Canadian Forest Service Publications
Cumulative effects of chronic deer browsing and clear-cutting on regeneration processes in second-growth white spruce stands. 2014. Barrette, M.; Bélanger, L.; De Grandpré, L.; Ruel, J.-C. For. Ecol. Manag. 329:69-78.
Issued by: Laurentian Forestry Centre
Catalog ID: 35819
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Interactions between multiple disturbances can alter resilience mechanisms, thereby triggering alternative successional pathways. Regeneration processes are important mechanisms of forest resilience because they drive successional pathways. On Anticosti Island, chronic browsing by introduced white-tailed deer (Odocoileus virginianus) shifted composition of understory regeneration of overmature balsam fir (Abies balsamea) forests toward dominance by white spruce (Picea glauca). Historic clear-cutting of these altered forests generated mature second-growth white spruce stands. However, the cumulative effect of chronic deer browsing and recent clear-cutting on regeneration processes of mature second growth white spruce stands has not yet been evaluated. Our objective is to evaluate if regeneration processes would enable white spruce stands to recover from the cumulative effects of these two disturbances. We studied regeneration in relation to seed availability, substrate suitability for seedling establishment, and substrate availability in mature second-growth white spruce stands and recent clear-cuts of mature second-growth white spruce stands. Our results indicate regeneration failure in both ecosystems, which can be explained by a lack of suitable rotten logs for sufficient establishment of white spruce seedlings. Hence, the cumulative effects of chronic deer browsing and clear-cutting of mature second-growth white spruce stands have altered regeneration processes and triggered an alternative successional pathway toward parklands, i.e., partial deforestation. We propose shelterwood cuttings that create nurse logs should be investigated to maintain white spruce stands without planting.
Plain Language Summary
This study showed that white spruce stands on Anticosti Island were having difficulty regenerating. This difficulty stems mainly from two disturbances: severe deer browsing of fir seedlings for several decades and the logging of fir stands in the 1930s and 1940s, which regenerated as white spruce.
Deer browsing changed the composition of stands on the island, with fir giving way to white spruce. Because white spruce stands were more numerous, they underwent more logging. Clearcutting, the type of cutting practiced at the time, did not leave enough seed trees to ensure proper regeneration of the stands.
The objective of this study was to examine whether white spruce stands could regenerate despite the cumulative effect of these two disturbances. To do so, the researchers studied the regeneration of white spruce based on seed availability and sites favourable to their germination. They also looked at the effect of browsing on the change in stand composition.
To mitigate this problem, the researchers suggest shelterwood cutting instead of clearcutting in order to retain seed trees, which will increase the total number of seedlings.