Ecosystem services and disservices by birds, bats and monkeys change with macadamia landscape heterogeneity

Abstract

1. The relative importance of ecosystem services and disservices can change with landscape structure in a poorly understood way.2. We compare the impact of biocontrol, provided by bats and birds, with that of crop raiding by vervet monkeys on yield in South African macadamia orchards.Insectivorous bats and birds are known to feed on macadamia pest insect species, like the macadamia nut borer or the green vegetable bug. Vervet monkeys move into the orchards during the day to feed on premature macadamia nuts. Bats, birds and monkeys benefit from patches of natural vegetation adjacent to orchards. With exclusion experiments (four treatments: day, night, day and night, control) we quantified the relative importance of biocontrol and crop raiding on yield, comparing two different landscape settings of the orchards, a natural and a human-modified. 4. Crop raiding occurred only close to natural vegetation and caused yield losses of about 26%. Biocontrol by bats and birds was higher near natural vegetation, but still significant in human-modified landscapes, at up to 530 m distance to forest patches. Prevented biocontrol through the exclusion of bats and birds resulted in yield losses of up to 60%.5. Effects of biocontrol by bats and birds (USD ~5,000 ha/year) were economically more important than the losses of crop raiding (USD ~1,600 ha/year). As both are linked to the vicinity of forest patches, the removal of natural vegetation to limit monkey abundances would also limit biocontrol service provision. Synthesis and applications.This study highlights the high economic benefits of biocontrol by bats and birds, which outweighed negative impacts through yield losses caused by crop raiding monkeys. Management practices to prevent crop damage, such as guarding, excluding vertebrates or removal of adjacent natural vegetation, would also limit access for bats and birds and the great economic benefits provided by their biocontrol. Ecosystem services by bats and birds can be promoted by the exposure of artificial roost and nest sites, but research into species-specific preferences is needed. The education of farmers is crucial, as many are unaware 2070 | Journal of Applied Ecology LINDEN Et aL.

Designing optimal human‐modified landscapes for forest biodiversity conservation

“…2013; Linden et al . 2019). Similarly, in Costa Rica, insectivorous birds increase in abundance and exert stronger control on borer populations on coffee plantations inserted in more forested landscapes (Karp et al .…”

Threat analysis of modelled potential migratory routes forMiniopterus natalensisin South Africa

“…During a 6-year period, 135 cases of organophosphorus poisonings and 57 incidents of carbamate poisonings of birds and mammals were reported by the Agricultural Research Council -Onderstepoort Veterinary Institute's Toxicology Laboratory (Botha et al 2015). Various South African bats species are consumers of crop pest insects, providing economically important ecosystem services (Taylor et al 2017;Linden et al 2019). Whilst Brinati et al 2016).…”

Conceptual ambiguity hinders measurement and management of ecosystem disservices

“…Yet, the conceptual and methodological ambiguities of how ecosystem disservices are supplied and delivered remain unreconciled as the body of literature rapidly grows. In particular, treating negative (disservices) and positive (services) outcomes for human well‐being in isolation hinders understanding of actual ecosystem services supply in social–ecological systems (Linden et al., 2019; Peisley et al., 2015; Pejchar et al., 2018; Saunders et al., 2016). In practice, it is still unclear how disservices should be treated in management and accounting frameworks.…”

“…For example, in agricultural landscapes, land use intensification and clearing of natural vegetation may exacerbate pest pressures, which could lead to increased disservices (e.g. Ehrmann et al., 2018; Linden et al, 2019). Similarly, the risk of zoonotic disease transmission from wildlife to humans often increases with human disturbance of biodiversity, not the presence of biodiversity per se (Ostfeld & Keesing, 2017).…”