Long-term Vegetation Monitoring Research Articles

Evolution and Effectiveness of Salt Marsh Restoration: A Bibliometric Analysis

Salt marshes play a critical role in supporting water quality, erosion control, flood protection, and carbon sequestration. Threats from climate change and human activities have prompted global restoration initiatives. We analyzed restoration efforts worldwide from 1978 to 2022, using the Web of Science database and SciMAT mapping tool. After a PRISMA screening to identify methodologies, success rates, and key indicators, a total of 62 publications underwent detailed analysis, to increase knowledge on the best practices to employ in future restoration interventions and evaluation of their effectiveness. The research reveals a growing interest in ecosystem dynamics, biodiversity, anthropogenic impacts, and ecosystem services. Assisted interventions emerged as the predominant restoration method, employing 15 indicators across vegetation, sediment, fauna, and water, each one using different metrics for the intervention evaluation based on how good the outcome of the interventions described in the reviewed studies met the desired result. Our analysis suggests that combining natural interventions such as managed realignment with reconnection to tidal waters, along with long-term monitoring of vegetation, fauna, and water indicators such as sedimentation and erosion rates, plant cover and biomass, as well as fauna diversity and density, leads to the most successful outcomes. We provide valuable insights into best practices for future restoration interventions, offering guidance to future practitioners and policymakers based on a comprehensive review of the scientific literature, contributing to the resilience of these vital ecosystems, and ensuring effective restoration actions in the coming years.

A spatio-temporal fusion method based on Landsat and MODIS normalized vegetation index data

Abstract. Normalized difference vegetation index (NDVI) can simply and effectively reflect the growth status of plants, and has a linear relationship with vegetation coverage, thus it is an important indicator to identify vegetation growth status and coverage. However, the commonly used MODIS NDVI or Landsat NDVI cannot simultaneously achieve the high temporal and spatial resolution. To this end, we proposed a generic and automatic method to fuse MODIS and Landsat satellite vegetation index (NDVI) into daily high-resolution products which takes time series NDVI data from MODIS/Landsat as input, filters noise pixels, and generates high-resolution and high-frequency products through a fusion process of temporal-linearly interpolation to increase the temporal resolution and spatial filtering to alleviate the blocky artifacts from MODIS pixel border. The fused NDVI maps are visually compared to evaluate the performance of this method, and more quantitative assessment will be continued in the next step. This study can provide important support for large-scale long-term surface vegetation monitoring.

Super resolution of historic Landsat imagery using a dual generative adversarial network (GAN) model with CubeSat constellation imagery for spatially enhanced long-term vegetation monitoring

Detailed spatial representations of terrestrial vegetation are essential for precision agricultural applications and the monitoring of land cover changes in heterogeneous landscapes. The advent of satellite-based remote sensing has facilitated daily observations of the Earth’s surface with high spatial resolution. In particular, a data fusion product such as Planet Fusion has realized the delivery of daily, gap-free surface reflectance data with 3-m pixel resolution through full utilization of relatively recent (i.e., 2018-) CubeSat constellation data. However, the spatial resolution of past satellite sensors (i.e., 30–60 m for Landsat) has restricted the detailed spatial analysis of past changes in vegetation. In order to overcome the spatial resolution constraint of Landsat data for long-term vegetation monitoring, we propose a dual remote-sensing super-resolution generative adversarial network (dual RSS-GAN) approach combining Planet Fusion and Landsat 8 data to simulate spatially enhanced long-term time-series of the normalized difference vegetation index (NDVI) and near-infrared reflectance from vegetation (NIRv). We evaluated the performance of the dual RSS-GAN against in situ tower-based continuous measurements (up to 8 years) and remotely piloted aerial system-based maps of cropland and deciduous forest in the Republic of Korea. The dual RSS-GAN enhanced spatial representations in Landsat 8 images and captured seasonal variation in vegetation indices (R2 > 0.90, for the dual RSS-GAN maps vs in situ data from all sites). Overall, the dual RSS-GAN reduced Landsat 8 vegetation index underestimations compared with in situ measurements; relative bias values of NDVI ranged from − 5.8 % to 0.3 % and − 12.4 % to − 3.7 % for the dual RSS-GAN and Landsat 8, respectively. This improvement was caused by spatial enhancement through the dual RSS-GAN, which reflects fine-scale information from Planet Fusion. Finally, the dual RSS-GAN maps showed both spatial enhancement and reducing the underestimation of vegetation index in historic Landsat dataset from 1984. This study presents a new approach for resolving sub-pixel spatial information in Landsat images.

