L approche écosystémique et son rôle fonctionnel dans le maintien de la diversité biologique des aires protégées en forêt boréale

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1 L approche écosystémique et son rôle fonctionnel dans le maintien de la diversité biologique des aires protégées en forêt boréale Ecosystem-oriented approaches and their functional role in maintaining biodiversity within protected areas of the boreal forest. Pierre Drapeau 1 3 Yves Bergeron 1,2,3 et Alain Leduc 1,3 1 Université du Québec à Montréal 2 Université du Québec en Abitibi-Témiscamingue. 3 Chaire industrielle CRSNG UQAT-UQAM en aménagement forestier durable Colloque Aires protégées en zone boréale CCEA 18 Septembre 2008 Québec Protected Areas External Threats Bennett

2 Linkages between protected areas and the managed matrix. Bennett 2003 Bennett

3 Disturbances in Boreal Forest Landscapes Québec Productive Landbase Area disturbed (1 000 ha) Wildfire Harvest Alberta Productive Landbase % Area Disturbed Harvest Wildfire Decades Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented approaches and species-oriented approaches to set conservation targets in managed landscapes 3

4 Assistants de terrain Jocelyn Thibault François Gagnon Réjean Deschênes Marie-Hélène Hachey Alexandre Giroux Nicolas Luigi Valérie Saint-Amant Simon-Pierre Babski Alexandre Faille Marjorie Gobeil Valérie Guay Élise Bolduc Daniel Brongo Alexandre Roby Marcello Brongo Simon Laurin-Lemay Annie-Ève Gagnon Ugo Ouellet-Lapointe Aide précieuse et collaborateurs Michel Saint-Germain Virginie-Arielle Angers Mélanie Desrochers Daniel Lesieur Alain Leduc Stéphane Daigle Tyler Rudolph Ronnie Drever Dave Gervais Labo Drapeau Labo Tim Work Acknowledgements Support financier CRSNG découverte FQRNT- Programme Actions Concertées Fonds Forestiers Service canadien de la faune Service canadien des forêts Fondation de la faune du Québec Chaire CRSNG-UQAT-UQAM en AFD FERLD Société québécoise pour la protection des oiseaux Horizons-Science SÉPAQ-Parc national des Grands-Jardins MRNF SFMN 4

5 Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented approaches and species-oriented approaches to set conservation targets in managed landscapes What do we know about fire and the status of late-seral forests in naturally disturbed boreal forest landscapes? Fire history studies across Québec 1 Bergeron et al

6 Proportion of forests >100 and 200 years old No. Site % > 100 yrs % > 200 yrs 1 Abitibi nord-ouest LAMF Abitibi sud-ouest Abitibi est Abitibi sud-est* 75-5 Témiscamingue nord Témiscamingue sud* Waswanipi* (Cree) Centre Québec Côte-Nord* Gaspésie* * Unpublished data 6

7 % OF THE AREA OCCUPIED BY STANDS INITIATED IN EACH DECADE 0,14 % of the area 0,12 0,10 0,08 0,06 0,04 0,02 mean age: 139 years 57% > 100yrs 23% > 200yrs 0, Time since last fire (10 yr classes) Old-growth forests through the Holocene: Paleoecological reconstruction of fire frequency using lake sediments (Carcaillet et al. (2001) J. Ecol. 50 N 49 N 79 W 78 W Lac à la Pessière Coniferous boreal N Lac Pas-de-Fond Mixed boreal N Lac Francis Mixed boreal N 48 N 7

8 Fire activity since 7650 BP in Abitibi Old-growth forest were abundant during all the Holocene. Current conditions are outside Natural range of variability 8

9 Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented approaches and species-oriented approaches to set conservation targets in managed landscapes Proportion in the land base 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Early-seral (0-35) Young (35-75) Mature (75-100) Fire cycle of 140 years Timber Rotation of 100 years Overmature ( ) Old-growth (>180) Stand Age (years) 9

10 A decrease in the proportion of late-seral forests in evenaged managed forest landscapes of northwestern Québec Natural forest Regeneration Mature Even-aged Managed forest > 60 % Regeneration Mature Less than 10%? Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented approaches and species-oriented approaches to set conservation targets in managed landscapes 10

11 Consequences of shifting landscapes from old to young forest cover types?????? Fire Fire Fire Gaps Regeneration Time Adapté de Bergeron et al. (2002) ) Modifié de Jetté,J, MRNFQ Study sites Site 1 Old-growth forests LAMF Val Paradis - Selbaie 11

