Population structure and spatial pattern of Caragana tibetica communities in Nei Mongol shrub-encroached grassland

Zhang, Pujin; Qing, Hua; Zhang, Lei; Xu, Yanda; Mu, Lan; Ye, Ruhan; Xiao, Qiu; Chang, Hong; Hai-Hua, SHEN; Jie, and YANG

doi:10.17521/cjpe.2015.0448

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…The main misclassification cases involved shrub-steppe and steppe, steppe and cropland, and steppe and wetland. Specifically, the misclassification between shrub-steppe and steppe in this study can be attributed to the natural shrub-steppe structure formed by steppe degradation [84,85] and the artificially planted shrub on steppe, both of which retain a steppe background and share similar ecological and visual characteristics, including some common herbaceous vegetation types [9,28]. Additionally, in some areas, the similar graminoid vegetation and moisture conditions present in steppe, cropland, and wetland ecosystems have led to misclassification among these ecosystems.…”

Section: Mapping Ecosystems In Dryland Regionsmentioning

confidence: 70%

Mapping Dryland Ecosystems Using Google Earth Engine and Random Forest: A Case Study of an Ecologically Critical Area in Northern China

Li,

Guo,

Sun

et al. 2024

Land

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Drylands are characterized by unique ecosystem types, sparse vegetation, fragile environments, and vital ecosystem services. The accurate mapping of dryland ecosystems is essential for their protection and restoration, but previous approaches primarily relied on modifying land use data derived from remote sensing, lacking the direct utilization of latest remote sensing technologies and methods to map ecosystems, especially failing to effectively identify key ecosystems with sparse vegetation. This study attempts to integrate Google Earth Engine (GEE), random forest (RF) algorithm, multi-source remote sensing data (spectral, radar, terrain, texture), feature optimization, and image segmentation to develop a fine-scale mapping method for an ecologically critical area in northern China. The results showed the following: (1) Incorporating multi-source remote sensing data significantly improved the overall classification accuracy of dryland ecosystems, with radar features contributing the most, followed by terrain and texture features. (2) Optimizing the features set can enhance the classification accuracy, with overall accuracy reaching 91.34% and kappa coefficient 0.90. (3) User’s accuracies exceeded 90% for forest, cropland, and water, and were slightly lower for steppe and shrub-steppe but were still above 85%, demonstrating the efficacy of the GEE and RF algorithm to map sparse vegetation and other dryland ecosystems. Accurate dryland ecosystems mapping requires accounting for regional heterogeneity and optimizing sample data and feature selection based on field surveys to precisely depict ecosystem patterns in complex regions. This study precisely mapped dryland ecosystems in a typical dryland region, and provides baseline data for ecological protection and restoration policies in this region, as well as a methodological reference for ecosystem mapping in similar regions.

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Section: Mapping Ecosystems In Dryland Regionsmentioning

confidence: 70%

Mapping Dryland Ecosystems Using Google Earth Engine and Random Forest: A Case Study of an Ecologically Critical Area in Northern China

Li,

Guo,

Sun

et al. 2024

Land

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“…Consistently with previous studies that found mostly anecdotal evidence supporting the existence of shrub encroachment in NE Patagonia, our results show a general increase in shrub density and cover between 1970 and 2018. Thus, NE Patagonia does not escape the general pattern of shrub encroachment found in most arid and semi‐arid regions of the world (D'Odorico et al, 2012; Goslee et al, 2003; McGlynn & Okin, 2006; Peng et al, 2013; Robinson et al, 2008; Zhang et al, 2017; Zhou et al, 2019). The average rate of increase in shrub cover in this 48‐year period was 0.268%, which is similar to the rates reported by other studies (e.g., Britz & Ward, 2007; Laliberte et al, 2004).…”

