The latter was divided in two other groups: the high-altitudinal (median altitudes higher than 750 m, frost average frequency greater than 3 days/year) and low-altitudinal. Both mesophyllous floristic blocks were subdivided according to soil conditions (texture, eutrophism, acid or allic dystrophism, iron content). At the family level the relations were weak, but also showed the soil nutritional status as a possible constraint to the spatial partition of families.

Spatial distribution of an undergrowth palm in fragments of the Brazilian Atlantic Forest

The occurrence of disturbed sectors may be as important as microscaleedge effects in tropical forests fragments. We considered the spatialdistribution dynamics of life stages (youngs, immatures, and adults) of theacaulescent, endemic palm Attalea humilis Mart. ex.Spreng.in fire-prone fragments of the Brazilian Atlantic forest to investigatepopulation responses to fragment size and fire occurrence. From 1996 to 1999,werecorded the number of individuals in different life stages in adjacent10×10-m plots in two perpendicular transects across each of threefragments of different sizes (1.6, 6.4, and 9.9 ha) in the ReservaNacional de Poço das Antas, Southeastern Brazil. A fire burnt thefragments studied in 1997. Application of Morisitas Index showed clumping atmost scales, with a marked reduction in clumping degree from youngs to adults,apattern not influenced by fragment size. After fire, clumping degree increasedtemporarily among the youngs. No association between life stages was detectedusing presence/absence data. Palm density concentrated in the most disturbedtransect arms, a pattern very little affected by fragment size or fire. Noconsistent relationship between palm density and distance from fragment edgewasdetected for any stage, fragment, or year. We hypothesize that short-distanceseed dispersal by scatterhoarding rodents results in discrete, low-densityclumps of youngs dissociated from reproductive plants. The spatial pattern oflater stages is probably conditioned by the distribution of canopy gaps in thelargest, more closed fragment. In the other fragments, the presence of largedisturbed sectors promotes the formation of large, continuous stands of palms.This pattern would be reinforced by fire, which is known to be recurrent onalready disturbed sites. For the species studied, large-scale variations in theforest structure (degraded vs. preserved fragment sectors) seems to be moreimportant than microscale edge effects.

Forms of rarity of tree species in the southern Brazilian Atlantic rainforest

The assessment of species rarity considers local abundance (scarce or abundant population), habitat affinity (stenoecious or euryecious species), and geographic distribution (stenotopic or eurytopic species). When analyzed together these variables classify species into eight categories, from common species to those having small populations, unique habitats, and restricted geographic distribution (form 7), as proposed by Rabinowitz in 1981. Based on these categories, it is possible to calculate the frequency of the different forms of rarity of the species present in a given site. The Brazilian Atlantic rainforest is considered a hotspot of the world biodiversity harboring many endemic species, which have restricted geographic distribution. Our objective was to identify the forms of rarity of tree species and their proportions in the southern portion of the Brazilian Atlantic rainforest using Rabinowitz’s forms of rarity. All the seven forms of rarity are present in the 846 tree species we analyzed: 46% eurytopic and 54% stenotopic, 73% euryecious and 27% stenoecious, 76% locally abundant and 24% locally scarce species. Eurytopic, euryecious locally abundant species accounted for 41.1%, whereas 58.9% were somehow rare: 4.5% eurytopic, euryecious locally scarce, 0.2% eurytopic, stenoecious locally abundant, 0.1% eurytopic, stenoecious locally scarce, 19.5% stenotopic, euryecious locally abundant, 8.0% stenotopic, euryecious locally scarce, 15.6% stenotopic, stenoecious locally abundant, and 11.0% stenotopic, stenoecious locally scarce. Considering that the most restrictive forms of rarity precedes extinction, the application of Rabinowitz’s system demonstrated that most tree species of the southern Brazilian Atlantic rainforest are threatened due to their restricted geographic distribution, restriction to a single habitat, reduced local abundance, or even to a combination of these variables.

