Acacia invasion is facilitated by landscape permeability: The role of habitat degradation and road networks

• Published in: Applied vegetation science Vol. 23; no. 4; pp. 598 - 609
• Main Authors: Heringer, Gustavo, Thiele, Jan, Amaral, Cibele Hummel, Meira‐Neto, João Augusto Alves, Matos, Fabio Antonio Ribeiro, Lehmann, Jan Rudolf Karl, Buttschardt, Tillmann Konrad, Neri, Andreza Viana, Morgan, John
• Format: Journal Article
• Language: English
• Published: Malden Wiley Subscription Services, Inc 01.10.2020
• Subjects: Acacia; Acacia mangium; Anthropogenic factors; Atlantic Rain Forest; Australian Acacia invasion; Buffers; Circuits; Conductance; Deforestation; Domains; Ecosystems; Environmental degradation; Forests; habitat degradation; Habitat fragmentation; Habitats; Highways; invasive alien species; Invasive species; Land degradation; landscape connectivity; Landscape design; landscape permeability; Mussununga; Networks; Permeability; Protected species; Resistance; resistance distance; road networks; Roads; Roads & highways; sandy‐savanna ecosystem; Savannahs; Transportation corridors; Atlantic Forest
• ISSN: 1402-2001; 1654-109X
• DOI: 10.1111/avsc.12520

Context The sandy‐savanna ecosystem “Mussununga”, a natural ecosystem that occurs as patches throughout the Atlantic Forest domain, is threatened by anthropogenic factors and biological invasions of Australian Acacia species. Habitat degradation in the Atlantic Forest domain and extensive road networks could facilitate Acacia invasion into Mussununga. Objectives We investigated whether: (a) landscape permeability (measured by effective conductance) facilitates Acacia invasion; (b) forest fragments are barriers, and roads and highways are corridors for invasive spread of Acacia; and (c) size and shape of Mussununga patches play a role in biological invasion. Methods Acacia invasion was investigated in 32 Mussununga sites within the Atlantic Forest domain. We tested the effect of a set of landscape permeability scenarios based on circuit analysis and nine other metrics of landscape structure on Acacia occurrence using three buffer‐zone sizes (0.5, 1, and 2 km). Results The likelihood of Acacia invasion significantly increased with landscape permeability. The best‐fitting landscape permeability scenario designated road networks as corridors, intact forests and water surfaces as barriers, and degraded habitats as non‐barriers. We also found that Mussununga areas within a 0.5 km buffer negatively affected the biological invasion by Acacia. Conclusions Extensive habitat degradation by deforestation and dense road networks facilitate Acacia invasion into sandy‐savanna Mussununga ecosystems. Landscape permeability may be used as a risk‐assessment tool for biological invasion by Acacia species. Mussununga patches can be protected from Acacia invasion through preserving or restoring forest belts around them and disconnecting them from the road network. In this paper, we investigated the role of the landscape on the biological invasion by Acacia mangium and Acacia auriculiformis into the sandy‐savanna Mussununga ecosystem. We found rain forest degradation and increases of the road network favor the landscape’s permeability to Acacia species, as well as that landscapes with less Mussununga area are more likely to be invaded.