`Ocean triads' in the Mediterranean Sea: physical mechanisms potentially structuring reproductive habitat suitability (with example application to European anchovy, Engraulis encrasicolus)

Summaries of maritime weather reports and mean seasonal satellite-sensed ocean colour distributions for the Mediterranean Sea are used to identify characteristic configurations of physical mechanisms promoting (i) nutrient enrichment, (ii) concentration of larval food distributions, and (iii) local retention of eggs and larvae. Five subbasin scale `ocean triads', hypothesized to be particularly favourable groupings, are identified in the Aegean Sea, the Gulf of Lions and nearby Catalan Coast, the Alboran Sea, the Straits of Sicily/Tunisian Coast, and the Adriatic Sea. These are examined in relation to available knowledge of anchovy spawning grounds. All areas are characterized by patterns of linked wind-driven Ekman upwelling and downwelling. All areas except the Straits of Sicily are found to have inputs of less saline surface waters offering raised nutrient concentrations, enhanced upper layer stability, and frontal density contrasts, and to have areas where the characteristic rate of turbulent mixing energy input by the wind fall below a reference intensity level. All areas, except the Sicilian Channel/Tunisian Coast, also contain abundant locally reproducing anchovy populations.     

Are the long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) population related to environmental changes?

We tested whether synchronous, long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) trap catches, collected from the ancestral Mediterranean and Atlantic trap fishery, might be related to large‐scale environmental change. Nine time series of trap catches of more than 80 yr long were compared with long time series of three preselected environmental variables, i.e. the North Atlantic Oscillation (NAO), the Length of the Day Index (LOD, a proxy of the atmospheric circulation index) and the temperature. Spectral analyses of trap catches, LOD and temperature displayed similar spectra with peaks at low frequencies, whereas those of the NAO exhibited a broad band spectrum. Regression analyses and tests of correlation did not reveal any clear relationship between trap catches on the one hand and NAO and LOD on the other hand. In contrast, long‐term fluctuations in trap catches appear to be closely and negatively related to long‐term trends in temperature. Underlying processes that could explain such a relationship are discussed, with special focus on changes in migration patterns of the Atlantic bluefin tuna.     

漓江流域2000—2020年土地利用和覆被变化时空分异特征

[目的]分析2000—2020年漓江流域土地利用和覆被变化时空分异规律,为协同人类活动及生态安全提供空间治理依据。[方法]基于遥感信息识别和GIS空间分析平台,应用扩张强度、转移矩阵及时空统计、空间自组织分析等方法,从多维时空尺度研究流域土地利用及景观结构变化规律。[结果](1)漓江流域以林地、耕地为主体景观,合占景观面积的比例超过90%,2000—2020年其面积变率小于0.37%,扩张强度小于年均3.59%,表明流域具有高质量的景观生态资源和建成国际旅游中心的生态资本,景观结构稳定,水生态良好;(2)建设用地增长最快,扩张显著,2000—2020年其面积增长了163.41%,其中临桂新区年均扩张37.79%,城镇化是流域景观类型及结构变化的主要驱动;(3)流域景观类型多样性丰富、分布均衡,多样性和均匀度指数在城镇及旅游中心形成高值中心,山地区则为低值连片;连通性或延展性较好,山区为高值中心,城镇为低值中心,人类活动对草地形态及城镇周边(中值区)的扰动较显著。[结论]流域景观指数结构受相似的发生环境和分异因素影响而具有空间集聚性分布特征,城镇扩张及旅游活动是漓江流域景观格局分异的主要...     

1980—2020年汾河流域生态系统服务价值的时空变化

[目的]分析1980—2020年汾河流域生态系统服务价值时空变化特征,为该流域生态环境的科学调控和管理提供理论参考。[方法]利用汾河流域1980—2020年5期Landsat-MSS/TM/ETM遥感影像解译数据研究了流域土地利用变化特征,并估算了生态系统服务价值。[结果] 1980—2020汾河流域土地利用中耕地、林地和草地一直处于主导地位,土地利用整体变化表现为耕地向建设用地转移;土地利用动态度表明2000—2020年土地变化明显高于1980—2000年。1980—2020年汾河流域土地利用总生态服务价值持续减少,空间分布整体上呈上游高,中下游低的趋势。从不同功能价值来看,调节和支持服务减少最多。不同土地利用程度与ESVI双变量LISA聚集图呈现出明显的空间负相关性,主要以汾河上游的低土地利用程度与高ESVI聚集分布为主。[结论] 1980—2020年汾河流域土地利用/覆被变化对生态服务价值有较大影响。可以通过提高土地集约利用水平,促进该区土地利用结构向高生态服务价值发展。     

