Smaller and Isolated Grassland Fragments Are Exposed to Stronger Seed and Insect Predation in Habitat Edges

Abstract

Habitat fragmentation threatens terrestrial arthropod biodiversity, and thereby also leads to alterations of ecosystem functioning and stability. Predation on insects and seeds by arthropods are two very important ecological functions because of their community-structuring effects. We addressed the effect of fragment connectivity, fragment size, and edge effect on insect and seed predation of arthropods. We studied 60 natural fragments of two grassland ecosystems in the same region (Hungarian Great Plain), 30 forest-steppes, and 30 burial mounds (kurgans). The size of fragments were in the range of 0.16–6.88 ha for forest-steppe and 0.01–0.44 ha for kurgan. We used 2400 sentinel arthropod preys (dummy caterpillars) and 4800 seeds in trays for the measurements. Attack marks on dummy caterpillars were used for predator identification and calculation of insect predation rates. In the case of seeds, predation rates were calculated as the number of missing or damaged seeds per total number of exposed seeds. Increasing connectivity played a role only in generally small kurgans, with a negative effect on insect and seed predation rates in the edges. In contrast, fragment size moderated edge effects on insect and seed predation rates in generally large forest-steppes. The difference between edges and centres was more pronounced in small than in large fragments. Our study emphasizes the important role of landscape and fragment-scale factors interacting with edge effect in shaping ecosystem functions in natural grassland fragments of modified landscapes. Managing functional landscapes to optimize the assessment of ecosystem functions and services needs a multispatial scale approach.

Ancient Burial Mounds Provide Safe Havens for Grassland Specialist Plants in Transformed Landscapes—A Trait-Based Analysis

“…Due to the marked changes in the landscape composition and configuration of fertile lowland areas, kurgans often function as terrestrial habitat islands (Deák et al, 2016(Deák et al, , 2020aDembicz et al, 2020;Kuli-Révész et al, 2021). The colonization and persistence of grassland specialists in grassland islands are considerably influenced by the special environmental characteristics (such as area, management, microclimate, soil fertility) and the degree of isolation providing several abiotic and biotic filters shaping the local species assemblages (Szabó et al, 2012;Heinken and Weber, 2013;Deák et al, 2018;Dembicz et al, 2020;Ottaviani et al, 2020).…”

Small grassland fragments and connectivity support high arthropod functional diversity in highly modified landscapes

“…Forest‐steppes and kurgans had two different spatial contexts, that is, forest‐steppe fragments were embedded in a matrix of relatively small‐scale pine forest plantations, and kurgans were situated in large‐scale agricultural landscapes (mostly maize, sunflower, alfalfa and winter cereal fields). Therefore, we made the GIS calculations within a radius of 500 m for forest‐steppes and 1000 m for kurgans (Gallé et al, 2022; Kuli‐Révész et al, 2021). To calculate Hanski's connectivity index, we used the following equation: where α is a parameter describing a species' dispersal ability, and β is a parameter that describes the scaling of immigration.…”

“…This process leads to homogenous landscapes with small, fragmented and isolated remnant habitats (Batáry et al, 2020; Deák, Tóthmérész, et al, 2016; Habel et al, 2013). As a consequence, communities associated with grasslands are adversely affected resulting in their altered species richness (Gallé et al, 2022; Rösch et al, 2013), functional composition (Birkhofer et al, 2015; Török et al, 2022) and ecosystem functioning (Kuli‐Révész et al, 2021; Martinson & Fagan, 2014).…”

A törpe mandula (Prunus tenella) tömeges előfordulása szántásból felhagyott kunhalmon

“…A jó állapotú gyepekkel borított halmok sok esetben őriznek kiemelkedően nagy biodiverzitást, amely elsősorban annak köszönhető, hogy a változatos topográfiájú kurgánokon kis területük ellenére számos eltérő környezeti adottságú mikro-élőhely található (DEÁK et al 2021a). A gyepes halmok számos esetben élőhely-szigetekként vannak jelen az ember által átformált agrártájakban (DEÁK et al 2021b, KULI-RÉVÉSZ et al 2021. Az intenzíven művelt agrártájakban található halmokon fennmaradt gyepi szigeteken a gyepi specialista növény-és állatfajok fajgazdagsága összemérhető a védett területeken található halmokéval (DEÁK et al 2020).…”