Efficient application of a browsing repellent: Can associational effects within and between plants be exploited?

Abstract

Browsing can reduce forest productivity, particularly when the apical shoots of trees are damaged. Repellents are used widely to reduce browsing, but application is costly. To improve efficiency, it may be possible to take advantage of associational plant refuge effects, requiring repellents to be applied only to some trees or parts of trees, or reapplied less frequently. Using captive moose (Alces alces) and constructed stands of Scots pine (Pinus sylvestris), we tested for potential refuges by applying a commercial repellent (HaTe2) to all, alternate or none of the apical shoots, or all of the previous-year apical shoots. We also tested for potential refuges under field conditions, applying the repellent to all, alternate or none of the apical pine shoots in forest stands. Captive moose (two individuals in a 2.1-ha enclosure, ~ 95 individuals km −2) browsed 100% of trees, but were significantly less likely to browse apical shoots treated with repellent. Associational refuge was ineffective both within and between trees. In the field (0.84 moose km −2), only 1.3% of trees sustained browsing damage. Applying the repellent to the apical shoots of pines had no direct repellent effect nor any within-plant associational effects. Trees with treated apical shoots provided some protection for untreated neighbouring trees, but this was not biologically meaningful given the low percentage of trees browsed overall. Here, a simple captive experiment was not predictive of the browsing response observed in the field, demonstrating the need to test repellent application strategies in situ.

Spatial patterns in neighbourhood effects on woody plant selection and bark stripping by deer in a lowland alluvial forest

“…These are also the scales at which the utilization of neighbourhood effects can be attempted for management purposes, e.g. to reduce excessive herbivory impacts on tree recruitment (Bergvall & Leimar, 2017; Stutz et al, 2019). This is very challenging, however, especially in communities with a natural spatial distribution of plants because the strength and spatial extent of neighbourhood effects may be determined by variation in local plant density and the distance between plants (Champagne et al, 2016; Holík, et al, 2021; Underwood et al, 2014).…”

Захист Незімкнених Культур Сосни Звичайної Від Потрави Дикими Парнокопитними Тваринами В Київському Поліссі

“…Численні факти загибелі лісових культур сосни звичайної внаслідок збільшення чисельності диких парнокопитних тварин також відмічають на теренах Польщі, Швеції, Норвегії, Шотландії, Фінляндії, Латвії та інших країн (Vehvilainen & Koricheva 2006, Long et al 2007, Yevtushevskyi 2008, Wallgren et al 2013, Nilsson et al 2016, Bergvall & Leimar 2017, Velamazán et al 2017, Felton et al 2018, Stutz et al 2019, Lindmark et al 2020, Dūmiņš et al 2021. Ступінь пошкодження насаджень унаслідок потрави тваринами залежить не лише від щільності популяцій останніх на одиницю площі, але й від віку деревостану, його структури, складу, а також системи ведення лісового господарства.…”

“…Результати окремих досліджень (Lindmark et al 2020, Dūmiņš et al 2021) свідчать про позитивний досвід застосування репелентів для захисту незімкнених лісових культур від пошкодження парнокопитними. Водночас застосування в лісах репелентів є дорогим, оскільки цей захід слід повторювати щороку (Stutz et al 2019).…”