scholarly journals The Sensitivity of Vegetation Phenology to Extreme Climate Indices in the Loess Plateau, China

2021 ◽  
Vol 13 (14) ◽  
pp. 7623
Author(s):  
Tingting Pei ◽  
Zhenxia Ji ◽  
Ying Chen ◽  
Huawu Wu ◽  
Qingqing Hou ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Growing Season ◽  
Sensitivity Coefficient ◽  
Scientific Basis ◽  
Maximum Temperature ◽  
Climate Indices ◽  
Vegetation Phenology ◽  
The Loess Plateau ◽  
Extreme Climate ◽  
Yearly Maximum

Climate changes, especially increased temperatures, and precipitation changes, have significant impacts on vegetation phenology. However, the response of vegetation phenology to the extreme climate in the Loess Plateau in Northwest China remains poorly quantified. The research described here analyzed the spatial change in vegetation phenology and the response of vegetation phenology to climate change in the Loess Plateau from 2001 to 2018, using data from seven extreme climate indices based on the ridge regression method. The results showed that extreme climate indexes, TNn (yearly minimum value of the daily minimum temperature), TXx (yearly maximum value of the daily maximum temperature), and RX5day (yearly maximum consecutive five-day precipitation) progressively increased from 2001 to 2018 in the Loess Plateau region, but decrease trend was found in DRT (diurnal temperature range). The start of the growing season (SOS) of vegetation gradually advanced with precipitation from northwest to southeast, and the rate was +0.38 d/a. The overall vegetation end of the growing season (EOS) was delayed, and the trend was −2.83 d/a. The sensitivity of the different vegetation phenology to different extreme weather indices showed obvious spatial differences, the sensitivity coefficient of SOS being mainly positive in the region, whereas the sensitivity coefficient of EOS was negative generally. More sensitivity was found in the EOS to extreme climate indexes than in the SOS. Forest, shrubland and grassland have similar responses to DRT and TNn; namely, both SOS and EOS are advanced with the increase in DRT and delayed with the increase in TNn (the sensitivity coefficient is quite different) but have different responses to RX5day and TXx. These results reveal that extreme climate events have a greater impact on vegetation EOS than on vegetation SOS, with these effects varying with vegetation types. This research can provide a scientific basis for formulating a scientific basis for regional vegetation restoration strategies and disaster prediction on the Loess Plateau.

scholarly journals Grassland Phenology’s Sensitivity to Extreme Climate Indices in the Sichuan Province, Western China

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1650
Author(s):  
Benjamin Adu ◽  
Gexia Qin ◽  
Chunbin Li ◽  
Jing Wu
Keyword(s):  
Climate Change ◽  
Vegetation Type ◽  
Temporal Distribution ◽  
Sensitivity Coefficient ◽  
Scientific Basis ◽  
Sichuan Province ◽  
Western China ◽  
Climate Indices ◽  
Extreme Climate ◽  
Minimum Daily Temperature

Depending on the vegetation type, extreme climate and drought events have a greater impact on the end of the season (EOS) and start of the season (SOS). This study investigated the spatial and temporal distribution characteristics of grassland phenology and its responses to seasonal and extreme climate changes in Sichuan Province from 2001 to 2020. Based on the data from 38 meteorological stations in Sichuan Province, this study calculated the 15 extreme climate indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The results showed that SOS was concentrated in mid-March to mid-May (80–140 d), and 61.83% of the area showed a significant advancing trend, with a rate of 0–1.5 d/a. The EOS was concentrated between 270–330 d, from late September to late November, and 71.32% showed a delayed trend. SOS was strongly influenced by the diurnal temperature range (DTR), yearly maximum consecutive five-day precipitation (RX5), and the temperature vegetation dryness index (TVDI), while EOS was most influenced by the yearly minimum daily temperature (TNN), yearly mean temperature (TEMP_MEAN), and TVDI. The RX5 day index showed an overall positive sensitivity coefficient for SOS. TNN index showed a positive sensitivity coefficient for EOS. TVDI showed positive and negative sensitivities for SOS and EOS, respectively. This suggests that extreme climate change, if it causes an increase in vegetation SOS, may also cause an increase in vegetation EOS. This research can provide a scientific basis for developing regional vegetation restoration and disaster prediction strategies in Sichuan Province.

scholarly journals Evolutionary Characteristics and Trade-Offs’ Development of Social–Ecological Production Landscapes in the Loess Plateau Region from a Resilience Point of View: A Case Study in Mizhi County, China

