The influences of climatic and biotic parameters on the isotopic offset among topsoil waters in typical vegetation types in alpine

2021 ◽  
Author(s):  
Wenyi Qin ◽  
Guo Chen ◽  
Peng Wang ◽  
Xiang Wang ◽  
Xiaozhen Li
Keyword(s):  
Climatic Factors ◽  
Soil Layer ◽  
Water Isotopes ◽  
Biotic Factors ◽  
Vegetation Types ◽  
Water Usage ◽  
Western Sichuan ◽  
Hydrologic Processes ◽  
Alpine Regions ◽  
Oxygen Stable Isotope

<p>Hydrogen and oxygen stable isotope compositions in soil waters have been widely used to investigate hydrologic cycles, particularly for understanding plant water usage. However, most studies of soil water isotopes have traditionally ignored the importance of O-horizon that may potentially influence the accurate evaluation of hydrologic processes, especially in alpine regions where O-horizon are thick due to low temperatures. Therefore, we investigated the isotopic differences (via mean effect size, lnRR) of waters from O-horizon and 0–10 cm soil layer in grasslands and woodlands of Western Sichuan alpine regions and evaluated the influences of climatic and biotic factors on observed differences. The results indicated that the δ<sup>2</sup>H and δ<sup>18</sup>O of O-horizon water were significantly higher than those of the 0–10 cm soil layer in grasslands, but these differences were not significant in woodlands. The influence of climatic factors on lnRR was limited relative to biotic factors, and the influence of climate contrasted with expectations based on evaporation principles. Rather, above ground biomass (AGB) was the most important factor associated with lnRR and it was significantly correlated with lnRR between and within soil waters from two vegetation types. Consequently, the observed differences were mainly related to vegetation conditions that influence microclimates within canopies. Therefore, investigations of hydrological processes may inaccurately estimate their influences when not separately considering the high stable isotopes values of O-horizon in grasslands of alpine regions with thin soil layers. In particular, the influence of O-horizon should especially be considered when AGB was lower than 100 t/hm<sup>2</sup> not only in grassland but also in other vegetation types.</p>

scholarly journals Effects of climatic factors on the net primary productivity in the source region of Yangtze River, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhe Yuan ◽  
Yongqiang Wang ◽  
Jijun Xu ◽  
Zhiguang Wu
Keyword(s):  
Climate Change ◽  
Primary Productivity ◽  
Yangtze River ◽  
Net Primary Productivity ◽  
Climatic Factors ◽  
Source Region ◽  
Primary Reason ◽  
Vegetation Types ◽  
Temperature And Precipitation ◽  
Increasing Trend

AbstractThe ecosystem of the Source Region of Yangtze River (SRYR) is highly susceptible to climate change. In this study, the spatial–temporal variation of NPP from 2000 to 2014 was analyzed, using outputs of Carnegie–Ames–Stanford Approach model. Then the correlation characteristics of NPP and climatic factors were evaluated. The results indicate that: (1) The average NPP in the SRYR is 100.0 gC/m2 from 2000 to 2014, and it shows an increasing trend from northwest to southeast. The responses of NPP to altitude varied among the regions with the altitude below 3500 m, between 3500 to 4500 m and above 4500 m, which could be attributed to the altitude associated variations of climatic factors and vegetation types; (2) The total NPP of SRYR increased by 0.18 TgC per year in the context of the warmer and wetter climate during 2000–2014. The NPP was significantly and positively correlated with annual temperature and precipitation at interannual time scales. Temperature in February, March, May and September make greater contribution to NPP than that in other months. And precipitation in July played a more crucial role in influencing NPP than that in other months; (3) Climatic factors caused the NPP to increase in most of the SRYR. Impacts of human activities were concentrated mainly in downstream region and is the primary reason for declines in NPP.

scholarly journals Partitioning tree water usage into storage and transpiration in a mixed forest

