Effects of microhabitat on rodent-mediated seed removal of endangered Kmeria septentrionalis in the karst habitat

Abstract

Seed removal behaviors of rodents are largely influenced by microhabitat. Although the karst ecosystem is composed of a broad variety of microhabitats, we have no information on how they affect such behaviors. We investigated rodents’ seed removal behaviors in four karst microhabitats (stone cavern, stone groove, stone surface, and soil surface) using three types of Kmeria septentrionalis seeds: fresh, black (intact seeds with black aril that dehydrates and darkens), and exposed (clean seeds without the aril). We show that Rattus norvegicus, Leopoldamys edwardsi and Rattus flavipectus were the predominant seed predators. Even though all seed types experienced a high removal rate in all four microhabitats, but rodents preferentially removed seeds from the three stone microhabitats (stone caves: 69.71 ± 2.74%; stone surface: 60.53 ± 2.90%; stone groove: 56.94 ± 2.91%) compared to the soil surface (53.90 ± 2.92%). Seeds that had been altered by being exposed to the environment were more attractive to rodents than fresh seeds (76.25 ± 2.20% versus 36.18 ± 2.29%). The seed removal behavior of rodents was significantly affected by the microhabitat and seed type. Finally, seeds that had fallen on the soil surface microhabitat incurred a lower predation risk than seeds fallen on other microhabitats, which increased their probability to germinate. Our results indicate that the lower predation rate of seeds from the endangered K. septentrionalis dropped on the soil surface increases trees’ likelihood of survival.

Prediction of the potential distribution pattern of the great gerbil (Rhombomys opimus) under climate change based on ensemble modelling

“…39 Rodents have strict criteria for habitat selection, which is usually closely related to local food, topographic, and vegetation cover conditions. 40,41 R. opimus is a small rodent, and its migration and spread rely more on natural processes than on human assistance. Based on field surveys and isotope analyses, R. opimus can migrate up to 70 km.…”

“…Guisan and Thuiller referred to the broad bioclimatic range as the ‘potential distribution’ and defined the ‘actual distribution’ as the bioclimatic range filtered by dispersal, disturbance and biotic interactions 39 . Rodents have strict criteria for habitat selection, which is usually closely related to local food, topographic, and vegetation cover conditions 40, 41 . R. opimus is a small rodent, and its migration and spread rely more on natural processes than on human assistance.…”

Strategy Trade-Off of Predominant Stress Tolerance Relative to Competition and Reproduction Associated with Plant Functional Traits under Karst Forests

“…The karst landform in southwest China, a fragmental ecosystem, is the most extensivecontinuous distribution representing typical development [30,31]. Landscape fragmentation of karst leads to different microhabitats, such as stone caverns, grooves, surfaces, and soil surfaces [32]. These microhabitats are interlaced distribution each other, resulting in a highly heterogeneous habitat [33,34], due to high rock exposure rate, discontinuous soil cover, and poor water retention led to infertile soil such as N or P [4,35].…”

Effect of Leaf Litter on Seed Survival of Kmeria septentrionalis in Karst Habitat

“…This species is slow to recover because of seed-predator pressure, where low nutritional quality and lack of water in karst soils are not conducive for seed germination and seedling growth. Female plants bear 100-300 fruits where each fruit contains 4-14 seeds (mean±standard error: length, 1.14±0.15 cm; width, 0.49±0.06 cm; and weight, 0.23±0.03 g; n=30) (Wang et al, 2020) with fleshy arils that turn red in autumn, when birds forage for the fruit and disperse the seeds (Wang et al, 2019). A large fraction of fruits fell beneath the mother plant, and approximately about 60% of these seeds are consumed by three species of rodents: Leopoldamys edwardsi, Rattus norvegicus, and R. flavipectus (Wang et al, 2020).…”

“…Female plants bear 100-300 fruits where each fruit contains 4-14 seeds (mean±standard error: length, 1.14±0.15 cm; width, 0.49±0.06 cm; and weight, 0.23±0.03 g; n=30) (Wang et al, 2020) with fleshy arils that turn red in autumn, when birds forage for the fruit and disperse the seeds (Wang et al, 2019). A large fraction of fruits fell beneath the mother plant, and approximately about 60% of these seeds are consumed by three species of rodents: Leopoldamys edwardsi, Rattus norvegicus, and R. flavipectus (Wang et al, 2020). This intense seed predation reduces the number of seeds available for subsequent germination.…”