Impact of Removal of Copper Leaf (<i>Acalypha fruticosa</i>Forssk.) on Plant Species Diversity and Abundance at Chemeron, Baringo County, Kenya

Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (Acalypha fruticosa) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without Acalypha fruticosa)? Are there variations in plant species diversity between the two study sites? Two sites (one with A. fruticosa and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (H’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without A. fruticosa compared to that where this invasive species was present. Higher H’ (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to H’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with A. fruticosa present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with A. fruticosa, respectively. Further, there were more grasses (Aristida keniensis, Cynodon dactylon, Brachiaria lucrantha, Eragrostis racemosa, and Enteropogon macrostachyus) in the site without A. fruticosa compared to that with the invasive plant. The plants were also more evenly distributed in the site without A. fruticosa compared to that where the invasive plant was present. We conclude that A. fruticosa has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that A. fruticosa be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.

Monitoring River Restoration Efforts: Do Invasive Alien Plants Endanger the Success? A Case Study of the Traisen River

River restoration activities are challenging for the native vegetation and the colonization process. The development of invasive alien plant species (IAS) as well as the development of the pioneer vegetation cover and seed bank were observed in one year prior to construction of a new river bed and within the first two years after construction, along the downstream section of the river Traisen in Austria. One year after completion of the new river channel, the occurrence of IAS above ground decreased while the occurrence of target species increased. Furthermore, no seeds of IAS were detected in the new river bed as a result of proper management of soil movement. Despite the positive impact on the abundance of IAS, the restoration project of the river Traisen shows that the fact that such a restoration activity is a disturbance event must be taken into consideration already during the planning process. Supporting the competitiveness of native plant species is an important tool for reducing the danger of establishment of invasive alien species.

Effects of Water Extract of Erigeron canadensis L. on Seed Germination of Plants

[Objective] The paper was to explore the effect of water extract of Erigeron canadensis L. on seed germination of plants. [Method] Using constant temperature culture method, the effects of water extracts of roots, stems and leaves of E. canadensis on seed germination of 14 species of test plants （crops and weeds） were studied. [Result] Water extracts of roots, stems and leaves of E. canadensis had obvious inhibition effect on seed germination of test plants. The water extract of leaves had the strongest inhibition effect, which could completely inhibit the seed germination of Crepis tectorum L., Amaranthus tricolor L. and Chrysanthemum coronarium L. under the lower concentrations of 0.050 and 0.075 g/ml, and completely inhibit seed germination of all the plants under the concentration of 0.400 g/ml except Zea maize L. and Allium fistulosum L.; followed by water extract of stems, and the water extract of roots had the lowest the inhibition effect, except for completely restraining seed germination of Lycopersicum esculentum L. under the concentration of 0.300 g/ml, it still could not completely restrain seed germination of the other plants under the highest concentration of 0.500 g/ml. The inhibition effect of water extract of E. canadensis on seed germination of plants had obvious selectivity, which had more obvious effect on dicotyledonous plants than monocotyledonous plants. [Conclusion] The study provided reference for screening and utilization of allelochemicals of E. canadensis and research on its allelopathy mechanism.

Development of a mathematical model to evaluate the rate of aggregate risk of invasive alien plant species： Fuzzy risk assessment approach

This study presents a novel approach to evaluate the rate of aggregate risk of Invasive Alien Plant Species. Using risk values and grade of importance of weights of risk factors which may reflect invasiveness of plant species are considered. We use Linguistic Ordered Weighted Averaging operator to evaluate the grade of important of weights. Since the risk values and important weights are identified from two different linguistic term sets, fuzzy set theory techniques were used to combine the two sets. The rates obtained from the model were compared with NRA risk levels and the model was validated with data from known and non-invasive species. The model is improved by weighting the risk values of risk factors. The improved model produced significant results and resulted a better tracking system for identifying potential invaders than the conventional risk assessment.

Co-invasion of daisy fleabane and Canada goldenrod pose synergistic impacts on soil bacterial richness

Understanding the impacts of co-invasion of multiple invaders on soil bacterial communities is significant in understanding the mechanisms driving successful invasion.This study aimed to determine the response of soil bacterial communities to co-invasion of two invaders daisy fleabane(Erigeron annuus)and Canada goldenrod(Solidago canadensis).Daisy fleabane and/or Canada goldenrod invasion significantly enhanced the operational taxonomic unit richness,Shannon index,and Chao1 index of soil bacterial communities.Canada goldenrod under light degree of invasion and co-invasion of daisy fleabane and Canada goldenrod regardless of invasion degree signally improved the ACE index of soil bacterial communities.Thus,the two invaders can enhance soil bacterial diversity and richness to facilitating subsequent invasion due to the fact that higher soil bacterial diversity and richness can enhance the levels of soil function and nutrients acquisition of plant species.ACE index of soil bacterial communities subjected to co-invasion of daisy fleabane and Canada goldenrod regardless of invasion degree was greater than that under the independent invasion of either daisy fleabane or Canada goldenrod.Hence,co-invasion of the two invaders can impose synergistic impacts on soil bacterial richness,which may build a preferable soil micro-environment via the intensified soil bacterial communities,which is contributive to their following invasion.

