Effects of deer abundance on broad-leaf tree seedling establishment in the understory of Abies sachalinensis plantations

Abstract

Browsing by sika deer (Cervus nippon) has significant negative effects on regeneration in many forests in Japan; however, the effects of browsing on regeneration processes have not been determined quantitatively. Our study was conducted in Abies sachalinensis plantations in seven tracts with differences in deer abundance on Hokkaido, northern Japan, to identify indicators for the effects of deer on the regeneration of broad-leaf species from observing seedlings. Five 5 9 20-m plots were located within each tract, and the densities of seedlings 30-200 cm tall and percentages of browsed seedlings were determined. We used sightings per unit effort (SPUE) by hunters and spotlight survey counts (SLCs) as indices of deer abundance for each tract. Seedling density was negatively correlated with deer abundance and coverage of dwarf bamboo, and basal areas of overstory trees also affected number of seedlings. Percentage of browsed seedlings was positively correlated with deer abundance, and it was affected by deer preferences among seedling species. However, the percentage of browsed seedlings was more clearly related to deer abundance than seedling density. There were few seedlings of tree species C100 cm tall in tracts with the highest deer abundance. Based on these results, deer abundances of SPUE [6 sightings per hunter-day or SLC [15 animals per 10 km are likely to prevent regeneration of broad-leaf species. The percentage of browsed seedlings and density and browsing damage on tree seedlings C100 cm tall are useful indicators of the effects of deer.

Applying typology analyses to management issues: Deer harvest and declining hunter numbers

“…Abundant populations of large herbivores can have several undesirable effects on ecosystems, such as diminishing biodiversity, altering nutrient cycling, and suppressing primary production (McShea and Underwood , Côté et al , McLaren et al , Ims et al , Rooney ). High ungulate densities can also damage agricultural and timber crops (Takatsuki , Apollonio et al , Akashi et al ), increase the risk of zoonotic diseases (Wilkins et al , Trout and Steelman ), and escalate the frequency of costly deer–vehicle collisions (Groot Bruinderink and Bruinderink , Mysterud , Dussault et al , Danks and Porter ).…”

Influence of Deer Hunting and Residual Stand Structure on Tree Regeneration in Deciduous Forests

“…Relative to hunted areas, declines of native species densities were greater in areas without deer hunting in northern Wisconsin (Rooney et al 2004). The link between high cervid populations and inadequate or reduced regeneration levels has been reported for studies at various scales: exclosure–enclosure (McCormick et al 1993, Horsley et al 2003, Rooney 2009; but see Marquis 1981); statewide (Gubanyi et al 2008, Lesser et al 2019); regional (Russell et al 2017, McWilliams et al 2018, Miller and McGill 2019); and international (Putnam et al 1989, Akashi et al 2011).…”

Appropriate vegetation indices for measuring the impacts of deer on forest ecosystems

“…Accordingly, serious impacts of deer on forest ecosystems, including tree debarking (Akashi and Nakashizuka, 1999;Verheyden et al, 2006;Vospernik, 2006;Kiffner et al, 2008;Takeuchi et al, 2011), reduction of sapling density (Horsley et al, 2003;Kumar et al, 2006;Gill and Morgan, 2010;Randall and Walters, 2011;Nuttle et al, 2014), browsing on saplings and understory vegetation (Takatsuki, 1989;McLaren et al, 2000;Morellet et al, 2001;Rooney and Waller, 2003;Heuze et al, 2005;Akashi et al, 2011), changes in species diversity and/or composition of understory vegetation (Stewart and Burrows, 1989;Horsley et al, 2003;Beguin et al, 2011;Suzuki et al, 2013;Filazzola et al, 2014), and soil disturbance (Beguin et al, 2011) have been documented. Such deer impacts would be irreversible (Waller and Alverson, 1997;Horsley et al, 2003;Côté et al, 2004;Tanentzap et al, 2012) given sufficiently high deer density over time.…”