运用植物区系质量指数快速评估湿地植被恢复成效

目前通常采用的评估湿地保护和恢复成效的指标体系较为复杂, 常涉及生物学、环境科学和社会学等多个学科, 导致监测评估成本高, 并难以实现综合的定量评估, 因此有必要提出能够在较大程度上表达生态环境状况的综合生态指标。植物区系质量指数(Floristic Quality Assessment Index, FQAI)反映了植物区系中物种的生态保守性程度, 作者将其作为主要生态指标, 来验证该指标用于湿地植被恢复成效定量评估的有效性。作者以四川盆地丘陵和平原地区湿地植物为对象, 构建了区域库塘及河滩湿地植物区系质量指数计算方法与赋值表, 以成都市重要水源地——云桥湿地的3年生态恢复成效为案例进行了检验。结果表明, 在云桥湿地3年恢复期间, 植物物种组成及其比例在恢复年限间无显著差异, Shannon-Wiener指数、Pielou指数和Simpson指数在3年中也并未发生显著变化, 但生态保守性系数平均值(CC_mean)和植物区系质量指数(FQAI)均随恢复年限显著上升, 表明FQAI可以快速、有效地实现生态系统水平湿地植被恢复成效的比较和定量评估。     

Responses of ground flora to coppice management in an English woodland – a study using permanent quadrats

Changes in the ground flora in sweet chestnut (Castaneasativa) woodland were studied over 11 years usingpermanent quadrats in two coppiced plots and one plot in a ride widened by treeremoval. Light and temperature were also recorded. The temperature range wasgreater in the ride than in the coppice plots. Light reaching the woodland floorin summer fell to less than 1% of incident radiation at later stages of thecoppice cycle. Species richness peaked in the second and third year aftercoppicing and then declined in both the coppice plots and the ride. A similarpattern was seen in total percentage frequency of cover. The dominant species,Anemone nemorosa, showed little response to the coppicecycle in terms of frequency, but showed a fourfold increase in floweringintensity in the second and third year following coppicing. Other speciesgenerally declined in frequency through the coppice cycle, and flowering waslargely suppressed in the later stages. The results are discussed in relation toalternative methods of woodland management.     

The ecological condition of geographically isolated wetlands in the southeastern United States: The relationship between landscape level assessments and macrophyte assemblages

Geographically isolated wetlands (GIWs) are common features of the Dougherty Plain physiographic region in southwestern Georgia. Due to lack of protection at the state and federal levels, these wetlands are threatened by intensive agricultural and silvicultural land uses common in the region. Recently, the ecological condition of such GIWs was assessed for the southeastern United States using the Landscape Development Intensity Index (LDI), a practical assessment tool that relies on remotely sensed land use and land cover (LULC) data surrounding isolated wetlands to rapidly predict wetland condition. However, no assessments have been attempted for GIWs in the Dougherty Plain specifically. Our goal was to develop a framework to guide and refine remote assessment of wetland condition within this agriculturally intense region of the southeastern USA. In this study, we characterized human disturbances associated with isolated wetlands in the Dougherty Plain, and paired the rapid assessment of GIWs using LDI with an intensive assessment of wetland plant communities. Specifically, we: (1) examined how macrophyte assemblages and vegetation metrics vary across a human disturbance gradient in the Dougherty Plain; (2) compared multiple condition assessment outcomes using variations of the LDI method that differed in spatial extent and resolution of LULC categories; and (3) determined the predicted condition of GIWs in the Dougherty Plain as indexed by LDI and compared with region-wide assessments of GIWs of the southeastern USA. Generally, the relationship between wetland plant communities and surrounding land use supported the assumptions of the LDI index in that wetlands surrounded by agricultural land use classes featured distinct plant communities relative to those surrounded by forested land use classes. Our results indicated that finer spatial resolution of LULC data improved the predictive ability of LDI. However, based on incongruence between wetland vegetation composition and LDI scores in some forested landscapes, this study identified limitations of the LDI assessment method, particularly when applied in regions in which prescribed fire is an important ecological driver of vegetation and habitat. Thus, we conclude that LDI may be biased toward an overestimation of reference condition GIWs, even though the habitat may be functionally degraded by the absence of natural processes such as fire. Regardless, relative to the assessment of the entire southeastern US, a greater proportion of total GIWs of the Dougherty Plain were identified as impaired due to the intensity of irrigated agricultural land use.     

