Ecological responses to hydrological connectivity in grassland riparian zones: Insights from vegetation and ground-dwelling arthropods.

Riparian wetlands have suffered from degradation due to global climate change and human activities, which can alter flora and fauna community patterns and disrupt material cycles in the riparian zones. Hydrological connectivity identified by functional and structural connectivity is an important driving force of riparian ecosystems. However, the role of hydrological connectivity in linking riparian hydrology and ecology remains unclear, especially in dryland rivers. By taking the riparian zone of the Xilin River in Eurasian steppe as an example, the functional connectivity was represented by the groundwater depth in the riparian zones. The structural connectivity was quantified by integrating the soil, and vegetation properties of the riparian zone. The structural connectivity decreased from upstream to downstream. Laterally, the highest structural connectivity was found in the riparian zone 25 m away from the river channel. The abundance of three groups of ground-dwelling arthropods (except Araneae) showed a threshold behavior in response to the functional connectivity, with the highest abundance occurring in the medium level of functional connectivity. Both vegetation biomass and ground-dwelling arthropod abundance were significantly and positively correlated to the structural connectivity strength. The results of structural equation models (SEMs) also indicated that structural connectivity was a key factor affecting vegetation and ground-dwelling arthropod abundance. The results underscore the essential function of hydrological connectivity in maintaining the biodiversity in the riparian zones. The study provides a scientific reference of riparian-zone restoration based on hydrological connectivity.

Three new species of the Clubionacorticalis group (Araneae, Clubionidae) from China.

Three new species of the Clubionacorticalis group in China are described: Clubionabidactylinasp. nov., C.camelasp. nov., and C.subhuimingsp. nov.

The influence of landscape alterations on changes in ground beetle (Carabidae) and spider (Araneae) functional groups between 1995 and 2013 in an urban fringe of China.

Urbanization is one of the main causes of land use change, especially from 1990 to now in China, but knowledge of its effect on different functional groups of carabids and spiders in the adjacent rural areas over time remains limited. We assessed whether landscape alterations (1993 versus 2013) drove changes in carabid and spider functional groups (1995 versus 2013) in an agricultural landscape located on the fringe of a rapidly growing city in China. Although built-up land increased from 6.3% to 32% across the whole landscape, the overall species richness of carabids and spiders did not decline. In contrast to the reduction in species richness of large carabids, the species richness of small carabids increased. Species richness of both large and small spiders increased. The species composition of carabids and spiders significantly changed between 1995 and 2013. Species compositions of large, predatory carabids and large or ground-hunting spiders were more sensitive to the changes in built-up land than those of small, omnivorous carabids and small or web-building spiders. The amount of grassland (abandoned land covered by wild grass) also increased as farmers began to work in the city. The increased grassland significantly contributed to the increased species richness of predatory and macropterous carabids. However, increased landscape diversity did not affect species richness of either carabids or spiders. High landscape diversity was related to reduction in field size, resulting in a decrease in the mean body size of carabids. This indicates that evaluating the effect of landscape change on carabid and spider diversity should be based on their functional traits. Different taxa, even different functional groups, have different responses to landscape change. The increase in built-up land did not immediately reduce species richness at the urban fringe. Increasing wild grasslands and combining smaller fields may benefit farmland biodiversity in this region.

Productive Oilseed Rape Strips Supplement Seminatural Field-Margins in Promoting Ground-Dwelling Predatory Invertebrates in Agricultural Landscapes.

Intensively managed flowering crops like canola (Brassicales: Brassicaceae) (oilseed rape, OSR) provide significant short-term nectar resources for pollen consumers. They may also play important roles as annual "service strips" in temporarily promoting predatory invertebrates. We set out to test this assumption by comparing overall and functional group-specific species richness, activity density, and assemblage composition of carabids (Coleoptera: Carabidae) and spiders (Araneae), in three types of service strips-OSR, woody, and grassy strips established in direct vicinity to cropland. OSR strips were found to harbor the highest carabid species richness and activity density of small carabids. The activity density of carabids overall and of omnivorous species, the species richness and activity density of spiders across size classes and feeding strategies were all significantly reduced in woody strips. The percentage of seminatural habitat in the wider landscape was positively linked to the activity density of spiders overall, ground hunting and large spiders, whereas in carabids, positive effects were limited to large species occurring in grassy strips. Habitat type was the main predictor of both carabid and spider assemblage composition. Our results indicate that carabid and spider activity density across functional groups responded more strongly to changes in the landscape composition than the diversity of individual taxonomic groups. For agricultural landscape management, the establishment of habitat mosaics that include regular OSR could promote abundant, species-rich predatory invertebrates particularly in early spring. In contrast, structurally homogenous woody strips represent limited value in promoting the investigated biological pest control agents.