Life-form spectra of Brazilian cerrado sites

Summary The cerrado, the second largest vegetation type in Brazil, presents a wide physiognomic range, from grasslands to tall woodlands, but with most of its physiognomies fitting the definition of tropical savanna. We compiled Raunkiaer’s life-form spectra from cerrado sites and from other vegetation types, comparing them among themselves with ordination analyses. In all cerrado life-form spectra, the main life-form classes were the hemicryptophytes and the phanerophytes, the former prevailing in sites with open physiognomies and the latter prevailing in sites with closed physiognomies. When compared with life-form spectra from other vegetation types, the cerrado sites formed a distinct group, with scores closer to those of the hemicryptophytes and phanerophytes. The cerrado sites distinguished themselves from the savanna sites by their under-representation of therophytes. The ordination plot indicated the likeliness of two gradients in the determination of biological spectra in the world, one from wet to dry, the other from hot to cold, thus stressing the role of precipitation and temperature on plant forms. Even if sometimes criticized in its application on tropical communities, Raunkiaer’s system was useful to characterize the cerrado floras and to separate them from other vegetation types.

Microsite specialization and spatial distribution of Geonoma brevispatha, a clonal palm in south-eastern Brazil

We tested the hypotheses that: (i) reproductive Geonoma brevispatha, an understorey clonal palm endemic to South American swamps, is most abundant in more brightly lit microsites but the abundance of juveniles is not responsive to light availability, (ii) the species is restricted to the transitional zones between flooded and well-drained microsites, (iii) if hypotheses (i) and/or (ii) are accepted, the microhabitat specialization they represent should be reflected in the spatial distribution of the individuals at distinct scales. The study was carried out in a swamp forest in south-eastern Brazil. Soil moisture was autocorrelated at distances up to approximately 1 m, reflecting a fine-scale microtopographic pattern of flooded pits and channels delimited by drier mounds. The first hypothesis was rejected, but the second hypothesis was accepted. No genets occurred on flooded microsites. A juvenile emergence experiment showed that seeds were unable to develop into juveniles under flooded conditions, but canopy openness did not influence the number of juveniles emerging. The third hypothesis was accepted. Individual genets were randomly distributed at scales corresponding to soil moisture patches, but were aggregated at larger scales. Juvenile genets were positively associated with reproducer genets. Our results indicate that palms may specialize on narrow parts of moisture gradients in swamp forests, and that this specialization can exclude them from even subtly distinct microhabitats.

Florestas de restinga e de terras baixas na planície costeira do sudeste do Brasil: vegetação e heterogeneidade ambiental

It was evaluated the floristic similarity between two Atlantic Rainforest physiognomies in Brazilian coast area, herein called Restinga and Lowland forests. The hypothesis was that, due the differences in geomorphologic processes, these forests would differ on soil physical and chemical properties, floristic composition, live above-ground biomass and litterfall production. It was sampled 1 ha (100 × 100 m) for each site located in Ubatuba, Sao Paulo state, SE Brazil. Within each hectare it was recorded trees with DBH > 4.8 cm in all 10 × 10 m contiguous plots, and collected soil and litterfall samples. The cluster and ordination analyses indicated the two communities as distinct groups considering soil and floristic composition, agreeing with the initial hypothesis. Species diversity was higher (p 0.05) between the two forests. This apparent paradox could be explained assuming that, since different species establish themselves in the Restinga or Lowland forests and find a favorable spectrum of conditions and resources, they would tend to persist and to develop in that place; even so the edaphic conditions differ between the Restinga and Lowland forests, each species could respond in a particular way to these variations, and then both forests could reach similar values of biomass and litterfall production. It is probable that the environmental filter conditioned by soils has being important for the strong floristic segregation between these two forests.

Alienígenas na sala: o que fazer com espécies exóticas em trabalhos de taxonomia, florística e fitossociologia?

(Aliens in the room: what to do with exotic species in taxonomic, floristic and phytosociological studies?): The ever-growing presence of exotic organisms (many of which become invasive) throughout the planet has led to the emergence of biological invasions as a field of study within ecology. To enable communication between scientists in this field, a terminology has developed. However, this terminology has been ignored by many botanists in Brazil where there is confusion regarding definition of exotic, naturalized, invasive, weed and ruderal species, leading to inconsistent use of the concepts. Moreover, different authors have adopted antagonistic positions when dealing with exotic species existing in their study areas, either in the preparation of taxonomic treatments or in floristic and phytosociological surveys. While some authors include in floras cultivated, non reproducing species, others exclude even widespread and common invasives. We present here, in Portuguese, the main concepts related to the theme of bioinvasion and draw the attention of Brazilian authors to the necessity for consistent use of the terminological framework available for biological invasions. We also propose that authors should clearly label exotic plants reported in their work, differentiating exotics from native species. Finally, we suggest criteria to help botanists decide when exotic plants should or should not be included in taxonomic treatments or in floristic surveys.