Abstract

Restoration of mixed oak forest in northern temperate regions is important for biodiversity and for adaptation of forest management to climate change. Direct seeding has been considered as a cost-effective method for the assisted regeneration of oaks. However, removal of acorns by granivorous rodents hinders its application. Patterns of acorn removal can vary with habitat type, presence of predators, and acorn size. In this field study, we tested the effects of distance to forest edge, predator excrement as a repellent, and acorn size on the performance of direct-seeded oak in southern Sweden. The experiment was carried out at two different sites. Our hypotheses were: (i) in clear-cuts, acorn removal is higher closer to the forest edge compared to open areas, (ii) treatment with predator excrement reduces acorn removal without affecting germination, and (iii) larger acorns will be removed more readily than smaller acorns. Finally, we also investigated if seedlings from larger acorns survive better and grow taller compared to smaller acorns in relation to habitat structure and predator excrement as repellent. Acorn removal differed at the two sites. At Skrylle (older clear-cut), no forest edge effects were found. At Klåveröd (new clear-cut site), our results suggest that removal of acorns was higher in the open clear-cut due to the presence of large slash piles. Less vegetation coverage correlated with lower rates of acorn removal, except near slash piles. Our results therefore suggest that forest managers should reduce understory vegetation and avoid slash piles during direct seeding of oak. Mink excrement failed to protect acorns against removal, but did not reduce acorn germination. Bigger acorns produced taller seedlings but did not enhance overall woodland establishment due to their higher removal rate. Our results further suggest a potential food satiation effect due to an extra supply of additional food. Satiation manipulation might potentially be a method of mitigating the impact of seed predation by granivorous rodents during the direct seeding of oak, but such an approach requires further research before it could be recommended.

Keywords

Clear-cut; Pest control; Quercus; Regeneration; Repellent; Sowing

Published in

Forest Ecology and Management
2020, Volume: 477, article number: 118484

SLU Authors

• Villalobos, Adrian

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

• Schlyter, Fredrik

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    
  • Czech University of Life Sciences Prague

• Olsson, Gert

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

• Witzell, Johanna

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

• Löf, Magnus

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network


Sustainable Development Goals

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1016/j.foreco.2020.118484

Permanent link to this page (URI)

https://res.slu.se/id/publ/107357