scholarly journals Pattern Dynamics of Vegetation Growth With Saturated Water Absorption

2021 ◽  
Vol 9 ◽  
Author(s):  
Li Li ◽  
Jia-Hui Cao ◽  
Xin-Yue Bao
Keyword(s):  
Water Absorption ◽  
Vegetation Dynamics ◽  
Vegetation Pattern ◽  
Typical Feature ◽  
Water Model ◽  
Absorption Effect ◽  
Vegetation Growth ◽  
Pattern Dynamics ◽  
Saturated Water ◽  
Water Absorption Effect

Regular pattern is a typical feature of vegetation distribution and thus it is important to study the law of vegetation evolution in the fields of desertification and environment conservation. The saturated water absorption effect between the soil water and vegetation plays an crucial role in the vegetation patterns in semi-arid regions, yet its influence on vegetation dynamics is largely ignored. In this paper, we pose a vegetation-water model with saturated water absorption effect of vegetation. Our results show that the parameter 1/P, which is conversion coefficient of water absorption, has a great impact on pattern formation of vegetation: with the increase of P, the density of vegetation decrease, and meanwhile it can induce the transition of different patterns structures. In addition, we find that the increase of appropriate precipitation can postpone the time on the phase transition of the vegetation pattern. The obtained results systematically reveal the effect of saturated water absorption on vegetation systems which well enrich the findings in vegetation dynamics and thus may provide some new insights for vegetation protection.

scholarly journals Fracture Toughness Investigation on Long Kenaf/Woven Glass Hybrid Composite Due To Water Absorption Effect

2012 ◽  
Vol 41 ◽  
pp. 1667-1673 ◽  
Author(s):  
Z. Salleh ◽  
Y.M. Taib ◽  
Koay Mei Hyie ◽  
M. Mihat ◽  
M.N. Berhan ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Water Absorption ◽  
Hybrid Composite ◽  
Absorption Effect ◽  
Water Absorption Effect

Water Absorption Effect on the Propagation Velocity of Normal Waves in Composite Rebars

2019 ◽  
Vol 970 ◽  
pp. 202-209
Author(s):  
Olga V. Muravieva ◽  
Robert R. Khasanov ◽  
Viktor A. Strizhak ◽  
Sergey S. Mkrtchyan
Keyword(s):  
Water Absorption ◽  
Propagation Velocity ◽  
Mechanical Characteristics ◽  
Experimental Studies ◽  
Absorption Effect ◽  
Acoustic Waveguide ◽  
Torsional Waves ◽  
Water Absorption Effect ◽  
Waveguide Method ◽  
Physical And Mechanical Characteristics

The article proposes the use of the acoustic waveguide method with normal Pochhammer waves to estimate the water absorption of composite fiberglass rebars. The results of experimental studies on the water absorption and temperature influence on the propagation velocity of rod and torsional waves in composite rebars samples with different physical and mechanical characteristics are presented. The sensitivity of the wave velocity parameter to water absorption and temperature fluctuations is estimated. The proposed acoustic waveguide method is characterized by high accuracy, reliability and efficiency.

Water Absorption Effect on the Dynamic Properties of Nylon-6 by Dielectric Spectroscopy

2003 ◽  
Vol 36 (26) ◽  
pp. 9840-9850 ◽  
Author(s):  
E. Laredo ◽  
M. Grimau ◽  
F. Sánchez ◽  
A. Bello
Keyword(s):  
Water Absorption ◽  
Dielectric Spectroscopy ◽  
Dynamic Properties ◽  
Nylon 6 ◽  
Absorption Effect ◽  
Water Absorption Effect

scholarly journals Effects of Climate Change on Land Cover Change and Vegetation Dynamics in Xinjiang, China

2020 ◽  
Vol 17 (13) ◽  
pp. 4865 ◽  
Author(s):  
Haochen Yu ◽  
Zhengfu Bian ◽  
Shouguo Mu ◽  
Junfang Yuan ◽  
Fu Chen
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Land Cover Change ◽  
Extreme Precipitation ◽  
Vegetation Dynamics ◽  
Pearson Correlation ◽  
Extreme Temperature ◽  
Climate Extremes ◽  
Linear Regression Method ◽  
Vegetation Growth

