Oribatid mites (Acari, Oribatida) from “Parco Naturale delle Alpi Marittime” (Piedmont, Italy)

Oribatid mites were investigated in six sites in the Alpi Marittime Natural Park (Prov. Cuneo, Piedmont, northern Italy) which is part of the NATURA 2000 network. The selected locations cover 4 forested (fir, ash, 2 beech forests) and 2 grassland sites (mountain meadow, xeric grassland). Altogether 173 described oribatid species belonging to 51 families were encountered, complemented by one undetermined species (Scheloribates (Topobates) cf. carpathicus), added together 174 species. Among them 11 species are new records for Italy. A comparison with other Italian alpine provinces shows high similarity of the oribatid species composition from the investigated sites with the provinces of Bolzano, Trento, Sondrio. A total of 37 species from the Marittime Alps has also been recorded in the southern part of the nearby Swiss canton Ticino. The majority of the species in the investigated sites are known as silvicolous; xerophilous species were mainly found in the xeric grassland site at lower altitude. High species similarities are observed between the forested sites, which also show high species numbers (up to 96 spp. found in the fir forest), lowest similarities are found between the open grassland sites and the forested sites, as well as between the grassland sites themselves.

Recolonization by Slugs: Vertical and Horizontal Dispersal by the Field Slug, Deroceras reticulatum

Following treatment with molluscicides or other controls, slugs can recolonize a site very quickly, but the proportion of the colonizing slugs moving from adjacent areas (horizontal dispersal) and the proportion from within the soil (vertical dispersal) has not previously been established. At a grassland site, barriers were used to exclude and trap slugs in order to estimate horizontal and vertical movement over a period of 32 months. For the first 15 months vertical movement made a significant contribution to the slugs recolonizing a grassland area. The ecological mechanisms occurring and the implications for the control of slugs are discussed.

Surface Urban Heat and Cool Islands and Their Drivers: An Observational Study in Nanjing, China

Urban heat islands (UHIs) are caused by a multitude of changes induced by urbanization. However, the relative importance of biophysical and atmospheric factors in controlling the UHI intensity remains elusive. In this study, we quantify the magnitude of surface UHIs (SUHIs), or surface urban cool islands (SUCIs), and elucidate their biophysical and atmospheric drivers on the basis of observational data collected from one urban site and two rural grassland sites in and near the city of Nanjing, China. Results show that during the daytime a strong SUCI effect is observed when the short grassland site is used as the reference site whereas a moderate SUHI effect is observed when the tall grassland is used as the reference site. We find that the former is mostly caused by the lower aerodynamic resistance for convective heat transfer at the urban site and the latter is primarily caused by the higher surface resistance for evapotranspiration at the urban site. At night, SUHIs are observed when either the short or the tall grassland site is used as the reference site and are predominantly caused by the stronger release of heat storage at the urban site. In general, the magnitude of SUHI is much weaker, and even becomes SUCI during daytime, with the short grassland site being the reference site because of its larger aerodynamic resistance. The study highlights that the magnitude of SUHIs and SUCIs is mostly controlled by urban–rural differences of biophysical factors, with urban–rural differences of atmospheric conditions playing a minor role.

Comparison of Wind Lidar Data and Numerical Simulations of the Low-Level Jet at a Grassland Site

For the increasing importance of the wind energy branch, exact wind climatologies at the operation altitudes are essential. As wind turbines of increasing hub height are erected, the rotors are located at an altitude interval influenced by the phenomenon of low-level jet (LLJ). The main objective of the study is to assess if and how numerical simulations can represent the development especially of nocturnal LLJs in comparison to measurements. In this article, the microscale numerical model HIRVAC2D is used for a range of parameters. The simulated results for properties of the LLJ are compared to lidar data at an altitude range of 40 m to 500 m at the study site Braunschweig in the North German Plain, a grassland location that may be representative for a large area. Similarities and differences of the occurrence, height and maximum wind speed of the nocturnal LLJ are discussed using two different criteria to define a LLJ. The analysis of the lidar data set for the grassland site revealed for the first time increasing height of the LLJ with increasing wind speed during the summer months June to August 2013. The comparison of measurements and simulation data shows that boundary (and inital) conditions have to be adapted in model simulations to provide realistic LLJ properties. It was found that land use and vegetation parameters are important for practical LLJ prognosis, both for wind climatologies and nowcasting.

