DEFORESTATION IN CENTRAL SASKATCHEWAN: EFFECTS ON LANDSCAPE STRUCTURE AND ECOSYSTEM CARBON DENSITIES A Thesis Submitted to the College ofGraduate Studies and Research in Partial Fulfilment ofthe Requirements for the Degree ofDoctor ofPhilosophy in the Department ofPlant Sciences University of Saskatchewan Saskatoon By Michael Joseph Fitzsimmons Spring, 2003 © Copyright Michael Joseph Fitzsimmons, 2002. All rights reserved. PERMISSION TO USE In presenting this thesis in partial fulfilment ofthe requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying ofthis thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head ofthe Department or the Dean ofthe College in which my thesis work was done. It is understood that any copying or publication or use ofthis thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made ofany material in my thesis. Requests for permission to copy or to make other use ofmaterial in this thesis in whole or part should be addressed to: Head ofthe Department ofPlant Sciences University of Saskatchewan Saskatoon, Saskatchewan S7H 5A8 ABSTRACT Deforestation is recognized as a serious global problem that contributes to biodiversity loss, soil degradation and atmospheric change. This thesis is an investigation ofdeforestation in central Saskatchewan. The purposes are: to quantify the extent and rates of deforestation and associated changes in spatial structure for multi­ jurisdictional boreal landscapes; and to estimate the magnitude ofcarbon losses associated with agriculture-induced deforestation at sites within one ofthese landscapes. Deforestation was analyzed using topographic map chronosequences for two 460 000 ha landscapes in central Saskatchewan. An estimated 16 400 ha was deforested between 1963 and 1990 within the Waskesiu Hills landscape (53 0 45' N, 1060 15' W) and 371 000 ha was deforested between 1957 and 1990 within the Red Deer River landscape (520 45' N, 103 0 00' W). Federal and provincial legislation establishing publicly owned parks and forests served to inhibit deforestation within portions ofthese landscapes. On agricultural lands within the two landscapes, where private holdings dominate and forests are not protected under federal or provincial law, deforestation occurred at rates exceeding 1.2 % yfl over the time periods examined even though human populations declined. Within the two study areas, extant forests that are unprotected by legislation remain vulnerable to deforestation. Spatial structure was analyzed for portions ofthese two landscapes using landscape metrics. A positive correlation between largest patch size index and proportion ofland area wooded was evident for both 1975/76 (r2 = 0.99, p < 0.01) and 2 1990 (r = 0.99, p < 0.05). Since past deforestation disproportionately reduced the sizes ofthe largest wooded patches, future reforestation efforts should be aimed at expanding large patches. Reforestation with large patches contiguous to protected forests may initiate a reversal ofthe process offragmentation that has impaired forest wildlife and ecosystem processes. 11 Vegetation carbon densities were compared at six forest sites, six pasture sites and six cultivated sites on hummocky glacial till landforms across three townships within the Waskesiu Hills landscape. Medians for aboveground biomass (60 Mg C ha-] for forests, 1 Mg C ha- l for pastures and 4 Mg C ha- l for cultivated sites) were significantly different (p < 0.15). Including estimated losses ofcoarse roots, deforestation and subsequent agricultural land use led to losses ofapproximately 70 Mg C ha- l for vegetation. Statistically significant losses ofsoil organic carbon were not detected between the forest sites and the agricultural sites. The experimental design accounted for land use and topographic landform effects, but these were small « 20 Mg C ha- l) relative to the inherent range ofvariation in soil organic carbon within the study area (> 50 Mg C ha-] for natural forest sites). Across all sites regardless of land use, there was a positive correlation (rs = 0.76, P < 0.01) between soil organic carbon and the proportional frequency of groundwater influenced soils (Gleysols plus Woody Calcareous Chemozems). Terrestrial carbon losses due to deforestation within the Waskesiu Hills and Red Deer River landscapes prior to 1990 were crudely estimated as approximately 100 Gg C y{l. Carbon releases due to deforestation across the Boreal Plain Ecozone of Saskatchewan prior to 1990 were estimated to be an order ofmagnitude greater, and may have exceeded direct carbon emissions resulting from fossil fuel burning