Felled Scots pine (Pinus sylvestris) as supplemental forage for moose (Alces alces): Browse availability and utilization

Abstract

Old trees felled by forestry actions or natural disturbances can supply large herbivores with a substantial amount of forage and thereby potentially affect browsing patterns. To explore the felling of mature Scots pine (Pinus sylvestris L.) as a management practice (and potentially divert moose from young pine forests) this study identified how much browse there is available on felled trees and to what extent this browse is used by moose (Alces alces L.). Pine trees were surveyed in two study areas in Sweden and one in Norway. Pine crowns from thinning-stage trees held on average 8 kg of potential moose forage (dry weight). Corresponding figures for mature trees and seed trees were 29 kg and 12 kg, respectively. When the trees were processed during commercial felling, much of the potential forage became unavailable, and only approximately 1.5 kg per tree was available for moose after processing. The utilization of the forage on felled trees ranged between 5 and 15%. No significant difference in utilization between tree ages or between tops and bases within the tree crowns were found. However, the bite diameters on twigs differed between parts and age stages of the trees. This study illustrates that felling of trees can influence the availability of winter forage for moose and thereby has the potential to decrease browsing pressure on young forest stands. The substantial effect that storms can have on short-term forage supply for moose is also emphasized.