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We examined the abundances of three small-mammal species, Korean field mice (Apodemus peninsulae), Korean red-backed voles (Myodes regulus), and striped field mice (A. agrarius), and a stand structure of unburned and burned stands resulting from two different post-fire silvicultural management practices within a pine forest in South Korea. The habitat structure changed dramatically depending on the post-fire silvicultural practices. Most measured variables of the stand structure and downed trees were significantly different among the differently-managed stands. We captured 776 animals of five species (1114 captures in total) in nine stands, each trapped during the two-year study period. The total abundances of captured small mammals did not differ significantly among the differently-managed stands. Mean Jolly—Seber estimates of the population density of M. regulus were 79%–291% higher in the post-burned untreated stand, whereas those of A. agrarius were 214%–491% higher in the post-burned Japanese red pine (Pinus densiflora) planted stand. The preferred stands for small mammal species were generated by forest fire and post-fire silvicultural practices. The values of understory vegetation, coarse woody debris, and downed trees were most strongly related to small-mammal abundance following post-fire silvicultural practices. Therefore, the effects of post-fire silvicultural practices on small-mammal populations should be considered in the post-fire management of a burned pine forest.
Neutral theory focuses on random dispersal and species equivalence, and challenges views on the ecological importance of life history traits and habitat properties in explaining community assembly and the spatial distribution of species. Ground beetles are a popular model taxon to test predictions of contrasting macroecological theories. Here we investigate the effects of habitat properties and life history on the occurrence and community structure of 71 carabid beetle species inhabiting 15 lake islands in NE Poland. Island properties, particularly area and habitat quality, were positively linked to the occurrences of 42% of the species and correlated with species richness and β-diversity. Life history traits (hibernation type, dispersal ability and average abundances) significantly influenced species occurrences. Thus, site and species properties influence the spatial distribution of species and macroecological patterns on islands.
In polygynous species, male reproductive effort has been measured both directly in the form of somatic costs and indirectly using behavioral data. We used 12 years of data collected from a semi-domesticated reindeer population in northern Finland to investigate age- and time-specific patterns of dominant males' reproductive effort. Overall, we found that activity levels differed both between young and old dominant reindeer males, and among the early, peak, and late rut, the pattern being age-specific. Reproductive effort was generally higher for old than young dominant males; however, old males reduced their effort in the late-rut period, while young males maintained the same level of activity. There was a positive relationship between somatic costs and activity level only during the early rut for young dominant males, and only during the peak rut for old dominant males. Thus, old males incur the highest energetic costs from rut-related activities when most of the females in the herd are in oestrus. Conversely, young males appear to time their rut-related energetic cost to coincide with the early rutting period, before most females have reached oestrus. Old males are more efficient in timing their reproductive effort so as to maximize their reproductive success. This can be attributed to young males being less experienced than old males or to using an alternative mating tactic by young males who try to avoid competition with old males during the peak rut.
Geographical gradients of patterns of species associations in ecological communities are largely unknown. Previous evidence indicated nested community assembly — caused mainly by unequal colonization probabilities and habitat capacity — and a tendency towards negative species associations in arid and tropical plant and animal communities. Patterns of community assembly in arctic environments are poorly studied. Here we use a data set on arctic plant and animal species obtained from arctic islands of the Kandalaksha Bay (White Sea), to infer patterns of species association across taxa and trophic groups. We performed co-occurrence and nestedness analyses to study patterns of community assembly and diversity of 1109 plant and animal species grouped according to taxa, dispersal ability, and ecological guild membership. Twelve out of 50 (24%) sufficiently species-rich families and orders on the environmentally relatively stable forested islands showed significantly negative species associations (segregation), while this proportion decreased to less than 13% on less stable heath, rocky, and sea-shore islands. Segregation was not linked to spatial species turnover across islands. Species richness of plants and animals decreased at higher levels of disturbance. We detected evidence for a gradient in species richness and ecological interactions from the most disturbed sea-shore and rocky islands to more stable forested islands. Species spatial distributions appeared to be largely random, in contrast to previous meta-analyses that used mainly communities at lower latitudes. We speculate that in arctic environments spatial turnover of species (vicariant segregation) is of less importance than turnover-independent (checkerboard) segregation. Our data support the view that ecological assemblages in high-latitude environments are less structured by ecological interactions than comparable assemblages in lower latitudes. We also add to the evidence that environmental disturbance regimes work against stable community structures. We notice the need for a formal meta-analysis on latitudinal trends in community structure.
The Tibetan Plateau is one of the areas in the world most sensitive to global warming. Dung beetles are the most abundant decomposer species group responsible for cattle dung removal in the Tibetan alpine meadow, and are critical to nutrient cycling and primary production of the grazing system. This study evaluates the possible effects of global warming on early life-history traits of dung beetles. We established three warmed open-top chambers (OTCs, about 2.3 °C higher than the control) and three ambient OTCs, each containing nine fresh dung pats that were bagged with a nylon screen (0.2 mm in mesh size). Twenty adults of a dominant coprophagous beetle species, Aphodius erraticus (Coleoptera: Scarabaeidae) had been put into each dung bag at the beginning of the experiment and the timings of egg-laying and hatching, and egg and larval size were followed for 80 days. Artificial warming advanced egg-laying and hatching by 4.1 and 7.2 days, respectively; warming decreased egg and larval size by 22.1% and 33.4%, respectively. This short-term study demonstrates that early lifehistory traits of A. erraticus are sensitive to artificial warming, which suggests that global warming may also change life history traits of other organisms in detritus-based systems.
Geoffroy's and Pampas cats are small felids with large distribution ranges in South America. A camera trap survey was conducted in the Espinal of central Argentina to estimate abundance based on capture—recapture data. For density estimations we used both non-spatial methods and spatially explicit capture—recapture models (SECR). For Geoffroy's cat we also obtained density estimates from 8 radio-tracked individuals. Based on the data on 10 Geoffroy's cats and 7 Pampas cats, non-spatial methods produced density ranges of 16.21–21.94 indiv./100 km2 and 11.34–17.58 indiv./100 km2, respectively. The density estimated using SECR models was 45 animals/100 km2 for Geoffroy's cat, whereas we were unable to produce a reliable estimate for the Pampas cat. The SECR estimate for Geoffroy's cat is more similar to that obtained from telemetry data (58.82 cats/100 km2). In agreement with the hypothesis of its greater adaptability, Geoffroy's cat was more abundant than the Pampas cat.