Effect of legume species introduction to early abandoned field on vegetation development

One of the most important areas in ecology is to elucidate the factors that drive succession in ecosystems. The purpose of our study was to assess the effects of legume species (Medicago sativa, Melilotus suaveolens and Astragalus adsurgens) introduction to abandoned arable land on vegetation development in the Loess Plateau, China. Results from our study showed that addition of legume species strongly affected the composition of recently abandoned-field vegetation. Legume species were effective at reducing the number and dominance of natural colonizers (mainly weeds from the seed bank). The introduction of legume species into newly abandoned fields maintained high total cover and above-ground biomass and could improve soil organic carbon and total nitrogen. However, the effects of the treatments were species-specific. Melilotus suaveolens turned out to be severely suppressive to natural colonizers (weed species). Also, Melilotus suaveolens-adding maintained the highest cover and above-ground biomass and was helpful to improve later succession species, e.g. Stipa breviflora and Astragalus polycladus, to invade and establish. Medicago sativa-adding was superior in enhancing the soil organic carbon and total nitrogen. The present results suggested that addition of legume species with greater cover and biomass strongly suppressed the dominance of the weedy species in early succession and the course of old-field succession may be accelerated by introduction of legume species at least temporarily. However, the experimental period was too short to assess to what extent succession may be affected in the longer term.     

Driving when distracted and sleepy: The effect of phone and passenger conversations on driving performance

ABSTRACT

This study investigates the effect of passenger and phone conversations on sleep-restricted driving. Six volunteers (50% male, mean age 24.8 ± 4.3 years) had their sleep restricted to 4 h in bed followed by a 20-min simulated drive on three separate occasions. Each drive included either a passenger conversation, a mobile phone conversation or a quiet passenger. The effect size of a phone conversation on lane deviation was large while passenger conversation was small. The main effect of conversation on lane deviation was non-significant (F(2,10) = 2.57, p = 0.126). Combining sleep-restricted driving with conversations warrants further investigation.     

Biocatalysts: measurement, modelling and design of heterogeneity

Multiple phenomena are involved in conversions by immobilized biocatalysts. A paradox is identified between analytical desires on one hand and analytical boundary conditions on the other: while the study of interdependent phenomena would call for their simultaneous analysis in an integrated context, the available experimental options may impose a series of separate and dedicated analyses. From this analysis, bottlenecks in particle performance may be identified, if possible supported by a mechanistic model and performance criteria. Subsequently, a strategy for further biocatalyst development may be chosen. Finally, possibilities for future improvement of biocatalysts are discussed for various fields of research. Some examples of recent developments in enzyme and matrix characteristics, reactor operation, and micro-technology are discussed.     

北方半干旱荒漠草原生态区生态脆弱性变化遥感监测及其驱动机制分析

针对研究区的生态环境特征(风力侵蚀、沙漠化、盐渍化严重、水力侵蚀严重),引入了大尺度景观格局指数(香农均匀性指数和蔓延度指数)和极端气候指数(极端高温日数、极端低温日数和极端降雨日数),构建了北方半干旱荒漠草原生态区生态脆弱性评价体系,进而分析和探讨了该地区近13年的生态脆弱性时空变化格局和驱动机制。结果表明,北方半干旱荒漠草原生态区的生态脆弱性总体上属于中度脆弱状态,呈现自西向东递减的趋势。2000-2013年,北方半干旱荒漠草原生态区生态脆弱性呈现减小趋势。近13年北方半干旱荒漠草原生态区的生态脆弱性时空变化格局受GDP密度、气温、降水、地形等因子影响显著。这些为北方半干旱荒漠草原生态区的生态环境修复及保护提供重要的科学支撑。     

深圳市景观格局演变及其驱动因素分析

在遥感与GIS技术支持下,以深圳市域1978年MSS影像与1986、1990、1995和1999年4期TM影像为主要数据源。研究了深圳市域景观的空间格局特征及其动态变化。探讨了不同尺度下景观格局演变的驱动因素与变化机制．结果表明,深圳市近20年景观特征发生了深刻变化,耕地面积比例由31．06％下降至2．67％,城建用地则由0．33％上升至22．52％．景观多样性指数1978～1995年上升近25％,1999年稍有下降;蔓延度指数先降后升,整体破碎度由0．0042上升到0．0073;景观修改分维数1990年以前有所下降,20世纪90年代则呈现递增趋势．景观格局指数的变化,反映了人为活动对区域景观特征的深刻影响．人为活动已成为深圳市景观格局演变的主要驱动因素．其中,斑块形状复杂化主要是受个体经济单元的经济利益驱动,景观空间构型的变化取决于产业布局与地域分工的影响,景观整体多样性的演变受到社会经济发展水平的强烈影响,而自然生态条件则是景观整体结构变化的重要约柬因子。     

