Where can palatable young trees escape herbivore pressure in a protected forest?

FOREST ECOLOGY AND MANAGEMENT

卷:472

Article

Milne-Rostkowska, Fiona¹  Holeksa, Jan¹  Bogdziewicz, Michal¹  Piechnik, Lukasz²  Seget, Barbara²  Kurek, Przemyslaw¹  Buda, Jakub¹  Zywiec, Magdalena² 

[1] Adam Mickiewicz Univ, Fac Biol, Umultowska 89, PL-61614 Poznan, Poland

[2] Polish Acad Sci, W Szafer Inst Bot, Lubicz 46, PL-31512 Krakow, Poland

关键词: Browsing;    Seedling and sapling bank;    Herbivory;    Natural regeneration;    Sorbus aucuparia;    Coarse woody debris;    Red deer;    Subalpine spruce forest;    Hiking trails;    Ungulates;   

DOI  :  10.1016/j.foreco.2020.118221

来源: Elsevier

【 摘 要 】

Browsing damage by ungulates is among the most decisive factors affecting the establishment and growth of young trees. In recent decades, ungulate populations have been expanding in the Northern Hemisphere; impairment of tree regeneration by their activity is an increasing problem. Herbivore-induced changes in tree regeneration may alter the composition and biodiversity of the future tree stand. In this study we determined where young trees can leave the seedling bank and succeed to higher forest strata in a protected natural forest that is under strong herbivore pressure. We studied rowan (Sorbus aucuparia) regeneration in a subalpine spruce forest growing in a strictly protected area of Babia Gora National Park (Western Carpathians). Rowan is one of the most palatable forest species, so browsing can significantly limit its growth. We predicted that factors, that restrict the movement of red deer (Cervus elaphus), decrease their visits in some forest patches, which will result in a higher share of rowan saplings. We also considered two other factors that can affect the distribution of rowan saplings: light availability and distance to maternal trees. In particular, we tested whether the occurrence of rowan saplings was related to: (i) slope angle, amount of logs lying on the forest floor, and distance to the hiking trails; (ii) distance to fruit-bearing trees; and (iii) canopy openness. The results confirmed our main predictions concerning the relation between the occurrence of palatable tree saplings and the availability of a forest area to ungulates. Factors related to the availability of terrain to red deer significantly influenced the distribution of rowan saplings taller than 1 m. The probability of rowan sapling occurrence increased when the amount of logs was higher and the distance to hiking trails was shorter. Slope had a significant negative impact on sapling occurrence. We found no effect of proximity of fruit-bearing rowan trees or canopy gap area. Thus, in the natural forest, the likelihood that young palatable trees will make the transition from seedlings to taller saplings seems to be determined mainly by factors related to ungulate activity. This suggests that the increase of ungulate populations and their browsing behavior will affect the species composition and spatial structure of future tree stands.

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