INRAE, UR EFNO, Nogent-sur-Vernisson, France.
Département Recherche et Développement, Office National des Forêts, Fontainebleau, France.
Ecol Appl. 2022 Apr;32(3):e2531. doi: 10.1002/eap.2531. Epub 2022 Mar 15.
Conventional conservation policies in Europe notably rely on the passive restoration of natural forest dynamics by setting aside forest areas to preserve forest biodiversity. However, since forest reserves cover only a small proportion of the territory, conservation policies also require complementary conservation efforts in managed forests in order to achieve the biodiversity targets set up in the Convention on Biological Diversity. Conservation measures also raise the question of large herbivore management in and around set-asides, particularly regarding their impact on understory vegetation. Although many studies have separately analyzed the effects of forest management, management abandonment, and ungulate pressure on forest biodiversity, their joint effects have rarely been studied in a correlative framework. We studied 212 plots located in 15 strict forest reserves paired with adjacent managed forests in European France. We applied structural equation models to test the effects of management abandonment, stand structure, and ungulate pressure on the abundance, species richness, and diversity of herbaceous vascular plants and terricolous bryophytes. We showed that stand structure indices and plot-level browsing pressure had direct and opposite effects on herbaceous vascular plant species diversity; these effects were linked with the light tolerance of the different species groups. Increasing canopy cover had an overall negative effect on herbaceous vascular plant abundance and species diversity. The effect was two to three times greater in magnitude than the positive effects of browsing pressure on herbaceous plants diversity. On the other hand, a high stand density index had a positive effect on the species richness and diversity of bryophytes, while browsing had no effect. Forest management abandonment had few direct effects on understory plant communities, and mainly indirectly affected herbaceous vascular plant and bryophyte abundance and species richness and diversity through changes in vertical stand structure. Our results show that conservation biologists should rely on foresters and hunters to lead the preservation of understory vegetation communities in managed forests since, respectively, they manipulate stand structure and regulate ungulate pressure. Their management actions should be adapted to the taxa at stake, since bryophytes and vascular plants respond differently to stand and ungulate factors.
欧洲传统的保护政策主要依赖于通过划出森林区域来保护森林生物多样性，从而被动地恢复自然森林动态。然而，由于森林保护区仅覆盖了领土的一小部分，保护政策还需要在管理的森林中进行补充保护工作，以实现《生物多样性公约》设定的生物多样性目标。保护措施还提出了在保留地内外管理大型食草动物的问题，特别是关于它们对林下植被的影响。虽然许多研究分别分析了森林管理、管理放弃和有蹄类动物对森林生物多样性的影响，但很少在相关框架中研究它们的共同影响。我们研究了位于法国欧洲的 15 个严格森林保护区及其相邻管理森林中的 212 个样地。我们应用结构方程模型来测试管理放弃、林分结构和有蹄类动物压力对草本维管束植物和地衣苔藓植物丰富度、物种丰富度和多样性的影响。我们表明，林分结构指数和样地水平的采食压力对草本维管束植物物种多样性具有直接和相反的影响；这些影响与不同物种组的光耐受性有关。冠层覆盖度的增加对草本维管束植物的丰富度和物种多样性有整体的负面影响。这种影响的大小是采食压力对草本植物多样性的正影响的两到三倍。另一方面，高林分密度指数对苔藓植物的物种丰富度和多样性有积极影响，而采食没有影响。森林管理放弃对林下植物群落几乎没有直接影响，主要通过改变垂直林分结构间接影响草本维管束植物和苔藓植物的丰富度、多样性和丰富度。我们的结果表明，保护生物学家应该依靠林务员和猎人来领导管理森林中下木植被群落的保护，因为他们分别操纵林分结构和调节有蹄类动物的压力。他们的管理行动应该适应于有争议的分类群，因为苔藓植物和维管束植物对林分和有蹄类动物因素的反应不同。