12 Post-fire seral stages in Black Spruce forests of the boreal shield with indicator bird species.. 1 year 20 years BBWO DEJU AMRO CSWA LISP COYE ALFL OSFL WIWA years > 200 years BOCH BRCR GCKI SWTH RBNU TTWO PAWA TEWA GRJA Drapeau et al. (2003) Forestry Chronicle 79: Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented oriented approaches and species-oriented approaches to set conservation targets in managed landscapes 12

13 A major challenge Maintain within managed landscapes a composition and structure of the forest mosaic within the range of natural variability.. Kafka 1999 REPRODUCE THE AGE STRUCTURE OF NATURAL MOSAÏCS Area (%) Lengthening rotation % % % 1 23% 1 14% 14% Area (%) Time since last harvesting Varying harvesting practices 13

14 Ecosystem-oriented coarse filter approach in the eastern black spruce forest Fire Fire Fire Gaps Cohort Zero Cohort 1 Cohort 2 Cohort 3 (Post fire) Mature to Overmature (Old growth) Even-aged Uneven-aged Selection-based silviculture (clearcut) silviculture (shelterwood, silviculture thinning, careful logging) OLD-GROWTH Clear-cut (fire) Selection cut (gap dynamic) Partial cut (succession) 14

15 Multicohort management based on fire cycle and maximum yield age (Adapted from Bergeron et al. 1999) Âge maximal d exploitabilité CYCLE DE FEU cohorte (%) cohorte (%) cohorte (%) cohorte (%) cohorte (%) I II III I II III I II III I II III I II III N. Alberta N. 59Abitibi Côte 25 Nord Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented approaches and species-oriented approaches to set conservation targets in managed landscapes 15

16 Bennett 2003 Joutel Lebel-sur-Quévillon Amos Study Area km 2 in northwestern Québec (between N and W ) 16

17 Remnant patches Riparian buffers (20m) km 2 Cutblock separators m 7 species known to use older forest seral stages (cavity nesters, dead wood associates, residents, closed canopy users). Tree-toed Woodpecker Black-backed Woodpecker Boreal Chickadee Brown Creeper Winter Wren Red-breasted Nuthatch Golden-crowned Kinglet 17

18 Isolation (configuration) effects Mean abundance/count point 3,5 3 2,5 2 1,5 1 0,5 0 A <10 km B B B B km km km > 40 km BRCR WIWR Distance from unharvested forest matrix Plot of cumulative number of individuals of sensitive species detected per count point relative to distance from unharvested forest matrix (Mann-Whitney-Wilcoxon, Chi square = 4,66 ; p =0.031) RBNU BOCH In summary.. Boreal birds are tolerant to both habitat loss and habitat fragmentation (p/a and abundance) However, in highly fragmented landscapes, birds are not solely affected by habitat loss but also by fragmentation effects Distance from unharvested forests is a significant factor in remnant occupancy of these species 18

19 Conservation and Forest Management Implications In even-aged systems Reduce Isolation of remnants by Limiting the size of harvested areas and maintain large tracts of older forests at less than 10 km from the centre of harvested areas. Design permanent patch retention with regards to habitat quality of remnants, i.e., legacy trees. Large forest track retention between Even-aged cut-over areas Distance = 20 km Large Forest tracks Cut-over area 400 km 2 20 km X 20 km = 19

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21 Outline What do we know about the age structure of forest landscapes under natural disturbances? How far are managed forest landscapes from the natural variability? Which elements of biodiversity are of concern? Bridging ecosystem-oriented oriented approaches and species-oriented approaches to set conservation targets in managed landscapes 90 Proportion of the landbase (%) > 100 years > 200 years Fire cycle in northwestern Québec = 139 years +/- SD Fire Cycle (Years) 21

22 Rate of occupancy (%) Swainson s Thrush NDBM targets ROC/ Kappa cut-levels Amount of late-seral forest within 1 km (%) Drapeau, Leduc and Bergeron in press 10 Conservation and Forest Management Implications: Setting conservation targets with regards to quantitative wildlife responses to habitat alteration can refine coarse filter management approaches - 22

23 Conservation and Protected Areas Implications: Setting conservation targets based on complementarities between ecosystem-oriented and species-oriented management approaches is likely to improve the functional role of protected areas in biodiversity maintenance. 23