scholarly journals Projections for the changes in growing season length of tree-ring formation on the Tibetan Plateau based on CMIP5 model simulations

2017 ◽  
Vol 62 (4) ◽  
pp. 631-641 ◽  
Author(s):  
Minhui He ◽  
Bao Yang ◽  
Vladimir Shishov ◽  
Sergio Rossi ◽  
Achim Bräuning ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Growing Season ◽  
Ring Formation ◽  
The Tibetan Plateau ◽  
Cmip5 Model ◽  
Season Length ◽  
Model Simulations ◽  
Growing Season Length

scholarly journals Growing Season Precipitation Rather than Growing Season Length Predominates Maximum Normalized Difference Vegetation Index in Alpine Grasslands on the Tibetan Plateau

2020 ◽  
Vol 12 (3) ◽  
pp. 968
Author(s):  
Jiang Wei Wang ◽  
Meng Li ◽  
Guang Yu Zhang ◽  
Hao Rui Zhang ◽  
Cheng Qun Yu
Keyword(s):  
Tibetan Plateau ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Season Length ◽  
Alpine Grasslands ◽  
Vegetation Productivity ◽  
Growing Season Length ◽  
Growing Season Precipitation

Precipitation and growing season length (GSL) are vital abiotic and biotic variables in controlling vegetation productivity in alpine regions. However, their relative effects on vegetation productivity have not been fully understood. In this study, we examined the responses of the maximum normalized difference vegetation index (NDVImax) to growing season precipitation (GSP) and GSL from 2000 to 2013 in 36 alpine grassland sites on the Tibetan Plateau. Our results indicated that NDVImax showed a positive relationship with prolonged GSL (R2 = 0.12) and GSP (R2 = 0.39). The linear slope of NDVImax increased with that of GSP rather than GSL. Therefore, GSP had a stronger effect on NDVImax than did GSL in alpine grasslands on the Tibetan Plateau.

Process-based modeling of tree-ring formation and its relationships with climate on the Tibetan Plateau

2017 ◽  
Vol 42 ◽  
pp. 31-41 ◽  
Author(s):  
Minhui He ◽  
Vladimir Shishov ◽  
Nazgul Kaparova ◽  
Bao Yang ◽  
Achim Bräuning ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Ring Formation ◽  
The Tibetan Plateau

scholarly journals ANALYZING THE VELOCITY OF VEGETATION PHENOLOGY OVER THE TIBETAN PLATEAU USING GIMMS NDVI3g DATA

2018 ◽  
Vol XLII-3 ◽  
pp. 2575-2578
Author(s):  
Y. K. Zhou
Keyword(s):  
Tibetan Plateau ◽  
Global Environmental Change ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Vegetation Phenology ◽  
Terrestrial Vegetation ◽  
Velocity Change ◽  
Growing Season Length ◽  
Change Context ◽  
Gimms Ndvi3g

Global environmental change is rapidly altering the dynamics of terrestrial vegetation, and phenology is a classic proxy to detect the response of vegetation to the changes. On the Tibetan Plateau, the earlier spring and delayed autumn vegetation phenology is widely reported. Remotely sensed NDVI can serve as a good data source for vegetation phenology study. Here GIMMS NDVI3g data was used to detect vegetation phenology status on the Tibetan Plateau. The spatial and temporal gradients are combined to depict the velocity of vegetation expanding process. This velocity index represents the instantaneous local velocity along the Earth’s surface needed to maintain constant vegetation condition. This study found that NDVI velocity show a complex spatial pattern. A considerable number of regions display a later starting of growing season (SOS) and earlier end of growing season (EOS) reflected by the velocity change, particularly in the central part of the plateau. Nearly 74 % vegetation experienced a shortened growing season length. Totally, the magnitude of the phenology velocity is at a small level that reveals there is not a significant variation of vegetation phenology under the climate change context.

scholarly journals Reconciling the Discrepancy of Post-Volcanic Cooling Estimated from Tree-Ring Reconstructions and Model Simulations over the Tibetan Plateau

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 738
Author(s):  
Jianping Duan ◽  
Peili Wu ◽  
Zhuguo Ma
Keyword(s):  
Tibetan Plateau ◽  
Climate Variability ◽  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
The Tibetan Plateau ◽  
Model Simulations ◽  
Internal Climate Variability

Volcanic eruptions are a major factor influencing global climate variability, usually with a cooling effect. The magnitudes of post-volcanic cooling from historical eruptions estimated by tree-ring reconstructions differ considerably with the current climate model simulations. It remains controversial on what is behind such a discrepancy. This study investigates the role of internal climate variability (i.e., El Niño/Southern Oscillation (ENSO) warm phase) with a regional focus on the Tibetan Plateau (TP), using tree-ring density records and long historical climate simulations from the fifth Coupled Model Intercomparsion Project (CMIP5). We found that El Niño plays an important role behind the inconsistencies between model simulations and reconstructions. Without associated El Niño events, model simulations agree well with tree-ring records. Divergence appears when large tropical eruptions are followed by an El Niño event. Model simulations, on average, tend to overestimate post-volcanic cooling during those periods as the occurrence of El Niño is random as part of internal climate variability.

scholarly journals Tree growth and its climate signal along latitudinal and altitudinal gradients: comparison of tree rings between Finland and the Tibetan Plateau

2017 ◽  
Vol 14 (12) ◽  
pp. 3083-3095 ◽  
Author(s):  
Lixin Lyu ◽  
Susanne Suvanto ◽  
Pekka Nöjd ◽  
Helena M. Henttonen ◽  
Harri Mäkinen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Tree Growth ◽  
Latitudinal Gradient ◽  
Ring Width ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Climate Variables ◽  
Climate Data ◽  
Altitudinal Gradients

