The Role of Small Lowland Patches of Exotic Forests as Refuges of Rare Endemic Azorean Arthropods

Abstract

Islands have been disproportionately affected by the current biodiversity crisis. In island biotas, one of the most recurrent anthropic alterations is species introduction. Invasion of exotic species may represent a major threat for island biotas, because invasive species may change species composition and simplify community dynamics. We investigated diversity patterns of native and introduced species in native and exotic forests of Terceira Island (Azores, Portugal) by using diversity profiles based on Hill numbers. Use of diversity profiles allows for a complete characterization of the community diversity because they combine information on species richness, rarity, and dominance. We found that native forest remnants are crucial for the maintenance of endemic Azorean arthropod diversity. However, we also found that some lowland patches of exotic forests can sustain populations of rare endemic species. Our findings reinforce the importance of the few and small remnants of native forests, which are a pillar to the conservation of Azorean endemic arthropods. However, areas occupied by exotic forests, whether they are large and contiguous or small and isolated, close to native forests, or embedded in a matrix of agriculture activities, can also play a role in the conservation of native species, including endemics.

SLAM Project - Long Term Ecological Study of the Impacts of Climate Change in the Natural Forest of Azores: II - A survey of exotic arthropods in disturbed forest habitats

“…Additionally, the proportion of introduced arthropod species in Azores is higher than native (around 60%) and, due to the higher adaptability to environmental conditions of many introduced species, they represent one of the main threats to indigenous biota in the native forest areas ( Borges et al 2019b ). Moreover, Tsafack et al (2021) showed the importance of isolated and small native forest patches, as well exotic and mixed forests close to native areas, which can function as refuges for native and rare endemic species, playing a relevant role for conservation of native biota outside Azorean protected areas.…”

“…This publication is the second data paper of the project “SLAM Project - Long Term Ecological Study of the Impacts of Climate Change in the Natural Forest of Azores” (see first in Costa and Borges 2021 ) that aims to monitor the distribution and abundance of arthropods in native forests from Azores using SLAM traps (Sea, Land and Air Malaise traps). Additional publications, using data coming from this project, tested specific ecological questions, namely patterns of seasonal variation on species abundance ( Borges et al 2017 ), patterns of temporal beta diversity in native and exotic species ( Matthews et al 2018 ), the potential decline of endemic insects ( Borges et al 2020 ), patterns of arthropod diversity in Azorean urban gardens ( Arteaga et al 2020 ), patterns of species richness and beta diversity in a small elevational gradient ( de Vries et al 2021 ) and the investigation of the role of small lowland patches of exotic forests as refuges for rare endemic Azorean arthropods ( Tsafack et al 2021 ).…”

A Small-Scale Analysis of Elevational Species Richness and Beta Diversity Patterns of Arthropods on an Oceanic Island (Terceira, Azores)

“…As explained in detail in Borges et al [47,49], Costa and Borges [58] and supported by sensitivity analyses in Matthews et al [48], the SLAM sampling methodology is highly standardised and unlikely to cause notable differences in sampling intensity. Moreover, these traps were also very efficient in detecting rare endemic beetle species at low elevation exotic sites in Terceira island [67]. However, field circumstances, such as weather conditions, may have affected individual samples.…”

Monitoring Arthropods in Azorean Agroecosystems: the project AGRO-ECOSERVICES

“…However, although exotic species have a competitive advantage to colonise new human-altered habitats given that their tolerance to wide range of environmental conditions and habitats (e.g. generalist behaviour) ( Rigal et al 2017 ), these non-natural habitats also offer opportunities to native biota ( McKinney and Lockwood 1999 , Blackburn et al 2004 , Sax 2008 , Tsafack et al 2021 ).…”

“…Although most surveys have been conducted in native forests (e.g. Borges et al 2005 , Ribeiro et al 2005 , Borges et al 2006 ), several also included anthropogenic habitats, as exotic forest plantations, pastures for cattle grazing and other agricultural areas ( Cardoso et al 2009 , Florencio et al 2015 , Rigal et al 2017 , Marcelino et al 2021 , Tsafack et al 2021 ).…”