Changes in plant community and soil ecological indicators in response to Prosopis juliflora and Acacia mearnsii invasion and removal in two biodiversity hotspots in Southern India

Invasion of alien plant species can alter local plant diversity and ecosystem processes closely linked to soil organic carbon(SOC)and nutrient dynamics.Soil ecosystem processes such as microbial respiration and enzyme activity have been poorly explored under alien plant invasion and especially following invasive plant species removal.We studied the impact of Prosopis juliflora and Acacia mearnsii invasion and subsequent removal on local plant community composition and diversity and on soil microbial respiration and enzyme activity in two biodiversity hotspots in Southern India.Removal of Prosopis promoted recolonisation of local vegetation as indicated by a 38% and 28% increase in species richness and ground vegetation cover,respectively,compared to an unremoved site.Prosopis and Acacia removal led to a significant reduction in soil microbial biomass C(MBC),respiration,dehydrogenase and urease activity due to increased microbial respiration and N mineralisation rate.Higher metabolic quotients qCO_(2) in soil at Prosopis and Acacia removed sites indicate that MBC pools declined at a faster rate than SOC,resulting decreased MBC/SOC ratios compared to their respective removed sites.Natural and undisturbed ecosystems maintain more SOC through increased belowground and aboveground C input in the soil,resulting in a higher MBC content per unit SOC.Our results indicate that the interaction between above-and below-ground communities is a critical factor determining the structure and dynamics of local plant communities,especially in ecosystems affected by plant invasions.

SCENIC HUDSON'S LONG DOCK PARK CULTIVATING RESILIENCE:TRANSFORMING A POST-INDUSTRIAL BROWNFIELD INTO A FUNCTIONAL ECOSYSTEM

Scenic Hudson’s Long Dock Park is a resilient living work of art and a vibrant community asset for the Hudson River Valley.A 23-acre peninsula on the east side of the Hudson at Beacon,New York,the site includes the Peter J.Sharp Park and the Klara Sauer Hudson River Trail.Two decades in the making,beginning in 1997,it took a decade to plan and remediate,and,by its completion in early 2017,it will have taken just as long to build and recover.In 1997,nonprofit Scenic Hudson,the largest environmental and land preservation group focused on the Hudson River Valley,started assembling the different ownership parcels of the Long Dock site.From 1999 to 2003,they engaged the Beacon community through a series of community meetings and workshops to articulate its vision for its waterfront and cleanup of the site began.From 2003 to 2007,the design team developed the architectural and site program for the project,restoration measures,and its physical expression with the client.Working with the City and the New York State Department of Environmental Conservation(NYSDEC),the project completed the State Environmental Quality Review Act(SEQR)process,filing a Draft Environmental Impact Statement(DEIS)and received approval of the final EIS ensuring that there was significant environmental,social,or economic value.The NYSDEC and the U.S.Army Corps of Engineers(USACE)were also directly involved in oversight of the brownfield remediation and work within the Hudson River and site wetlands.With the SEQR process complete and approval of a mitigation plan from the USACE,the team worked with the City of Beacon to complete the site plan application process for construction.Our mandate was clear from the start-build resilience,but realize it incrementally.The project’s first phase,opened in 2009,included additional remediation and removal of contaminated soils,removal of invasive species,stabilization of the south shoreline,a test plot for different materials,a wetland boardwalk and interior pathways,installation of native plantings,and site-specific artwork.By 2014,the landscape’s multiple character zones were complete:the established meadow,the connective network of trails and boardwalks,the working site infrastructure of wetlands with swales and seeps,the dynamic intertidal zone,and earthen buttresses.A new pavilion for kayak storage and rentals and an arts and environmental education center in the historic Red Barn were significant additions for the program and community engagement of the park(refer to Figure 1).Over the past summer of 2016,portions of the site originally designed as a LEED platinum eco-hotel and conference center are now being remediated and reconceived as a new civic plaza,amphitheater,overlook west deck,boardwalk at Quiet Harbor,and a shade structure with an area for food trucks.Long Dock Park will continue to adjust and adapt to changing circumstances of ecology,climate change,flooding and sea level rise,and culture.Our original goals of renewing and revealing the historic waterfront,increasing public access to the river,restoring degraded environmental conditions,and demonstrating exemplary,environmentally sensitive development-these are complete.And the park was one of the first pilot projects for the Sustainable-SITES certification program and subsequently received SITES’s highest rating of a SITES project at the time.Even as we considered program,spatial organization,and aesthetics,our work also sought to create in Long Dock a functional and sustainable ecosystem.The park’s design needed to initiate natural processes for the degraded post-industrial brownfield to function and sustain ecosystem services that had not existed before.The design of healthy soils,the integration of hydrology,and the establishment of native plant communities form the true story of the site’s transformation from postindustrial ruin into a significant waterfront park.

Mapping common and glossy buckthorns (Frangula alnus and Rhamnus cathartica) using multi-date satellite imagery WorldView-3, GeoEye-1 and SPOT-7

Buckthorns(Glossy buckthorn,Frangula alnus and common buckthorn,Rhamnus cathartica)represent a threat to biodiversity.Their high competitivity lead to the replacement of native species and the inhibition of forest regeneration.Early detection strategies are therefore necessary to limit invasive alien plant species’impacts,and remote sensing is one of the techniques for early invasion detection.Few studies have used phenological remote sensing approaches to map buckthorn distribution from medium spatial resolution images.Those studies highlighted the difficulty of detecting buckthorns in low densities and in understory using this category of images.The main objective of this study was to develop an approach using multi-date very high spatial resolution satellite imagery to map buckthorns in low densities and in the understory in the Québec city area.Three machine learning classifiers(Support Vector Machines,Random Forest and Extreme Gradient Boosting)were applied to WorldView-3,GeoEye-1 and SPOT-7 satellite imagery.The Random Forest classifier performed well(Kappa=0.72).The SVM and XGBoost’s coefficient Kappa were 0.69 and 0.66,respectively.However,buckthorn distribution in understory was identified as the main limit to this approach,and LiDAR data could be used to improve buckthorn mapping in similar environments.