Abundance and diversity in reforestation and natural regeneration of the Tamaulipan Thornscrub under selective management practices

Abstract

The Tamaulipan Thornscrub (TTS) is distributed in Northeastern Mexico, especially in the states of Nuevo León, Tamaulipas and Coahuila. This subtropical ecosystem is highly fragmented due to land-use changes. To mitigate the associated impacts, active restoration projects are being promoted. The objective of this study was to compare species diversity and abundance between natural Regeneration and a Reforestation area in the TTS. The area was reforested with 25 native species and subjected to selective weeding, supplemental irrigation, pruning, and phytosanitary care. Five years after planting, individuals of shrub and tree species that had germinated in the area were counted, estimating abundance as well as alpha and beta diversity indexes. A total of 29 species were recorded in the Regeneration area, 21 of which were shared with the Reforestation. Abundance was higher in the Reforestation (4 875 individuals ha^-1) than in the Regeneration (2 286 individuals ha^-1). The Margalef Index showed a significant difference (p=4.24e-05), with greater richness in the Regeneration area. However, the Shannon Index (p=0.2639), true diversity (p=0.2639), Simpson Index (p=0.7499), and Simpson complement (p=0.7499) did not show significant differences. Among the beta diversity indexes, Sørensen Index indicated the highest similarity percentage, at 77 %. Although natural Regeneration presented higher species richness, both strata shared a similar abundance structure. Natural Regeneration, as a complement, could be a viable and cost-effective alternative for restoring the TTS, especially when surrounding vegetation fragments are preserved and the land-use history is considered.