Linking Floristic Patterns With Soil Heterogeneity and Satellite Imagery in Ecuadorian Amazonia

Abstract

Florisitic ground surveys in tropical rain forests are laborious and time consuming, so we tested to what degree reflectance differences visible in Landsat Thematic Mapper (TM) satellite images can be used to predict differences in florisitic composition and species richness among rain forest sites. To gain ecological understanding of the rain forest ecosystem, we also tested to what extent variation in these vegetation characteristics can be explained by edaphic site conditions. The study was conducted in a relatively homogeneous area of Amazonian rain forest in Yasuní National Park, Ecuador. We established 27 transects of 5 m × 500 m within an area of ∼20 km × 25 km to study edaphic and floristic patterns mainly within the tierra firme (non‐inundated) forest. In each transect, soil samples were collected for chemical and textural analyses, and the abundance of each species belonging to two understory plant groups, pteridophytes (ferns and fern allies) and the Melastomataceae, was assessed. Floristic similarity between transect pairs varied widely and ranged from almost no overlap in species composition to very high overlap. The among‐transect floristic similarity patterns of the two plant groups were strongly correlated with each other no matter whether presence–absence or abundance data were used. The floristic similarity patterns were also strongly correlated with the similarity in pixel values of the infrared bands in the Landsat TM satellite image and with the similarity in most of the measured soil variables. Similarity in species richness, on the contrary, was neither correlated with similarity in pixel values nor with similarity in most of the soil variables. We conclude that reflectance patterns in satellite images can be efficiently used to predict landscape‐scale floristic and edaphic patterns in tierra firme rain forest. Predicting patterns in species richness, on the other hand, is not possible in the same straightforward manner. These results have important practical implications for land use and conservation planning as well as for ecological and biodiversity research. Corresponding Editor: C. A. Wessman.

RAPELD: a modification of the Gentry method for biodiversity surveys in long-term ecological research sites

“…This may not be so in areas subject to strong faulting and distortion of sedimentary layers. Tuomisto et al (2003) oriented plots down slopes. This increased the variability within plots, which is useful if a single plot has to represent the region.…”

“…However, there is much small-scale (1 -10 km) beta diversity in tropical forest vegetation, even within vegetation "types", such as terra firme forest (Clark et al 1999, Phillips et al 2003, Tuomisto & Ruokolainen 1994, Vormisto et al 2000, Tuomisto et al 2003. Therefore, the area sampled for inter-site comparisons needs to be large.…”

Habitat niche partitioning by 16 species of Myristicaceae in Amazonian Ecuador

“…Attempts to understand the relative importance of niche differentiation for species coexistence have motivated many of these studies (reviewed by Grubb 1977;Wright 2002), including 4y Springer several studies of the relationship between plant distribution and physical environmental factors in the western Amazon (e.g. Tuomisto et al 2003). The abiotic factors that potentially influence species coexistence and distributions include soil chemistry, water availability, topography and light availability; uncoupling these factors and their associated spatial autocorrelation entails careful analyses.…”

Different slopes of a mountain can determine the structure of ferns and lycophytes communities in a tropical forest of Brazil

“…The Atlantic forest is known for its wide range distribution along the Brazilian coast, presenting a quite variable topography and thus a broad array of environmental factors (Oliveira-Filho and Fontes 2000, Tonhasca Jr. 2005, Nettesheim et al 2010. Despite its variable terrain and habitat heterogeneity, the Amazon forest can be considered to have a rather plain topography and mild collection of environmental factors when compared to its eastern close relative, the Atlantic forest (Rizzini 1997, Tuomisto et al 2003a. Perhaps, the low ferns and lycophytes similarity values between the Marambaia paleoisland slopes is a consequence of the topographic heterogeneity of this forest (Tuomisto et al 2002, Karst et al 2005, Jones et al 2006, 2008, Nettesheim et al 2010.…”

“…The environmental model has provided consistently better predictive power for Amazonian ferns structure than for trees and palms (Ruokolainen et al 1997, Pitman et al 2001, Potts et al 2002, Tuomisto et al 2003a, b, c, Phillips et al 2003, Vormisto et al 2004. It is reasonable to associate such a result to the fact that ferns are plants which present variable taxon specific establishment success.…”