Habitat fragmentation is the most dominant human-driven cause of global environmental change. Fragmentation in the landscape impacts entire ecosystems, from the genetic structure of populations to the dispersal of individuals to the biodiversity in an entire region. Understanding the consequences of habitat fragmentation and how we can mitigate its most negative effects remains one of the key goals for all conservation practitioners.
The January issue of Ecography is highlighted as a Special Issue focusing habitat fragmentation, particularly the integration of long-term experiments and theory development. As Editor Nick Haddad and co-authors explain in the introduction to the issue: “Here, we draw together for the first time: 1) experiments that are now mature, up to several decades old, permitting evaluations of the effects of fragmentation on different dimensions of biological responses, including never-before documented lengthy time lags in responses; 2) a proliferation of theories that can now be synthesized and evaluated against experimental data, permitting a new round of fresh theory synthesis; and 3) a new understanding of applications of the science of fragmentation to conservation.”
The Special Issue features 12 new publications from authors and experiments that span the globe and span decades, including research on church forests in Africa, wild bee populations in France and Australia, and tree communities in central Amazonia. Key highlights from the articles include:
- There is little experimental evidence to support the habitat amount hypothesis, which suggests that sample area effect overrides patch size and patch isolation effects of habitat fragmentation on species richness.
- Sacred natural sites, such as the church forests across northern Ethiopia, may act a useful middle ground between experimental and observational studies of fragmentation.
- The interplay of ecology and evolution modulates processes and interactions in fragmented landscapes, and there still exists a large gap between theory and experiment.
- It is unlikely that fragmented tropical landscapes with limited human disturbance will revert back to early or mid-succesional states in the future, since future composition is strongly dependent on present-day composition.
- Regardless of whether a fragmented landscape has strongly or weakly defined structural edges, conceptual models that view the landscape as a simple patch-matrix are less effective than models that view it as an ecological continuum or as a hybrid of continuum and patch-matrix models.
- A new framework allows for species and community-level predictions for the change and loss of biodiversity under global change by comparing the processes behind species-area relationships (SAR), metapopulation models (MEP), and species distribution models (SDM).
- Habitat fragmentation has had a significant impact on the evolution of dispersal strategies and dispersal syndromes, affecting our ability to predict and manage populations in fragmented landscapes.
- The loss of habitat and connectivity in metacommunity networks leads to lower species diversity, loss of ecosystem function, and less stability by eroding the “spatial insurance” that ecosystems enjoy.
- A survey of conservation practitioners shows that landscape connectivity and patch area are highly valued, but there is an information gap between what is learned from studies of habitat fragmentation and factors central to the practice of biodiversity conservation.
- Plant community composition responds differently to fragmentation over time based on changes to the matrix and how the habitat became fragmented in the first place.
- The distribution of ecological traits in bees shifts along a gradient of habitat amount and habitat fragmentation, indirectly affecting ecosystem services such as crop pollination.
- New methods to determine thresholds for habitat loss provide more realistic models and suggest that the maximum permissible habitat loss threshold is 40%.
Table of Contents: Ecography Fragmentation Special Issue. January 2017. Issue 40, Volume 1, Pages 1-237.
Haddad, N. M., R. D. Holt, R. J. Fletcher, M. Loreau, and J. Clobert. 2017. Connecting models, data, and concepts to understand fragmentation’s ecosystem-wide effects. Ecography 40(1): 1-8.
Brudvig, L. A., S. J. Leroux, C. H. Albert, E. M. Bruna, K. F. Davies, R. M. Ewers, D. J. Levey, R. Pardini and J. Resasco. 2017. Evaluating conceptual models of landscape change. Ecography 40(1): 74-84.
Carrié, R., E. Andrieu, S. A. Cunningham, P. E. Lentini, M. Loreau, and A. Ouin. 2017. Relationships among ecological traits of wild bee communities along gradients of habitat amount and fragmentation. Ecography 40(1): 85-97.
Collins, C. D., C. Banks-Leite, L. A. Brudvig, B. L. Foster, W. M. Cook, E. I. Damschen, A. Andrade, M. Austin, J. L. Camargo, D. A. Driscoll, R. D. Holt, W. F. Laurance, A. O. Nicholls and J. L. Orrock. 2017. Fragmentation affects plant community composition over time. Ecography 40(1): 119-130.
Cote, J., E. Bestion, S. Jacob, J. Travis, D. Legrand and M. Baguette. 2017. Evolution of dispersal strategies and dispersal syndromes in fragmented landscapes. Ecography 40(1): 56-73.
Ewers, R. M., A. Andrade, S. G. Laurance, J. L. Camargo, T. E. Lovejoy and W. F. Laurance. 2017. Predicted trajectories of tree community change in Amazonian rainforest fragments. Ecography 40(1): 26-35.
Haddad, N. M., A. Gonzalez, L. A. Brudvig, M. A. Burt, D. J. Levey and E. I. Damschen. 2017. Experimental evidence does not support the Habitat Amount Hypothesis. Ecography 40(1): 48-55.
Legrand D., J. Cote, E. A. Fronhofer, R. D. Holt, O. Ronce, N. Schtickzelle, J. M. J. Travis and J. Clobert. 2017. Eco-evolutionary dynamics in fragmented landscapes. Ecography 40(1): 9-25.
Leroux, S. J. Leroux, C. H. Albert, A.-S. Lafuite, B. Rayfield, S. Wang and D. Gravel. 2017. Structural uncertainty in models projecting the consequences of habitat loss and fragmentation on biodiversity. Ecography 40(1): 36-47.
Resasco, J. , E. M. Bruna, N. M. Haddad, C. Banks-Leite and C. R. Margules. 2017. The contribution of theory and experiments to conservation in fragmented landscapes. Ecography 40(1): 109-118.
Reynolds, T. W., C. D. Collins, A. Wassie, J. Liang, W. Briggs, M. Lowman, T. Shimekach Sisay and E. Adamu. 2017. Sacred natural sites as mensurative fragmentation experiments in long-inhabited multifunctional landscapes. Ecography 40(1): 144-157.
Thompson, P. L., B. Rayfield, and A. Gonzalez. 2017. Loss of habitat and connectivity erodes species diversity, ecosystem functioning, and stability in metacommunity networks. Ecography 40(1): 98-108.
Yin, D., S. J. Leroux, and F. He. 2017. Methods and models for identifying thresholds of habitat loss. Ecography 40(1): 131-143.