Introduced and native ground beetle assemblages (Coleoptera: Carabidae) along a successional gradient in an urban landscape

According to the intermediate disturbance hypothesis (IDH), species diversity should be higher at sites with intermediate levels of disturbance. We tested this hypothesis using ground beetles (Coleoptera: Carabidae) collected in pitfall traps from sites that varied in time since last disturbance. This successional gradient was embedded in an urban landscape near Montreal, Quebec. We predicted that diversity in young forests and old fields would be higher than in agricultural fields and old forests. Fifty-five species (2932 individuals) were found in 2003 and 46 species (2207 individuals) in 2004. In both years, species richness was highest from traps placed in agricultural fields. We collected nine introduced species; these had higher catch rates than the native species in both years (64.8% of total catch). When introduced species were removed from the Nonmetric Multidimensional Scaling ordination analysis, the assemblages from agricultural fields were less distinct compared to those of the other habitats, suggesting the introduced fauna is important in structuring carabid assemblages from the agricultural fields. Introduced species may play a significant role in the community composition of ground beetles in urban landscapes, and their influence may be the cause of the lack of support found for the IDH.     

Pollen productivity estimates and relevant source area of pollen for selected plant taxa in a pasture woodland landscape of the Jura Mountains (Switzerland)

Relevant source area of pollen (RSAP) and pollen productivity for 11 key taxa characteristic of the pasture woodland landscape of the Jura Mountains, Switzerland, were estimated using pollen assemblages from moss polsters at 20 sites. To obtain robust pollen productivity estimates (PPEs), we used vegetation survey data at a fine spatial-resolution (1 × 1 m²) and randomized locations for sampling sites, techniques rarely used in palynology. Three Extended R value (ERV) submodels and three distance-weighting methods for plant abundance calculation were applied. Different combinations of the submodels and distance-weighting methods provide slightly different estimates of RSAP and PPEs. Although ERV submodel 1 using 1/d (d = distance in meters) best fits the dataset, PPE values for heavy pollen types (e.g. Abies) were sensitive to the method used for distance-weighting. Taxon-specific distance-weighting methods, such as Prentice’s model, emphasize the intertaxonomic differences in pollen dispersal and deposition, and are thus theoretically sound. For the dataset obtained in this project, Prentice’s model was more appropriate than other distance-weighting methods to estimate PPEs. Most of the taxa have PPEs equal to (Fagus, Plantago media and Potentilla-type), or higher (Abies, Picea, Rubiaceae and Trollius europaeus) than Poaceae (PPE = 1). Acer, Cyperaceae, and Plantago montana-type are low pollen producers. This set of PPEs will be useful for reconstructing heterogeneous, mountainous pasture woodland landscapes from fossil pollen records. The RSAP for moss polsters in this semi-open landscape region is ca. 300 m.     

渔场重心信度测算及渔场重心修正理论构建——以闽南-台湾浅滩渔场二长棘鲷为例

渔场重心是表征渔场位置的重要参数,准确掌握渔场重心,对判断鱼类洄游路线、确定中心渔场、表征鱼群分布特征和变化规律具有重要意义。渔场重心计算采用的是固定物体重心计算方法,然而运动的鱼类和固定物体有着本质的区别。因此,由固定物体重心计算的渔场重心能否体现鱼群分布特征,值得深入研究。渔场重心信度是用于度量由固定物体重心计算的渔场重心表征鱼群分布特征的能力,体现渔场重心的可信程度,而渔场重心修正是为了提升渔场重心表征鱼群分布特征的能力,提高渔场重心信度,以准确掌握渔场重心。以闽南-台湾浅滩渔场二长棘鲷(Parargrops edita Tanaka)为例,采用渔场重心、几何中心和单位捕捞努力量渔获量(Catch Per Unit Effort,CPUE)为参数,首次建立了渔场重心信度测算及渔场重心修正理论和方法,分析了渔场重心信度,研究了渔场重心修正方法和渔场重心的分布特征,旨在从更精细地水平上掌握二长棘鲷渔场重心,为生态智慧在渔业资源开发和管理的应用提供可靠的数据支持。结果表明:(1)二长棘鲷渔场重心信度各月变化在0.12—1.00,平均值0.67,均方差0.31,各月渔场重心可信度波动较大,12月份和2月份渔场重心信度最大为1.00,鱼群对称和均匀分布于渔场重心,渔场重心可信度最高,3—8月份渔场重心信度低于0.70,鱼群在渔场重心周围的对称性和均匀度差,渔场重心可信度差,其中3月份渔场重心信度最小为0.12;(2)渔场重心信度不仅反映了渔场重心可信程度,还体现了鱼群在渔场重心周围的分布特征,可作为研究鱼群分布特征的重要参数,渔场重心信度低于0.70,渔场重心需要修正;(3)渔区修正系数用于判别鱼群所在渔区是否排除,通过去除渔区修正系数小于0.5的鱼群,能保留85%以上的鱼群数量,提高渔场重心信度0.70以上;(4)修改后的渔场重心变化规律较显著,4—5月份,幼鱼群体重心向西迁移,6—7月份,索饵群体重心向东北方向移动,8月份,索饵群体重心开始往南迁移,9—11月份,越冬群体重心逐渐向南移动,12月份,生殖群体重心继续往南迁移,1—3月份生殖群体主要集中在305渔区(119°15'E,23°15'N)附近进行生殖活动,鱼群少有迁移。     