Low assimilate partitioning to root biomass is associated with carbon losses at an intensively managed temperate grassland

Aims This study aimed to investigate how efficiently assimilated carbon (C) is incorporated in plant biomass at an intensively managed old permanent grassland, how C is partitioned between shoots and roots and what are the implications for C sequestration. Methods Using the eddy covariance technique, the atmosphere-biosphere exchange of CO2 was measured for two years at a sandy grassland site in northern Germany. In addition to aboveground net primary production (ANPP), belowground NPP (BNPP) was observed using the ingrowth core method. Results The grassland showed a high productivity in terms of biomass yield (14.8 Mg dry matter ha−1 yr−1) and net CO2 uptake (−2.82 Mg CO2-C ha−1 yr−1). Photosynthetically assimilated C was converted to biomass with a high carbon use efficiency (CUE) of 71% during the growing season. However, a comparably low fraction of 17% of NPP was allocated to roots (fBNPP). Consequently, the main fraction of NPP was removed during harvest, turning the site into a net source of 0.29 Mg C ha−1 yr−1. Conclusions Our study showed the flexibility of grass root growth patterns in response to alterations in resource availability. We conclude that highly fertilized grasslands can lose their ability for C sequestration due to low belowground C allocation.

Understanding N2O Emissions in African Ecosystems: Assessments from a Semi-Arid Savanna Grassland in Senegal and Sub-Tropical Agricultural Fields in Kenya

This study is based on the analysis of field-measured nitrous oxide (N2O) emissions from a Sahelian semi-arid grassland site in Senegal (Dahra), tropical humid agricultural plots in Kenya (Mbita region) and simulations using a 1D model designed for semi arid ecosystems in Dahra. This study aims at improving present knowledge and inventories of N2O emissions from the African continent. N2O emissions were larger at the agricultural sites in the Mbita region (range: 0.0 ± 0.0 to 42.1 ± 10.7 ngN m−2 s−1) than at the Dahra site (range: 0.3 ± 0 to 7.4 ± 6.5 ngN m−2 s−1). Soil water and nitrate (NO3−) contents appeared to be the most important drivers of N2O emissions in Dahra at the seasonal scale in both regions. The seasonal pattern of modelled N2O emissions is well represented, though the model performed better during the rainy season than between the rainy and dry seasons. This study highlighted that the water-filled pore space threshold recognised as a trigger for N2O emissions should be reconsidered for semi-arid ecosystems. Based on both measurements and simulated results, an annual N2O budget was estimated for African savanna/grassland and agricultural land ranging between 0.17–0.26 and 1.15–1.20 TgN per year, respectively.

Male size and alternative mating tactics in white-tailed deer and mule deer

Within populations, individual males adopt different courtship tactics due to differences in their competitive ability, which may vary depending on the animal’s age and size. To test the hypothesis that mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) males vary their courtship behavior based on their size, we conducted focal observations of 144 mule deer and 85 white-tailed males that varied in size, at a large grassland site in southern Alberta. The smallest mule deer males devoted more time to feeding, were less likely to engage in late-stage courtship than larger males and were less likely to move among female groups. Other males, including small white-tailed males, appeared to use a roving strategy to search for estrous females in different groups, which is consistent with recent research on male movements. Both medium and large males increased the time they spent in one-male groups, and specifically isolated pairs, as courtship advanced, presumably to reduce competition with other males. However, this trend was most pronounced for medium mule deer males, and for all size classes of white-tailed deer. In contrast, large mule deer males spent a similar proportion of time tending females in all group types. Our results identified potential size-dependent tactics for mule deer males. In contrast, white-tailed males of all sizes appeared to rely on a tactic of finding and tending estrous females in isolation from other males.