Spatio-Temporal Connectivity in Dynamic Tropical Fragmented Landscapes

Expanding human occupation on the planet reduces and fragments native habitats, threatening biodiversity, ecosystem functioning, and services. Tropical regions have recently been experiencing unprecedented amounts of forest conversion and fragmentation. As tropical forests harbor a large fraction of the worldâ s biodiversity, their loss and fragmentation has spearheaded the sixth mass extinction. Nevertheless, the tropical regions experience unique low intensity land-use and bioclimatic characteristics that result in highly dynamic forested landscapes. These dynamical landscapes, when subjected to the current scenario of intense global change, poses particular challenges for biodiversity conservation in human-modified landscapes. This thesis provides insights towards (i) the development of new metrics to quantify landscape dynamics; (ii) the assessment of the effects of land-use intensification on spatio-temporal dynamics and connectivity; and (iii) the quantification of potential drivers of these changes in the spatial dynamics. In the first part of my thesis, I developed a graph-theoretical method that incorporates the spatial dynamics of the landscape in the evaluation of landscape connectivity. I tested this method using a large set of Atlantic Forest landscapes of Brazil. In the second part of the thesis, I evaluated the effects of different drivers of landscape spatial dynamics, particularly focusing on land-use intensification alongside its economic and social drivers. My results pointed to the fact that land-use intensification reduces spatio-temporal dynamics of landscapes, as a large fraction of the land is locked up into one or a few intensified land cover types and the proportion of land abandoned to native habitat regeneration is low. Taken together, my findings have two broad impacts: (i) the new spatio-temporal indices reveal insights about landscape connectivity missed by purely spatial connectivity indices; and (ii) land-use intensification is happening across the globe, independent of the agricultural commodity that is being produced, reducing spatial dynamicity, which will lead to a decline in connectivity. Therefore, more land should be spared for biodiversity conservation in more highly intensified landscapes. Both findings have direct implications for spatial planning for conservation.

Department dc:contributor.department

Ecology and Evolutionary Biology

Year dc:date.issued

2017

Author dc:creator

• Martensen, Alexandre Camargo

Advisor dc:contributor.advisor

• Fortin, Marie-Josee

• biodiversity conservation
• connectivity metrics
• Ecological networks
• graph theory
• landscape network dynamics
• spatial dynamics

Handle dc:identifier.uri

http://hdl.handle.net/1807/78942

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/78942