Silicon distribution in meadow steppe and typical steppe of northern China and its implications for phytolith carbon sequestration

2017 ◽  
Vol 73 (2) ◽  
pp. 482-492 ◽  
Author(s):  
Z. Ji ◽  
X. Yang ◽  
Z. Song ◽  
H. Liu ◽  
X. Liu ◽  
...  
2014 ◽  
Vol 34 (19) ◽  
Author(s):  
柴曦 CHAI Xi ◽  
梁存柱 LIANG Cunzhun ◽  
梁茂伟 LIANG Maowei ◽  
韩伟华 HAN Weihua ◽  
李智勇 LI Zhiyong ◽  
...  

2014 ◽  
Vol 36 (6) ◽  
pp. 601 ◽  
Author(s):  
Xiangyang Hou ◽  
Yantin Yin ◽  
David Michalk ◽  
Xiangjun Yun ◽  
Yong Ding ◽  
...  

Herders’ desirable stocking rates and their opinions of overstocking were studied using survey and multi-regression methods in the meadow steppe, typical steppe and desert steppe regions of northern China. It was found that individual herders had their own perception of their particular ‘desirable stocking rate’, which referred to the number of livestock that the herders thought they could keep or maintain on an area of rangeland over a specified period of time. These perceptions were not in line with the ‘balancing animals and grass’ policy of the Chinese government, and herders used them as a guide to adjust stock-breeding practices. Most herders admitted that they bred more livestock now than 10 years ago, but insisted that there was no overstocking and many even thought that their rangelands could still carry more livestock. They also held the view that they took into account the carrying capacity of rangelands when making decisions about livestock-breeding practices. Individual herders thought that the reasonable stocking rate range should be 0.75–1.50 sheep units ha–1 (meadow steppe), 0.60–1.50 sheep units ha–1 (typical steppe), and 0.50–0.75 sheep units ha–1 (desert steppe), respectively. The herders from the desert steppe regions were most concerned about the overstocking of rangelands, and the concern of herders was in the order desert steppe > typical steppe > meadow steppe. The herders with more formal education and those who worked in a village council and had smaller areas of rangelands, were more concerned about the overstocking of rangelands. It is argued that such herders should be given more access to policy and market information, including extensive grazing and modern stall-feeding technologies, and encouraged to reduce their desirable stocking rates, leading to more sustainable rangeland management in northern China.


2018 ◽  
Vol 7 (8) ◽  
pp. 290 ◽  
Author(s):  
Jun Wang ◽  
Tiancai Zhou ◽  
Peihao Peng

Because the dynamics of phenology in response to climate change may be diverse in different grasslands, quantifying how climate change influences plant growth in different grasslands across northern China should be particularly informative. In this study, we explored the spatiotemporal variation of the phenology (start of the growing season [SOS], peak of the growing season [POS], end of the growing season [EOS], and length of the growing season [LOS]) across China’s grasslands using a dataset of the GIMMS3g normalized difference vegetation index (NDVI, 1985–2010), and determined the effects of the annual mean temperature (AMT) and annual mean precipitation (AMP) on the significantly changed phenology. We found that the SOS, POS, and EOS advanced at the rates of 0.54 days/year, 0.64 days/year, and 0.65 days/year, respectively; the LOS was shortened at a rate of 0.62 days/year across China’s grasslands. Additionally, the AMT combined with the AMP explained the different rates (ER) for the significantly dynamic SOS in the meadow steppe (R2 = 0.26, p = 0.007, ER = 12.65%) and typical steppe (R2 = 0.28, p = 0.005, ER = 32.52%); the EOS in the alpine steppe (R2 = 0.16, p < 0.05, ER = 6.22%); and the LOS in the alpine (R2 = 0.20, p < 0.05, ER = 6.06%), meadow (R2 = 0.18, p < 0.05, ER = 16.69%) and typical (R2 = 0.18, p < 0.05, ER = 19.58%) steppes. Our findings demonstrated that the plant phenology in different grasslands presented discrepant dynamic patterns, highlighting the fact that climate change has played an important role in the variation of the plant phenology across China’s grasslands, and suggested that the variation and relationships between the climatic factors and phenology in different grasslands should be explored further in the future.


2020 ◽  
Author(s):  
Xuguang Tang ◽  
Yanlian Zhou ◽  
Hengpeng Li ◽  
Li Yao ◽  
Zhi Ding ◽  
...  

