Responses of Plant Bud Bank Characteristics to the Enclosure in Different Desertified Grasslands on the Tibetan Plateau

Asexual reproduction is the main mode of alpine plant reproduction, and buds play an important role in plant community succession. The purpose of this study is to explore whether the desertified grassland can recover itself through the existing bud bank. The bud bank composition, distribution and size of different desertified grasslands were studied using unit volume excavation on the Tibetan Plateau. The bud bank consisted of tiller, long and short rhizome buds, and more than 40% of buds were distributed in the 0–10 cm soil layer. Enclosure changed the bud density, distribution and composition. The bud densities were 4327 and 2681 No./m2 in light and middle desertified grasslands before enclosure, while that decreased to 3833 and 2567 No./m2 after enclosure. Tiller bud density and proportion of middle desertified grassland were the highest, increased from 2765 (31.26%, before enclosure) to 5556 No./m3 (62.67%, after enclosure). There were new grasses growing out in the extreme desertified grassland after enclosure. The meristem limitation index of moderate desertified grassland was the lowest (0.37), indicating that plant renewal was limited by bud bank. Plants constantly adjust the bud bank composition, distribution, and asexual reproduction strategy, and desertified grasslands can recover naturally, relying on their bud banks through an enclosure.

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Mixed reproduction strategy and polyploidy facilitate dominance ofKobresia pygmaeaon the Tibetan Plateau

Journal of Plant Ecology ◽

10.1093/jpe/rtv035 ◽

2015 ◽

pp. rtv035 ◽

Cited By ~ 3

Author(s):

Elke Seeber ◽

Georg Miehe ◽

Isabell Hensen ◽

Yongping Yang ◽

Karsten Wesche

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Reproduction Strategy

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Evaluating and improving simulations of diurnal variation in land surface temperature with the Community Land Model for the Tibetan Plateau

PeerJ ◽

10.7717/peerj.11040 ◽

2021 ◽

Vol 9 ◽

pp. e11040

Author(s):

Xiaogang Ma ◽

Jiming Jin ◽

Lingjing Zhu ◽

Jian Liu

Keyword(s):

Thermal Conductivity ◽

Tibetan Plateau ◽

Surface Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Soil Layer ◽

Surface Model ◽

The Tibetan Plateau ◽

Soil Thermal Conductivity ◽

Community Land Model

This study evaluated and improved the ability of the Community Land Model version 5.0 (CLM5.0) in simulating the diurnal land surface temperature (LST) cycle for the whole Tibetan Plateau (TP) by comparing it with Moderate Resolution Imaging Spectroradiometer satellite observations. During daytime, the model underestimated the LST on sparsely vegetated areas in summer, whereas cold biases occurred over the whole TP in winter. The lower simulated daytime LST resulted from weaker heat transfer resistances and greater soil thermal conductivity in the model, which generated a stronger heat flux transferred to the deep soil. During nighttime, CLM5.0 overestimated LST for the whole TP in both two seasons. These warm biases were mainly due to the greater soil thermal inertia, which is also related to greater soil thermal conductivity and wetter surface soil layer in the model. We employed the sensible heat roughness length scheme from Zeng, Wang & Wang (2012), the recommended soil thermal conductivity scheme from Dai et al. (2019), and the modified soil evaporation resistance parameterization, which was appropriate for the TP soil texture, to improve simulated daytime and nighttime LST, evapotranspiration, and surface (0–10 cm) soil moisture. In addition, the model produced lower daytime LST in winter because of overestimation of the snow cover fraction and an inaccurate atmospheric forcing dataset in the northwestern TP. In summary, this study reveals the reasons for biases when simulating LST variation, improves the simulations of turbulent fluxes and LST, and further shows that satellite-based observations can help enhance the land surface model parameterization and unobservable land surface processes on the TP.

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On the freeze–thaw cycles of shallow soil and connections with environmental factors over the Tibetan Plateau

10.21203/rs.3.rs-479298/v1 ◽

2021 ◽

Author(s):

Ning Li ◽

Lan Cuo ◽

Yongxin Zhang

Keyword(s):

Tibetan Plateau ◽

Soil Temperature ◽

Coniferous Forest ◽

Soil Layer ◽

Surface Air Temperature ◽

The Tibetan Plateau ◽

Near Surface ◽

Freeze Thaw ◽

Shallow Soil ◽

Thaw Cycle

Abstract Changes in the freeze–thaw cycles of shallow soil have important consequences for surface and subsurface hydrology, land–atmosphere energy and moisture interaction, carbon exchange, and ecosystem diversity and productivity. This work examines the shallow soil freeze–thaw cycle on the Tibetan Plateau (TP) using in–situ soil temperature observations in 0–20 cm soil layer during July 1982 – June 2017. The domain and layer averaged beginning frozen day is November 18 and delays by 2.2 days per decade; the ending frozen day is March 9 and advances by 3.2 days per decade; the number of frozen days is 109 and shortens by 5.2 days per decade. Altitude and latitude combined could explain the spatial patterns of annual mean freeze–thaw status well. Stations located near 0–ºC contour line experienced dramatic changes in freeze–thaw cycles as seen from subtropical mountain coniferous forest in the southern TP. Soil completely freezes from surface to 20–cm depth in 15 days while completely thaws in 10 days on average. Near–surface soil displays more pronounced changes than deeper soil. Surface air temperature strongly influences the shallow soil freeze – thaw status but snow exerts limited effects. Different thresholds in freeze–thaw status definition lead to differences in the shallow soil freeze–thaw status and multiple–consecutive–day approach appears to be more robust and reliable. Gridded soil temperature products could resolve the spatial pattern of the observed shallow soil freeze–thaw status to some extent but further improvement is needed.

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