Associational relationships at multiple spatial scales affect forest damage by moose

Abstract

15Increasing abundance of large herbivores combined with changes in forestry practices has led 16 to increased forest damage in many temperate and boreal forest areas. The role of alternative 17 forage as a driver for browsing pressure on tree species important for forestry has received 18 increased attention. However, actions to reduce damage through altering forage abundance 19 must be carried out at spatial scales that correspond to the behavioral processes that generate 20 the browsing pattern. We used a multi-scaled dataset on browse abundance and utilization in 21 Southern Norway to assess how pine browsing damage was related to abundance and quality 22 of browse measured at different spatial scales. Pine trees had a lower probability to be 23 browsed at high pine abundance at all spatial scales. However, the abundance and quality of 24 alternative browse was negatively related to pine browsing (i.e. associational resistance) at 25 several spatial scales, with the highest explanatory power at the largest spatial scale. 26Management actions to reduce pine browsing by moose should focus on facilitating high 27 abundance of both pine and alternative high-quality browse, and should be carried out at 28 sufficiently large spatial scales (moose home range scale or larger).

Pervasive moose browsing in boreal forests alters successional trajectories by severely suppressing keystone species

“…These could be called keystone species due to their disproportionately large importance to the habitat value for other organisms, including lichens, fungi, insects, and birds (e.g., Bendiksen et al 2008). Moose also browse common and often dominant species like the two birches Betula pubescens and B. pendula (hereafter just birch) and the coniferous Scots pine (Pinus sylvestris, hereafter just pine; M ansson et al 2007, Speed et al 2013a, Herfindal et al 2015. Norway spruce (Picea abies, hereafter just spruce) is the most economically important timber species in this region, particularly on rich and welldrained soils, while pine is gradually more important in poorer and/or drier areas.…”

Interactions between ungulates, forests, and supplementary feeding: the role of nutritional balancing in determining outcomes

“…If the preferred option is to retain animal densities, the larger question must therefore be raised as to what alternatives are available or even preferable to supplementary feeding. With respect to alleviating forest damage, plausible alternatives involve increasing the amount of natural browse at larger spatial scales to minimize the contrast in food availability between regenerating stands and the surrounding mature forest (Kuijper et al 2009;Milner et al 2013), and thereby decrease the browsing damage burden on any one forest owner (Heikkilä and Härkönen 1996;Herfindal et al 2015;. For example, due to the concerted effort of a large number of private forest owners in one region of southern Sweden, the planting of Scot's pine has increased significantly in recent years, resulting in lower rates of forest damage and less conflict between hunters and forest owners (pers.…”

“…If the level of browsing damage is sufficiently high, or perceived to be problematic, Norway spruce is currently favored at the expense of other production forest alternatives, including broadleaf tree species and Scots pine (Lidskog and Sjödin 2014), with negative implications for biodiversity and forest resilience (Felton et al 2016a;Felton et al 2016b). This can readily create a feedback loop, in which the resultant intensified browsing damage in the remaining pine and deciduous forest areas (Herfindal et al 2015) provides further motivation for the increased use of Norway spruce in production forests. The extent to which supplementary feeding influences this feedback loop needs to be addressed.…”

Spatial correlations between browsing on balsam fir by white‐tailed deer and the nutritional value of neighboring winter forage

“…Browsing on fir was also negatively correlated with fiber content and positively correlated with digestibility of white spruce at this scale and inside cutover areas. Recent studies have demonstrated large‐scale associational effects linked to neighboring plant abundance (Herfindal et al., ; Moore, Britton, et al., ). In contrast to those results and our hypothesis, the abundance of neighboring trees did not generate associational effects, potentially because of the high abundance of resources and the low browsing rate in the study area.…”

“…Recently, Moore, Britton, Iason, Pemberton, and Pakeman () described increased grazing by red deer ( Cervus elaphus ) and cattle on protected heathland areas with greater proportions of species‐rich grassland within 1,000 m of the heathland. Browsing on Scots pine ( Pinus sylvestris ) by moose ( Alces alces ) declined with increasing presence of preferred alternative browse at the scale of moose management units (415 km 2 ; Herfindal, Tremblay, Hester, Lande, & Wam, ). Such studies conducted at large spatial scales, however, are rare and needed to assess the spatial extent of associational effects (Champagne et al., ).…”