Invasive alien acacias rapidly stock carbon, but threaten biodiversity recovery in young second-growth forests.

Under the UN-Decade of Ecosystem Restoration and Bonn Challenge, second-growth forest is promoted as a global solution to climate change, degradation and associated losses of biodiversity and ecosystem services. Second growth is often invaded by alien tree species and understanding how this impacts carbon stock and biodiversity recovery is key for restoration planning. We assessed carbon stock and tree diversity recovery in second growth invaded by two Acacia species and non-invaded second growth, with associated edge effects, in the Brazilian Atlantic Forest. Carbon stock recovery in non-invaded forests was threefold lower than in invaded forests. Increasingly isolated, fragmented and deforested areas had low carbon stocks when non-invaded, whereas the opposite was true when invaded. Non-invaded forests recovered threefold to sixfold higher taxonomic, phylogenetic and functional diversity than invaded forest. Higher species turnover and lower nestedness in non-invaded than invaded forests underpinned higher abundance of threatened and endemic species in non-invaded forest. Non-invaded forests presented positive relationships between carbon and biodiversity, whereas in the invaded forests we did not detect any relationship, indicating that more carbon does not equal more biodiversity in landscapes with high vulnerability to invasive acacias. To deliver on combined climate change and biodiversity goals, restoration planning and management must consider biological invasion risk. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

Diversidad y formas de vida de una comunidad leñosa-herbácea en los complejos rocosos de cuarcita del Quadrilátero Ferrífero brasileño

Aunque los campos rupestres son afloramientos rocosos icónicos con un alto valor biogeográfico en las tierras altas de Brasil, se sabe poco sobre los modeladores responsables de los patrones de comunidades vegetales. Estudiamos la diversidad y las formas de vida de los componentes leñosos y herbáceos que se encuentran a lo largo de diferentes fitofísionomías de los complejos rocosos de cuarcita en las tierras altas del Quadrilátero Ferrífero brasileño, Estado de Minas Gerais, Brasil. Se realizaron un total de 130 parcelas en tres fitofisionomías a lo largo del gradiente pedogeomorfológico: i) campo rupestre herbáceo; ii) estratos superior e inferior del bosque montano (capão florestal) y iii) matorral. En general, se muestrearon 4 446 individuos, distribuidos en 218 especies, especialmente de familias: Asteraceae y Myrtaceae en la comunidad de leñosas; y Poaceae y Cyperaceae, en la comunidad herbácea. La diversidad de especies, las formas de vida y la abundancia mostraron marcadas diferencias entre las fitofisionomías. La forma de vida más frecuente fue la fanerófita (bosque de montaña y matorral), seguida de hemicriptófita (campo rupestre herbáceo). Nuestro estudio revela diferencias marcadas de la composición florística, la riqueza y el espectro de las formas de vida entre fitofisionomías en los complejos rocosos a escala local. Tales diferencias probablemente indican que existe una alta heterogeneidad ambiental en pequeñas escalas espaciales.

Although campos rupestres are iconic rock outcrops with a high biogeographic value in Brazilian highlands, little is known about the drivers responsible for the plant community pattern. We studied the diversity and life forms of the woody and herbaceous components occurring along different phytophysiognomies of the quartzite rocky complexes in highlands of the Quadrangle, Minas Gerais State, Brazil. A total of 130 plots were allocated in three phytophysiognomies along the pedogeomorphological gradient: i) herbaceous campo rupestre; ii) upper and lower strata of montane forest (capão florestal) and iii) scrub. Overall, 4 446 individuals were sampled, distributed among 218 species, especially from families: Asteraceae, in general; Myrtaceae, in the woody community; and Poaceae and Cyperaceae, in the herbaceous community. Species diversity, life forms, and abundance showed differences between phytophysiognomies. The most frequent life form was phanerophyte (montane forest and scrub), followed by hemicryptophyte (herbaceous campo rupestre). Our study reveals marked differences in the floristic composition, species richness, and life form spectrum among phytophysiognomies on a local scale. Such differences probably indicate that there is a high environmental heterogeneity at a small spatial scale.