Free-ranging livestock cause forest understory degradation in giant panda (Ailuropoda melanoleuca) habitat

Free-ranging livestock are common in reserves established for giant pandas (Ailuropoda melanoleuca), which rely almost exclusively on bamboo in the montane forests of southwestern China. Previous studies have showed that overgrazing by livestock had led to a reduction in bamboo abundance. However, there is limited knowledge of how livestock impact the structure of the understory vegetation. Conducted in the Wanglang National Nature Reserve with a livestock exclosure experiment, our study aimed to fill this gap by examining the impact of livestock grazing on two important elements of forest understory bamboo and moss in giant panda habitat, and quantifying their recovery after excluding livestock. Measurements of bamboo and moss showed that both elements were severely degraded. With a closer examination, we found moss growth was worse in areas with dense bamboo or no bamboo at all, but better when there were many dead stems in bamboo clump, suggesting bamboo exerted both negative competition and positive shelter effects from livestock trampling on moss. Livestock exclusion with fence indeed exempted bamboo and moss from continuous damage which were exemplified by more bamboo shoots inside the fence and significantly decreased moss height outside the fence. However, we observed no recovery of damaged bamboo and moss inside fenced quadrats in two years. Neither the sprouted bamboo shoots matured into stems after the growing season, nor the height of moss increased. Collectively, our results suggested that long-term livestock grazing drastically altered understory layer of bamboo and moss and interactions in between, and there was hardly recovery of the understory bamboo and moss in a short term. Therefore, we recommend artificial intervention with bamboo and moss planting in severely degraded areas and long-term monitoring of understory vegetation to restore the habitat of giant panda.

Vegetation Growth Status and Topographic Effects in Frozen Soil Regions on the Qinghai–Tibet Plateau

The Qinghai–Tibet Plateau (QTP), which is known as Earth’s “Third Pole”, is a driver of global climate change, and long-term monitoring of QTP vegetation can reveal changes attributable to climatic and human influences. Previous research monitoring vegetation on the QTP focused primarily on spatiotemporal variations of vegetation indices, while few studies have considered fractional vegetation cover (FVC) in relation to topographic and frozen soil factors. We used MODIS-EVI, digital elevation models, and frozen soil data to investigate topographic effects on vegetation growth status in different soil types on the QTP during 2000–2020. (1) FVC showed a trend of increase during 2000–2020, and the FVC on the QTP decreased from the southeast to the northwest in spatial distribution. FVC in permafrost regions was the lowest, followed by seasonal frozen soil areas; FVC in unfrozen areas was the highest. (2) With increasing elevation, FVC of permafrost, seasonal frozen, and unfrozen soil areas showed downward trends for each aspect. In seasonal frozen soil areas, at elevation ≤4000 m (>4000 m), FVC of sunny (shady) slopes was greater than that of shady (sunny) slopes. In permafrost regions, except at elevations of 3000–4000 m, FVC of shady slopes was greater than that of sunny slopes. In unfrozen soil areas, at elevation >4000 m, FVC of sunny slopes was obviously greater than that of shady slopes. (3) With increasing slope, FVC in seasonal frozen and permafrost soil (unfrozen soil) regions showed a trend of increase (decrease). In seasonal frozen soil areas, FVC of sunny (shady) slopes was greater than that of shady (sunny) slopes on slopes ≤6° (>6°). In permafrost regions, FVC of sunny slopes was less than that of shady slopes. With increasing slope, the influence of aspect became more obvious. In unfrozen soil areas, FVC of sunny slopes was slightly greater than that of shady slopes. Topographic effects especially the elevation and slope effects might significantly affect the spatiotemporal variations of vegetation growth status in frozen soil regions on the QTP.

Municipal solid waste landfill: Evidence of the effect of applied landfill management on vegetation composition.

