Ground Cover Area Research Articles

Choosing perennial plants for extensive green roofs in a semi-arid climate

Abstract The main challenge in establishing and maintaining shallow, extensive (non-irrigated) green roofs in semi-arid climate is plant selection. The chosen species should cover the roof and remain green all-year round and at the same time to survive the long, hot and dry summer in this harsh microhabitat. Three perennial species were selected for the present study conducted on a green roof at Haifa University, Israel: Sedum sediforme, Carpobrotus edulis and Portulacaria afra. These succulents were planted in non-irrigated plots, in a 17 cm deep substrate that consisted a mixture of 90% perlite and 10% compost. All three species have survived two consecutive summers and manifested notable spreading ability. Their groundcover area has increased between 3-5 times during the 18 months monitoring period of this study. These results suggest that they are suitable for the design of extensive green roofs in the semi-arid areas of Israel. Two additional species Aptenia cardifolia and Malephora crocea showed varying results, but nevertheless should be regarded as reasonable candidates. In contrast, ten other perennial plant species that were tested in the same conditions did not survive the dry summer. The results suggest, that a main factor of extensive green roofs design in semi-arid areas is species selection, namely identifying, choosing and monitoring of the fittest plant species for this harsh microhabitat.

Influence of cashew apple utilization on soil nutrient replenishment and performance of cashew seedlings

Sustainable soil nutrient management has been a current focus on different crop cultivation including cashew (Anacardium occidentale L.). Scarce availability of manure and high cost of inorganic fertilizers, triggered evaluation of cashew apple on soil fertility and performance of cashew. Cashew seeds were sown into soiled polythene bags incorporated with fresh, decayed, and fermented juicy of cashew apple at 0.25, 0.5, and 1.0 Kg/Kg Soil with 0.005 KgDAP and untreated as controls in screenhouse at TARI-Naliendele from 2019 to 2022. Findings revealed that fermented juicy and decayed apple at 0.25 Kg/Kg soil influenced 60–70% seed germination analogous with diammonium phosphate (DAP) and untreated (80–90%). About 1.0 Kg/Kg soil of decayed and fermented juicy exhibited higher plant height (70 cm), wider canopy spread (36.4 cm), and huge stem girth (2.6 cm) compared to others. Also, decayed apple had high number of branches and medium tap root with numerous lateral roots. High ground cover area (1011.5 cm2), leaf area (LA) (123.5 cm2), and canopy to girth ratio (14.5) were displayed with decayed and fermented juicy at 1.0 Kg/Kg Soil. On biomass yield, decayed and juicy had succulent fresh weight and high dry weight outperforming other treatments. Furthermore, decayed and fermented juicy exhibited high available nitrogen, phosphorus and potassium at 1.0 Kg/Kg Soil after 196 d of application. Fresh apple at all rates showed high soil moisture content and temperature. Therefore, this new research suggests the application of decayed cashew apple at 1.0 Kg/Kg soil as organo-fertilizers for replenishing soil nutrient and improving growth and development of cashew.

Analysis of the Spatial and Temporal Evolution of Land Subsidence in Wuhan, China from 2017 to 2021

Land subsidence is a common geological hazard. Rapid urban expansion has led to different degrees of ground subsidence within Wuhan in the past few years. The novel coronavirus outbreak in 2020 has seriously impacted urban construction and people’s lives in Wuhan. Land subsidence in Wuhan has changed greatly with the resumption of work and production. We used 80 Sentinel-1A Synthetic Aperture Radar (SAR) images covering Wuhan to obtain the land subsidence change information of Wuhan from July 2017 to September 2021 by using the small baseline subset interferometric SAR technique. Results show that the subsidence in Wuhan is uneven and concentrated in a few areas, and the maximum subsidence rate reached 57 mm/yr during the study period. Compared with land deformation before 2017, the land subsidence in Wuhan is more obvious after 2020. The most severe area of subsidence is located near Qingling in Hongshan District, with a maximum accumulated subsidence of 90 mm, and obvious subsidence funnels are observed in Qiaokou, Jiangan, Wuchang and Qingshan Districts. The location of subsidence centers in Wuhan is associated with building intensity, and most of the subsidence funnels are formed in connection with urban subway construction and building construction. Carbonate belt and soft ground cover areas are more likely to lead to karst collapse and land subsidence phenomena. Seasonal changes are observed in the land subsidence in Wuhan. A large amount of rainfall can replenish groundwater resources and reduce the rate of land subsidence. The change in water level in the Yangtze River has a certain impact on the land subsidence along the rivers in Wuhan, but the overall impact is small. An obvious uplift is observed in Caidian District in the south of Wuhan, and the reason may be related to the physical and chemical expansion effects of the expansive clay.

