Predator-induced flow disturbances alert prey,from the onset of an attack

Many prey species, from soil arthropods to fish, perceive the approach of predators, allowing them to escape just in time. Thus, prey capture is as important to predators as prey finding. We extend an existing framework for understanding the conjoint trajectories of predator and prey after encounters, by estimating the ratio of predator attack and prey danger perception distances, and apply it to wolf spiders attacking wood crickets. Disturbances to air flow upstream from running spiders, which are sensed by crickets, were assessed by computational fluid dynamics with the finite-elements method for a much simplified spider model: body size, speed and ground effect were all required to obtain a faithful representation of the aerodynamic signature of the spider, with the legs making only a minor contribution. The relationship between attack speed and the maximal distance at which the cricket can perceive the danger is parabolic; it splits the space defined by these two variables into regions differing in their values for this ratio. For this biological interaction, the ratio is no greater than one, implying immediate perception of the danger, from the onset of attack. Particular attention should be paid to the ecomechanical aspects of interactions with such small ratio, because of the high degree of bidirectional coupling of the behaviour of the two protagonists. This conclusion applies to several other predator–prey systems with sensory ecologies based on flow sensing, in air and water.     

Definition and stabilisation of the quiescent centre in rice roots

The definition of a quiescent centre (QC) in Arabidopsis has been adequately demonstrated. However, the QC structure of rice has not yet been described in detail. In this research, using histological and marker gene expression analysis, we concluded that the rice QC is very small, and is similar to that of Arabidopsis. Next we investigated the stability of the rice QC during nutrient deficiencies or external hormone treatments, and found that nutrient deficiencies, auxin treatment and cytokinin treatment did not change the cell patterns of the QC. However, ethylene induced irregular transverse cell divisions in the QC and changed formative cell divisions of the ground tissue stem cells (GTSCs) in rice.     

Grass allometry and estimation of above‐ground biomass in tropical alpine tussock grasslands

The puna/páramo grasslands span across the highest altitudes of the tropical Andes, and their ecosystem dynamics are still poorly understood. In this study we examined the above‐ground biomass and developed species specific and multispecies power‐law allometric equations for four tussock grass species in Peruvian high altitude grasslands, considering maximum height (h_max), elliptical crown area and elliptical basal area. Although these predictors are commonly used among allometric literature, they have not previously been used for estimating puna grassland biomass. Total above‐ground biomass was estimated to be of 6.7 ± 0.2 Mg ha^?1 (3.35 ± 0.1 Mg C ha^?1). All allometric relationships fitted to similar power‐law models, with basal area and crown area as the most influential predictors, although the fit improved when tussock maximum height was included in the model. Multispecies allometries gave better fits than the other species‐specific equations, but the best equation should be used depending on the species composition of the target grassland. These allometric equations provide an useful approach for measuring above‐ground biomass and productivity in high‐altitude Andean grasslands, where destructive sampling can be challenging and difficult because of the remoteness of the area. These equations can be also applicable for establishing above‐ground reference levels before the adoption of carbon compensation mechanisms or grassland management policies, as well as for measuring the impact of land use changes in Andean ecosystems.     

Effects of Top‐Soil Preparation and Broad‐Leaved Tree Mixture on Carabid Beetles in Afforested Fallow Plots

A 2‐year study to evaluate the effect of four soil preparation techniques and four species compositions in a pine plantation with an admixture of broad‐leaved trees on the species diversity and structure of ground beetle assemblages (Carabidae) was conducted. The soil preparation techniques were full shallow agricultural plowing (25 cm deep with three variants—plowing, plowing with ridge formation, and plowing with subsoiling) and full deep plowing (50 cm deep). The plantation species compositions were pine 7000/hectare, pine 5500/hectare + broad‐leaved species 1500/hectare, pine 4000/hectare + broad‐leaved species 3000/hectare, and pine 2000/hectare + broad‐leaved species 5000/hectare. Carabidae were sampled monthly with pitfall traps in the plantation from May to November in 2003 and 2004—the fourth and fifth years after afforestation. Only the soil preparation technique affected species diversity. The mean number of carabid species and the Shannon–Wiener index were higher in the case of the full agriculture plowing with subsoiling treatment and the full agriculture plowing with ridge formation than in the full shallow agriculture plowing. The structure of the assemblages was dependent on the soil preparation technique, but not on tree species composition. In general, deep plowing and shallow plowing with subsoiling were conducive to an increase in the proportion of individuals representing late succession species, whereas shallow plowing favored early succession species. The results suggest that for effective plantation of a managed stand, deep plowing or shallow plowing with subsoiling is more beneficial for afforestation of fallow fields than typical shallow agricultural plowing.     

A remarkably modified species of the tribe Platynini (Coleoptera,Carabidae) from a limestone cave in Jiangxi Province,eastern China

Morimotoidius zhushandong sp. n. is described and illustrated from a limestone cave called Zhushan Dong II in Wanzhai Xian (=County) of western Jiangxi Province, eastern China. This species is the most modified species within the tribe Platynini in China by having very slender body and appendages, extremely elongated head, and especially, narrowed and barrel-liked pronotum which is as wide as head. However, the above derived characters are autapomorphies to adapt the subterranean environment. M. zhushandong sp. n. must be a troglobite though it has well pigmented body and flat eyes.     

Morariopsis dumonti n.sp. (Crustacea: Copepoda: Harpacticoida) – a new species from an unsaturated karstic zone in Slovenia

The genus Morariopsishas a disjunct distribution. It has been found in south-eastern Europe and in the Baikal region in Russia. In Europe two species are known, both from the Dinaric region. They have been found in three caves only, but always in puddles filled with percolating water. This indicates that they inhabit an unsaturated karstic environment. A third species, Morariopsis dumontin.sp has now been found, in the same type of habitat, on several dates, in a small cave in central Slovenia. Males were recorded for the first time in this genus.The new species is related to Morariospsis kieferiPetkovski, 1959 from Dalmatia. The main differences are in the ornamentation of the furca and of the abdominal segments. P5 and particularly endopodite of P4 in males suggest a close relation between Morariaand Morariopsis.     

川西亚高山采伐迹地草坡群落对模拟增温的短期响应

采用开顶式生长室(open-top chamber, OTC),研究了川西亚高山采伐迹地草坡群落物候、群落结构和地上生物量对模拟增温的初期响应.生长季中OTC内日平均气温较对照(CK)增加2.2 ℃,5 cm土壤温度增加0.8 ℃.和CK相比,建群种牛尾蒿和糙野青茅萌动期、花蕾期和花期均显著提前,而枯黄期显著推迟.群落各种群高度、密度和重要值增加、减少或无影响,生物多样性指数有所下降,群落结构发生一定变化.OTC内糙野青茅和牛尾蒿地上生物量较CK分别增加46.3%和42.0%.中华羊茅和其它草类植物地上生物量有所下降,但差异不显著.地上总生物量增加34.0%.     

中华鲟产卵场平面平均涡量计算与分析

采用Delft3D-Flow模型对葛洲坝下游中华鲟产卵场河段进行流场模拟,用实测资料对模型进行验证和参数率定,模拟结果和实测资料基本吻合.在此基础上,阐述了平面平均涡量计算方法,利用模拟所得流速场,通过计算得到中华鲟产卵场河段区域平面平均涡量强度分布.计算结果表明,鱼卵密集区的平面平均涡量为1.38×10-3～1.64×10-3s-1,说明中华鲟产卵对区域平面涡量强度有偏好选择,这种选择具有生物学意义.可为今后保护中华鲟产卵场水力学环境提供理论支持和参考.