Proper management of municipal solid waste (MSW) is crucial to avoid pollution, environmental impacts and threat to public health. The problem of MSW is mainly arising from inadequate landfill site management. The objective of this study was to evaluate the impact of management practices and environmental risks at two landfill sites. The landfills were subject to long-term (10 years) vegetation monitoring. The vegetation was assessed using a floristic survey of identified plant species. The vegetation analysis showed that significant differences existed between the two landfill locations, with neophytes, invasive and expansive species dominating on one of the landfill sites, which may be attributed to climatic and geomorphological differences between the two sites, but also to variations in landfill management. These environmentally problematic species can potentially spread from the landfill into adjacent ecosystems, displace native plants and degrade adjacent farmland areas. The study of vegetation monitoring data suggests that, in addition to other types of monitoring, landfills should be subjected to regular vegetation biomonitoring, too. Landfill management practices should target the regulation of unwanted species, create conditions that are favourable to native plant species and provide as early as possible the restoration of filled cells.

Vegetation structure and composition associated with Aloe lettyae in dwindling grassland fragments: Fine-scale baseline data to underpin conservation efforts

Fine-scale data on species of special concern in fragments of highly threatened vegetation types are important for conservation management. This study investigated the vegetation structure and composition associated with the range-restricted long-lived Aloe lettyae and documented mesic Woodbush Granite Grassland (WGG) fragments. Google Earth imagery was used to detect WGG remnants in the highly fragmented landscape within the original WGG polygon as outlined on the National Vegetation Map. Field-verified WGG fragments were described (size, ownership, location, condition, observed threats and surrounding land cover types) and searched for A. lettyae. In six of the currently known 13 WGG fragments boasting an A. lettyae population, including two intact large (60–192 ha), two intact small (9–14 ha) and two degraded small (9–10 ha) WGG fragments, we studied the vegetation structure and composition associated with A. lettyae. For all sampled WGG fragments combined, vegetation structure (percentage aerial cover of grass, forb and woody species, bare soil and rock, maximum height (cm) of grass, forb and woody species and standing vegetation biomass (kg/ha)) within 1 m of each A. lettyae individual (n = 378) and ≥ 5 m away from A. lettyae plants (n = 442) varied very little. However, vegetation structure variables differed significantly between WGG fragments. For the intact large WGG fragments, percentage aerial cover for grass, forb and woody species were 49–50, 26–37 and 5–15%, respectively, with the small remaining percentages being made up of bare soil and rock cover. In the intact small WGG fragments, percentage aerial cover for grass, forb and woody species was similar to that in the large fragments. In the degraded small WGG fragments, however, percentage aerial cover for grass was significantly higher (66–74%) while the percentage forb cover tended to be lower (8–13%) than in the intact fragments. WGG fragment size ranged from <1 to 192 ha, with the estimate of all currently known extant WGG fragments amounting to a total of ∼6 km2, or ∼1% of the estimated historical WGG extent. Therefore, it is imperative to conserve all remaining WGG fragments. We provide fine-scale baseline data on the vegetation structure and composition associated with A. lettyae and a description of extant WGG fragments for long-term vegetation monitoring, management and biodiversity conservation decisions and future research.

The succession of submerged vegetation in the northern part of Lake Fuxian and its ecological indication significance(1987-2020)

