Comparing the relationship between seed germination and temperature for Stipa species on the Tibetan Plateau

Botany ◽  
2014 ◽  
Vol 92 (12) ◽  
pp. 895-900 ◽  
Author(s):  
Shihai Yang ◽  
Xiong Li ◽  
Yunqiang Yang ◽  
Xin Yin ◽  
Yongping Yang

Alpine steppe grasslands dominated by Stipa species (Poaceae) on the Tibetan Plateau are important model ecosystems. Here, we present data on seed germination of three typical Stipa species (Stipa purpurea Griseb., Stipa glareosa P.A.Smirn., and Stipa capillacea Keng) from the northern core region of the Tibetan Plateau. We carried out laboratory investigations of germination behavior under both constant and alternating temperatures. Germination varied significantly with temperature. Under constant temperature, we found that temperature and species, but not their interaction, had significant effects on seed germination. Under alternating temperatures, species had a significant effect on seed germination, whereas the effects of alternating temperature and the interaction between species and alternating temperature were not significant. In addition, light and the interaction of light and species had no significant effect on seed germination; however, species had a significant effect, implying that Stipa species on the Tibetan Plateau are not inhibited by light. Base temperatures of S. glareosa, S. purpurea, and S. capillacea were 1.0 °C, 0.1 °C, and –1.4 °C, respectively, with corresponding thermal times at suboptimal temperatures of 233 °C-day, 154 °C-day, and 263.2 °C-day. Our results suggest that Stipa seed germination characteristics are adaptions to a harsh environment and are species-specific.

2020 ◽  
Vol 776 ◽  
pp. 228300
Author(s):  
Xingqian Xu ◽  
Lijun Su ◽  
Junzhe Liu ◽  
Wanhuan Zhou ◽  
Aimin Gong ◽  
...  

Author(s):  
Jian SUN ◽  
Yu LIU ◽  
Tiancai ZHOU ◽  
Guohua LIU ◽  
Jingsheng WANG

ABSTRACTSoil erosion can pose a serious problem to environmental quality and sustainable development. On the Tibetan Plateau, soil erosion is one of the main challenges to regional ecological security. Our analysis investigates soil erosion and evaluates its economic value in alpine steppe, alpine meadow, alpine desert steppe and forest ecosystems on the Tibetan Plateau. Analysis was carried out from 1984 to 2013. The results show that the annual average potential soil erosion, practical soil erosion and soil conservation calculated by the Revised University Soil Loss Equation model were 2.19×109ta–1, 2.16×109ta–1 and 2.72×107ta–1, respectively. The economic value of retaining soil nutrients, reducing the formation of wasteland and the economic benefit of reducing sediment deposition were 1.98×108RMBa–1, 2.55×1012RMBa–1 and 7.44×104RMBa–1, respectively. From comparing different ecosystems, we found that the forest ecosystem had the greatest soil retention and economic values. We also found that the potential and actual soil erosion values were extremely high on the Tibetan Plateau. The study highlights that state and local policymakers must give greater emphasis to ecological protection in the future.


2015 ◽  
Vol 51 (2) ◽  
pp. 1069-1083 ◽  
Author(s):  
Ning Ma ◽  
Yinsheng Zhang ◽  
Jozsef Szilagyi ◽  
Yanhong Guo ◽  
Jianqing Zhai ◽  
...  

2013 ◽  
Vol 14 (4) ◽  
pp. 227-234 ◽  
Author(s):  
Xiangde Xu ◽  
Chungu Lu ◽  
Yihui Ding ◽  
Xiaohui Shi ◽  
Yudi Guo ◽  
...  

