Integrating Environmental Characteristics and Fisheries Management in Northern Finland River Impoundments

/ Three large rivers in northern Finland, the Kemijoki, Iijoki, and Oulujoki rivers, were dammed for hydropower generation in the 1940s-1960s. Due to differences in environmental conditions, these impoundments require detailed study to produce guidelines for fisheries management.Water quality, hydrology, vegetation, and geomorphology data of 16 impoundments were gathered. Shoreline land-use data were derived from maps, and fish assemblage data were collected by exploratory fishing and from the annual fishery statistics. The relations among environmental variables were studied, and a classification of the impoundments was developed by hierarchical cluster analysis. Consequently, three impoundment groups with different environmental characteristics were formed. Significant differences among impoundment groups were also detected in fish yield. We conclude that the variation in environmental conditions, together with differences in fish communities in the impoundments were important enough to justify the claim that impoundments of different types require different management strategies. KEY WORDS: Impoundments; River regulation; Fish assemblage; Water quality; Aquatic vegetation; Finland     

Monitoring The Dynamics Of Coastal Vegetation In Southwestern Taiwan

This study analyzes the results of the first 5 years of long-term environmental monitoring of the dynamics of coastal vegetation communities in southwestern Taiwan. Seven permanent plots were established in major vegetation communities, including grassland, windbreak forest, and secondary succession forest. Results showed that species richness decreased yearly in grasslands but fluctuated moderately in the forest plots. A Jaccard similarity coefficient was used to evaluate the similarities of species composition between different monitoring years. Species composition changed rapidly in grassland sites, with the similarity coefficient dropping from 82 to 29% in 5 years. The similarity coefficient of vegetation in the compositehardwood forest dropped from 80 to 50%, indicating that at least half the species were the same as those in the beginning and that the composition of forest communities was more stable than that of grassland communities. Dominant species in the forest community changed gradually during the monitoring period. The original planting of Casuarina equisetifolia in windbreak forests decreased year by year in most of the plots, while Cerbera manghas and Ficus microcarpa became the dominant species. The trend of replacement of dominant species indicates that most of the vegetation communities are still in successional stages.     

Landscape Change and Ecosystem Classification in a Municipal District of a Small City (Isernia,Central Italy)

Landscape changes taking place from 1954 to 1992 in the muncipal district of Isernia city (Central Italy) were described in relation to a system of ecosystem classification. Isernia municipal district was selected for study because recent historic changes in this area represent a typical example of landscape transformation similar to many small cities of Italy and other Mediterranean countries. To assess overall changes, three land cover maps (scale 1:25,000) were derived from panchromatic aerial photographs and field surveys. These were then digitalised in a Geographic Information System. A Land Facet (LF) map was derived by combining a phytoclimatic, a lithostatigrafic and a topographic map, and then digitalised as data layers in the same GIS. Results demonstrated two main landscape transformation trends: forest and semi-natural areas increased (8%), whereas agricultural areas decreased (12%). The urban area was relatively small during the entire analysed period, growing from 1% in 1954, to just 5% in 1992. Forest coverage was significant on reliefs, on hillside ecosystems such as limestone and on clay and marl hills LF. Arable land was particularly significant in flat ecosystems with deeper soils, such as on recent alluvial plain LF. These temporal changes were interpreted as being related to the replacement of traditional farming methods (grazing pastures) with more intensive methods (crop fields), especially on alluvial plains.     

围封对固沙樟子松林下植被群落数量特征及多样性的影响

为揭示围封对人工樟子松固沙林林下植被群落及生态系统的影响,选择章古台围封37年生和46年生固沙樟子松林为研究对象,以邻近未围封林地为对照,采用野外调查法研究不同条件下樟子松林下植被的群落特征与物种多样性。结果表明:研究区共发现林下植被58种,分属18科42属,围封条件下促进禾本科植物与多年生植物种有所增加,多年生及灌木植物的重要值增大。围封降低先锋物种的重要值,明显增加羊草的重要值。围封有利于增加固沙樟子松林下植被群落的平均盖度、高度和生物量,而且随着围封年限的增加呈现不同程度的增长趋势;林下植被群落的物种多样性指数、优势度指数、均匀度指数在半围封5年较未围封状态略高,而在全围封10年则均低于未围封状态。因此,围封有利于樟子松林下植被群落的恢复与生长,适度的围封有利于林下群落多样性,进而保障群落的演替及生态系统稳定性的维持。     

