Wetlands Ecol Manage (2008) 16:451–461 DOI 10.1007/s11273-008-9082-x ORIGINAL PAPER Tree species composition and environmental relationships in a Neotropical swamp forest in Southeastern Brazil Aloysio de P. Teixeira Æ Marco A. Assis Æ Fernando R. Siqueira Æ Jose´ C. Casagrande Received: 31 May 2007 / Accepted: 18 January 2008 / Published online: 26 February 2008 Ó Springer Science+Business Media B.V. 2008 Abstract We examined the relationships between and 35 species in the superior topographic section. topography, soil properties and tree species compo- Some species were among the 10 most abundant sition in a Neotropical swamp forest in southeastern ones, both in the overall sampled area and in each Brazil. Plots were sampled in the forest, encompass- topographical section, with alternation events occur- ing three different soil ground water regimes along ring only with their abundance position. However, the topographical declivity. All non-climbing plant substantial differences in floristic composition individuals with trunk height [1.3 m were sampled. between sections were detected in a fine spatial A canonical correspondence analysis—CCA—of the scale, due to higher number of species, diversity species–environmental relationships grouped tree index (H0) and species unique (exclusives) in the species according to drainage and chemical soil inferior topographic section. These higher values can conditions. A total of 86 species were found, being 77 be attributed to its higher spatial heterogeneity that species in the inferior, 40 species in the intermediate included better drained and seasonally waterlogged soils, higher soil fertility and lower acidity. The Aloysio de P. Teixeira (&) increase of the soil water saturation and the uniform Programa de Po´s-Graduac¸a˜o em Cieˆncias Biolo´gicas, conditions derived from the superficial water layer A´ rea de Biologia Vegetal, Universidade Estadual Paulista, has led to a lower number of species and an increase CP 199, Av. 24A 1515, 13506-900 Rio Claro, SP, Brazil on the palm trees abundance in the intermediate and e-mail: [email protected] superior sections. Our results showed that at a small M. A. Assis spatial scale niche differentiation must be an impor- Departamento de Botaˆnica, Universidade tant factor related to the increase of the local Estadual Paulista, CP 199, Av. 24A 1515, diversity. The wide distribution of the most abundant 13506-900 Rio Claro, SP, Brazil e-mail: [email protected] species in the studied area and the increase of local diversity corroborate the pattern of distribution of F. R. Siqueira species in larger scales of swamp forests, in which the Centro Nacional de Populac¸o˜es Tradicionais e most abundant species repeat themselves in high Desenvolvimento Sustenta´vel, Instituto Brasileiro de Meio Ambiente e Recursos Naturais Renova´veis, densities in different remnants. However, the floristic Scen trecho 2, 70818-900 Brasilia, DF, Brazil composition of each remnant is strongly variable, contributing to the increase of regional diversity. J. C. Casagrande Departamento de Recursos Naturais e Protec¸a˜o Ambiental, Universidade Federal de Sa˜o Carlos, Keywords Diversity Á Fine spatial scale Á Rod. Anhanguera Km 174, 13600-970 Araras, SP, Brazil Riverine forests Á Semi-deciduous forests Á 123 452 Wetlands Ecol Manage (2008) 16:451–461 Topographic gradient Á Topography Á Silva et al. 2007). Although these forests resemble Tropical Swamp forests Á Waterlogged soils each other in structure, their floras are variable, with a large number of unique species in each forest (Teixeira and Assis 2005). Despite their ecological importance in the conser- Introduction vation of water resources, swamp forests are very small and fragile environments, extremely vulnerable In riverine zones, tree species composition and to anthropogenic impacts, e.g., palm heart and tree distribution are affected by environmental factors extraction, canal building, embankment construction, such as soil texture and moisture content, nutrient highway activities, and urban expansion. They have status, tree gap dynamics, and the composition of been little studied but are gradually disappearing neighbouring vegetation (Oliveira-Filho et al. 1990; (Torres et al. 1994; Gomes et al. 2006). Because Medley 1992; Felfili 1995). Riverine swamp forests those forests are restricted to very small areas of the contain almost permanently waterlogged soils in landscape where permanently waterlogged soils depressions, lowlands, headwaters and watercourse occur, they are naturally split into fragments sur- margins. In these forests, a few flood-tolerant plant rounded by other kinds of vegetation. They occur species are often represented by many individuals mainly in bottom valleys in the inlands of southeast- (Scarano 2002; Koponen et al. 2004; Allen et al. ern Brazil, in areas that are useless for crops, which 2005). Many species usually associated with well nevertheless surround them. drained soils in surrounding forests also occur in Micro-topography variations in swamp