Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

Abstract

invertebrate herbivory on dwarf birch (Betula glandulosa-nana 1 complex) increases with temperature and precipitation across the tundra biome ' Polar biology, vol. 40, no. 11, pp. 2265-2278. DOI: 10.1007%2Fs00300-017-2139 Digital Object Identifier (DOI): 10.1007%2Fs00300-017-2139-7 Link: Link to publication record in Edinburgh Research Explorer Document Version: Peer reviewed version Published In: Polar biology General rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately and investigate your claim. Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, 78 yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to 79 predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the 80 intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), 81 and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, 82 mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our 83 results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low 84 intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The 85 damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% 86 leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a 87 lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on 88 average, foliar losses to invertebrates on dwarf birch are likely to increase by 6-7% over the current levels with a 1 89 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in 90 magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory 91 should be included in predictions of climate change impacts on tundra ecosystems. 92 3

Trophic interactions and abiotic factors drive functional and phylogenetic structure of vertebrate herbivore communities across the Arctic tundra biome

“…While our study includes mammalian and avian herbivores, some of which are functionally convergent, to fully understand herbivore functional diversity, non-vertebrate herbivores should also be considered. Invertebrate herbivory is widespread across the Arctic tundra (Barrio et al 2017) and can interact with vertebrate herbivory (Olofsson et al 2013, Biuw et al 2014). Patterns of trophic functional diversity may only be fully understood by including both invertebrate and vertebrate herbivores in the same analysis.…”

Tundra arthropods provide key insights into ecological responses to environmental change

“…Barrio et al (2017) and Koltz et al (2018a), despite having vastly different research approaches, reached similar conclusions about low impacts of invertebrate herbivory, specifically direct consumption of live plant biomass, on plant damage and nutrient cycling. Barrio et al (2017) assessed invertebrate herbivory on over 30,000 birch leaves (Betula sp.) that were collected across the Arctic using standardized protocols.…”

“…In fact, Barrio et al (2017) already demonstrated this. Their leaf samples were collected from 56 locations between 2008 and 2015.…”

“…Biological feedback mechanisms from, e.g., insect herbivores could play an important role in this respect (Phoenix and Bjerke 2016;Lund et al 2017). Barrio et al (2017) and Koltz et al (2018a), despite having vastly different research approaches, reached similar conclusions about low impacts of invertebrate herbivory, specifically direct consumption of live plant biomass, on plant damage and nutrient cycling. Barrio et al (2017) assessed invertebrate herbivory on over 30,000 birch leaves (Betula sp.)…”

“…One set of papers (Docherty et al 2018;Høye et al 2018;Bowden et al 2018;Convey et al 2018;Hein et al 2018;Turney et al 2018) is broadly focused on characterizing how the abundance and life-history traits of tundra arthropods vary in relation to spatial and temporal environmental variation. The second set (Barrio et al 2017;Koltz et al 2018a;Sanchez-Ruiz et al 2018;Urbanowicz et al 2017;Müllerová et al 2018) is focused on characterizing the ecological roles of tundra arthropods in food webs and ecosystems. We have organized the synopsis around these two broad themes.…”