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.

Altitudinal Pattern of Plant Species Diversity in Shennongjia Mountains, Central China

One hundred and sixty plots, approximately every 100 m above sea level （a.s.1.） along an altitudinal gradient from 470 to 3 080 m a.s.1, at the southern and northern watershed of Mt. Shennongjia, China, were examined to determine the altitudinal pattern of plant species diversity. Mt. Shennongjia was found to have high plant species diversity, with 3 479 higher plants recorded. Partial correlation analysis and detrended canonical correspondence analysis （DCCA） based on plant species diversity revealed that altitude was the main factor affecting the spatial pattern of plant species diversity on Mt. Shennongjia and that canopy coverage of the arbor layer also had a considerable effect on plant species diversity. The DCCA based on species data of importance value further revealed that altitude gradient was the primary factor shaping the spatial pattern of plant species. In addition, the rule of the “mid-altitude bulge” was supported on Mt. Shennongjia. Plant species diversity was closely related to vegetation type and the transition zone usually had a higher diversity. Higher plant species diversity appeared in the mixed evergreen and deciduous broadleaved forest zone （900-1500 m a.s.1.） and its transition down to evergreen broadleaved forest zone or up to deciduous broadleaved forest zone. The largest plant species diversity in whole communities on Mt. Shennongjia lay at approximately 1 200 m a.s.1. Greatest tree diversity, shrub diversity, and grass diversity was found at approximately 1 500, 1 100, and 1 200 m a.s.l., respectively. The southern watershed showed higher plant species diversity than the northern watershed, with maximum plant species diversity at a higher altitude in the southern watershed than the northern watershed. These results indicate that Mt. Shennongjia shows characteristics of a transition region. The relationship between the altitudinal pattern of plant species diversity and the vegetation type in eastern China are also discussed and a hypothesis about the altitudinal pattern of plant species diversity in eastern China is proposed.

Plant assemblage and diversity variation with human disturbances in coastal habitats of the western Arabian Gulf

Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats.This study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity,composition,identity and assemblage of vascular plant species.Plant survey data from 113 plots （5m×5m each） were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities （high,moderate and low） and were statistically analyzed.The results revealed that about 76% of the recorded species are considered threatened species in Kuwait,most of which are being lost in high disturbed habitats.Disturbance led to the dominance of Zygophyllum qatarense,Cornulaca aucheri and Salsola imbricata,which are species of disturbance indicators.Richness,total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed habitats.Beta diversity between high and low disturbed habitats was higher than either between high and moderate,or between moderate and low disturbed habitats.Cluster analyses showed statistically significant differences in composition of plant assemblages,which indicate high beta diversity between the habitat types.Intensive urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in Kuwait.Establishing protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.

Glade and Forest-Edge Plant Community Attributes for Three Glade Types in Arusha National Park, Tanzania

The aim of the study was to compare glade and forest-glade edge plant community attributes for man-made, upper and lower natural glades. Two plots were set up in twelve glades at 2.5, 12.5 m and three plots in thirteen glades at 2.5, 12.5 and 22.5 m depending on the size of the glade. The results showed that plants total abundance, percentage basal cover, species richness and species diversity for upper and lower natural glades differed significantly p < 0.05 and p < 0.01 respectively and species diversity for man-made glades p < 0.001. Plant species abundance, richness and diversity were highest at the forest-glade edge and decreased towards the glade interior. Plant species composition of the three glades types differed significantly (MRPP: T = -4.51, p < 0.001 and A = 0.17). Grasses’ total abundance and species richness and forbs species diversity differed significantly for man-made glades p < 0.01. For upper natural glades, grasses species richness was highly significant p < 0.001 while for forbs species richness and diversity were significant P < 0.01. Lower natural glades grasses and forbs’ total abundance, species richness and species diversity differed significantly p < 0.01 and p < 0.001 respectively. Growth forms in the lower natural glades were associated with the forest-glade edge or glade interior χ2 = 15.95, df = 4, p Eleusine jaegeri, Heterogon contortus, Senna mimisoides, Digitaria scalarum, Clutia abyssinica) were habitat indicators for disturbed areas, wet humid grey/black clay soils for upper natural glades and three (Solanum incanum, Senna didymobotrya, and Pennistem mezianum, were indicators of overgrazed areas and black clay soils for man-made glades. In conclusion, plant species abundance, richness and diversity were highest at the forest-glade edge and decreased towards the glade interior, while plant species composition differed significantly between the three-glade types. The plant growth form for lower natural glades was associated with forest-glade edge and glade interior.

Canopy structure:An intermediate factor regulating grassland diversity-function relationships under human disturbances

Grasslands are one of the largest coupled human-nature terrestrial ecosystems on Earth,and severe anthropogenic-induced grassland ecosystem function declines have been reported recently.Understanding factors influencing grassland ecosystem functions is critical for making sustainable management policies.Canopy structure is an important factor influencing plant growth through mediating within-canopy microclimate(e.g.,light,water,and wind),and it is found coordinating tightly with plant species diversity to influence forest ecosystem functions.However,the role of canopy structure in regulating grassland ecosystem functions along with plant species diversity has been rarely investigated.Here,we investigated this problem by collecting field data from 170 field plots distributed along an over 2000 km transect across the northern agro-pastoral ecotone of China.Aboveground net primary productivity(ANPP)and resilience,two indicators of grassland ecosystem functions,were measured from field data and satellite remote sensing data.Terrestrial laser scanning data were collected to measure canopy structure(represented by mean height and canopy cover).Our results showed that plant species diversity was positively correlated to canopy structural traits,and negatively correlated to human activity intensity.Canopy structure was a significant indicator for ANPP and resilience,but their correlations were inconsistent under different human activity intensity levels.Compared to plant species diversity,canopy structural traits were better indicators for grassland ecosystem functions,especially for ANPP.Through structure equation modeling analyses,we found that plant species diversity did not have a direct influence on ANPP under human disturbances.Instead,it had a strong indirect effect on ANPP by altering canopy structural traits.As to resilience,plant species diversity had both a direct positive contribution and an indirect contribution through mediating canopy cover.This study highlights that canopy structure is an important intermediate factor regulating grassland diversity-function relationships under human disturbances,which should be included in future grassland monitoring and management.