2016 ◽  
Author(s):  
Jian Sun

Although the relationship between the aboveground net primary production (ANPP) and speciesdiversity (SR) have been widely reported, there is considerable disagreement about the fitting patterns of SR–ANPP, which has been variously described as ‘positive’, ‘negative’, ‘unimodal’, ‘U-shaped’ and so on. Not surprisingly, the effect-factors including precipitation, aridity index and geographic conditions (e.g.,altitude, longitude and latitude) on ANPP and SR continue to interest researchers, especially the effects at high altitude regions. We investigated ANPP and SR from 113 sampled sites (399 plots) across alpine meadow and steppe in the Tibetan Plateau, which included Tibet, Qinghai and Sichuan province. The effects of various environmental factors (precipitation, temperature, aridity index, altitude, longitude,latitude and vegetation type on SR and ANPP) were explored. The results indicate that a unimodal pattern was confirmed between ANPP and SR in alpine steppe (R 2 =0.45, P <0.0001), alpine meadow ( R 2 =0.4, P <0.0001), and all samples across alpine grassland ( R 2 =0.52, P <0.0001). For the aboveground net primary production, the appropriate precipitation and aridity is 600mm and 42, respectively. Under thesame moisture conditions, the maximum value of diversity is 0.75. Longitude ( R 2 =0.69, P <0.0001) and altitude ( R 2 =0.48, P <0.0001) have positive and negative effects on aboveground net primary production, and a similar relationship exists with diversity ( R 2 =0.44, P <0.0001 and R 2 =0.3, P <0.0001).The same patterns of diversity and production responding to precipitation and the aridity index were evident in alpine steppe and meadow, and a unimodal pattern was confirmed between ANPP and SR in both locations.


2020 ◽  
Author(s):  
Genhou Sun ◽  
Zeyong Hu ◽  
Yaoming Ma ◽  
Zhipeng Xie ◽  
Jiemin Wang ◽  
...  

Abstract. The Local land atmosphere coupling (LoCo) focuses on the interactions between soil conditions, surface fluxes, planetary boundary layer (PBL) growth, and the formations of convective clouds and precipitations. Study of LoCo over the Tibetan Plateau (TP) is of great significance for understanding TP's role in the Asian Water Tower. A series of real-case simulations using the Weather Research and Forecasting Model (WRF) with different combinations of land surface models (LSM) schemes and PBL schemes has been carried out to investigate the LoCo characteristics over a typical underlying surface in the central TP in rainy season. The LoCo characteristics in the study area are analyzed by applying a mixing diagram to the simulation results. The analysis indicates that the WRF simulations using the Noah with BouLac, MYNN, and YSU produce closer results to the observation in terms of curves of Cp*θ and Lv*q, surface fluxes (Hsfc and LEsfc), entrainment fluxes (Hent and LEent) at site BJ/Nagqu than those using the CLM with BouLac, MYNN, and YSU. The frequency distributions of Hsfc, LEsfc, Hent, and LEent in the study area confirm this result. The spatial distributions of simulated Hsfc, LEsfc, Hent, and LEent using WRF with Noah and BouLac suggest that the spatial distributions of Hsfc and LEsfc in the study area are consistent with that of soil moisture, but the spatial distributions of Hent and LEent are quite different from that of soil moisture. A close examination of the relationship between entrainment fluxes and cloud water content (QCloud) reveals that the grids with small Hent and large LEent tend to have high QCloud and Hsfc, suggesting that high Hsfc is conductive to convective cloud formation, which leads to small Hent and large LEent. Sensitivity analysis of LoCo to the soil moisture at site BJ/Nagqu indicates that on a sunny day, an increase in soil moisture leads to an increase in LEsfc but decreases in Hsfc, Hent, and LEent. The sensitivity of the relationship between simulated maximum daytime PBL height (PBLH) and mean daytime evapotranspiration (EF) in the study area to soil moisture indicates that the rate at which the maximum daytime PBLH decreases with the mean EF increase as the initial soil moisture goes up. The analysis of simulated Hsfc, LEsfc, Hent, and LEent under different soil moisture conditions reveals that the frequency of Hent ranging from 80 to 240 W/m2 and the frequency of LEent ranging from −240 to −90 W/m2 both increase as the initial soil moisture increases. Coupled with the changes in QCloud, the changes in Hent and LEent as the initial soil moisture increases indicate that the rise in soil moisture leads to an increase in the cloud amount but a decrease in QCloud.


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