Since the Silk-road Economic belt initiatives were proposed, Xinjiang has provided a vital strategic link between China and Central Asia and even Eurasia. However, owing to the weak and vulnerable ecosystem in this arid region, even a slight climate change would probably disrupt vegetation dynamics and land cover change. Thus, there is an urgent need to determine the Normalized Difference Vegetation Index (NDVI) and Land-use/Land-cover (LULC) responses to climate change. Here, the extreme-point symmetric mode decomposition (ESMD) method and linear regression method (LRM) were applied to recognize the variation trends of the NDVI, temperature, and precipitation between the growing season and other seasons. Combining the transfer matrix of LULC, the Pearson correlation analysis was utilized to reveal the response of NDVI to climate change and climate extremes. The results showed that: (1) Extreme temperature showed greater variation than extreme precipitation. Both the ESMD and the LRM exhibited an increased volatility trend for the NDVI, with the significant improvement regions mainly located in the margin of basins. (2) Since climate change had a warming trend, the permanent snow has been reduced by 20,436 km2. The NDVI has a higher correlation to precipitation than temperature. Furthermore, the humid trend could provide more suitable conditions for vegetation growth, but the warm trend might prevent vegetation growth. Spatially, the response of the NDVI in North Xinjiang (NXC) was more sensitive to precipitation than that in South Xinjiang (SXC). Seasonally, the NDVI has a greater correlation to precipitation in spring and summer, but the opposite occurs in autumn. (3) The response of the NDVI to extreme precipitation was stronger than the response to extreme temperature. The reduction in diurnal temperature variation was beneficial to vegetation growth. Therefore, continuous concentrated precipitation and higher night-time-temperatures could enhance vegetation growth in Xinjiang. This study could enrich the understanding of the response of land cover change and vegetation dynamics to climate extremes and provide scientific support for eco-environment sustainable management in the arid regions.

scholarly journals Identification of the Roles of Climate Factors, Engineering Construction, and Agricultural Practices in Vegetation Dynamics in the Lhasa River Basin, Tibetan Plateau

2020 ◽  
Vol 12 (11) ◽  
pp. 1883 ◽  
Author(s):  
Dan Li ◽  
Hongying Luo ◽  
Tiesong Hu ◽  
Dongguo Shao ◽  
Yuanlai Cui ◽  
...  
Keyword(s):  
River Basin ◽  
Vegetation Dynamics ◽  
Anthropogenic Activities ◽  
Adverse Impact ◽  
Favorable Effect ◽  
Growth Trend ◽  
Vegetation Growth ◽  
Lhasa River Basin ◽  
Reservoir Construction ◽  
Lhasa River

Understanding vegetation dynamics is necessary to address potential ecological threats and develop sustainable ecosystem management at high altitudes. In this study, we revealed the spatiotemporal characteristics of vegetation growth in the Lhasa River Basin using net primary productivity (NPP) and normalized difference vegetation index (NDVI) during the period of 2000–2005. The roles of climatic factors and specific anthropogenic activities in vegetation dynamics were also identified, including positive or negative effects and the degree of impact. The results indicated that the interannual series of NPP and NDVI in the whole basin both had a continuous increasing trend from 102 to 128 gC m−2 yr−1 and from 0.417 to 0.489 (p < 0.05), respectively. The strongest advanced trends (>2 gC m−2 yr−1 or >0.005 yr−1) were detected in mainly the southeastern and northeastern regions. Vegetation dynamics were not detected in 10% of the basin. Only 20% of vegetation dynamics were driven by climatic conditions, and precipitation was the controlling climatic factor determining vegetation growth. Accordingly, anthropogenic activities made a great difference in vegetation coverage, accounting for about 70%. The construction of urbanization and reservoir led to vegetation degradation, but the farmland practices contributed the vegetation growth. Reservoir construction had an adverse impact on vegetation within 6 km of the river, and the direct damage to vegetation was within 1 km. The impacts of urbanization were more serious than that of reservoir construction. Urban sprawl had an adverse impact on vegetation within a 6 km distance from the surrounding river and resulted in the degradation of vegetation, especially within a 3 km range. Intensive fertilization and guaranteed irrigation improved the cropland ecosystem conditions, creating a favorable effect on the accumulation of crop organic matter in a range of 5 km, with an NPP trend value of 1.2 gC m−2 yr−1. The highly intensive grazing activity forced ecological environmental pressures such that the correlation between livestock numbers and vegetation growth trend was significantly linear negative.