Abstract. Latitudinal and altitudinal gradients can be utilized to forecast the impact of climate change on forests. To improve the understanding of how these gradients impact forest dynamics, we tested two hypotheses: (1) the change of the tree growth–climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. To address this, we utilized tree-ring data from a latitudinal gradient in Finland and from two altitudinal gradients on the Tibetan Plateau. We analysed the latitudinal and altitudinal growth patterns in tree rings and investigated the growth–climate relationship of trees by correlating ring-width index chronologies with climate variables, calculating with flexible time windows, and using daily-resolution climate data. High latitude and altitude plots showed higher correlations between tree-ring chronologies and growing season temperature. However, the effects of winter temperature showed contrasting patterns for the gradients. The timing of the highest correlation with temperatures during the growing season at southern sites was approximately 1 month ahead of that at northern sites in the latitudinal gradient. In one out of two altitudinal gradients, the timing for the strongest negative correlation with temperature at low-altitude sites was ahead of treeline sites during the growing season, possibly due to differences in moisture limitation. Mean values and the standard deviation of tree-ring width increased with increasing mean July temperatures on both types of gradients. Our results showed similarities of tree growth responses to increasing seasonal temperature between latitudinal and altitudinal gradients. However, differences in climate–growth relationships were also found between gradients due to differences in other factors such as moisture conditions. Changes in the timing of the most critical climate variables demonstrated the necessity for the use of daily-resolution climate data in environmental gradient studies.

scholarly journals Insights into elevation-dependent warming in the Tibetan Plateau-Himalayas from CMIP5 model simulations

2016 ◽  
Vol 48 (11-12) ◽  
pp. 3991-4008 ◽  
Author(s):  
Elisa Palazzi ◽  
Luca Filippi ◽  
Jost von Hardenberg
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Cmip5 Model ◽  
Model Simulations

scholarly journals New perspective on spring vegetation phenology and global climate change based on Tibetan Plateau tree-ring data

2017 ◽  
Vol 114 (27) ◽  
pp. 6966-6971 ◽  
Author(s):  
Bao Yang ◽  
Minhui He ◽  
Vladimir Shishov ◽  
Ivan Tychkov ◽  
Eugene Vaganov ◽  
...  
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Tibetan Plateau ◽  
Tree Ring ◽  
Remote Sensing Data ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Vegetation Phenology ◽  
Sensing Data ◽  
Tree Ring Data

Phenological responses of vegetation to climate, in particular to the ongoing warming trend, have received much attention. However, divergent results from the analyses of remote sensing data have been obtained for the Tibetan Plateau (TP), the world’s largest high-elevation region. This study provides a perspective on vegetation phenology shifts during 1960–2014, gained using an innovative approach based on a well-validated, process-based, tree-ring growth model that is independent of temporal changes in technical properties and image quality of remote sensing products. Twenty composite site chronologies were analyzed, comprising about 3,000 trees from forested areas across the TP. We found that the start of the growing season (SOS) has advanced, on average, by 0.28 d/y over the period 1960–2014. The end of the growing season (EOS) has been delayed, by an estimated 0.33 d/y during 1982–2014. No significant changes in SOS or EOS were observed during 1960–1981. April–June and August–September minimum temperatures are the main climatic drivers for SOS and EOS, respectively. An increase of 1 °C in April–June minimum temperature shifted the dates of xylem phenology by 6 to 7 d, lengthening the period of tree-ring formation. This study extends the chronology of TP phenology farther back in time and reconciles the disparate views on SOS derived from remote sensing data. Scaling up this analysis may improve understanding of climate change effects and related phenological and plant productivity on a global scale.

scholarly journals Challenges in Reconciling Satellite-Based and Locally Reported Estimates of Wetland Change: A Case of Topographically Constrained Wetlands on the Eastern Tibetan Plateau

2021 ◽  
Vol 13 (8) ◽  
pp. 1484
Author(s):  
Jianing Fang ◽  
Benjamin Zaitchik
Keyword(s):  
Tibetan Plateau ◽  
Vegetation Structure ◽  
Reference Evapotranspiration ◽  
Growing Season ◽  
Scientific Data ◽  
Balance Model ◽  
The Tibetan Plateau ◽  
Wetland Degradation ◽  
Landsat Images ◽  
Growing Season Length

The coupling of rapid warming and wetland degradation on the Tibetan Plateau has motivated studies of climate influence on wetland change in the region. These studies typically examine large, topographically homogeneous regions, whereas conservation efforts sometimes require fine-grained information in rugged terrain. This study addresses topographically constrained wetlands in Eastern Tibetan, where headers report significant wetland degradation. We used Landsat images to examine changes in wetland areas and Sentinel-1 SAR images to investigate water level and vegetation structure. We also analyzed trends in precipitation, growing season length, and reference evapotranspiration in weather station records. Snow cover and the vegetation growing season were quantified using MODIS observations. We analyzed estimates of actual evapotranspiration using the Atmosphere-Land Exchange Inverse model (ALEXI) and the Simplified Surface Energy Balance model (SSEBop). Satellite-informed analyses failed to confirm herders’ accounts of reduced wetland function, as no coherent trends were found in wetland area, water content, or vegetation structure. An analysis of meteorological records did indicate a warming-induced increase in reference evapotranspiration, and both meteorological records and satellites suggest that the growing season had lengthened, potentially increasing water demand and driving wetland change. The discrepancies between the satellite data and local observations pointed to temporal, spatial, and epistemological gaps in combining scientific data with empirical evidence in understanding wetland change on the Tibetan Plateau.

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