Passive regeneration of subtropical grassland vegetation in a chronosequence of ex‐cultivated fields in Australia

The accurate estimation of grassland vegetation parameters at a high spatial resolution is important for the sustainable management of grassland areas. Unmanned aerial vehicle (UAV) light detection and ranging (LiDAR) sensors with a single laser beam emission capability can rapidly detect grassland vegetation parameters, such as canopy height, fractional vegetation coverage (FVC) and aboveground biomass (AGB). However, there have been few reports on the ability to detect grassland vegetation parameters based on RIEGL VUX-1 UAV LiDAR (Riegl VUX-1) systems. In this paper, we investigated the ability of Riegl VUX-1 to model the AGB at a 0.1 m pixel resolution in the Hulun Buir grazing platform under different grazing intensities. The LiDAR-derived minimum, mean, and maximum canopy heights and FVC were used to estimate the AGB across the entire grazing platform. The flight height of the LiDAR-derived vegetation parameters was also analyzed. The following results were determined: (1) The Riegl VUX-1-derived AGB was predicted to range from 29 g/m2 to 563 g/m2 under different grazing conditions. (2) The LiDAR-derived maximum canopy height and FVC were the best predictors of grassland AGB (R2 = 0.54, root-mean-square error (RMSE) = 64.76 g/m2). (3) For different UAV flight altitudes from 40 m to 110 m, different flight heights showed no major effect on the derived canopy height. The LiDAR-derived canopy height decreased from 9.19 cm to 8.17 cm, and the standard deviation of the LiDAR-derived canopy height decreased from 3.31 cm to 2.35 cm with increasing UAV flight altitudes. These conclusions could be useful for estimating grasslands in smaller areas and serving as references for other remote sensing datasets for estimating grasslands in larger areas.

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Comprehensive Assessment Indicator of Ecosystem Resilience in Central Asia

Water ◽

10.3390/w13020124 ◽

2021 ◽

Vol 13 (2) ◽

pp. 124

Author(s):

Xue Fan ◽

Xingming Hao ◽

Haichao Hao ◽

Jingjing Zhang ◽

Yuanhang Li

Keyword(s):

Central Asia ◽

Net Primary Productivity ◽

Ecosystem Resilience ◽

Mountainous Areas ◽

Grassland Vegetation ◽

High Coverage ◽

Casa Model ◽

Assessment Indicator ◽

Multiple Dimensions ◽

Resilience Index

The ecosystems in the arid inland areas of Central Asia are fragile and severely degraded. Understanding and assessing ecosystem resilience is a challenge facing ecosystems. Based on the net primary productivity (NPP) data estimated by the CASA model, this study conducted a quantitative analysis of the ecosystem’s resilience and comprehensively reflected its resilience from multiple dimensions. Furthermore, a comprehensive resilience index was constructed. The result showed that plain oasis’s ecosystem resilience is the highest, followed by deserts and mountainous areas. From the perspective of vegetation types, the highest resilience is artificial vegetation and the lowest is forest. In warm deserts, the resilience is higher in shrubs and meadows and lower in grassland vegetation. High coverage and biomass are not the same as the strong adaptability of the ecosystem. Moderate and slightly inelastic areas mainly dominate the ecosystem resilience of the study area. The new method is easy to use. The evaluation result is reliable. It can quantitatively analyze the resilience latitude and recovery rate, a beneficial improvement to the current ecosystem resilience evaluation.

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High land-use intensity exacerbates shifts in grassland vegetation composition after severe experimental drought

Global Change Biology ◽

10.1111/gcb.14046 ◽

2018 ◽

Vol 24 (5) ◽

pp. 2021-2034 ◽

Cited By ~ 32

Author(s):

Andreas Stampfli ◽

Juliette M. G. Bloor ◽

Markus Fischer ◽

Michaela Zeiter

Keyword(s):

Land Use ◽

Land Use Intensity ◽

Vegetation Composition ◽

Grassland Vegetation

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Response of calcareous grassland vegetation to mowing and fluctuating weather conditions

Journal of Vegetation Science ◽

10.1111/j.1654-1103.2007.tb02524.x ◽

2007 ◽

Vol 18 (1) ◽

pp. 141-146 ◽

Cited By ~ 8

Author(s):

Nele Ingerpuu ◽

Tiiu Kupper

Keyword(s):

Weather Conditions ◽

Calcareous Grassland ◽

Grassland Vegetation

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Regulation and Critical Threshold of Grass Cover on Slope Runoff in LoessHilly Gully Region under Artificial

10.5194/egusphere-egu21-4363 ◽

2021 ◽

Author(s):

Qiufen Zhang ◽

Xizhi Lv ◽

Rongxin Chen ◽

Yongxin Ni ◽

Li Ma

Keyword(s):