Research on the Criterion and Classification of Swelling Rock

2011 ◽  
Vol 261-263 ◽  
pp. 1836-1840
Author(s):  
Xun Guo Zhu
Keyword(s):  
Water Absorption ◽  
Soft Rock ◽  
Saturated Water ◽  
Swelling Rock

Criterion and classification are two important content of swelling soft rock research. On the basis of the study of predecessors’ achievements, the percentage of hydrophilic minerals is considered as a key index of the new standard, and the saturated water absorption, limit swelling increment, limit swelling force are considered as main indexes. Finally, the new standard is used to analyze and study on the projects in references.

Global transpiration modelling: can the optimality hypothesis improve partitioning of ecosystem-scale evapotranspiration?

2020 ◽  
Author(s):  
Alison Prior ◽  
Iain-Colin Prentice
Keyword(s):  
Climate Models ◽  
Gross Primary Production ◽  
Vapour Pressure Deficit ◽  
Co2 Concentration ◽  
Water Model ◽  
Model Parameters ◽  
Water Runoff ◽  
Vegetation Growth ◽  
Green Vegetation ◽  
Surface Water Runoff

&lt;p&gt;The volume of water entering the atmosphere through transpiration is thought to be greater than the flow of all rivers to the oceans. It makes up the majority of evapotranspiration (ET) and significantly contributes to rainfall and therefore also to surface water runoff. However, there is no consensus on how transpiration responds to a changing environment; or even as to whether it is increasing over time. Global transpiration estimates are most commonly made through the partitioning of ET models. &amp;#160;However, in many ET models, the dynamics of vegetation growth and associated impacts on evapotranspiration are overlooked. Therefore, global estimates of transpiration from climate models are poorly constrained, with large uncertainties especially in stomatal conductance.&lt;/p&gt;&lt;p&gt;The &amp;#8216;P model&amp;#8217; (for Production) is a recently developed, &amp;#8216;next-generation&amp;#8217; model for Gross Primary Production, GPP. Derived from biochemical process of plants, the P model is built upon the established standard model for photosynthesis &amp;#8211; combined with optimality hypotheses for the adaptation and acclimation of key model parameters &amp;#8211; to determine GPP. The P model has the potential to provide a coupled global carbon and water model that responds correctly to changing environmental conditions. It requires only elevation, CO2 concentration, incident solar radiation, vapour pressure deficit (VPD) and temperature as inputs, in addition to remotely sensed green vegetation cover (fAPAR). The key idea motivating this research is that by exploiting the coupling of land-atmosphere carbon and water exchanges through stomatal behaviour, it should be possible to develop a near real-time transpiration monitoring system in which fAPAR is a key input. The P-model provides the means to do this. Initial results will be shown for both transpiration and GPP, with validation at &gt;100 eddy-covariance flux-tower sites.&lt;/p&gt;

scholarly journals Local properties of patterned vegetation: quantifying endogenous and exogenous effects

2013 ◽  
Vol 371 (2004) ◽  
pp. 20120359 ◽  
Author(s):  
Gopal G. Penny ◽  
Karen E. Daniels ◽  
Sally E. Thompson
Keyword(s):  
Soil Depth ◽  
Fourier Method ◽  
Vegetation Pattern ◽  
Aerial Images ◽  
Local Pattern ◽  
Natural Systems ◽  
Pattern Dynamics ◽  
Dryland Ecosystems ◽  
Local Properties ◽  
Gradual Variation

Dryland ecosystems commonly exhibit periodic bands of vegetation, thought to form due to competition between individual plants for heterogeneously distributed water. In this paper, we develop a Fourier method for locally identifying the pattern wavenumber and orientation, and apply it to aerial images from a region of vegetation patterning near Fort Stockton, TX, USA. We find that the local pattern wavelength and orientation are typically coherent, but exhibit both rapid and gradual variation driven by changes in hillslope gradient and orientation, the potential for water accumulation, or soil type. Endogenous pattern dynamics, when simulated for spatially homogeneous topographic and vegetation conditions, predict pattern properties that are much less variable than the orientation and wavelength observed in natural systems. Our local pattern analysis, combined with ancillary datasets describing soil and topographic variation, highlights a largely unexplored correlation between soil depth, pattern coherence, vegetation cover and pattern wavelength. It also, surprisingly, suggests that downslope accumulation of water may play a role in changing vegetation pattern properties.

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