Enhancing the Rural Landscape Character: The Low Frequency of Inter-Row Wildflower Meadow Harvest Positively Affects Biodiversity While Maintaining Grape Quantitative and Qualitative Traits in a ‘Sultanina’ Vineyard in Greece

The development of inter-row wildflower meadows in vineyards could restore and preserve biodiversity as well as enhance the local rural landscape character. Herein, the prospect of inter-row development of a wildflower meadow from spontaneous vegetation growing within a table grape ‘Sultanina’ vineyard was studied for two years through the effect of different intensities of harvest on the meadow composition, arthropod presence, and grape vine produce. Three harvest treatments (constant, periodic, and none) were examined. The growth (height and area of groundcover) and number of plants per species that composed the inter-row wildflower meadow as well as the insects found within it and on the grape vine plants were recorded. At maturity, the main quantitative (yield/vine) and qualitative characteristics (soluble solids, pH, and total titratable acidity) of the grapes were evaluated. Results showed that both the quantitative and qualitative characteristics of the grape vines did not differ between treatments. The inter-row vineyard meadow composition that constituted of 21 herbaceous species did not differ between the periodic- and no-harvest treatments. Insect pests hosted within the meadow did not pose a threat to ‘Sultanina’ grapes, although thrips within the inter-row meadow showed a preference for Convolvulus arvensis. The overall results suggest the application of either a periodic- or no-harvest on the spontaneous vegetation of a Mediterranean ‘Sultanina’ vineyard over two years and constitutes the development of inter-row wildflower meadows from spontaneous vegetations as an appealing and promising sustainable vineyard floor management practice for permanent use that needs to be further researched.

Testing the enemies hypothesis in peach orchards in two different geographic areas in eastern China: the role of ground cover vegetation.

Many studies have supported the enemies hypothesis, which suggests that natural enemies are more efficient at controlling arthropod pests in polyculture than in monoculture agro-ecosystems. However, we do not yet have evidence as to whether this hypothesis holds true in peach orchards over several geographic locations. In the two different geographic areas in eastern China (Xinchang a town in the Shanghai municipality, and Hudai, a town in Jiangsu Province) during a continuous three-year (2010–2012) investigation, we sampled arthropod pests and predators in Trifolium repens L. and in tree canopies of peach orchards with and without the ground cover plant T. repens. No significant differences were found in the abundances of the main groups of arthropod pests and predators in T. repens between Hudai and Xinchang. The abundance, richness, Simpson's index, Shannon-Wiener index, and Pielou evenness index of canopy predators in ground cover areas increased by 85.5, 27.5, 3.5, 16.7, and 7.9% in Xinchang, and by 87.0, 27.6, 3.5, 17.0 and 8.0% in Hudai compared to those in the controls, respectively. The average abundance of Lepidoptera, Coleoptera, Homoptera, true bugs and Acarina canopy pests in ground cover areas decreased by 9.2, 10.2, 17.2, 19.5 and 14.1% in Xinchang, and decreased by 9.5, 8.2, 16.8, 20.1 and 16.6% in Hudai compared to that in control areas, respectively. Our study also found a higher density of arthropod species resources in T. repens, as some omnivorous pests and predators residing in T. repens could move between the ground cover and the orchard canopy. In conclusion, ground cover in peach orchards supported the enemies hypothesis, as indicated by the fact that ground cover T. repens promoted the abundance and diversity of predators and reduced the number of arthropod pests in tree canopies in both geographical areas.

Ecological engineering of ground cover vegetation enhances the diversity and stability of peach orchard canopy arthropod communities

Ecological engineering of ground cover vegetation in agro-ecosystem may affect the diversity and stability of arthropod communities. Factors affecting the stability of arthropod community in turn influence the relationship between arthropod diversity and stability, which has been rarely investigated. We conducted a 2-year field-experiment in Shanghai and Jiangsu province in eastern China, examining the effects of the ecological engineering of ground cover plant Trifolium repens on the diversity and stability of canopy arthropod community in peach orchards. The results indicated that five diversity indices (abundance, species richness, Simpson's index, Shannon–Wiener index and Pielou's evenness index) and four stability indices (Nn/Np, Sn/Sp, (Nn+Nd)/Np and (Sn+Sd)/Sp) were all significantly higher but the coefficient of variation (ds/dm) was significantly lower in ground cover areas than control areas. The results of Pearson's correlations were significantly negative for abundance/richness and the above four stability indices both in ground cover areas and control ones in both sites; correlations between Pielou evenness index and the above four stability indices were all positive in control areas, while those in ground cover areas were not the same. Our study provides a more comprehensive understanding for arthropod community stability, suggesting that regulating harmful arthropods by beneficial and neutral arthropods was the basic implication of arthropod stability, and demonstrates that the ecological engineering of ground cover T. repens can enhance the diversity and stability of canopy arthropod communities but increased arthropod diversity will not always positively affect arthropod stability.