抚仙湖有近210亿m³的优质淡水资源，具有重要战略价值，但是近年来出现水质退化的现象.沉水植被是湖泊生态系统功能维持的重要生物门类，其演变过程能反映和影响整个生态系统的变化，目前还缺乏对抚仙湖沉水植被长期连续地观测记录.本文基于Landsat遥感数据分析了抚仙湖北部沉水植被面积的动态变化，结合气候变化和水质水文要素分析发现：抚仙湖北部湖区沉水植物在1987—2020年间存在先减少后增加的变化趋势；1987—1995年，沉水植物分布面积约占北部湖区面积的1.64%；1996—2010年北部湖区沉水植被分布面积缩减，湖泊处于高水位低营养状态，水位上升是此时期沉水植物面积减少的主要原因；2011—2020年，水位降低，营养增加，营养和水位的共同作用导致抚仙湖北部湖区沉水植物面积显著增加.沉水植物覆盖度变化伴随着沉水植被以苦草为优势种群转为以穗花狐尾藻为优势种群，沉水植被结构转向耐污染性更强的属种.通过抚仙湖北部湖区沉水植被发育与营养、水位等驱动因子的关系分析，建议现阶段需要严格限制入湖氮磷排放，强化水生植被的长期动态监测，构建水量、水质、水生态一体化监测体系，并开展抚仙湖生态系统演变的模拟和预测，防止抚仙湖生态系统出现突变，以维持抚仙湖生态系统功能多样性.;Lake Fuxian has nearly 21 billion cubic meters of high-quality freshwater resources which has important strategic value, but the water quality has been degraded in recent years. Submerged vegetation is an important biological category for the function maintenance of the lake ecosystem, and its succession can reflect and influence the changes of the whole ecosystem. At present, there is a lack of long-term continuous observation records of submerged vegetation in Lake Fuxian. Based on Landsat remote sensing data, this paper analyzes the dynamic changes of submerged vegetation in the northern part of Lake Fuxian. Integrating climate change and water quality hydrological elements, submerged vegetation in the northern part of Lake Fuxian showed a decrease followed by an increase from 1987 to 2020. From 1987 to 1995, the distribution area of submerged vegetation accounted for about 1.64% of the northern lake area. From 1996 to 2010, the submerged vegetation in the northern lake area reduced, and the lake was in a state of high water level and low nutrients. The rise of the water level was the main reason for the reduction of submerged vegetation area during this period. From 2011 to 2020, the water level decreased and nutrients increased, and the combined effect of nutrients and water level led to a significant increase in the area of submerged vegetation in the northern lake area of Lake Fuxian. The change in submerged vegetation coverage was accompanied by a shift in submerged vegetation from Vallisneria natans as the dominant population to Myriophyllum spicatum as the dominant population, and the structure of submerged vegetation turns into more pollution-tolerant species. In this study, the analysis of the relationship between the development of submerged vegetation and the driving factors such as nutrients and water level in the north of Lake Fuxian suggests that at this stage, it is necessary to strictly restrict the discharge of nitrogen and phosphorus into the lake, strengthen the long-term dynamic monitoring of aquatic vegetation, build an integrated monitoring system for water quantity, quality and ecology, and carry out simulation and prediction of the Lake Fuxian ecosystem change to prevent Lake Fuxian ecosystem from regime shifts and maintain its functional diversity Lake Fuxian.

Spatial-Temporal Variation Characteristics and Influencing Factors of Vegetation in the Yellow River Basin from 2000 to 2019

Vegetation is a crucial and intuitive index that can be used to evaluate the ecological status. Since the 20th century, land use has changed significantly in Yellow River Basin (YRB), along with great changes of vegetation, serious soil erosion, and gradual ecological deterioration. To improve the ecological environment in the YRB, China has carried out a series of ecological protection projects since the 1970s. Therefore, long-term sequence monitoring of vegetation in YRB is necessary to show the conservation effect and better support the further protection and restoration. This study analysed vegetation changes from 2000 to 2019 based on an annual mean fractional vegetation cover (FVC) dataset. The Theil–Sen median trend analysis method was used to analyse trends in FVC. The results showed that the vegetation in the YRB has improved significantly, with an average annual growth rate of 0.65%, and the ‘green line’ of vegetation has moved approximately 300 km westward. The influence of climate on vegetation is essential; therefore, this study also analysed the influence of temperature and precipitation on vegetation over time and space. Ecological control and afforestation are important anthropogenic factors that affect vegetation. The growth trend (0.6%/a) in key ecological function regions (KEFRs) was the fastest, and even though the protection measures are not strict, they provide space for afforestation. The China Ecological Conservation Red Line (CECRL) and the national nature reserves (NNRs) showed relatively flat trends. Ecological afforestation projects were closely correlated with the growth trend of the FVC. The correlation between FVC and the intensity of ecological engineering was significant in typical areas.

Climate change and its effect on groundwater quality.