Abstract Background: Grassland ecosystems play an important role in the terrestrial carbon cycles through carbon emission by ecosystem respiration (Re) and carbon uptake by plant photosynthesis (GPP). Surprisingly, given Re occupies a large component of annual carbon balance, rather less attention has been paid to developing the estimates of Re compared to GPP.Results: Based on 11 flux sites over the diverse grassland ecosystems in northern China, this study examined the amounts of carbon released by Re as well as the dominant environmental controls across temperate meadow steppe, typical steppe, desert steppe and alpine meadow, respectively. Multi-year mean Re revealed relatively less CO2 emitted by the desert steppe in comparison with other grassland ecosystems. Meanwhile, C emissions of all grasslands were mainly controlled by the growing period. Correlation analysis revealed that apart from air and soil temperature, soil water content exerted a strong effect on the variability in Re, which implied the great potential to derive Re using relevant remote sensing data. Then, these field-measured Re data were up-scaled to large areas using time-series MODIS information and remote sensing-based piecewise regression models. These semi-empirical models appeared to work well with a small margin of error (R2 and RMSE ranged from 0.45 to 0.88 and from 0.21 to 0.69 g C m-2 d-1, respectively). Conclusions: Generally, the piecewise models from the growth period and dormant season performed better than model developed directly from the entire year. Moreover, the biases between annual mean Re observations and the remotely-derived products were usually within 20%. Finally, the regional Re emissions across northern China's grasslands was approximately 100.66 Tg C in 2010, about 1/3 of carbon fixed from the MODIS GPP product. Specially, the desert steppe exhibited the highest ratio, followed by the temperate meadow steppe, typical steppe and alpine meadow. Therefore, this work provides a novel framework to accurately predict the spatio-temporal patterns of Re over large areas, which can greatly reduce the uncertainties in global carbon estimates and climate projections.


2020 ◽  
Author(s):  
Xuguang Tang ◽  
Yanlian Zhou ◽  
Hengpeng Li ◽  
Li Yao ◽  
Zhi Ding ◽  
...  

Abstract Background : Grassland ecosystems play an important role in the terrestrial carbon cycles through carbon emission by ecosystem respiration ( R e ) and carbon uptake by plant photosynthesis (GPP). Surprisingly, given R e occupies a large component of annual carbon balance, rather less attention has been paid to developing the estimates of R e compared to GPP. Results : Based on 11 flux sites over the diverse grassland ecosystems in northern China, this study examined the amounts of carbon released by R e as well as the dominant environmental controls across temperate meadow steppe, typical steppe, desert steppe and alpine meadow, respectively. Multi-year mean R e revealed relatively less CO 2 emitted by the desert steppe in comparison with other grassland ecosystems. Meanwhile, C emissions of all grasslands were mainly controlled by the growing period. Correlation analysis revealed that apart from air and soil temperature, soil water content exerted a strong effect on the variability in R e , which implied the great potential to derive R e using relevant remote sensing data. Then, these field-measured R e data were up-scaled to large areas using time-series MODIS information and remote sensing-based piecewise regression models. These semi-empirical models appeared to work well with a small margin of error ( R 2 and RMSE ranged from 0.45 to 0.88 and from 0.21 to 0.69 g C m -2 d -1 , respectively). Conclusions : Generally, the piecewise models from the growth period and dormant season performed better than model developed directly from the entire year. Moreover, the biases between annual mean R e observations and the remotely-derived products were usually within 20%. Finally, the regional R e emissions across northern China's grasslands was approximately 100.66 Tg C in 2010, about 1/3 of carbon fixed from the MODIS GPP product. Specially, the desert steppe exhibited the highest ratio, followed by the temperate meadow steppe, typical steppe and alpine meadow. Therefore, this work provides a novel framework to accurately predict the spatio-temporal patterns of R e over large areas, which can greatly reduce the uncertainties in global carbon estimates and climate projections.


2014 ◽  
Vol 478 ◽  
pp. 1-11 ◽  
Author(s):  
Haotian Yang ◽  
Xinrong Li ◽  
Zengru Wang ◽  
Rongliang Jia ◽  
Lichao Liu ◽  
...  

2019 ◽  
Vol 11 (12) ◽  
pp. 3256 ◽  
Author(s):  
Jie Yang ◽  
Zhiqiang Wan ◽  
Suld Borjigin ◽  
Dong Zhang ◽  
Yulong Yan ◽  
...  

Normalized difference vegetation index (NDVI) is commonly used to indicate vegetation density and condition. NDVI was mostly correlated with climate factors. We analyzed changing trends of NDVI in different types of grassland in Inner Mongolia and the response of NDVI to climatic variation from 1982 to 2011. NDVI of meadow steppe increased significantly in spring while it decreased in other seasons. The annual mean NDVI in typical steppe and desert steppe increased significantly in the last 30a. However, in the greatest area of steppe desert, the NDVI had no significant change in summer, autumn, and the growing season. In meadow steppe, typical steppe, and desert steppe, the area showed a positive correlation of NDVI to temperature as highest in spring compared to other seasons, because warming in spring is beneficial to the plant growth. However, in the greatest area of steppe desert, the correlation of NDVI to temperature was not significant. The NDVI was positively correlated to precipitation in four types of grassland. In the steppe desert, the precipitation had no significant effect on the NDVI due to the poor vegetation cover in this region. The NDVI was not significantly correlated to the precipitation in autumn because of vegetation withering in the season and not need precipitation. Precipitation was a more important factor rather than temperature to NDVI in the region. The response of NDVI to temperature and precipitation in different seasons should be studied in more detail and the effect of other factors on NDVI should be considered in future research.


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