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  • Spatio-Temporal Connectivity in Dynamic Tropical

    Fragmented Landscapes

    by

    Alexandre Camargo Martensen

    A thesis submitted in conformity with the requirements

    for the degree of Doctor of Philosophy

    Department of Ecology and Evolutionary Biology

    University of Toronto

    © Copyright by Alexandre Camargo Martensen 2017

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    Spatio-Temporal Connectivity in Dynamic Tropical Fragmented

    Landscapes

    Alexandre Camargo Martensen

    Doctor of Philosophy

    Department of Ecology and Evolutionary Biology

    University of Toronto

    2017

    Abstract

    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 world’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

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    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.

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    Acknowledgments

    This work would not have been possible without a supportive group of collaborators, friends and

    family. I want to thank, first and foremost, three people who were particularly vital for the

    conclusion of my PhD. Without the unconditional love, support, patience, dedication and

    partnership of Kika and Cauê, none of this would have been possible. For their sacrifices, I will

    be eternally grateful. Also to my mentor Dr. Marie-Josée Fortin, who has taught me so much

    well beyond academic knowledge. Her example as an advisor has gone far beyond what I

    expected, which has set the bar really high for mentorship. No words can express my gratitude

    for how comprehensive she was with aspects of my personal life and the way that she welcomed

    me, Kika and Cauê. I am also thankful to my committee members, Dr. Don Jackson and Dr. Ben

    Gilbert, for their kind support, guidance and encouragement. I am very grateful for the help of

    Dr. Santiago Saura, who embraced my research, illuminated my ideas and helped me to format

    my results as papers. I am thankful for the long standing partnership with Dr. Milton Cezar

    Ribeiro who has been influential since the initial stages of this work, including the generation of

    the Atlantic Forest dataset used in the second and third chapters. Also many thanks to Kate Kirby

    for helping me in different phases of this study. The Connaught International Scholarships for

    Doctoral Students provided financial support for my work and a Discovery Grant and CRC Tier

    1 awarded to my advisor, Dr. Fortin. Additional funding was provided by the Department of

    Ecology and Evolutionary Biology at the University of Toronto. I was privileged to have worked

    with a great group of friends in the LeLab, all of whom contributed in some way to this work.

    Huge thanks to Colin, Amanda, Andrew, Chris Edge, Chris Blackford, Stephanie, Stephen,

    Lanna, Kate, and many others who helped me translate what I have written to English. Enormous

    thanks to Amanda, Colin, Paul, Kate, Ilona, Lanna, Aaron, Andrew, Alex, Cassidy, Carina,

    Korryn, Flávia, Claudia, Iñaki, Jennifer, Anna, Henrique, Fernando, Jonathan, Emily and many

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    others who made my life in Toronto much happier and easier. Finally, I want to thank my Mom,

    Dad and brother for their constant support and encouragement.

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    Chapter Acknowledgements

    This thesis is composed of five chapters divided as follow: three analytical chapters (Chapters 2

    to 4), that are either in review or in preparation for submission; one introductory one (Chapter 1)

    that provides the basis for the dissertation; and a final closing chapter (Chapter 5) that presents

    some conclusion remarks, as well as future research avenues that could be a starting point for

    forthcoming inquires. The experimental design, analyses, and manuscript preparation were all

    carried out by myself. Co-authors of the chapters contributed on conceptual discussions (Saura

    and Fortin), maps datasets (Ribeiro), expertise in computer programming (Saura), and editing of

    written materials (Saura and Fortin).

    1. Martensen, A.C., Saura, S. and Fortin, M.-J. (In review) Spatio-temporal connectivity:

    Assessing the amount of reachable habitat in dynamic landscapes (Chapter 2)

    2. Martensen, A.C., Saura, S., Ribeiro, M.C. and Fortin M.-J (In prep.) Land-use intensification

    constraints spatio-temporal connectivity of fragmented tropical forest landscapes (Chapter 3)

    3. Martensen, A.C., Saura, S., and Fortin, M.-J. (In prep.) Forest and land-use dynamics in the

    Amazon: Convergent effects of human activities (Chapter 4)

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    Table of Contents

    Abstract ........................................................................................................................................... ii

    Acknowledgments.......................................................................................................................... iv

    Chapter Acknowledgements .......................................................................................................... vi

    Table of Contents .......................................................................................................................... vii

    List of Tables ...................................................................................................................................x

    List of Figures ............................................................................................................................... xii

    - Spatio-temporal dynamics of tropical forest .............................................................................1

    General introduction ............................................................................................................1

    Research questions and thesis roadmap ...............................................................................4

    - Spatio-temporal connectivity: Assessing the amount of reachable habitat in dynamic

    landscapes ...................................................................................................................................8

    Abstract ................................................................................................................................8

    Introduction ..........................................................................................................................9

    Methods..............................................................................................................................10

    2.3.1 Spatio-temporal landscape networks .....................................................................10

    2.3.2 Modelling movement in dynamic landscapes ........................................................11

    2.3.3 Metrics of spatio-temporal habitat reachability .....................................................13

    2.3.4 Case study in the Atlantic Forest ...........................................................................15

    2.3.4.1 Model parametrization ...........................