Comment arising from a paper by Wittmer et al.: hypothesis testing for top-down and bottom-up effects in woodland caribou population dynamics

Asexual fungal endophytes, which do not produce reproductive structures, spread in host populations only vertically via the propagules of their hosts. With such a close relationship between the fitness of the asexual endophyte and that of the host, the relationship is traditionally thought to be mutualistic. Here we present data showing that the positive effect of asexual endophytes may concern only a short period of the host’s life and that its lifetime reproductive success may be reduced. We followed 180 individuals of a perennial grass, Puccinellia distans, for the first 3 years of their growth both in the field and in a common garden experiment. In the first 2 years, infected individuals produced more generative shoots with longer inflorescences. Three-year-old individuals produced significantly fewer generative shoots with shorter inflorescences when infected with the fungus Epichloë typhina. Moreover, the dry mass of above- and belowground parts after three seasons was significantly lower in infected individuals. We suggest that if the endophyte retains control over plant reproduction and if shorter generation time is more crucial for the fungus than for the perennial host, then the fungus should stimulate plant reproduction early in life even though infection incurs a future cost. This reasoning suggests that discovering an endophyte’s beneficial effect on its perennial host in one season provides insufficient grounds for concluding that a mutualistic relationship exists.     

Fish community responses to ecosystem stressors in coastal estuarine wetlands: a functional basis for wetlands management and restoration

Functional responses of estuarine fish species to environmental perturbations such as wetland impoundment, changes in water quality, and sediment accretion are investigated. The study focuses on the feeding, growth and habitat use by California killifish (Fundulus parvipinnis), topsmelt (Antherinops affinis), and juvenile California halibut (Paralichthys californicus) in impacted coastal wetlands to provide an ecological basis for guidance on the management and restoration of these ecosystems. The ecology of California killifish, Fundulus parvipinnis, is closely tied with the marsh surface, which they access at high tide to feed and grow. Field estimates of food consumption show that killifish can increase their food intake by two-fold to five-fold by adding marsh surface foods to their diet. Bioenergetics modeling predicts that killifish can grow over an order of magnitude faster if they add intertidal marsh surfaces to their subtidal feeding areas. Tidal inlet closures and increased marsh surface elevations due to sediment accretion can restrict killifish access to the marsh surface, affecting its growth and fitness. An open tidal inlet and tidal creek networks that allow killifish to access the marsh at high tide must be incorporated into the restoration design. Topsmelt and California halibut are also adversely affected by tidal inlet closures. Food consumption rates of topsmelt are 50% lower when the tidal inlet is closed, compared to when the estuary is tidally-flushed. Tidal inlet closures inadvertently induce variations in water temperature and salinity and negatively affect growth of juvenile California halibut. Tidal creek networks which consist of channels and creeks of various orders are also important to halibut. Large halibut (>200 mm TL) inhabit deeper, high order channels for thermal refuge, while small halibut (<120 mm TL) are abundant in lower order channels where they can feed on small-sized prey which are typically less abundant in high order channels. Maintaining an open tidal inlet, implementing sediment management programs and designing coastal wetlands with tidal creek networks adjacent to intertidal salt marsh habitat (for fish access) are key elements that need to be considered during the planning and implementation of coastal wetland restoration projects.     

