Effect of Land Disturbance and Stress on Species Traits of Ground Beetle Assemblages

Abstract

In this paper we test whether the morphology and life traits of species (in our case ground beetles of the family Carabidae) can be related to the main underlying axes of environmental variability of their habitats. Sites were selected a priori to maximize two gradients: land use as a general measure of disturbance characterized by an index of land management, and habitat adversity or stress as characterized by elevation and vegetation structure. The underlying environmental axes and the relationships of the morphology and life traits of the species with them were investigated using RLQ analysis, a multivariate ordination method able to relate a species trait table to a site characteristics table by way of a species abundance table. The first environmental axis was highly statistically significant and explained most of the variability. It was strongly negatively related to the intensity of land management, and positively related to increasing elevation and a set of variables reflecting vegetation stress. Two predictions were tested and found to be valid in the studied system: in highly managed lowland sites species were smaller, and the frequency of macropterous species (with better dispersal abilities) was higher. Other traits also showed significant relationships with the main environmental axis: in the intensively managed lowland sites species had broader bodies, longer trochanters, and wider femora (characters associated with plant eaters), were paler in color, overwintered only as adults, bred in spring or autumn, and were active in summer. We conclude that the ground beetle assemblages of the studied sites respond in a similar way to the same underlying environmental factors. This allows the precise definition of functional groups, which can be used to characterize functional diversity and its relationships with changes in land management.

List of sampled individuals

“…Gobbi and Fontaneto (2008) noted that proportions of short winged, large and predatory species were negatively related to habitat disturbance. Similar results were found by Pizzolotto (2009) and Ribera et al (2001), stressing that management intensity can influence trait dispersion and morphological characteristics of ground beetles, such as body size or wing morphology. For agricultural landscapes Hendrickx et al (2009) found that especially ground beetles with low dispersal ability are threatened by habitat fragmentation and Lambeets et al (2008) demonstrated multiple trait shifts of ground beetles along gradients of flood disturbance.…”

“…Bates et al (2006) and Lambeets et al (2009) confirmed these assumptions, showing that several life-history traits of riverbank spiders and ground beetles are strongly affected by flood disturbance parameters. According to Ribera et al (2001), Lambeets et al (2009) and , disturbance mainly affects the dispersal capacity and the body size of ground beetles. Hence, a small body size and fully developed wings enable species to quickly evade the disturbance or quickly recolonise the disturbed plots.…”

“…However, hydrological factors might not necessarily have similar impacts on the trait variation than habitat disturbance parameters. Habitat disturbance primarily affect morphological characteristics of the species, like wing morphology or body size (Ribera et al 2001;Lambeets et al 2009). In contrast, the alternation of hydrological parameters might more relate to reproductive traits, as shown in this study.…”

Responses to River Inundation Pressures Control Prey Selection of Riparian Beetles

“…Trait groupings were defined by behavioural and morphological characteristics [56], and these groupings became clearly functionally delineated when relative isotopic niche positions were investigated. An increasing utilization of aquatic subsidies was present when the species possessed traits that reduced the risks associated with high flows.…”

“…In an adaptation of the methodology used by Ribera et al [56] six specimens of each of twelve dominant sampled Coleoptera had wing, leg and body measurements taken, these were then Ln transformed to attain statistical normality, which was accepted following visualisation and assessment of linearity via QQ plots [74]. These morphological data provided ratios of wing: body and leg: body which were analysed using ANOVA with a post-hoc Tukey test to identify statistically-significantly/similar different groups.…”