2020 ◽  
Vol 17 (4) ◽  
pp. 1308
Author(s):  
Hang Zhang ◽  
Hai Chen ◽  
Tianwei Geng ◽  
Di Liu ◽  
Qinqin Shi
Keyword(s):  
Loess Plateau ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Production Optimization ◽  
Evaluation Framework ◽  
The Loess Plateau ◽  
Plateau Region ◽  
Social Ecological ◽  
Trade Offs ◽  
The Social

Social-ecological production landscape resilience (SELPR) is a significant representation of the continuous supply capacity of landscape services. It is a quantitative assessment of the spatial-temporal evolution of SELPR under internal and external disturbances that provides a scientific basis for regional ecological environments and socio–economic development. Taking Mizhi County for the study of the Loess Plateau region, a three-dimensional (social system, ecosystem, and production system) SELPR evaluation framework was constructed. Data integration was performed using the watershed as the evaluation unit. This study quantitatively evaluated the spatial–temporal differentiation of the social–ecological production landscape (SELPs) subsystem’s resilience and the total SELPR in the study area and classified the areas from the three-system resilience combination level to achieve regional development trade-offs. The results were as follows: (1) In 2009–2018, the change in the social–ecological production landscapes pattern in Mizhi County showed a significant reduction in agricultural production landscapes, relatively stable social living landscapes, and an increase in ecological landscapes; (2) in 2009–2018, the SELPR increased by 12.38%. The spatial distribution of resilience was significantly different, showing a distribution pattern of high central and low surrounding areas; (3) the county’s watershed development zones were divided into five partitions: synergistic promotion areas, ecological restoration areas, social development areas, production optimization areas, and comprehensive remediation areas. The five types of zones have a certain agglomeration effect. In addition, the main obstacle factors affecting the SELPR of each zone are quite different. The key issues and development directions of different types of watersheds are also proposed in this paper.

Impact of revegetation of the Loess Plateau of China on the regional growing season water balance

2020 ◽  
Author(s):  
Weidong Guo ◽  
Andrew Pitman ◽  
Jun Ge ◽  
Beilei Zan ◽  
Congbin Fu
Keyword(s):  
Soil Moisture ◽  
Loess Plateau ◽  
Wrf Model ◽  
Growing Season ◽  
Weather Research And Forecasting ◽  
The Loess Plateau ◽  
Deep Soil ◽  
Bare Land ◽  
Biophysical Changes ◽  
The Impact

<p>To resolve a series of ecological and environmental problems over the Loess Plateau, the was initiated at the end of 1990s. Following the conversion of croplands and bare land on hillslopes to forests, the Loess Plateau has displayed a significant greening trend with soil erosion being reduced. However, the GFGP has also affected the hydrology of the Loess Plateau which has raised questions whether the GFGP should be continued in the future. We investigated the impact of revegetation on the hydrology of the Loess Plateau using high resolution simulations and multiple realisations with the Weather Research and Forecasting (WRF) model. Results suggests that land cover change since the launch of the GFGP has reduced runoff and soil moisture due to enhanced evapotranspiration. Further revegetation associated with the GFGP policy is likely to increase evapotranspiration further, and thereby reduce runoff and soil moisture. The increase in evapotranspiration is associated with biophysical changes, including deeper roots that deplete deep soil moisture stores. However, despite the increase in evapotranspiration our results show no impact on rainfall. Our study cautions against further revegetation over the Loess Plateau given the reduction in water available for agriculture and human settlements, without any significant compensation from rainfall.</p>

scholarly journals Climate change: vegetation and phenological phase dynamics

2020 ◽  
Vol 12 (4) ◽  
pp. 495-509
Author(s):  
Yang Li ◽  
Yaochen Qin ◽  
Liqun Ma ◽  
Ziwu Pan
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Growing Season ◽  
Vegetation Coverage ◽  
The Loess Plateau ◽  
Content Type ◽  
Phase Dynamics ◽  
Filtering Algorithm ◽  
The Past ◽  
Environmental Treatment

Purpose The ecological environment of the Loess Plateau, China, is extremely fragile under the context of global warming. Over the past two decades, the vegetation of the Loess Plateau has undergone great changes. This paper aims to clarify the response mechanisms of vegetation to climate change, to provide support for the restoration and environmental treatment of vegetation on the Loess Plateau. Design/methodology/approach The Savitsky–Golay (S-G) filtering algorithm was used to reconstruct time series of moderate resolution imaging spectroradiometer (MODIS) 13A2 data. Combined with trend analysis and partial correlation analysis, the influence of climate change on the phenology and enhanced vegetation index (EVI) during the growing season was described. Findings The S-G filtering algorithm is suitable for EVI reconstruction of the Loess Plateau. The date of start of growing season was found to gradually later along the Southeast–Northwest direction, whereas the date of the end of the growing season showed the opposite pattern and the length of the growing season gradually shortened. Vegetation EVI values decreased gradually from Southeast to Northwest. Vegetation changed significantly and showed clear differentiation according to different topographic factors. Vegetation correlated positively with precipitation from April to July and with temperature from August to November. Originality/value This study provides technical support for ecological environmental assessment, restoration of regional vegetation coverage and environmental governance of the Loess Plateau over the past two decades. It also provides theoretical support for the prediction model of vegetation phenology changes based on remote sensing data.

