Spatial patterns of medium and large size mammal assemblages in várzea and terra firme forests, Central Amazonia, Brazil

<div><p>Várzea forests account for 17% of the Amazon basin and endure an annual inundation that can reach 14 m deep during 6–8 months. This flood pulse in combination with topography directly influences the várzea vegetation cover. Assemblages of several taxa differ significantly between unflooded <i>terra firme</i> and flooded várzea forests, but little is known about the distribution of medium and large sized terrestrial mammals in várzea habitats. Therefore, our goal was to understand how those habitats influence mammalian species distribution during the dry season. Specifically, we: (1) compared the species composition between a terra firme (Amanã Sustainable Development Reserve) and a várzea forest (Mamirauá Sustainable Development Reserve); and (2) tested the influence of the várzea habitat classes on the number of records, occurrence and species composition of mammalian assemblages. The sampling design in each reserve consisted of 50 baited camera trap stations, with an overall sampling effort of 5015 camera trap days. We used Non-Metric Multidimension Scaling (NMDS) to compare species composition between terra firme and várzea forests, and used Generalized Linear Models (GLM) to assess how habitat types and a habitat diversity index affect mammal distributions. We recorded 21 medium and large sized mammalian species, including 20 species in terra firme and only six in várzea (3443 records). Flood pulse and isolation in várzea forest drove the dissimilarity between these two forest types. In várzea forest, medium size mammals, in general, avoided habitats associated with long flooding periods, while jaguars (<i>Panthera onca</i>) appeared to prefer aquatic/terrestrial transition zones. Habitats that remain dry for longer periods showed more mammalian occurrence, suggesting that dispersion via soil is important even for semi-arboreal species. This is the first study to evaluate differential use of várzea habitats by terrestrial mammalian assemblages.</p></div

Map of the study areas in Mamirauá Sustainable Development Reserve (MSDR) and Amanã SDR, Central Amazonia, Brazil.

<p>Map of the study areas in Mamirauá Sustainable Development Reserve (MSDR) and Amanã SDR, Central Amazonia, Brazil.</p

Area of coverage (km²) of the five habitat classes in várzea of Mamirauá Sustainable Development Reserve, Central Amazonia, and the Shannon index in the 500 m and 1000 m scales buffers around the camera trap stations.

<p>Data are presented as mean ± standard deviation and between parenthesis minimum and maximum values.</p

Non-metric multidimensional scaling ordination of the medium and large mammal species composition in terra firme (T) of Amanã Sustainable Development Reserve (ASDR) and várzea (V) of Mamirauá SDR, Central Amazonia, Brazil.

<p>Non-metric multidimensional scaling ordination of the medium and large mammal species composition in terra firme (T) of Amanã Sustainable Development Reserve (ASDR) and várzea (V) of Mamirauá SDR, Central Amazonia, Brazil.</p

Distribution of the medium and large mammal species records in 101 camera trap stations installed in terra firme forest of Amanã Sustainable Development Reserve (ASDR) and várzea forest of Mamirauá SDR.

<p>The dotted line divides the two forest types.</p

Partial regressions of the response variables with significant relationship to the habitat classes in várzea forest of Mamirauá Sustainable Development Reserve, Central Amazonia, Brazil.

<p>(A) Porcupine (<i>Coendou prehensilis</i>)–High Várzea; (B) Composition–Chavascal; (C) Number of Records–Chavascal; (D) Opossum (<i>Didelphis marsupialis</i>)–Chavascal; (E) Coati (<i>Nasua nasua</i>)–Chavascal; (F) Coati (<i>N</i>. <i>nasua</i>)–Soil/Herbaceous; (G) Jaguar (<i>Panthera onca</i>)–High Várzea.</p