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ziqiang Liu ◽  
Qianqian Liu ◽  
Zijun Wei ◽  
Xinxiao Yu ◽  
Guodong Jia ◽  
...  
Keyword(s):  
Rainy Season ◽  
Soil Layer ◽  
Mixed Forest ◽  
Water Storage ◽  
Experimental Period ◽  
Ratio Method ◽  
Water Fluxes ◽  
Water Usage ◽  
Platycladus Orientalis ◽  
Quercus Variabilis

Abstract Background Water migration and use are important processes in trees. However, it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration. Therefore, it is necessary to quantify the water transpired and stored in plants. Method The δ2H/δ18O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species, including the proportions of water used for transpiration and water storage. Results Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources. Platycladus orientalis primarily used groundwater (30.5%) and the 60–100-cm soil layer (21.6%) throughout the experimental period and was sensitive to precipitation, absorbing water from the 0–20-cm layer (26.6%) during the rainy season. Quercus variabilis absorbed water from all sources (15.7%–36.5%) except from the 40–60-cm soil layer during the dry season. In addition, it did not change its water source but increased its groundwater uptake during the rainy season. The annual mean water fluxes of P. orientalis and Q. variabilis were 374.69 and 469.50 mm·year− 1, with 93.49% and 93.91% of the water used for transpiration, respectively. However, nocturnal sap flow in P. orientalis and Q. variabilis was mainly used for water storage in the trunk rather than transpiration, which effectively alleviated drought stress and facilitated the transport of nutrients. Conclusions The water stored in both species comprised 6%–7% of the total water fluxes and, therefore, should be considered in water balance models.

scholarly journals Fire and vegetation dynamics in northwest Siberia during the last 60 years based on high-resolution remote sensing

2021 ◽  
Vol 18 (1) ◽  
pp. 207-228
Author(s):  
Oleg Sizov ◽  
Ekaterina Ezhova ◽  
Petr Tsymbarovich ◽  
Andrey Soromotin ◽  
Nikolay Prihod'ko ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Carbon Balance ◽  
Climatic Factors ◽  
Carbon Sink ◽  
Vegetation Types ◽  
Burned Areas ◽  
Northern Areas ◽  
Global Carbon

Abstract. The rapidly warming Arctic undergoes transitions that can influence global carbon balance. One of the key processes is the shift towards vegetation types with higher biomass underlining a stronger carbon sink. The shift is predicted by bioclimatic models based on abiotic climatic factors, but it is not always confirmed with observations. Recent studies highlight the role of disturbances in the shift. Here we use high-resolution remote sensing to study the process of transition from tundra to forest and its connection to wildfires in the 20 000 km2 area in northwest Siberia. Overall, 40 % of the study area was burned during a 60-year period. Three-quarters of the burned areas were dry tundra. About 10 % of the study area experienced two–three fires with an interval of 15–60 years suggesting a shorter fire return interval than that reported earlier for the northern areas of central Siberia (130–350 years). Based on our results, the shift in vegetation (within the 60-year period) occurred in 40 %–85 % of the burned territories. All fire-affected territories were flat; therefore no effect of topography was detected. Oppositely, in the undisturbed areas, a transition of vegetation was observed only in 6 %–15 % of the territories, characterized by steeper topographic slopes. Our results suggest a strong role of disturbances in the tree advance in northwest Siberia.

scholarly journals Grazing exclosures solely are not the best methods for sustaining alpine grasslands

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6462 ◽  
Author(s):  
Xixi Yao ◽  
Jianping Wu ◽  
Xuyin Gong ◽  
Xia Lang ◽  
Cailian Wang
Keyword(s):  
Soil Properties ◽  
Management Strategy ◽  
Nutritional Value ◽  
Soil Layer ◽  
Plant Functional Types ◽  
Vegetation Types ◽  
Nutritional Values ◽  
Functional Types ◽  
Species Type