scholarly journals Seasonal Variations in Carbon, Nitrogen, and Phosphorus Stoichiometry of a Robinia pseudoacacia Plantation on the Loess Hilly Region, China

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 214
Author(s):  
Congguo Dong ◽  
Yuning Qiao ◽  
Yang Cao ◽  
Yunming Chen ◽  
Xu Wu ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Seasonal Variations ◽  
Environmental Changes ◽  
Robinia Pseudoacacia ◽  
Growing Season ◽  
Utilization Efficiency ◽  
The Loess Plateau ◽  
N Content ◽  
C:N:P Stoichiometry ◽  
Hilly Region

Seasonal variations in stoichiometry are a crucial regulatory mechanism for plant communities that respond to environmental changes. However, the seasonal characteristics of stoichiometry in plants, litter, and soil are poorly understood, especially in plantation ecosystems. Therefore, we explored the seasonal variations of C, N, and P contents and ratios between plants, litter, and soil of a Robinia pseudoacacia plantation on the Loess Plateau in China in 2017. The results indicate that the C, N, P contents and ratios in plants, litter and soil showed different seasonal patterns. The N and P contents of tree and shrub leaves substantially decreased over the growing season, while the C:N, C:P, and N:P ratios exhibited the opposite trend. The utilization efficiency of the N and P elements by trees and shrubs gradually increased with the change of the growing season. These results suggest that the C:N:P stoichiometry of plants was more sensitive to seasonal changes than the litter and soil; therefore, the potential impacts of time should be considered when using stoichiometry to explore the utilization of plant nutrients. Additionally, the P content between tree leaves and soil and the N content between herb leaves and soil were significantly positively correlated, indicating that the growth of the tree and herb layer in the R. pseudoacacia plantation in the area was restricted by P and N, respectively. Meanwhile, the N content in the leaves between trees and herbs showed a significant negative correlation, indicating that N competition existed between R. pseudoacacia and understory herbs, which was not conducive to the effective use of environmental resources by the R. pseudoacacia plantation ecosystem. This study contributes to vegetation restoration and plantation management on the Loess Plateau and provides basic information for global stoichiometric analyses.

The impact of plant water uptake and recharge on groundwater level at a site in the Loess Plateau of China

2012 ◽  
Vol 44 (1) ◽  
pp. 106-116 ◽  
Author(s):  
H. Yasuda ◽  
R. Berndtsson ◽  
O. Hinokidani ◽  
J. Huang ◽  
T. Saito ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Loess Plateau ◽  
Water Uptake ◽  
Shallow Groundwater ◽  
Seasonal Fluctuation ◽  
Growing Season ◽  
Diurnal Fluctuation ◽  
Plant Water ◽  
The Loess Plateau ◽  
Plant Water Uptake

Shallow groundwater in unconsolidated sediments represents a substantial water resource in the Chinese Loess Plateau. However, prior to development of the water supply for agriculture, annual and seasonal fluctuation of the recharge mechanism should be clarified. Since the region is arid, the effect of plant water uptake on groundwater fluctuation must also be assessed. A study was therefore undertaken to clarify groundwater recharge together with interaction between the plant ecosystem and shallow groundwater at a field site in the Loess Plateau of China. Observations showed that recharge response of the groundwater level (GWL) was limited except for intensive rainfall during the rainy season. The main recharge to the groundwater occurred from horizontal inflow from focused recharge at the upstream end of the site. Fluctuation of the GWL produced by plant water uptake was monitored during the growing season. For seasonal fluctuation of GWL, temperature was most important, while for diurnal fluctuation of GWL during the growing season, solar radiation was most important. During the growing season, the GWL declined during the daylight hours and recovered during the night. The diurnal fluctuation was well synchronized with the solar radiation, consistent with plant-water uptake by shrubs surrounding one of the observation wells.

scholarly journals PROYEKSI CURAH HUJAN DAN SUHU UDARA EKSTRIM MASA DEPAN PERIODE TAHUN 2021-2050 KOTA BANJARBARU KALIMANTAN SELATAN