Knowing water quality at larger scales and related ground and surface water interactions impacted by land use and climate is essential to our future protection and restoration investments. Population growth has driven humankind into the Anthropocene where continuous water quality degradation is a global phenomenon as shown by extensive recalcitrant chemical contamination, increased eutrophication, hazardous algal blooms, and faecal contamination connected with microbial hazards antibiotic resistance. In this framework, climate change and related extreme events indeed exacerbate the negative trend in water quality. Notwithstanding the increasing concern in climate change and water security, research linking climate change and groundwater quality remain early. Additional research is required to improve our knowledge of climate and groundwater interactions and integrated groundwater management. Long-term monitoring of groundwater, surface water, vegetation, and land-use patterns must be supported and fortified to quantify baseline properties. Concerning the ways climate change affects water quality, limited literature data are available. This study investigates the link between climate change and groundwater quality aquifers by examining case studies of regional carbonate aquifers located in Central Italy. This study also highlights the need for strategic groundwater management policy and planning to decrease groundwater quality due to aquifer resource shortages and climate change factors. In this scenario, the role of the Society of Environmental Geochemistry is to work together within and across geochemical environments linked with the health of plants, animals, and humans to respond to multiple challenges and opportunities made by global warming.

Long-term vegetation monitoring in the floodplain grasslands of the lower Havel Valley (northeastern Germany) and conclusions for sustainable management practices

As a result of water regulation measures and the subsequent introduction of intensive use practices, riverine floodplains have suffered severe habitat and species losses. With the changed economic conditions and decrease in animal stocking rates after 1990, opportunities arose for the partial restoration of species-rich vegetation areas in East Germany. Sixty permanent plots were established in the lower Havel Valley in the federal state of Brandenburg from 1993 to 1999. We studied the effects of extensification and partial rewetting in this area during a monitoring programme that lasted until 2018. For this purpose, groundwater levels, historical land use, and soil chemical parameters were investigated, and the soil seed bank and phytosociological relevés were sampled. Previous research has shown that an extended period of intensive grassland use eliminates the possibility of success in short- to medium-term natural restoration because of the lack of suitable propagules. Our question was as follows: how does a floodplain grassland respond to extensification and decreased water regulation in an area that experienced a shorter period of intensification in the past, such as the lower Havel floodplain? Tests of soil samples showed a depleted soil seed bank at the beginning of the monitoring period, but the seed bank was less depleted than those in other areas. Using cluster analysis followed by discriminant analysis, we identified water regime parameters and historical land-use intensity as the main drivers of vegetation differentiation. The classification resulted in the differentiation of vegetation into 13 plant communities. Plant communities were combined into 5 main groups based on their location in the ordination diagram of a detrended correspondence analysis. The shift in group centroids over time correlated with increases in the species diversity and moisture level for all groups. The altered species composition as a result of the changed water regime after 1990 influenced the usability of the grassland differently depending on the relief level. At the end of monitoring, vegetation at sites in the mesic moisture range was determined to have the highest fodder quality observed in this study. With increasing mean groundwater levels, the forage quality of the vegetation decreased until it was so low that the vegetation was hardly suitable for use as animal forage. The plant species diversity was negatively correlated with the plant-available P and Ellenberg N indicator value. Plant-available P, K and Mg showed evidence of leaching during the later study period. The abundance of red-listed species and extensive-use indicator species increased over the course of the study period. This positive trend was reversed by the extreme flood event in the summer of 2013. However, the high species richness and the species compositions of the reference communities were not equal in the other communities, even after almost 30 years of extensification. This finding underlines the importance of the few remaining meadows that are rich in typical floodplain species as donor areas of autochthonous seeds. The results of this study are discussed in light of sustainable management practices and global climate change.

Phytosociology of the vegetation communities of the Stelvio Pass area

ABSTRACT High elevation areas are sensitive and vulnerable to climate change and exhibited relatively rapid changes in response to warming involving changes of floristic composition, species upward migration, shrub and tree encroachment and surface area changes. For this reason, it is important to provide quantitative studies as tools allowing a long-term monitoring of vegetation in response to climate change. The Stelvio Pass area is a high elevation site located in the European Alps, and a unique case study on the alpine range providing historical detailed information on vegetation with the availability of phytosociological maps of vegetation elaborated in 1953 and 2003. Here we show and describe an updated and detailed phytosociological vegetation mapping which will constitute a robust base for the monitoring and quantitative assessment of any impacts of future climate and/or environmental change as well as a tool to plan suitable vegetation and biodiversity conservation actions in the alpine environment.