Effects of Plant Diversity, Vegetation Composition, and Habitat Type on Different Functional Trait Groups of Wild Bees in Rural Beijing.

The loss of flower-rich habitats and agricultural intensification have resulted in significant losses of wild bee diversity from agricultural landscapes that is increasingly threatening the pollination of zoochorous agricultural crops and agricultural sustainability. However, the links of different wild bee functional trait groups with habitat types and plant resources in agricultural landscapes remain poorly understood, thus impeding the formulation of effective policies for bee conservation. We therefore analyzed how bees representing different functional groups responded to variations in habitat type, vegetation composition and plant diversity. Natural shrubland sustained the highest diversity in bees overall, in large-sized bees, solitary bees and belowground-nesting bees, while each habitat harbored unique species. In half of the functional bee groups, species were negatively linked to tree coverage and herb coverage, respectively, while plant diversity was positively related to all functional groups except large-sized bees and aboveground-nesting bees. Overall bee abundance was positively related to abundance of plants in the Sympetalae, and negatively related to abundance of plants in the Archichlamydeae. Different bee functional groups showed distinct preferences for different plant communities. In order to conserve the diversity of wild bees across functional groups to optimize associated pollination services, a diverse habitat mosaic, and particularly plant species in Sympetalae need to be promoted in agricultural landscapes. Future studies should aim to enhance our understanding of plant-pollinator associations and specific food requirement of different wild bee species for their effective conservation.

A Novel Attitude Estimation Algorithm Based on the Non-Orthogonal Magnetic Sensors.

Because the existing extremum ratio method for projectile attitude measurement is vulnerable to random disturbance, a novel integral ratio method is proposed to calculate the projectile attitude. First, the non-orthogonal measurement theory of the magnetic sensors is analyzed. It is found that the projectile rotating velocity is constant in one spinning circle and the attitude error is actually the pitch error. Next, by investigating the model of the extremum ratio method, an integral ratio mathematical model is established to improve the anti-disturbance performance. Finally, by combining the preprocessed magnetic sensor data based on the least-square method and the rotating extremum features in one cycle, the analytical expression of the proposed integral ratio algorithm is derived with respect to the pitch angle. The simulation results show that the proposed integral ratio method gives more accurate attitude calculations than does the extremum ratio method, and that the attitude error variance can decrease by more than 90%. Compared to the extremum ratio method (which collects only a single data point in one rotation cycle), the proposed integral ratio method can utilize all of the data collected in the high spin environment, which is a clearly superior calculation approach, and can be applied to the actual projectile environment disturbance.

Heterogeneous Multiple Sensors Joint Tracking of Maneuvering Target in Clutter.

To solve the problem of tracking maneuvering airborne targets in the presence of clutter, an improved interacting multiple model probability data association algorithm (IMMPDA-MDCM) using radar/IR sensors fusion is proposed. Under the architecture of the proposed algorithm, the radar/IR centralized fusion tracking scheme of IMMPDA-MDCM is designed to guarantee the observability of the target state. The interacting multiple model (IMM) deals with the model switching. The modified debiased converted measurement (MDCM) filter accounts for non-linearity in the dynamic system models, and reduces the effect of measurement noise on the covariance effectively. The probability data association (PDA) handles data association and measurement uncertainties in clutter. The simulation results show that the proposed algorithm can improve the tracking precision for maneuvering target in clutters, and has higher tracking precision than the traditional IMMPDA based on EKF and IMMPDA based on DCM algorithm.

Two new species of the Clubionacorticalis-group from Yunnan Province, China (Araneae, Clubionidae).

The present paper describes two new Clubionacorticalis-group species collected from Xishuangbanna, Yunnan Province of China: Clubionasubmoralis sp. n. (♀♂) and Clubionapollicaris sp. n. (♀♂).

One new species of the Clubiona obesa-group from China, with the first description of Clubiona kropfi male (Araneae, Clubionidae).

The present paper describes two Clubiona obesa-group species: Clubiona bicuspidata sp. n. and the male Clubiona kropfi Zhang, Zhu & Song, 2003, which is described for the first time.