Dynamics of Grassland Vegetation Composition across different Land-use Types on the Qinghai Tibet Plateau: Implications to Combat Grassland Degradation

The constant biotic and abiotic interventions on the Qinghai Tibet Plateau (QTP) are seriously degrading the grasslands and, at the same time, restricting the active ecosystem function and grassland vegetation distribution on the plateau. This research analyses the dynamics of grassland vegetation composition across three land uses and counties. The degree of grassland degradation was divided into four land-use types based, i.e., healthy grassland (HG), restored grassland (RG), moderately degraded (MD) grassland, and severely degraded (SD) grassland. About 32 plant species were recorded in Tiebujia county, 28 in Maqin county, and 18 in Maduo county. Results showed Poa crymophila, Polygonum sibiricum, Leontopodium nanum and Oxytropis falcatabunge as the most abundant grassland species in all land-uses and counties. The richness of species ranged from 8 to 12 species per land-use, suggesting low richness and diversity in restored and degraded grassland. A positive non-significantly mean change (p<0.05) was detected for richness and evenness indices while a negative mean change (p<0.05) was detected for Simpson and Shannon indices in the alpine meadow and steppe in both Maqin and Maduo county. The results imply that degradation affects grassland vegetation, health, and distribution across the QTP. Plant total cover for the healthy grassland covered far more areas than other land-uses. Urgent mitigation measures to halt grassland degradation and decline in plant vegetation composition on the plateau should be adopted.

A Handheld Grassland Vegetation Monitoring System Based on Multispectral Imaging

Monitoring grassland vegetation growth is of vital importance to scientific grazing and grassland management. People expect to be able to use a portable device, like a mobile phone, to monitor grassland vegetation growth at any time. In this paper, we propose a handheld grassland vegetation monitoring system to achieve the goal of monitoring grassland vegetation growth. The system includes two parts: the hardware unit is a hand-held multispectral imaging tool named ASQ-Discover based on a smartphone, which has six bands (wavelengths)—including three visible bands (450 nm, 550 nm, 650 nm), a red-edge band (750 nm), and two near-infrared bands (850 nm, 960 nm). The imagery data of each band has a size of 5120 × 3840 pixels with 8-bit depth. The software unit improves image quality through vignetting removal, radiometric calibration, and misalignment correction and estimates and analyzes spectral traits of grassland vegetation (Fresh Grass Ratio (FGR), NDVI, NDRE, BNDVI, GNDVI, OSAVI and TGI) that are indicators of vegetation growth in grassland. We introduce the hardware and software unit in detail, and we also experiment in five pastures located in Haiyan County, Qinghai Province. Our experimental results show that the handheld grassland vegetation growth monitoring system has the potential to revolutionize the grassland monitoring that operators can conduct when using a hand-held tool to achieve the tasks of grassland vegetation growth monitoring.

Palinologia de turfas do alto curso do Arroio Cará, Coxilha Rica, Santa Catarina, Brasil

Palynology of peaty sediments from the high course of Cará Brook Creek, Coxilha Rica, Santa Catarina, Brazil. This paper presents the results of the palynological study of a sedimentary core collected in a bog in the upper part valley of Cará Brook Creek, in the cultural territory of Coxilha Rica, located in the Campos Gerais Plateau in Santa Catarina, Southern Brazil. The base of the core was dated in 6.900 14C years BP (7,845–7,690 cal years BP). The identification of the palynomorphs and the cluster analysis made possible to define two distinct palynological phases, despite the predominance of grassland vegetation throughout the whole core. From 34 cm, the frequency of bryophytes decreases, accompanied by the increase of the diversity of all vegetal taxa. Throughout the core, the most frequent families are Poaceae, Cyperaceae Apiaceae. The results indicate that the landscape of the upper course of the Brook Creek was characterized by grasslands from 6,900 14C years BP under a regional and humid climate, with a temperature increase in the historical period. Keywords: Middle Holocene, palynomorphs, grasslands, Araucaria forest, Highland.

Mapping of Kobresia pygmaea Community Based on Umanned Aerial Vehicle Technology and Gaofen Remote Sensing Data in Alpine Meadow Grassland: A Case Study in Eastern of Qinghai–Tibetan Plateau

The Kobresia pygmaea (KP) community is a key succession stage of alpine meadow degradation on the Qinghai–Tibet Plateau (QTP). However, most of the grassland classification and mapping studies have been performed at the grassland type level. The spatial distribution and impact factors of KP on the QTP are still unclear. In this study, field measurements of the grassland vegetation community in the eastern part of the QTP (Counties of Zeku, Henan and Maqu) from 2015 to 2019 were acquired using unmanned aerial vehicle (UAV) technology. The machine learning algorithms for grassland vegetation community classification were constructed by combining Gaofen satellite images and topographic indices. Then, the spatial distribution of KP community was mapped. The results showed that: (1) For all field observed sites, the alpine meadow vegetation communities demonstrated a considerable spatial heterogeneity. The traditional classification methods can hardly distinguish those communities due to the high similarity of their spectral characteristics. (2) The random forest method based on the combination of satellite vegetation indices, texture feature and topographic indices exhibited the best performance in three counties, with overall accuracy and Kappa coefficient ranged from 74.06% to 83.92% and 0.65 to 0.80, respectively. (3) As a whole, the area of KP community reached 1434.07 km2, and accounted for 7.20% of the study area. We concluded that the combination of satellite remote sensing, UAV surveying and machine learning can be used for KP classification and mapping at community level.

Effects of vegetation management on the composition and diversity of the insect community at Tianjin Binhai International Airport, China

The vegetation community affects the composition and diversity of the insect community in grasslands. To explore the effects of vegetation management on insect community abundance and diversity, regular mowing of the vegetation was conducted, and tall fescue (Festuca arundinacea) and ryegrass (Lolium perenne) were exclusively planted at Tianjin Binhai International Airport. A total of 1886 insects were collected, representing 8 orders, 23 families, and 29 species; Acrididae (Orthoptera), Coccinellidae (Coleoptera), and Chironomidae (Diptera) were the dominant taxa. The abundance and biomass of insects in the turf areas were significantly lower than those in the control area and were reduced by 45.8 and 48.5% in the ryegrass area, respectively. In all areas, insect abundance and biomass peaked in summer, and the abundance of individuals and taxa decreased as the temperature decreased. Greater diversity and richness were found in summer compared with the other two seasons, and the turf areas had lower diversity and richness indices than the control areas in spring and summer. Our results suggest that the abundance, biomass and diversity of insects can be effectively decreased by artificial regulation of grassland vegetation at the airport, the planting of a single turfgrass – specifically ryegrass had the greatest effect. The present study provides a theoretical basis for the ecological control of insects at the airport.