Structuring Effects of Deer in Boreal Forest Ecosystems

Steeve D Côté,Emilie Champagne,Nelson Thiffault,Sonia De Bellefeuille,Jean-Pierre Tremblay,Julien Beguin

doi:10.1155/2014/917834

Abstract

Many deer populations have recently increased worldwide leading to strong direct and indirect ecological and socioeconomical impacts on the composition, dynamic, and functions of forest ecosystems. Deer directly modify the composition and structure of vegetation communities, but they also indirectly affect other species of the ecosystem by modifying the structure of the vegetation. Here we review the results of a research program on overabundant white-tailed deer (Odocoileus virginianus) in the boreal forest of Anticosti Island (Québec, Canada) aimed at identifying deer densities compatible with forest regeneration. Various silvicultural systems and treatments failed to regenerate deer habitat at high deer densities, but planting size-adapted seedlings could be effective at moderate densities. Using a controlled deer density experiment, we found vegetation recovery at deer densities ≤ 15 deer/km2. The same experiment revealed that other groups of organisms such as insects and birds responded favorably to a reduction of deer density. We also found that alternative successional trajectories may occur after a certain period of heavy browsing during early succession. We conclude that one of the most important remaining research gaps is the need to identify habitat-specific threshold densities at which deer impacts occur and then to design effective wildlife and forest management strategies to limit deer impacts and sustain ecosystem integrity.

Highlights

Several populations of cervids have increased worldwide during the last decades causing strong direct and indirect ecological and socioeconomical impacts on the composition, dynamic, and functions of forest ecosystems [1]
This review summarizes the results of a research program on Anticosti Island (Quebec, Canada) that exemplified how an overabundant white-tailed deer population modified a boreal forest ecosystem
Heavy browsing caused by high deer densities directly impacts plant communities and tree regeneration dynamics (Figure 1)

Summary

Introduction

Several populations of cervids (hereafter deer) have increased worldwide during the last decades causing strong direct and indirect ecological and socioeconomical impacts on the composition, dynamic, and functions of forest ecosystems [1]. Heavy browsing caused by high deer densities directly impacts plant communities and tree regeneration dynamics (Figure 1) These impacts often lead to dominance of plant species tolerant to browsing into communities [4], lower abundance or extirpation of less tolerant species [5,6,7], and changes in compositional and functional patterns of plant diversity [8,9,10], possibly reducing the productivity of ecosystems [11, 12]. The lower abundance of primary consumers might initiate trophic ricochets (sensu [23]) on predators, carnivores, and decomposers altering the structure and interactions among the entire food web [24,25,26,27] To answer these questions, we have launched a long-term multidisciplinary research program on deer-boreal forest relationships [28]. We have established a controlled deer density experiment to investigate the response of several ecosystem components (e.g., soil properties, vegetation, insects, birds, and small mammals) along a gradient of deer browsing intensity

Context

Research on Anticosti

Findings

Outlook