Exploring Short-Term Climate Change Effects on Rangelands and Broad-Leaved Forests by Free Satellite Data in Aosta Valley (Northwest Italy)

Satellite remote sensing is a power tool for the long-term monitoring of vegetation. This work, with reference to a regional case study, investigates remote sensing potentialities for describing the annual phenology of rangelands and broad-leaved forests at the landscape level with the aim of detecting eventual effects of climate change in the Alpine region of the Aosta Valley (Northwest (NW) Italy). A first analysis was aimed at estimating phenological metrics (PMs) from satellite images time series and testing the presence of trends along time. A further investigation concerned evapotranspiration from vegetation (ET) and its variation along the years. Additionally, in both the cases the following meteorological patterns were considered: air temperature anomalies, precipitation trends and the timing of yearly seasonal snow melt. The analysis was based on the time series (TS) of different MODIS collections datasets together with Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) collection obtained through Google Earth Engine. Ground weather stations data from the Centro Funzionale VdA ranging from 2000 to 2019 were used. In particular, the MOD13Q1 v.6, MOD16A2 and MOD10A1 v.6 collections were used to derive PMs, ET and snow cover maps. The SRTM (shuttle radar topography mission) DTM (digital terrain model) was also used to describe local topography while the Coordination of Information on the Environment (CORINE) land cover map was adopted to investigate land use classes. Averagely in the area, rangelands and broad-leaved forests showed that the length of season is getting longer, with a general advance of the SOS (start of the season) and a delay in the EOS (end of the season). With reference to ET, significant increasing trends were generally observed. The water requirement from vegetation appeared to have averagely risen about 0.05 Kg·m−2 (about 0.5%) per year in the period 2000–2019, for a total increase of about 1 Kg·m−2 in 20 years (corresponding to a percentage difference in water requirement from vegetation of about 8%). This aspect can be particularly relevant in the bottom of the central valley, where the precipitations have shown a statistically significant decreasing trend in the period 2000–2019 (conversely, no significant variation was found in the whole territory). Additionally, the snowpack timing persistence showed a general reduction trend. PMs and ET and air temperature anomalies, as well as snow cover melting, proved to have significantly changed their values in the last 20 years, with a continuous progressive trend. The results encourage the adoption of remote sensing to monitor climate change effects on alpine vegetation, with particular focus on the relationship between phenology and other abiotic factors permitting an effective technological transfer.

Interobserver error in grassland vegetation surveys: sources and implications

Abstract Aims Observer error is an unavoidable aspect of vegetation surveys involving human observers. We quantified four components of interobserver error associated with long-term monitoring of prairie vegetation: overlooking error, misidentification error, cautious error and estimation error. We also evaluated the association of plot size with pseudoturnover due to observer error, and how documented pseudochanges in species composition and abundance compared with recorded changes in the vegetation over a 4-year interval. Methods This study was conducted at Tallgrass Prairie National Preserve, Kansas. Monitoring sites contained 10 plots; each plot consisted of a series of four nested frames (0.01, 0.1, 1 and 10 m2). The herbaceous species present were recorded in each of the nested frames, and foliar cover was visually estimated within seven cover categories at the 10 m2 spatial scale only. Three hundred total plots (30 sites) were surveyed, and 28 plots selected at random were resurveyed to assess observer error. Four surveyors worked in teams of two. Important Findings At the 10 m2 spatial scale, pseudoturnover resulting from overlooking error averaged 18.6%, compared with 1.4% resulting from misidentification error and 0.6% resulting from cautious error. Pseudoturnover resulting from overlooking error increased as plot size decreased, although relocation error likely played a role. Recorded change in species composition over a 4-year interval (excluding potential misidentification error and cautious error) was 30.7%, which encompassed both pseudoturnover due to overlooking error and actual change. Given a documented overlooking error rate of 18.6%, this suggests the actual change for the 4-year period was only 12.1%. For estimation error, 26.2% of the time a different cover class was recorded. Over the 4-year interval, 46.9% of all records revealed different cover classes, suggesting that 56% of the records of change in cover between the two time periods were due to observer error.

Does artificial snow fertilise the soil of mountain meadows in the Krkonoše National Park?