Ecological engineering of ground cover vegetation promotes biocontrol services in peach orchards

We conducted a 2-year field experiment at two sites in eastern China, examining the effects of the ground cover by Trifolium repens L. on the biocontrol services in peach orchards. The results indicated that compared to those in control areas, the abundances of aphids and Grapholitha molesta decreased, respectively, by 31.4% and 33.3% in Shanghai and by 30.1% and 33.3% in Jiangsu, while the abundance of generalist arthropod predators increased by 116.7% in Shanghai and by 115.8% in Jiangsu in ground cover areas. Compared to that in control areas, the ratio of generalist predator abundance to aphid abundance and to G. molesta abundance increased, respectively, by 260.0% and 384.2% in Shanghai and by 213.3% and 253.1% in Jiangsu in ground cover areas. Our study revealed that the ecological engineering of ground cover by T. repens promoted biocontrol services in peach orchards.

Carbon Isotope Discrimination in Diverging Growth Forms of Saxifraga oppositifolia in Different Successional Stages in a High Arctic Glacier Foreland

We investigated carbon isotope discrimination of two morphs of Saxifraga oppositifolia and other plant species in a glacier foreland in the High Arctic at Ny-Ålesund, Svalbard, Norway. At this site, soil conditions vary considerably along with the progress of primary succession within a small area. We compared growth forms and δ13C values, which reflect long-term leaf gas exchange characteristics, of plants growing in different successional stages with different soil conditions. Even though the soil mass water content (water mass/dry mass) increased from 10% to 140% with the progress of succession, the water and nitrogen content of the soil had negligible effects on the δ13C values of the observed species. The δ13C values were determined mainly by species and growth forms. We compared two morphs of S. oppositifolia, the prostrate form (P-form) and the cushion form (C-form), on the same riverbank in the glacier foreland. Regardless of the successional stage, the δ13C values of the C-form were about 2‰ more negative than those of the P-form. The ground cover area per plant mass (GA) of the C-form was less than 30% that of the P-form, and the product of GA and stomatal conductance appears to be an important factor in the relationship between transpiration and photosynthesis of a whole plant. We suggest that the relationship between GA and the root mass fraction is a crucial factor affecting the water utilization in high arctic environments. We also examined the relationship between life form and water utilization for other phototrophs, including lichens, mosses, narrow-leaved grasses, perennials, and shrubs.

Role of hedgerows and ground cover management on arthropod populations in pear orchards

With the failure of conventional chemical control against the pear tree psyllid Cacopsylla pyri (L.) (Homoptera: Psyllidae), strategies have been developed to enhance natural arthropod enemies of this pest. Modifying the vegetation adjacent to pear orchards is one integrated pest management (IPM) practice that can increase the agroecosystem plant diversity, thus favoring a natural balance between pest arthropods and their enemies. Different plant species were examined as sources of beneficial arthropods for the pear orchard. Arthropod faunas were sampled in the pear tree ( Pyrus communis L.) canopy, the ground cover, and in the hedgerow tree species surrounding the orchard. Inter-relationships between pear and hedgerow tree species were studied by Spearman's rank correlation. Ash trees and ivy display a diversified fauna that was correlated with the pear tree community, but not with each other. Their influence on pear tree fauna is different: ash trees host specific psyllids and gall midges (Diptera: Cecidomyiidae), providing food for beneficial pear arthropods and ivy acts as a shelter species for beneficial pear arthropods. Calculation of correlations between the faunas of non-crop and crop plant species appears as a useful tool for estimating the risk (correlation between phytophagous guilds) and benefit (correlation between beneficial guilds) of plants dedicated to environmental crop management. The following orchard ground covers were tested: (1) bare ground; (2) natural grass cover; and (3) sown ground cover. Multivariate analysis was performed to characterize ground cover arthropod communities. Natural ground cover and sown ground cover sheltered distinct arthropod communities; the natural ground cover beneficial fauna was characterized by spiders and the sown ground cover fauna was characterized by ants. The structure and numbers of the arthropod assemblages collected on pear trees from the three types of ground management were different. The main beneficial arthropods on pear tree were Anthocoridae (Heteroptera) and Miridae (Heteroptera) in the sown area; Empididae (Diptera) and Miridae in the natural ground cover area; and Forficulidae (Dermaptera) and Miridae in the bare ground area. Moreover, the sown ground cover favored a higher beneficial : phytophagous ratio to that in the pear tree canopy. These results imply that interactions are likely to occur between pear trees and hedgerow, and between pear trees and ground cover within the orchard agroecosystem. Manipulating beneficial arthropods through vegetal environment management using selected tree and grass species shows promise in optimizing pear orchard IPM.

Snowfall From Lake-Effect Storms

Abstract Three yr of winter lake-storm data were analyzed to determine snowfall distribution patterns downwind of Lake Erie and Lake Ontario. The total amount of snowfall and the area of ground cover in each of 23 lake-effect storms were determined for both lakes. Total snowfall mass was highly dependent on time of year; November and early December storms were two to five times more productive than January storms. A considerable variation in snow density (snowfall depth to melt water ratio) could be attributed mainly to differences in snow crystal type.