Section: Discussionmentioning

confidence: 98%

“…Woody plant encroachment, defined as the increase in density, cover and biomass of indigenous woody or shrubby plants (Eldridge et al, 2011), is a global phenomenon (Cao et al, 2019; Ding & Eldridge, 2023; D'Odorico et al, 2012; García Criado et al, 2020; Wang et al, 2021). In the last century, many arid and semiarid grasslands of the world have been invaded by woody species (Goslee et al, 2003; McGlynn & Okin, 2006; Peng et al, 2013; Robinson et al, 2008; Zhang et al, 2017; Zhou et al, 2019). Semi‐arid and arid ecosystems occupy approximately 41% of Earth's land surface and 10%–20% of those areas are being invaded by shrubs (Reynolds et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Shrub encroachment occurs near previously invaded areas in Patagonia (southern South America)

Romero‐Ovalle,

Campanella,

Pascual

et al. 2023

Land Degrad Dev

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During the last century shrub encroachment has occurred in many arid and semiarid areas of the world. Patagonia is a large xeric territory located in the southern tip of South America, which has been grazed by sheep for more than a century. In many areas overgrazing led to vegetation change (shrub encroachment), which in turn reduced sheep carrying capacity and caused ranch abandonment. However, these changes in physiognomy did not occur everywhere, and even some authors did not find evidence that shrub encroachment is currently occurring. Our objectives were to determine if encroachment really happened in NE Patagonia and, in the case of confirming shrub encroachment, to evaluate if the increase in shrub density was spatially homogeneous. We used object‐based image analysis to evaluate shrub density and cover in aerial photographs taken in 1970 and 2018. In both dates, shrub density showed a clear contrast between two kinds of areas showing higher and lower density than was expected by chance. Shrub density and cover more than doubled between 1970 and 2018. This increase was concentrated in those areas with moderate or high densities of shrubs in 1970. Our results confirm the occurrence of shrub encroachment in NE Patagonia and demonstrate that it is currently concentrated near previously invaded areas. These findings have implications when defining protocols for monitoring shrub encroachment since monitors should focus on both areas that already have shrubs and areas that lack them.

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Soil erosion facilitates shrub encroachment in Patagonian herbaceous steppes

2021

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Previous studies in northeastern Patagonia suggested that, mainly as a consequence of overgrazing by sheep, the herbaceous steppes are being replaced by shrub steppes dominated by Chuquiraga avellanedae as a consequence of shrub encroachment. The herbaceous steppe presents a thick sandy loam to loamy sand A‐horizon lying on a clay‐horizon while the shrub steppe presents the clay‐horizon at or near the soil surface. The thickness reduction of the remaining A‐horizon and the formation of desert pavements are evidence of soil erosion. As previous studies suggested that shrub encroachment co‐occurs with the erosion of the sandy A‐horizon, we hypothesized that shrub encroachment is favored by the presence of an clay‐horizon near the soil surface. We expected that C. avellanedae emergence and establishment would be higher as the clay horizon is closer to the soil surface and the A‐horizon is reduced. We performed field and greenhouse experiments to evaluate seedling emergence and establishment along a gradient of A‐horizon thickness. We found that the presence of a relatively thin sandy layer on the surface had a negative influence on both shrub emergence and establishment. The summer drought was not a critical period for the seedlings. Conversely, the highest seedling mortality took place during late winter in sandy soils, suggesting that these soils are more susceptible to frost heaving than clay soils. In conclusion, soil erosion in the northeastern Patagonian steppes would indirectly facilitate shrub encroachment due to differences in frost heaving susceptibility between sandy and clay soils.

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Population structure and spatial pattern of Caragana tibetica communities in Nei Mongol shrub-encroached grassland

Cited by 4 publications

References 16 publications

Mapping Dryland Ecosystems Using Google Earth Engine and Random Forest: A Case Study of an Ecologically Critical Area in Northern China

Mapping Dryland Ecosystems Using Google Earth Engine and Random Forest: A Case Study of an Ecologically Critical Area in Northern China

Shrub encroachment occurs near previously invaded areas in Patagonia (southern South America)

Soil erosion facilitates shrub encroachment in Patagonian herbaceous steppes

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