Insect decline in forests depends on species’ traits and may be mitigated by management

Staab, Michael; Goßner, Martin M.; Simons, Nadja K.; Achury, Rafael; Ambarlı, Didem; Bae, Soyeon; Schall, Peter; Weisser, Wolfgang W.; Blüthgen, Nico

doi:10.1038/s42003-023-04690-9

Cited by 33 publications

(29 citation statements)

References 105 publications

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“…the food chains of saproxylic species (Cagnolo et al, 2009;Komonen et al, 2000). This clearly indicates that insect predators are vulnerable to intensive forest management, a point that has been corroborated by recent research (Staab et al, 2023). Insect predation is an important ecosystem function that is sensitive to landscape simplification (Dainese et al, 2019), and greater diversity of beetle predators is related to higher insect predation rates in forests .…”

Section: Discussionmentioning

confidence: 68%

Saproxylic beetles' morphological traits and higher trophic guilds indicate boreal forest naturalness

Wetherbee,

Birkemoe,

Burner

et al. 2023

Ecology and Evolution

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Forests contribute to numerous ecosystem functions and services and contain a large proportion of terrestrial biodiversity, but they are being negatively impaced by anthropogenic activities. Forests that have never been clear‐cut and have old growth characteristics, termed “near‐natural,” often harbor different and richer species assemblages than managed forests. Alternative management strategies may be able to balance the needs of biodiversity with the demands of forestry, but evaluation efforts are limited by the challenges of measuring biodiversity. Species richness is frequently used as a simple measure of biodiversity, but research indicates that it may not adequately capture community‐level changes. Alternatively, trait‐based measures of biodiversity may prove to be useful, but research is lacking. In this paper, we use a large dataset that includes 339 obligate saproxylic beetle species collected over a decade in the boreal region throughout southern Norway to: (1) establish if there is a difference in beetle community composition between near‐natural and managed forests; and (2) determine which measures of beetle biodiversity best indicate forest naturalness. We arranged the sites in an ordination space and tested for differences in community composition between these forest types. We also tested different measures of biodiversity to determine which were the most predictive of forest naturalness. We found a clear difference in community composition between near‐natural and managed forests. Additionally, three measures of biodiversity were most predictive of forest naturalness: proportional abundance of predators, community weighted mean (CWM) of wing length, and CWM of body roundness. The probability that a forest was near‐natural increased with the proportional abundance of predators but decreased with CWM wing length and body roundness. Although species richness was higher in near‐natural forests, the effect was not significant. Overall, our findings underscore the conservation value of near‐natural forests and highlight the potential of several measures of biodiversity for determining forest quality.

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Section: Discussionmentioning

confidence: 68%

Saproxylic beetles' morphological traits and higher trophic guilds indicate boreal forest naturalness

Wetherbee,

Birkemoe,

Burner

et al. 2023

Ecology and Evolution

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“…To avoid potential bias in general stand type comparisons due to these short-term influences, we excluded all Scolytinae (bark beetles) from our dataset and added a 'leave one out' statistical analysis, removing all plots in the Harz Mountains (see statistical methods). All taxa were assigned to the feeding guilds of carnivores, herbivores, myceto-detrivores and omnivores following Staab et al (2023) and Rappa et al (2022), with the latter providing guild assignments on family level (Appendix S1: Table S2). These four guilds represent the main consumer types of beetles and thus their functional impact and reliance on specific resources as consumers (Staab et al, 2023).…”

Section: Beetle Sampling and Trait Informationmentioning

confidence: 99%

Beneficial effects of native broadleaved forests on canopy beetle diversity are not reduced by admixture of non‐native conifers

