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In temperate Europe, oak-dominated forests are widespread, supporting high biodiversity and providing important ecosystem services. Insufficient natural regeneration has, however, been a concern for over a century. The objective of this study was to gain insights into differences in regeneration success using artificial and natural regeneration techniques for reforestation of oak (Quercus robur L.) stands. We monitored seedlings following planting, direct seeding and natural regeneration over five years in a randomized block experiment in southern Sweden with fenced and non-fenced plots. Fencing had a strong positive effect on height growth, especially for planted seedlings that were taller than the other seedlings and more frequently browsed in non-fenced plots. In contrast, there was little effect of fencing on survival, establishment rate and recruitment rate of seedlings. Due to aboveground damage on seedlings from voles, protection of acorns did not improve establishment rate following direct seeding. Under current circumstances at the site with a sparse shelterwood of old oaks, we conclude that natural regeneration was the most cost-efficient regeneration method. It resulted in the most seedlings at the lowest cost. However, regeneration success was heavily influenced by interference from herbaceous vegetation. With a small additional investment in vegetation control, the results might have been improved for planting and direct seeding.

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Consumption and removal of buried seeds by granivorous rodents is one of the major problems when direct seeding is applied for restoration of oak (Quercus robur) and European beech (Fagus sylvatica) forests. In this laboratory study, the use of four seed treatments to potentially reduce bank vole (Myodes glareolus) consumption of beech nuts and acorns and a control was evaluated using a no-choice feeding setup. The five seed treatments were: Chili (Capsicum chinense)/coconut fat, citronella (Cymbopogon winterianus)/rapeseed oils, mink (Mustela vision) excrement, sand coating as a physical barrier and a control. Seed germination tests were carried out with all the treatments. A total of 40 bank voles were individually given access to beech nuts or acorns at a rate of one treatment per day during two sessions. Mink excrement and chili/coconut fat treatments greatly reduced the consumption of beech nuts, and also reduced touching of beech nuts and acorns. In contrast, the sand coating treatment increased the consumption of both types of seeds. Germination of both beech nuts and acorns was reduced by the chilli/coconut fat and citronella/rapeseed oils treatments. Our results suggest that mink excrement has a potential as an effective repellent against bank voles when direct seeding is applied. However, further studies to determine the best method of application, as well as the efficiency under field conditions, are needed before definitive recommendations can be given to restoration managers.

BACKGROUND Arvicolinae rodents are known pests causing damage to both agricultural and forest crops. Today, rodenticides for rodent control are widely discouraged owing to their negative effects on the environment. Rodents are the main prey for several predators, and their complex olfactory system allows them to identify risks of predation. Therefore, the potential use of predators' scents as repellents has gained interest as an ecologically based rodent control method. In a two‐choice experiment, we investigated the potential repellent effects of five synthetic predator compounds: 2‐phenylethylamine (2‐PEA), 2‐propylthietane (2‐PT), indole, heptanal and 2,5‐dihydro‐2,4,5‐trimethylthiazoline (TMT), at 1% and 5% doses, using the bank vole (Myodes glareolus) as a rodent model. RESULTS The compound 2‐PEA reduced both the food contacts and the time spent by voles in the treatment arm compared to the control arm. Likewise, 2‐PT‐treated arms reduced the food contacts, and the voles spent less time there, although this latter difference was not significant. Indole also showed a tendency to reduce the time spent at the treatment arm; however, this result was not significant. Unexpectedly, TMT had the reverse effect in showing attractive properties, possibly due to odor cues from differently sized predators and intraguild predation in nature. We found no dose‐related effects for any compounds tested. CONCLUSION Our results suggest that the 2‐PEA and 2‐PT are both effective odor stimuli for triggering reduced food contacts and area avoidance, and they may be good repellent candidates. We suggest further testing of 2‐PEA and 2‐PT in field experiments to further determine their dose‐efficiency as repellents against rodents in more natural environments. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.