forests swamp forests but are represented by only a few may promote a local drainage pattern variation individuals, increasing species richness (Imbert et al. (Scarano et al. 1997; Souza and Martins 2005), 2000; Scarano 2002). Nevertheless, tree species which can determine distinct patterns of spatial richness in swamp forests is generally lower than distribution for species, leading to different commu- that of other forests on higher grounds, due to the nity structures (Koponen et al. 2004; Scarano 2006). exclusion of species that are intolerant to waterlogged Nevertheless, forest structure, dynamics and internal soils (Lieberman et al. 1985; van Andel 2003). heterogeneity have received little attention in swamp Brazilian swamp forests are associated with forests (Souza and Martins 2005). Small scale studies different forest types according to the phytogeo- on the relationships between environment and veg- graphic units in which they occur, and they can also etation in Brazilian flood-prone forests have been vary within the same unit due to soil features. In the carried out mainly in the Amazon basin (e.g. south and southeastern regions, swamp forests are Wittmann et al. 2004), riverine forests within the mainly associated with the Atlantic Rain Forest Pantanal Matogrossense area (e.g. Damasceno-Junior domain. For example, in the coastal zone, freshwater et al. 2005), and in central and southeastern regions swamp forests occur on sandy, mainly Quaternary of Brazil (e.g. Oliveira-Filho et al. 1990; van den alluvium-derived substrates (Scarano 2002), and peat Berg and Oliveira-Filho 1999). forests occur on swampy peat soils (Sztutman and Souza and Martins (2005) evaluated spatial varia- Rodrigues 2002; Dorneles and Waechter 2004). In tion and dynamics of flooding, canopy openness, and southeastern regions, swamp forests are mainly structure relationships in a swamp forest in southeast- associated with semi-deciduous forests of the Atlantic ern Brazil. However, these authors did not study the forest domain (Toniato et al. 1998; Rocha et al. swamp forest floristic composition itself. We described 2005; Souza and Martins 2005). Gallery swamp the floristic and structural composition in a fine spatial forests are found in the Brazilian savannas (in the scale of a swamp forest in the countryside of Brazil Cerrado domain) throughout central Brazil (Oliveira- (Sa˜o Paulo state, southeastern Brazil). This forest Filho et al. 1990; Guarino and Walter 2005). The spreads over a topographical gradient of about 10%, swamp forests in interior southeastern regions have a which leads to its environmental heterogeneity in the structural resemblance in between based on an local drainage pattern. This spatial environmental important group of dominating species (Costa et al. condition differentiates this forest from other swamp 1997; Marques et al. 2003; Teixeira and Assis 2005; forests studied in central and southeastern Brazil, 123 Wetlands Ecol Manage (2008) 16:451–461 453 which occur in more gentle slopes (e.g. Costa et al. height between 11 and 14 m), and they are also 1997; Marimon et al. 2002; Nogueira and Schiavini represented by emerging trees that exceed 20 m in 2003). Because of this unique feature, we assessed soil height along with Cedrela odorata. Other species, and topography features to explain variations on both such as Dendropanax cuneatus, Calyptranthes con- structure and flora of the swamp forest. cinna, and the palm tree Euterpe edulis build the lower canopy (average height between 6 and 10 m). The understory stratum is characterized by Costus Methods spiralis, the palm tree Geonoma brevispatha, the even lower rosette plant Blechnum brasiliense, and Study site the shrub Psychotria spp. (Teixeira and Assis 2005). Lianas and epiphytes are not frequent and light entry The study area is located inside Sao Jose´ farm is favoured by the fall of trunks and branches from (22°220 S and 47°280 W), municipality of Rio Claro, the dominant canopy trees. Sao Paulo state (southeastern Brazil). The regional climate is Cwa type in Ko¨ppen’s Classification (Setzer 1967), with a rainy season from October to March and a Plant community survey dry season from April to September. Data from 1994 to 2003 obtained at the Meteorological Station located Fieldwork was carried out between September, 2002 8 km from the study site indicated an average annual and July, 2004. Three 0.15-ha sample plots were rainfall rate of 1,456 mm, from which 1,182 mm positioned along the topographical declivity. Plots concentrate in the rainy season, and 274 mm in the dry were distanced ca. 40 m from each other to encom- months. The average temperature in the coldest month pass different soil ground water regimes. Each plot (June) was 18°C, whereas in the hottest month was divided into 15 (10 9 10 m) contiguous quad- (January) it went up to 25°C. rats. The first sample plot (P1) was placed in the The farm has an area of 5,900 ha. The native inferior topographic section (ca. 632 m), on period- vegetation covered 2,250 ha until 1939.