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Presli Panusunan Simanjuntak ◽  
Annisa Dwi Nopiyanti ◽  
Agus Safril
Keyword(s):  
Air Temperature ◽  
Extreme Temperature ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Maximum Temperature ◽  
Future Climate Change ◽  
Climate Indices ◽  
Change Scenario ◽  
Extreme Climate ◽  
Rainfall Projection

Peningkatan konsentrasi gas rumah kaca telah menyebabkan perubahan pada kejadian iklim ekstrim. Penelitian ini menggunakan skenario RCP 4.5 sebagai skenario perubahaan iklim masa mendatang untuk mengetahui tren indeks suhu dan curah hujan ekstrim periode 2021-2050 di Kota Banjarbaru. Data suhu maksimum, suhu minimum dan curah hujan harian hasil proyeksi tahun 2021-2050 diolah dengan Software RClimDex sehingga didapatkan data indeks temperatur dan hujan ekstrim. Indeks-indeks tersebut merupakan indeks iklim ekstrim yang ditetapkan oleh ETCCDMI yang terdiri atas TN90p, , TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD dan CWD. Hasil penelitian ini menunjukkan bahwa diproyeksikan pada 2020-2050 tren suhu udara akan meningkat signifikan di kota Banjarbaru terutama suhu udara minimum selanjutnya pola prespitasi juga mengalami peningkatan terutama akumulasi curah hujan 5 hari berturut-turut. Meningkatknya jumlah hari kering dan berkurangnya jumlah hari basah, serta semakin tinggi akumulasi curah hujan harian namun hari basah yang sedikit akan menghasilkan curah hujan harian yang tinggi (ekstrim) setiap kejadian hari basah. Kata kunci: banjarbaru, curah hujan, ekstrim, suhu. ABSTRACT  Increased concentrations of greenhouse gases have caused changes in extreme climate events. This study uses the RCP 4.5 scenario as a future climate change scenario to determine the temperature index and extreme rainfall trends in the 2021-2050 period in Banjarbaru. Data of maximum temperature, minimum temperature and daily rainfall projection results in 2021-2050 are processed with RClimDex Software so that the temperature and extreme rain index data are obtained. The indices are extreme climate indices determined by ETCCDMI consisting of TN90p, TX90p, TNn, TNx, TXn, TXx, TMAXmean, TMINmean, RX1day, RX5day, SDII, CDD and CWD. The results of this study indicate that it is projected that in 2020-2050 air temperature trends will increase significantly in the city of Banjarbaru especially the minimum air temperature then the pattern of prespitations will also increase especially the accumulation of rainfall for 5 consecutive days. Increasing the number of dry days and decreasing the number of wet days, as well as the higher accumulation of daily rainfall but a small wet day will produce high daily rainfall (extreme) every event of a wet day. Keywords: banjarbaru, extreme, temperature, rainfall.

scholarly journals Trends in Extreme Climate Indices in Cherrapunji for the period 1979 to 2020

2021 ◽  
Author(s):  
Raju Kalita ◽  
Dipangkar Kalita ◽  
Atul Saxena
Keyword(s):  
Climate Change ◽  
Negative Trend ◽  
Maximum Temperature ◽  
Daily Minimum Temperature ◽  
Daily Maximum Temperature ◽  
Trend Test ◽  
Climate Indices ◽  
Daily Maximum ◽  
Positive Trend ◽  
Extreme Climate

Abstract We have used Mann-Kendall trend test and Sen’s slope estimator method to find out significant changes in extreme climate indices for daily temperature as well as precipitation over the period 1979 to 2020 in Cherrapunji. In the present study, a total of 24 precipitation and temperature based extreme climate indices were calculated using RClimDex v 1.9-3. Among 24 indices, 7 were derived from number of days above nn mm rainfall (Rnn) according to Indian Meteorological Department (IMD) convention and the rest were in accordance with the Expert Team on Climate Change Detection and Indices (ETCCDI). It was observed that, among all the indices, consecutive dry days (CDD), summer days (SU25) and very light rainfall (VLR) days increased significantly with 0.54, 1.58 and 0.14 days/year respectively, while only consecutive wet days (CWD) decreased significantly with 0.36 days/year. A slight negative trend was also observed in case of tropical nights (TR20) and among the other precipitation indices as well. Again, the indices associated with daily maximum temperature increased significantly with annual change of 0.06 to 0.07 ⁰C/year. And for indices associated with daily minimum temperature, almost no change or a slight negative change was observed, except a significant positive trend in February and significant negative trend in November for TNN only. The analysis reveals that some of the extreme climate indices which explains the climatic conditions of Cherrapunji has changed a lot over the period of 42 years and if this trend continues then Cherrapunji will be under threat when it comes to climate change.

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