向家坝工程扰动区植被恢复土壤质量评价

以向家坝工程扰动区6种植被恢复模式下的土壤为研究对象,综合考虑表征土壤物理、化学和生物特性的25个土壤指标,利用敏感性分析和最小数据集方法进行土壤质量综合评价.结果表明：基于敏感性分析和最小数据集的土壤质量综合评价模型均能有差别的反映不同植被恢复模式对土壤质量和功能的影响;加权算法下基于最小数据集所计算土壤质量综合评价指数（SQI-MWA）能更敏感的反映出植被恢复措施对土壤质量的影响;有机质、全磷和多酚氧化酶能更好反映土壤质量受不同植被恢复方式的影响差异,推荐作为反映向家坝工程扰动区土壤质量的最优指标组合;土壤质量表现为：植被混凝土样地>厚层基材样地>天然林样地>客土喷播样地>框格梁样地>弃渣地.     

1987～2015年嘉陵江源区植被覆盖度时空变化特征

江河源头地区植被建设与生态保护意义重大。应用遥感技术分析植被覆盖状况近年来已渐成热点。本文以嘉陵江源头所在地陕西省宝鸡市凤县为研究区,基于1987年、2000年和2015年3期Landsat卫星遥感影像,提取归一化植被指数NDVI（Normalized Difference Vegetation Index）,采用像元二分模型,运用ENVI 5.3和ArcGIS10.4软件计算得到研究区植被覆盖度分布格局及动态变化。结果表明：（1）1987~2015年期间研究区植被以高覆盖区为主,高覆盖区面积增加了5.96%,呈上升趋势;（2）研究区植被退化面积占3.91%,基本不变的面积占85.36%,改善面积占10.73%,研究区植被改善面积多于退化面积,与退耕还林还草工程关系密切;（3）植被覆盖度随坡度和高程的增大呈先增加后降低的趋势;阴坡的植被覆盖度低于阳坡,但高于平地,坡向对植被覆盖的影响主要体现在温度上;（4）矿产资源开发对植被破坏的影响大于风力发电场建设,建议当地政府加强矿山生态环境修复力度。研究结果可服务于嘉陵江源区生态保护与流域管理。     

京津冀城市扩张对植被和地表城市热岛的影响

基于MODIS-LST、EVI以及土地利用/覆盖数据,分析了2000~2015年京津冀13个城市生长季及不同季节城市扩张对植被（ΔEVI）和地表城市热岛影响的时间变化趋势以及二者之间的关系,结果表明,京津冀13个城市主城区生长季及不同季节的城市扩张对植被均存在消极影响（ΔEVI<0）,对夏季植被的影响最大（ΔEVI=-0.131）;白天和夜间的地表城市热岛强度（SUHII）最大值均出现在夏季,分别为2.594℃和1.859℃;不同季节的ΔEVI均值呈现显著下降趋势,其速率分别为-0.0038,-0.0033,-0.0045和-0.0018/a（P<0.01）;生长季、春季和夏季白天SUHII均呈显著增加趋势,速率分别为0.076,0.093和0.106℃/a（P<0.01）,不同季节夜间SUHII均呈显著增加的趋势,其增加速率分别为0.05,0.055,0.049,0.054和0.046℃/a;京津冀13个城市主城区的ΔEVI均值和SUHII均值呈显著负相关（P<0.01）,其相关系数介于-0.959~-0.592之间;白天SUHII与ΔEVI的相关性最高为生长季（r=-0.959）,夜间SUHII与ΔEVI的相关性最高为春季（r=-0.936）.     

