Temporal changes in molar wear rate of a sika deer population under density‐dependent food limitation

Takeshita, Kazutaka M.; Ishizaki, Masahiro; Mitsuya, Ryoko; Takahashi, Hiroshi; Yoshida, Terutoyo; Igota, Hiromasa; Ikeda, Takashi; Kubo, Mugino O.; Kaji, Koichi

doi:10.1111/jzo.12258

Cited by 5 publications

(1 citation statement)

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“…The large ungulate Cervus nippon yesoensis Heude (mean withers height 1.5 m, capable of foraging plants up to 2 m in height) was introduced between 1957 and 1966 and inhabits the entire island. The understory vegetation experienced overgrazing for >30 years by ungulates, with a density of 21-91 individuals/ km 2 up to 2012 58 , which was subsequently reduced to 12 individuals/km 2 after 2012 58 ; however, this density is still above the sustainable level for growth and reproduction of the understory 59 . In 2004, several exclosures (approximately 30 × 30 m) were set up on the island.…”

Section: Methodsmentioning

confidence: 99%

Interaction exposure effects of multiple disturbances: plant population resilience to ungulate grazing is reduced by creation of canopy gaps

Shinoda

Akasaka

2020

Sci Rep

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The impact of multiple disturbances on populations could be synergistic or antagonistic via disturbance interaction and are considered to be provoked by alternation of the impact of an ecosystem disturbance due to the effect of a preceding disturbance. The impact of a focal disturbance can also change when a preceding disturbance alters the proportion of individuals in a population exposed to these disturbances (i.e., interaction exposure effects), although this effect has not been addressed to date. Herein, we propose and test interaction exposure effects by elucidating disturbance interactions between canopy gap formation and ungulate grazing. Based on a vegetation and seed bank survey conducted on an island in Hokkaido, northern Japan, we examined whether canopy openness changes the impact of ungulate grazing on the occurrence probability of palatable plant species through the facilitation of germination. Species occurrence in the seed bank significantly decreased with increasing canopy openness under the presence of grazing; however, it slightly increased under the absence of grazing, suggesting that gap creation, which facilitates germination, exposes the seed bank to ungulate grazing. Because disturbances of various types often modify the habitat structure, these proposed disturbance interactions are expected to operate within various ecosystems and taxa. An understanding of the impacts of disturbances on ecosystems is indispensable for comprehending the persistence of populations 1-3. Climate change and increasing pressures from human development have increased disturbance frequency; therefore, it is more likely that ecosystems will be exposed to multiple co-occurring disturbances 4,5 that could severely impact these environments 6-8. Therefore, the interacting effects of multiple disturbances on populations should be understood to help predict the fate of ecosystems 4,9. The population impact of multiple disturbances may be larger or smaller than the sum of the impacts of respective individual disturbances 4,10-14. These cumulative or antagonistic impacts have been attributed to two types of interaction effects: interaction chain effects (linked disturbances in the context of Buma et al. 5) and interaction modification effects 4,9. Within the interaction chain effects, the total impact of disturbances on a population is altered by the indirect effects of a supportive disturbance to the strength and/or extent of main disturbances 15-17 (Fig. 1a), e.g., a typical example of an interaction chain effect would be enhanced severity of a forest fire within a severely blown-down forest 16. Within interaction modification effects, indirect effect(s) of supportive disturbance(s) on main disturbances modifies the per capita impact of the main disturbance 18,19 (Fig. 1b). An example of interaction modification effects is that of savanna fires reducing the resistance of tree trunks to hurricanes, as rapid tree growth following fires results in low wood density 18. Although both interaction chain and modification effec...

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Section: Methodsmentioning

confidence: 99%