There are no high mountains in the Czech Republic and only few of them are higher than 1500 m a.s.l. Nevertheless, skiing is one of the most popular winter sports in this country and has a long history and tradition. During the last two decades, climate change, big differences in snow cover from year to year and unusual warm winter periods causing the snow to melt resulted in visitors to Czech ski resorts going to the Alps. Managers of ski resorts facing this challenge recognised that artificial snow enables skiing throughout the entire season and overcomes the risk posed by climate to the skiing business. However, many ski resorts are located in protected areas and it is difficult to negotiate changes in the rules for preparing and applying artificial snow with conservationists, who are fearful of the negative effects of snowmaking on rare and protected species and habitats. This paper presents results of a case study conducted in the SkiResort CERNA HORA – PEC in the Krkonose National Park throughout the 2019 season. The seasonal changes in the water quality in two reservoirs and six creeks, from which water is used for making artificial snow, were determined in order to assess the risk of this snow adding fertiliser to the meadows on ski slopes. We found that the nutrients recorded in two reservoirs and six creeks were very low. Water quality parameters did not exceed the limits of permissible pollution of surface and drinking water. Several episodic increases in the parameters measured were recorded and the causes discussed. We did not measure the direct effects of artificial snow on grassland communities. However, the use of water from these reservoirs and creeks for snowmaking does not pose a significant risk in terms of adding fertiliser to the meadows on ski slopes. To eliminate these risks and unusual events, several management measures for improving the water regime in the area studied are proposed. To better understand the effect of artificial snow on mountain meadows, permanent plots and long-term monitoring of vegetation, soil invertebrates and soil chemistry are recommended.

Lateral and longitudinal distribution of riparian vegetation along an ephemeral river in Namibia using remote sensing techniques

Ephemeral rivers are key features of desert ecosystems, providing shallow groundwater and occasional surface flow, but compared to perennial systems, the structure of riparian forests in ephemeral rivers and their interactions with the hydrologic regime are poorly understood. This study examines the distribution of riparian woody species in the ephemeral Kuiseb River in central Namibia. Unmanned aerial vehicle (UAV) and satellite imagery were used to examine the structure of the riparian forest across lateral and longitudinal gradients. Woody plant abundance peaked in the terminal alluvial zone, the reach of the river where floods typically run dry. The five dominant species exhibited similar spatial patterns at latitudinal and longitudinal scales. Faidherbia albida and Salvadora persica were found more proximal to the active channel and concentrated in the terminal alluvial zone. Acacia (Vachellia) erioloba, Euclea pseudebenus, and Tamarix usneoides were more evenly dispersed laterally across the riparian zone and along the river's longitudinal profile. These spatial patterns correspond to plant physiological properties of hydrological dependence and gradients of water availability and soil composition. The tight coupling of plant distributions with water availability highlights the need for long-term monitoring of ephemeral riparian vegetation in light of potential future changes to the global hydrologic regime.

Applying LiDAR to Quantify the Plant Area Index Along a Successional Gradient in a Tropical Forest of Thailand

Long-term monitoring of vegetation is critical for understanding the dynamics of forest ecosystems, especially in Southeast Asia’s tropical forests, which play a significant role in the global carbon cycle and have continually been converted into various stages of secondary forests. In Thailand, long-term monitoring of forest dynamics during the successional process is limited to plot scales assuming from the distinct structure of successional stages. Our study highlights the potential of coupling airborne light detection and ranging (LiDAR) technology and stand age data derived from Landsat time-series to track back forest succession, and infer patterns in the plant area index (PAI) recovery. Here, using LIDAR data, we estimated the PAI of the 510 sample plots of a seasonal evergreen forest dispersed over the study area in Khao Yai National Park, Thailand, capturing a successional gradient of tropical secondary forests. The sample plots age was derived from the available Landsat time-series dataset (1972–2017). We developed a PAI recovery model during the first 42 years of the succession process. We investigated the relationship between the model residuals and PAI values with topographic factors, such as elevation, slope, and topographic wetness index. The results show that the PAI increased non-linearly (pseudo-R2 of 0.56) during the first 42 years of forest succession, and all three topographic factors have less influence on PAI variability. These results provide valuable information of the spatio-temporal PAI patterns during the successional process and help understand the dynamics of tropical secondary forests in Khao Yai National Park, Thailand. Such information is essential for forest management and local, regional, and global PAI synthesis. Moreover, our results provide significant information for ground-based spatial sampling strategies to enable more accurate PAI measurements.