不同降雨条件下植被对绿色屋顶径流调控效益影响

植被是绿色屋顶的重要组成部分,可通过截留雨水和蒸散耗水等过程影响绿色屋顶的径流调控效益.本文基于太阳花(Portulaca grandiflora)、佛甲草(Sedum lineare)、高羊茅(Festuca elata)和无植被等4种植被覆盖类型绿色屋顶2017年雨季26场降雨径流过程的监测数据,从径流和洪峰削减、产流和峰现时间延迟四方面定量分析植被在不同降雨条件下对绿色屋顶径流调控效益的影响.结果表明,绿色屋顶径流削减率与降雨量呈显著负相关(P 0. 01),降雨量10 mm时,绿色屋顶径流削减率等于或接近100%;降雨量超过30 mm,所有绿色屋顶的径流削减率降低到70%以下;当降雨量达到监测期内最大的81. 4 mm时,各绿色屋顶径流削减率都低于55%.植被覆盖类型对绿色屋顶径流调控效益的影响随降雨条件而改变,大雨条件下不同植被覆盖类型绿色屋顶的径流削减率差异最大,中雨和暴雨条件下次之,小雨条件下因各绿色屋顶几乎都不产流而无明显差异.在中雨、大雨和暴雨条件下,有植被覆盖绿色屋顶的径流削减率、洪峰削减率、产流和峰现时间延迟等4个指标都明显优于无植被覆盖的绿色屋顶.株高和单位面积地上生物量最高的太阳花绿色屋顶的径流调控效益优于佛甲草绿色屋顶.     

西南喀斯特区植被恢复对土壤氮素转化通路的影响

氮素是生态系统重要的限制性养分元素之一.研究氮素转化特征对于了解生态系统功能具有重要意义.然而,目前对喀斯特地区氮素转化特征的认识十分有限.同时,喀斯特地区正开展一系列的生态恢复工程措施,生态恢复将对土壤氮素转化过程产生何种影响尚不清楚.为此,本研究在广西环江县喀斯特区域选取3种典型的植被恢复阶段(草地、灌丛、次生林),以农田为参照,采集0~10 cm深度的土壤样品,测定了土壤净氨化速率(净氨化率、真菌氨化和细菌氨化)、净氮矿化速率(净氮矿化、真菌矿化和细菌矿化)、净硝化速率(净硝化、自养硝化、异养硝化、真菌硝化、细菌硝化)及相关土壤理化指标,研究喀斯特区植被恢复对土壤氮素转化速率的影响.结果表明,总体上喀斯特生态系统硝化速率很高,土壤无机氮主要以硝态氮形式为主,其中自养硝化和异养硝化分别占净硝化速率的80%和20%.添加真菌和细菌抑制剂后,氨化速率增加,而硝化速率下降.另外,随着植被的恢复,土壤氮矿化和硝化速率逐渐增加,而氨化速率逐渐下降.其原因与不同植被恢复阶段的土壤有机碳、总氮、硝态氮、微生物量及氮获取酶的活性有密切关系.这些发现为认识喀斯特生态系统氮素循环特征提供了关键的信息.     

Detecting the signal of atmospheric N deposition in recent national-scale vegetation change across Britain

Model estimates of NO_y and NH_x deposition across Britain for 1996 (5 km square resolution) were applied as explanatory variables to account for national-scale, fine-grained changes in plant species composition between 1990 and 1998. Plant species data were recorded from up to 27 fixed plots located within a stratified random sample of 596 1 km². The response variable was a cover-weighted Ellenberg fertility score for each plot. Analyses were carried out separately for woodlands, semi-natural grasslands and heaths/bogs. Most of the variation in the botanical response variable occurred between plots within squares and so could not be explained by the model deposition data. NH_x deposition estimates accounted for significant, but small components of between 1 km² variation in the change in Ellenberg score in grasslands (5.6%) and heath/bogs (9.8%) but not woodlands. NO_y deposition estimates were not significantly associated with vegetation change. Linear models provided the best fit and the slope of the relationship was lower for heath/bogs than grasslands. Further signal attribution at sub-kilometre square scales requires the development of fine-grained models of N deposition that can be generalised across regional sampling domains.