BackgroundGrazing is widely regarded as a critical factor affecting the vegetation structure, productivity and nutritional value of natural grasslands. To protect and restore degraded grasslands, non-grazed exclosures are considered as a valuable tool. However, it is not clear whether long term non-grazed exclosures of grazers can improve the condition and nutritional value of vegetation and soil properties.MethodsWe have compared the impact of long-term non-grazed and continuous grazed management strategy on vegetation structure, nutritional values and soil properties of alpine meadow of the Qinghai-Tibet Plateau by field investigation (11–13 years) and indoor analysis during 2015–2017.ResultsOur results showed that long-term non-grazed exclosures clearly increased the aboveground biomass and coverage of plant functional types. Long-term non-grazed exclosures improved the development of all vegetation types, except NG (GG, grass species type; SG, sedge species type; LG, leguminous species type; FG, forbs species type and NG, noxious species type). Long-term non-grazed exclosures significantly improved all six measured soil properties (TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus and AK, available potassium) in 0–10 cm soil layer, considerable effect on the improvement of all measured soil properties, except TK in 10–20 cm soil layer and all measured soil properties, except TN and TK in 20–30 cm soil layer were observed. However, long-term non-grazed exclosures significantly decreased biodiversity indicators i.e., species richness, Shannon diversity index and Evenness index of vegetation. A substantial decrease in the density, biodiversity and nutritional values (CP (crude protein), IVTD (in vitroture digestibility) and NDF (neutral detergent fiber)) of all vegetation types, except NG were recorded. While a downward trend in aboveground biomass and all measured soil properties except TP and TK were observed during 2015–2017 in alpine meadows due to long-term grazed treatment. The density, diversity and nutritional value (CP and IVTD) of long-term non-grazed alpine meadows showed a downward trend over time (2015–2017). By considering the biodiversity conservation and grassland livestock production, long-term non-grazed exclosures are not beneficial for the improvement of density, biodiversity and nutritional values of plant functional types. Thus, our study suggests that rotational non-grazed and grazed treatment would be a good management strategy to restore and improve the biodiversity and nutritional values of plant functional types in natural grassland ecosystems.

scholarly journals Substantiation of the Parameters of a Soil Tillage Machine Ripper

2021 ◽  
Vol 31 (2) ◽  
pp. 257-273
Author(s):  
Yuriy N. Syromyatnikov
Keyword(s):  
Energy Consumption ◽  
Climatic Factors ◽  
Ritz Method ◽  
Minimum Energy ◽  
Soil Layer ◽  
Energy Performance ◽  
Soil Tillage ◽  
Initial Moment ◽  
Total Energy Consumption ◽  
Rotor Drive

Introduction. Production of safe food requires the avoidance of using chemical means to bring weeds under control in cultivating crops. Existing tillage loosening and separating machine PRSM-5 Dokuchaevskaya optimizes the physical and mechanical state of the cultivated soil layer, while the weeds are carefully removed from the soil by combing out together with the whole weed root system and laid on the surface, where they dry up under the influence of climatic factors. During the operation of the tillage machine, about 30% of the total energy consumption is spent on the rotor drive. Therefore, this machine is not working satisfactorily in firm soils. Materials and Methods. The soil was considered as an elastic-plastic medium. The generalized Hookeʼs law model and a variant of the plastic flow theory were taken into account. To simplify the calculations, there was used the experimental study information on the position in space of the soil deformation surface. The intensity of stresses of polyplastic deformations of the soil layer was determined. For the numerical solution of the problem, the Ritz method was used. Results. In connection with the indicated disadvantages, the parameters of the rotor ripper are justified taking into account the reduction in energy consumption for its drive. As a result of solving the problem by the Ritz method, the geometric shape of the rotor ripper was determined. The energy performance of the section of the tillage machine was evaluated by the torque of the rotor drive of the loosening-separating device. The rotor drive torque was determined for rippers with flat, convex, and concave profiles and for the profile substantiated during the study. Discussion and Conclusion. The profile substantiated during the study provides the best conditions for transporting the soil at the initial moment of the rotor entry into the soil and the minimum energy consumption for its drive.