by the provincial agricultural production sector. Reestablishing natural forests on 2 % of agricultural lands within the Boreal Plain Ecozone might offset a substantial portion of the direct carbon emissions from agricultural fossil fuel burning in Saskatchewan. HI ACKNOWLEDGEMENTS I thank Dan Pennock and JeffThorpe, my co-supervisors, for their research methodology suggestions, tireless editing, and general encouragement. I would also like to thank current and former supervisory committee members for their guidance and advice: Yuguang Bai, Malcolm Devine, Geoff Hughes, Mark Johnston, Bob Redman, Jim Romo, Graham .. Scoles, and Ken Van Rees. Constructive criticism from the external examiner, Andrew Gordon (University ofGuelph), was appreciated. This research was supported by the Centre for Studies in Agriculture Law and Environment, the Department ofPlant Sciences, the Department of Soil Science, and the College ofAgriculture at the University of Saskatchewan. Additional assistance was received from Nature Saskatchewan, Parks Canada, and the Saskatchewan Research Council. Environment Canada, Parks Canada and the University ofRegina provided in­ kind contributions in support ofthe GIS analysis. I would like to thank Lorena Patifio (Canadian Plains Research Center, University ofRegina) and Kelly Best (National Water Research Institute, Environment Canada) for providing instruction and technical assistance. I am indebted to the many hours ofdigitizing performed by Colleen Watson, Diane Bolingbroke (Canadian Plains Research Center, University ofRegina), and Lara Smandych (University of Saskatchewan). I would especially like to thank all those who assisted with fieldwork: Colleen Watson, Michael Solohub, Masae Takeda, Randy Olson, Tyler Worrell, Dave Weider, Lillian Watson, Adam Pidwerbeski and Jonathon Melville. Lab instruction and advice was provided by Michael Solohub, Renato de Freitas and Barry Goetz. I am grateful for the lab assistance provided by Colleen Watson, Masae Takeda, Melissa Watson­ Worrell and Randy Olson. I would like to thank Parks Canada for providing educational leave to complete this research. I am grateful for the support ofmy current and former supervisors, Norm IV Stolle and Jean Fau, as well as the current and former Superintendents ofPrince Albert National Park, Anne Morin, John Allard, Bill Fisher and Peggy Clark. This research would not have been possible without the support oflandowners and land managers. I would like to thank Arnold Larsen, Helen Larsen, Kevin Larsen, Mary-Jean Herzog and Glen Herzog for allowing me to take soil and vegetation samples on their land. I would also like to thank George Derksen, the manager ofthe Cookson Community Pasture, for his cooperation. v DEDICATION This thesis is dedicated to my loving wife and life-partner Colleen Watson, for contributing her time and energy to digitize maps, drive to study sites, collect vegetation (amidst the bison, bears and snakes), dry and weigh samples, sieve sand, enter data, and perform many other vital tasks over the past five years; all the while generously providing love, friendship, encouragement and emotional support to her husband, parents, children and grandchild. VI TABLE OF CONTENTS PERMISSION TO USE . ABSTRACT......................................................................................................................... 11 ACKNOWLEDGEMENTS................................................................................................. IV DEDICATION..................................................................................................................... VI TABLE OF CONTENTS..................................................................................................... vii LIST OF TABLES............................................................................................................... x LIST OF FIGURES............................................................................................................. xii LIST OF ABBREVIATIONS.............................................................................................. XIV 1. INTRODUCTION................................................................................................ 1 1.1 Definitions............................................................................................................ 2 1.2 Global Deforestation............................................................................................. 2 1.3 Deforestation in Western Canada........................................................................