2000—2020年漓江流域生态服务价值时空分异

[目的] 研究2000—2020年漓江流域生态服务价值(ESV)时空分异格局及变化规律,为优化土地利用结构和实现“双碳”目标提供空间治理方法。[方法] 基于遥感信息挖掘和地理信息分析平台,用价值核算及其动态度、敏感性分析方法评估生态服务价值,用空间自相关方法研究ESV时空格局,用地理探测方法诊断ESV分异的主导因素及驱动机制。[结果] ①漓江流域土地利用/覆盖空间异质性显著;林地、耕地面积最大,但变化平稳,建设用地增长迅速。②漓江流域生态服务价值约合3.75×10⁷元,其中林地、草地的ESV值最高,占总价值的52.44%。其变化呈先迅速增加、后缓慢减少的趋势,其中原材料生产、水土保持价值增强显著,而食物供给、水源涵养价值降低明显。③ESV总体上呈中游低值与上、下游高值的分异格局,表现为正向的空间集聚特征。[结论] 城镇扩张是漓江流域ESV时空分异及其动态变化的核心驱动,人类活动对ESV的扰动趋向增强。     

Do model choice and sample ratios separately or simultaneously influence soil organic matter prediction?

This study was performed to examine the separate and simultaneous influence of predictive models’ choice alongside sample ratios selection in soil organic matter (SOM). The research was carried out in northern Morocco, characterized by relatively cold weather and diverse geological conditions. The dataset herein used accounted for 1591 soil samples, which were randomly split into the following ratios: 10% (～150 sample ratio), 20% (～250 sample ratio), 35% (～450 sample ratio), 50% (～600 sample ratio) and 95% (～1200 sample ratio). Models herein involved were ordinary kriging (OK), regression kriging (RK), multiple linear regression (MLR), random forest (RF), quantile regression forest (QRF), Gaussian process regression (GPR) and an ensemble model. The findings in the study showed that the accuracy of SOM prediction is sensitive to both predictive models and sample ratios. OK combined with 95% sample ratio performed equally to RF in conjunction with all the sample ratios, as the latter did not show much sensitivity to sample ratios. ANOVA results revealed that RF with a ～10% sample ratio could also be optimum for predicting SOM in the study area. In conclusion, the findings herein reported could be instrumental for producing cost-effective detailed and accurate spatial estimation of SOM in other sites. Furthermore, they could serve as a baseline study for future research in the region or elsewhere. Therefore, we recommend conducting series of simulation of all possible combinations between various predictive models and sample ratios as a preliminary step in soil organic matter prediction.     

基于化学蚀变指数的湟水河流域化学风化分析

以青海省湟水河表层沉积物为研究对象,选取该河流沉积物常量元素含量、CIA风化程度指数,通过与大陆壳表层、黄土相关元素的对比,分析了湟水河流域地表化学风化程度.结果表明,湟水河沉积物富Ca、m,而K在全流域含量变化小,与大陆壳表层含量基本一致,表明湟水河流域地表物质化学风化程度低,处于饱和硅铝阶段早期（即脱Ca、Na阶段）,地表的物理风化强于化学风化;CIA值大致反映了化学风化的程度,在中游段CIA低,上游和下游段CIA较高,具有相对稍强的化学风化过程.     

近33年衡阳盆地的气候变化与干旱发展趋势

全球变暖背景下区域气候变化响应已引起学术界的高度关注,将气候变化与干旱趋势相结合进行研究具有理论意义。利用衡阳盆地1981—2013年的逐日气温和降水量,综合分析衡阳盆地的气候变化特征与干旱发展趋势。结果表明:衡阳盆地的气候呈暖干趋势发展,年平均气温增加0.034 1℃,其中春季升温贡献最大,春季气温年增加0.054 4℃;年降水量约减少0.808 0 mm,呈缓慢减少趋势,以秋季降水的减幅最大,年减少3.335 1 mm;利用综合气象干旱指数(CDI)法计算出干旱频率年增加0.379 9%,其中秋季干旱频率增加最大,年增加0.910 4%,不同等级干旱类型中,以特旱频率增加率最大,年增加0.231 6%。     

鄱阳湖流域典型湿地植物需水规律研究

湿地植被需水量是维持湿地生态系统生态平衡和湿地植被正常生长,保障湿地系统生态功能正常发挥所需的水量。选取鄱阳湖流域8种典型湿地植物:藜蒿、菖蒲、美人蕉、茭白、高秆灯芯草、西伯利亚鸢尾、白莲、莲藕,于2013年在江西省灌溉试验中心站人工湿地试验场开展试验,分析了不同湿地植物全生育期需水量及其生育阶段和日变化规律,得到不同湿地植物的作物系数。结果表明,在湿地植物需水高峰期的5-10月,8种湿地植被日均需水量变化范围为4.3~6.1mm,其中菖蒲最高为6.1mm,白莲最低为4.3mm。经测定,湿地日均渗漏量为1.3mm;全生育期湿地植被需水量变化范围为800~1 125.6mm,是平均值的0.86倍至1.21倍;8种湿地植物全生育期作物系数变化范围为1.8~2.4,其中菖蒲最高为2.4,白莲和莲藕最低为1.8,而藜蒿、高杆灯芯草和西伯利亚鸢尾的全生育期作物系数为2.0左右,对照处理作物系数保持在1.7。本文研究结果为鄱阳湖流域不同湿地植物需水规律分析及其计算提供了依据。