EEG–EMG coupling as a hybrid method for steering detection in car driving settings

Understanding mental processes in complex human behavior is a key issue in driving, representing a milestone for developing user-centered assistive driving devices. Here, we propose a hybrid method based on electroencephalographic (EEG) and electromyographic (EMG) signatures to distinguish left and right steering in driving scenarios. Twenty-four participants took part in the experiment consisting of recordings of 128-channel EEG and EMG activity from deltoids and forearm extensors in non-ecological and ecological steering tasks. Specifically, we identified the EEG mu rhythm modulation correlates with motor preparation of self-paced steering actions in the non-ecological task, while the concurrent EMG activity of the left (right) deltoids correlates with right (left) steering. Consequently, we exploited the mu rhythm de-synchronization resulting from the non-ecological task to detect the steering side using cross-correlation analysis with the ecological EMG signals. Results returned significant cross-correlation values showing the coupling between the non-ecological EEG feature and the muscular activity collected in ecological driving conditions. Moreover, such cross-correlation patterns discriminate the steering side earlier relative to the single EMG signal. This hybrid system overcomes the limitation of the EEG signals collected in ecological settings such as low reliability, accuracy, and adaptability, thus adding to the EMG the characteristic predictive power of the cerebral data. These results prove how it is possible to complement different physiological signals to control the level of assistance needed by the driver.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11571-021-09776-w.     

Fuzzy Rough Set algorithm with Binary Shuffled Frog-Leaping (BSFL-FRSA): An innovative approach for identifying main drivers of carbon exchange in temperate deciduous forests

The spatial variability, driving forces, and uncertainties of the net ecosystem exchange (NEE) of carbon between the temperate forests and the atmosphere remain elusive. Here, we proposed a fuzzy rough set algorithm with binary shuffled frog leaping (BSFL-FRSA) to identify main driving variables and define the contribution rate of main drivers to NEE. As a case study, we applied the approach to nine deciduous forest eddy covariance flux sites in the northeastern United States. The results show that the BSFL-FRSA effectively retained most information using just a few variables, and it performed better than the GA-FRSA (fuzzy rough set with genetic algorithm). Temperature, radiation, and soil water content were identified as the most influential variables (impact in descending order) to NEE across all sites. Soil temperature was the most important variable explained 59.6% of the NEE variance. Soil temperature and net radiation together, explained 72.7% of the NEE variance, was the most important two variables among all possible two-variable combinations. The most influential three variables on NEE among all possible three-variable combinations were soil temperature, net radiation, and soil water content or relative humidity (explained 81.1% of the NEE variance). The variance attribution approach presented here is generic and can be applied to other studies; the dominant influence of soil temperature begs for accurate characterization of soil temperature dynamics in time and space particularly in the global warming context.     

2001年以来宝鸡地区植被覆盖时空演变及驱动力分析

植被在全球变化中影响着地-气系统的能量平衡,是自然和人文因素对环境影响的敏感指标。分析地表植被的覆盖现状并探究影响植被变化的驱动力因素对区域生态恢复以及区域经济发展和区域生态文明建设都有促进作用。本研究基于中分辨率成像光谱仪-归一化植被指数（MODIS-NDVI）数据,结合宝鸡11个气象站的气温和降水量实测数据、净初级生产力（NPP）以及宝鸡统计年鉴数据,采用趋势分析方法、Pearson相关分析法、主成分分析方法对2001-2013年宝鸡地区植被覆盖的时空演化特征进行了分析,并对自然驱动因子和人为驱动因子双重影响下的宝鸡地区植被覆盖演化状况进行了综合评价。结果显示：（1）2001-2013年宝鸡地区年均NDVI以0.025/10a的速度上升,比三北防护林工程区1982-2006年植被覆盖的增速（0.007/10a）快,且2001-2002年、2003-2004年两个年份段为年均NDVI值的两次高恢复期;（2）植被覆盖以轻度改善为主,基本不变和中度改善次之,严重退化和中度退化最弱。植被覆盖恢复状况整体上呈稳中上升的趋势（个别地区除外）;（3）自然因素中的降水量和NPP是制约植被生长的主要因素。整体来看,人为因素相对于自然因素对宝鸡全区的植被覆盖影响较大,贡献率在90%左右,呈先减小后增加的趋势。