Soil Erosion ◽

Rainfall Intensity ◽

Climatic Conditions ◽

Vegetation Coverage ◽

Critical Threshold ◽

Runoff Generation ◽

Grassland Vegetation ◽

Slope Flow ◽

The Impact ◽

Slope Runoff

The slope runoff caused by rainstorm is the main cause of serious soil and water loss in the loess hilly area, the grassland vegetation has a good inhibitory effect on the slope runoff, it is of great significance to reveal the role of grassland vegetation in the process of runoff generation and control mechanism for controlling soil erosion in this area. In this study, typical grassland slopes in hilly and gully regions of the loess plateau were taken as research objects. Through artificial rainfall in the field, the response rules of slope rainfall-runoff process to different grass coverage were explored. The results show that: (1) The time for the slope flow to stabilize is prolonged with the increase of vegetation coverage, and shortened with the increase of rainfall intensity; (2) At 60 mm&#183;h &#8722;1 rainfall intensity, the threshold of grassland vegetation coverage is 75.38%; at 90 mm&#183;h &#8722;1 rainfall intensity, the threshold of grassland vegetation coverage is 90.54%; at 120 mm&#183;h &#8722;1 rainfall intensity, the impact of grassland vegetation coverage on runoff is not significant; (3) the Reynolds number and Froude number of slope flow are 40.07&#8210;695.22 and 0.33&#8210;1.56 respectively, the drag coefficient is 1.42&#8210;43.53. Under conditions of heavy rainfall, the ability of grassland to regulate slope runoff is limited. If only turf protection is considered, about 90% of grassland coverage can effectively cope with soil erosion caused by climatic conditions in loess hilly and gully regions. Therefore, in loess hilly areas where heavy rains frequently occur, grassland's protective effect on soil erosion is obviously insufficient, and investment in vegetation measures for trees and shrubs should be strengthened.

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Nanostructure changes in diesel soot during NO2–O2 oxidation under diesel particulate filter-like conditions toward filter regeneration

International Journal of Engine Research ◽

10.1177/1468087418807608 ◽

2018 ◽

Vol 20 (8-9) ◽

pp. 953-966 ◽

Cited By ~ 4

Author(s):

Madhu Singh ◽

Mek Srilomsak ◽

Yujun Wang ◽

Katsunori Hanamura ◽

Randy Vander Wal

Keyword(s):

Diesel Particulate Filter ◽

Surface Oxidation ◽

Soot Oxidation ◽

Diesel Soot ◽

Particulate Filter ◽

Exhaust Gas ◽

Fringe Analysis ◽

Diesel Particulate ◽

Oxidation Rates ◽

Passive Regeneration

Development of the regeneration process on diesel particulate filters requires a better understanding of soot oxidation phenomena, especially its relation to soot nanostructure. Nitrogen dioxide (NO2) is known to play an essential role in passive regeneration by oxidizing soot at low temperatures, especially in the presence of oxygen (O2) in the exhaust. However, change in soot nanostructure due to oxidation by NO2–O2 mixtures has not received much attention. This work focuses on nanostructure evolution during passive regeneration of the diesel particulate filter by oxidation of soot at normal exhaust gas temperatures (300°C–400°C). High-resolution transmission electron microscopy of partially oxidized model carbons (R250, M1300, arc-generated soot) and diesel soot under NO2–O2 mixtures is used to investigate physical changes in nanostructure correlating with the material’s behavior during oxidation. Microscopy reveals the changing nanostructure of model carbons during oxidation while fringe analysis of the images points to the differences in the structural metrics of fringe length and tortuosity of the resultant structures. The variation in oxidation rates highlights the inter-dependence of the material’s reactivity with its structure. NO2 preferentially oxidizes edge-site carbon, promotes surface oxidation by altering the particle’s burning mode with increased overall reactivity of NO2+O2 resulting in inhibition of internal burning, typically observed by O2 at exhaust gas temperatures.

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Response of dry grassland vegetation to fluctuations in weather conditions: a 9-year case study in Prague (Czech Republic)

Biologia ◽

10.2478/s11756-011-0079-1 ◽

2011 ◽

Vol 66 (5) ◽

Cited By ~ 6

Author(s):

Jiří Dostálek ◽

Tomáš Frantík

Keyword(s):

Species Richness ◽

Czech Republic ◽

Weather Conditions ◽

Grass Species ◽

Individual Species ◽

Weather Variability ◽

Grassland Vegetation ◽

Dry Grassland ◽

Local Climate ◽

The Impact

AbstractThe extreme habitats of dry grasslands are suitable for investigations of the response of vegetation to local climate changes. The impact of weather variability on the dynamics of a plant community in a dry grassland was studied. Correlations were found between different functional groups of species and individual species and weather variability. During a 9-year study in five nature reserves in Prague (Czech Republic), the following responses of dry grassland vegetation to weather conditions were observed: (i) wetter conditions, especially in the winter, affected the dominance and species richness of perennial grass species and the decline of rosette plants; (ii) the year-to-year higher temperatures in the winter produced a decline in the dominance of short graminoids and creeping forbs; (iii) spring drought adversely impacted the overall abundance, especially the abundance of dicotyledonous species, and the species richness. However, these relationships may be manifested in different ways in different locations, and in some cases the vegetation of different locations may respond to weather conditions in opposite manners.

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