Maintaining landscape connectivity is the best long-term strategy for mitigating the effects of habitat fragmentation, habitat loss, and land-use and climate change. To turn the idea of connectivity into reality, managers and other conservation decision-makers often focus on creating protected network areas. Land is acquired over time across a fragmented landscape to establish a series of connected habitats that allow individuals to move more easily.
Mozelewski, T.G., Robbins, Z.J. and Scheller, R.M. 2022. Forecasting the influence of conservation strategies on landscape connectivity. Conservation Biology 36(5): e13904.
But deciding which land to conserve, and whether a particular plot of land will improve connectivity decades into the future, can be a difficult task. Simulation models can help this decision-making process by predicting the outcomes of different conservation strategies. These models have increasingly become more realistic by incorporating the dynamic nature of landscapes across space and time, and by considering a multitude of influences such as land-use change, climate change, community succession, and/or land management practices.
To better help with the decision-making process in improving connectivity, new research compares four conservation strategies:
- acquiring land near established conservation areas (cluster strategy);
- acquiring land as cheaply as possible (economic strategy);
- acquiring geodiverse lands (geodiversity strategy); and
- acquiring land randomly as it becomes available (opportunistic strategy).
Connectivity was evaluated under each of these strategies over an 80-year period using a graph theoretic approach. The analysis focused on a 1.5 million ha landscape in central North Carolina, where approximately half the land is forested and connectivity is under threat. Connectivity metrics incorporated dynamics such forest growth, succession, disturbance, and management, and were defined in the context of 4 species guilds: generalists and specialists, and long- and short-distance migrants.
So which strategy works best?
The cluster strategy improved connectivity the most, particularly for specialists by creating large core habitats. (Connectivity improvements for generalists were insignificant under any strategy.) The economic strategy was least effective for overall connectivity as compared with other strategies, even the opportunistic one, although the habitat it created could potentially serve as stepping stones to facilitate long-distance dispersal for some species. The geodiversity strategy achieved only moderate connectivity improvements, but is highly dependent on landscape characteristics and the type of habitat considered beneficial.
There can be big differences in connectivity outcomes depending on the conservation strategy used to create networks, and understanding how these differences play out before land acquisition can make conservation decisions more effective. Additional dynamics will always come into play – land use will change over time, climate change will steadily alter habitats – but having a realistic strategy that incorporates at least some landscape dynamics makes for a more effective decision-making process. Better informed land managers and stewards can create better connected landscapes for the future.
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