scholarly journals Spatial scale modulates the strength of ecological processes driving disease distributions

2016 ◽  
Vol 113 (24) ◽  
pp. E3359-E3364 ◽  
Author(s):  
Jeremy M. Cohen ◽  
David J. Civitello ◽  
Amber J. Brace ◽  
Erin M. Feichtinger ◽  
C. Nicole Ortega ◽  
...  
Keyword(s):  
Population Density ◽  
Human Population ◽  
Large Scale ◽  
Climatic Factors ◽  
Biotic Interactions ◽  
Amphibian Declines ◽  
Biotic Factors ◽  
Human Population Density ◽  
Single Scale ◽  
Anthropogenic Modifications

Humans are altering the distribution of species by changing the climate and disrupting biotic interactions and dispersal. A fundamental hypothesis in spatial ecology suggests that these effects are scale dependent; biotic interactions should shape distributions at local scales, whereas climate should dominate at regional scales. If so, common single-scale analyses might misestimate the impacts of anthropogenic modifications on biodiversity and the environment. However, large-scale datasets necessary to test these hypotheses have not been available until recently. Here we conduct a cross-continental, cross-scale (almost five orders of magnitude) analysis of the influence of biotic and abiotic processes and human population density on the distribution of three emerging pathogens: the amphibian chytrid fungus implicated in worldwide amphibian declines and West Nile virus and the bacterium that causes Lyme disease (Borrelia burgdorferi), which are responsible for ongoing human health crises. In all three systems, we show that biotic factors were significant predictors of pathogen distributions in multiple regression models only at local scales (∼102–103 km2), whereas climate and human population density always were significant only at relatively larger, regional scales (usually >104 km2). Spatial autocorrelation analyses revealed that biotic factors were more variable at smaller scales, whereas climatic factors were more variable at larger scales, as is consistent with the prediction that factors should be important at the scales at which they vary the most. Finally, no single scale could detect the importance of all three categories of processes. These results highlight that common single-scale analyses can misrepresent the true impact of anthropogenic modifications on biodiversity and the environment.

The response of net primary productivity of two different vegetation types to climatic factors and root turnover analysis on the Qinghai-Tibet Plateau

2019 ◽  
Vol 39 (14) ◽  
Author(s):  
戴黎聪 DAI Licong ◽  
郭小伟 GUO Xiaowei ◽  
张法伟 ZHANG Fawei ◽  
柯浔 KE Xun ◽  
曹莹芳 CAO Yingfang ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Climatic Factors ◽  
Tibet Plateau ◽  
Root Turnover ◽  
Vegetation Types ◽  
Qinghai Tibet Plateau

Application of14C-Labeled Herbicides in Lysimeter Studies

Weed Science ◽  
1985 ◽  
Vol 33 (S2) ◽  
pp. 11-17 ◽  
Author(s):  
Fritz Führ
Keyword(s):  
Plant Material ◽  
Major Part ◽  
Climatic Factors ◽  
Early Stage ◽  
Soil Layer ◽  
Great Influence ◽  
Soil Surface ◽  
Growing Season ◽  
Bare Soil ◽  
Factors Influencing

Most herbicides are applied preemergence onto bare soil or during the early stage of plant development. Therefore, the major part of the active ingredient either reaches the soil surface immediately or later with decaying plant material. The further fate of the herbicide depends largely on the physicochemical behavior of the respective compound, the amount and method of application, and a number of soil, plant, and climatic factors influencing the persistence and bio availability of organic compounds in a given soil (5, 7). Especially in the upper 2-cm soil layer, drastic changes in temperature and moisture content during a growing season have a great influence on the degradation and adsorption of herbicides in soil (10, 31).

Sign in / Sign up

Export Citation Format

Share Document