Wildermuth,

Hagge,

Seifert

et al. 2024

Journal of Applied Ecology

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Biodiversity loss and vast forest diebacks due to climate change‐induced disturbances require adapted forest management strategies that reconcile economic interests and conservation. Tree species selection, including admixture of fast‐growing and drought‐tolerant non‐native species to native forests, is an increasingly considered approach. However, we lack data on how such mixtures affect native forest biodiversity, especially for the sparsely researched major above‐ground part of trees, the canopy. In 40 temperate forest plots in northwest Germany, we investigated how monocultures and admixtures of introduced fast‐growing conifers (native Norway spruce planted outside its natural range and non‐native Douglas fir) to native broadleaved European beech forests affect abundance, biomass, taxonomic and functional diversity and community composition of canopy beetles across trophic guilds. Diverse arthropod communities are vital contributors to forest health and resilience, and therefore valuable indicators to assess and evaluate forestry measures. Monospecific stands of non‐native Douglas fir reduced canopy beetle abundance and diversity compared to native European beech, exceeding the negative effects of Norway spruce. These effects were more pronounced for herbivorous beetles, while they were less strong for predators. Beetle communities in monospecific Norway spruce stands had low functional richness. European beech and mixtures with non‐native Douglas fir had high dissimilarity between local communities (turnover, i.e. beta diversity) and high total beetle diversity at landscape scale (gamma diversity). Mixtures generally mitigated the negative effects of introduced conifers, including shifts in species community composition compared to native European beech. Synthesis and applications: Monospecific stands of fast‐growing non‐native Douglas fir and native Norway spruce planted outside its natural occurrence showed undesirable effects such as low diversity and a shifted community composition of canopy beetles compared to native European beech. However, mixed stands mitigated negative effects and specifically admixed non‐native Douglas fir did not reduce species turnover and landscape‐scale beetle diversity. In line with recent studies on other forest taxa, we conclude that admixtures of introduced conifers to European beech forests, but not monospecific plantations, can potentially serve as a compromise between conservational and economic interests.

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“…Woodland birds show, on average, stable trends across Europe (Gregory et al, 2019), but specialist woodland species tend to be declining in the United Kingdom (Harrison et al, 2016; Hewson et al, 2007). A multi‐taxa study of insect trends in German forests found declines in the majority of sites, species and trophic groups (apart from herbivores) over a 10‐year period (Staab et al, 2023). In the United Kingdom, woodland moths, especially those associated with coniferous woodland, have increased (Tordoff et al, 2022), but, overall, moth species have declined faster in wooded landscapes (Blumgart et al, 2022; Macgregor et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Idiosyncratic trends of woodland invertebrate biodiversity in Britain over 45 years

Bowler,

Cunningham,

Beale

et al. 2023

Insect Conserv Diversity

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Woodland cover in Britain has increased over the past century and is set to increase further through woodland creation schemes aiming to tackle climate change. Nonetheless, the wider repercussions of increasing woodland cover for species, especially invertebrates, have not been comprehensively assessed. Here, we quantified the woodland associations of 2762 invertebrate species in Britain across 21 broad taxon groups using species occurrence records collected by specialist recording societies. We then related the strength of species' woodland associations to published estimates of their long‐term national distribution trends between 1970 and 2015. Across all taxa, 29% of species were positively associated with broadleaf woodland cover, whereas 27% of species were negatively associated. There was a slight tendency for species associated with broadleaf woodland to have more positive long‐term distribution trends, but the effect had little explanatory power. For 15% of species, we detected a non‐monotonic association with broadleaf woodland cover, such that their occurrence peaked at intermediate levels of cover. Intermediate‐cover species had more positive long‐term distribution trends than species with monotonic positive or negative woodland associations. Our findings suggest that woodland invertebrates have not consistently increased, despite the increases in woodland cover. While some caution is warranted owing to our use of heterogeneous occurrence records, the considerable variation in distribution trends of woodland‐associated species could be explained by the high diversity of woodland species and ways in which they use woodland habitat. Woodland creation, or increasing tree cover in general, could have idiosyncratic impacts on species, depending on how new woodlands are created and managed.

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Insect decline in forests depends on species’ traits and may be mitigated by management

Cited by 33 publications

References 105 publications

Saproxylic beetles' morphological traits and higher trophic guilds indicate boreal forest naturalness

Saproxylic beetles' morphological traits and higher trophic guilds indicate boreal forest naturalness

Beneficial effects of native broadleaved forests on canopy beetle diversity are not reduced by admixture of non‐native conifers

Idiosyncratic trends of woodland invertebrate biodiversity in Britain over 45 years

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