Influence of a Municipal Solid Waste Landfill on the Surrounding Environment: Landfill Vegetation as a Potential Risk of Allergenic Pollen.

When the landfill use comes to end, important subsequent steps include aftercare, safety assurance, and ecological regeneration. Landfill revegetation is cost-effective and eco-friendly approach in the management of landfill areas, which serves the purpose of stabilization and provides a pleasant landscape. There are various vegetation types that can be planted, yet grass species are often used for low-cost reasons. Plants can be important sources of air pollution, particularly by grass pollen. The main goal of our study was to identify plant species that produce allergenic pollen. Long-term vegetation monitoring took place on three sites in the growing seasons of years 2008–2018. Studied objects were landfills located in the Czech Republic. The vegetation was assessed using a floristic survey of identified plant species. Plant species that produced allergens were recorded. During the monitoring, 298 plant species were determined. Plant species with allergenic pollen have a considerable share in the landfill vegetation. Thus, landfills are potential sources of various kinds of allergenic pollen. Moreover, our results indicated that there are three periods of pollen production: early spring, late spring, and early summer; late summer; and autumn. The second period is typical for the production of highly allergenic pollen by grasses. Most detected plant species with allergenic pollen are common for all monitored sites, which demonstrates that the vegetation of landfills is a significant source of allergenic pollen.

Could plant diversity metrics explain climate-driven vegetation changes on mountain summits of the GLORIA network?

High-elevation habitats host a large number of plant species and are characterized by high biodiversity. The vegetation dynamics in these cold adapted ecosystems are difficult to predict, being affected by global warming, especially in the last decades. With the aim to promote a better understanding of climate-driven changes of alpine vegetation, we investigated the variation in species richness, α-diversity, β-diversity, and total cover of plant functional types over a time lapse of 15 years, relying on multiple re-surveys of mountain summit vegetation in 2001, 2008 and 2015. The study area, included in the long term global observation network GLORIA, was at the boundary between temperate and Mediterranean mountains of S-Europe (northern Apennines, Italy). We identified a trend of loss in biodiversity and signals of biotic homogenization using multiple diversity metrics, despite the overall species richness increment observed in the study area. Cold-adapted and rare species declined while dominant species like graminoids and shrubs increased. Our results highlight that long-term vegetation monitoring activities paired with multiple measures of diversity are required to properly assess biodiversity and to obtain useful indications for future conservation activities in alpine environments. The methods here presented could be applied in all GLORIA sites to quantify biodiversity changes over time, obtaining comparable results for biodiversity monitoring in high-elevation habitats from all over the world.

Woody Regeneration Response to Overstory Mortality Caused by the Hemlock Woolly Adelgid (Adelges tsugae) in the Southern Appalachian Mountains

Adelges tsugae Annand (hemlock woolly adelgid, HWA, an invasive insect native to Japan), which causes defoliation and death of Tsuga canadensis (L.) Carrière (eastern hemlock), was introduced to the United States in the early 1950s and has spread throughout much of the range of T. canadensis causing widespread mortality. In 2016 and 2017, we resampled long-term vegetation monitoring plots across five forest types (ecogroups) within Great Smoky Mountains National Park that contained T. canadensis in 2003 (prior to the spread of HWA within the park) to examine changes in the species composition and diversity of the regeneration layer. We hypothesized that compositional changes in the seedling and sapling strata would be driven primarily by the pre-HWA importance value of T. canadensis and relative dominance of Rhododendron maximum L. (rosebay rhododendron), and that species diversity metrics would differ across year depending on ecogroup and the relative dominance of R. maximum. Non-metric multi-dimensional scaling (NMDS) revealed that the seedling and sapling strata of plots with greater pre-HWA importance of T. canadensis and lower basal area of R. maximum generally exhibited greater compositional change between 2003 and 2017. Topo-edaphic variables were also significant in both NMDS ordinations and were associated with the distribution of multiple hardwood species. Species richness, evenness, and Shannon-Wiener diversity varied with strata following the loss of T. canadensis, with the degree and direction of change varying with the dominance of R. maximum.