Topography-related variation in a Neotropical rain forest community attributes: insights from a new 1-ha plot at Los Tuxtlas, Mexico

Background: The role of topography in the spatial variation of tropical rainforest (TRF) community attributes remains insufficiently understood. We analyze community attributes in a newly-established 1-ha plot located in the 'Strongly dissected slopes' land unit in a Neotropical TRF and compare them with those assessed in an older 1-ha plot located in the 'Piedmont' land unit. Questions: What is the magnitude of topography-related spatial variation of TRF community attributes across a single locality? Does this variation influence the comparison of this TRF with similar forests worldwide? Study Site and Years: Los Tuxtlas Tropical Biology Station (Veracruz, southern Mexico); 2018-2019. Methods: We assessed community attributes (composition, structure, diversity) in the new plot by censusing all woody plants with DBH ≥ 1 cm. Results: We recorded 4,375 individuals (basal area, 43.35 m2), 188 species, and 58 families. Fifteen families, including Arecaceae, Moraceae, and Meliaceae, accounted for a large proportion of species (57 %), individuals (86 %), and basal area (79 %). Most recorded plants (90 %) had DBH ≤ 10 cm. The evenness factor indicated high dominance in the community. The plots differed primarily in species and family composition, individual density, and vertical structure. Conclusions: The community attributes of the TRF analyzed in plots located in different land units showed low variation. When compared with other TRFs worldwide, the Los Tuxtlas forest stands out for its low individual density and diversity but its higher basal area. Including the study site’s complex topography in this analysis did not significantly affect previous interregional comparisons.