基于生态安全格局的山水林田湖草生态保护修复优先区识别——以四川省华蓥山区为例

优先区识别,是科学有序推进山水林田湖草生态保护修复工作的重要基础。以山水林田湖草生态保护修复工程之一的四川华蓥山区为例,基于生态系统服务重要性提取生态源地共1392.63 km²,占华蓥山区总面积的35.60%;结合土地覆被类型与地质灾害敏感性构建生态阻力面,并利用最小累积阻力模型与电路模型提取生态廊道共84条,夹点区域0.1 km²,含夹点廊道10条;生态保护优先区主要分布在景观破碎化较为严重的广安区境内,以及华蓥山西南端的夹点廊道。以生态修复模拟方法识别障碍点,确定生态修复优先区93.86 km²,大致分两片。其中,广安区境内受到人类活动干扰的破碎化生态空间,主要生态修复策略为植被恢复与退耕还林;华蓥山、铜锣山、明月山等滑坡、泥石流地质灾害频发区,主要生态修复策略是矿山地质修复与植被恢复。本研究提出生态安全格局构建与生态修复模拟的思路,为山水林田湖草生态保护修复工作提供了可行的定量方法。     

校园再生水回用人工湿地景观绩效评价及优化设计——以辽宁公安司法管理干部学院为例

设计生态是相对于自然的生态而言的人工设计的生命与自然环境相互作用的系统,其是解决当代生态问题的新范式。从环境、社会、经济3个方面对辽宁公安司法管理干部学院人工湿地的设计生态的景观绩效进行了评价,主要得到以下结论:(1)人工湿地能对回用再生水产生一定的净化作用。再生水经过人工湿地后,TP、TN、NH_3-N、COD、SS分别减少74.9%、6.66%、61%、41.18%和64.71%,但整体水质类别保持不变。湿地基质土壤中TN、TP的含量与湿地水体有密切关系,再生水回用于人工湿地可以提高湿地基质中的土壤肥力。湿地周边植物生境类型为落叶阔叶林、灌木丛、草丛、浅水沼泽,其结构、优势种、下层植物差异明显。植物群落地域特征十分明显,整体多样性较为丰富,共计22科,37属,37种。(2)人工湿地景观为校园师生提供了较好的游憩、社交和视觉景观服务,超过80%的使用者对其总体评价在"满意"以上。同时,人工湿地运行、维护成本低,约每年可节约用水成本6.7万元。(3)以提供生态系统服务为目标的景观在设计初期,应当全面考虑运行中的地域独特性,提高设计绩效的预见度。     

Assessing high conservation value areas for rare,endemic and threatened (RET) species: A study in high altitude Changthang landscape of India

The Forest Stewardship Council developed the concept of High Conservation Values (HCVs) as a criteria in the forest certification process in order to promote sustainable forest management. It has six major components or values and component one and two of HCVs deal with the habitat for viable populations of “rare, endemic and threatened (RET) species” using the IUCN Red List category and other national / regional / local lists. But a consistent robust methodology for identification of these areas, does not exist. The present study tried to develop for the first time, a straight forward inclusive methodology for identification of HCVAs for the RET species on a spatio-temporal scale. A total of 50 RET and other significant species (32 flora, 10 fauna and 8 avifauna) were identified after a thorough literature review, field surveys and consultations with experts. Occurrence data of the selected species was collected from different secondary sources, field surveys, institutes and scientists who have worked on them. A 10 km grid-based approach and stratified random sampling was used for the primary GPS field surveys conducted during 2018–2019. MaxEnt species distribution model (SDM) software was used based on the occurrence data and environmental variables for identification of potential suitable habitats for the selected species. Linear support vector machine (LSVM) model was used for assessing the performance of the SDMs. The performance of each SDM has been validated through Cohen's Kappa (KAPPA), true skill statistic (TSS) and receiver operating characteristics (ROC) models. The proposed methodology addresses the urgent need for a holistic and robust set of techniques to apply the HCV toolkit. This is key to identify and map HCVAs for RET species at the landscape level and can be easily adapted to and adopted at the national, regional, state or local level in India. The methods offer an efficient, reliable approach for the application of the HCV concept, elsewhere in the world.