scholarly journals Soil Moisture and Soluble Salt Content Dominate Changes in Foliar δ13C and δ15N of Desert Communities in the Qaidam Basin, Qinghai-Tibetan Plateau

2021 ◽  
Vol 12 ◽  
Author(s):  
Weiling Niu ◽  
Hui Chen ◽  
Jianshuang Wu
Keyword(s):  
Soil Moisture ◽  
Tibetan Plateau ◽  
Plant Species ◽  
Qaidam Basin ◽  
Salt Content ◽  
High Elevation ◽  
Plant Ecology ◽  
Soluble Salt ◽  
Δ13c And Δ15n ◽  
Significant Difference

Changing precipitation and temperature are principal drivers for nutrient cycling dynamics in drylands. Foliar isotopic carbon (C) and nitrogen (N) composition (δ13C and δ15N) are often used to describe the plant’s water use efficiency and nitrogen use strategy in plant ecology research. However, the drivers and mechanisms under differential foliar δ13C and δ15N among plant species and communities are largely unknown for arid high-elevation regions. This study collected 462 leaf samples of ten top-dominant plant species (two or three replicates per species) across 16 sites in 2005 and 2010 to measure the community-weighted means (CWMs) of foliar δ13C and δ15N, northeastern Qaidam Basin, Qinghai-Tibetan Plateau. Our results showed that the CWM of foliar δ15N was higher in 2005 than in 2010 and was lower in the warm-dry season (July and August) than the cool-wet one (June and September) in 2010. Similarly, the CWM of foliar δ13C was higher in 2005 than in 2010, but no difference between warm-dry and cool-wet seasons in 2010. C4 plants have higher δ13C and generally grow faster than C3 species under warm-wet weathers. This might be why the CWM of foliar δ13C was high, while the CWM of foliar δ15N was low in the wet sampling year (2010). The general linear mixed models revealed that soil moisture was the most critical driver for the CWM of foliar δ15N, which explained 42.1% of the variance alone. However, the total soluble salt content was the crucial factor for the CWM of foliar δ13C, being responsible for 29.7% of the variance. Growing season temperature (GST) was the second most vital factor and explained 28.0% and 21.9% of the variance in the CWMs of foliar δ15N and δ13C. Meanwhile, remarkable differences in the CWMs of foliar δ15N and δ13C were also found at the species level. Specifically, Kalidium gracile and Salsola abrotanoides have higher foliar δ15N, while Ephedra sinica and Tamarix chinensis have lower foliar δ15N than other species. The foliar δ13C of Calligonum Kozlov and H. ammodendron was the highest among the ten species. Except for the foliar δ13C of E. sinica was higher than Ceratoide latens between the two sampling years or between the cool-wet and warm-dry seasons, no significant difference in foliar δ13C was found for other species. Overall, the CWMs of foliar δ15N and δ13C dynamics were affected by soil properties, wet-dry climate change, and species identity in high-elevation deserts on the Qinghai Tibetan Plateau.

scholarly journals Classification, description and mapping of the vegetation in Khutse Game Reserve, Botswana

2019 ◽  
Vol 13 (2) ◽  
pp. 8-23
Author(s):  
T Lori
Keyword(s):  
Plant Species ◽  
National Parks ◽  
Plant Communities ◽  
Plant Species Richness ◽  
Management Plan ◽  
Plant Ecology ◽  
Herbaceous Plants ◽  
Significant Difference ◽  
Game Reserve ◽  
Grewia Flava

There is currently no detailed classification and description of plant communities in Khutse Game Reserve (KGR), Botswana, using phytosociological techniques. The main aim of this study was to classify and describe plant communities in KGR. Classification and description of plant communities will help in understanding the plant ecology of KGR. Braun-Blanquet sampling method was applied in 91 stratified random relevés. Nine plant communities were identified and classified using Modified TWINSPAN which is contained in JUICE program. The results showed that there was a statistically significant difference in percentage cover of herbaceous plants between the different plant communities. Schmidtia pappophoroides-Stipagrostis uniplumis and Heliotropium lineare-Enneapogon desvauxii communities had higher cover (%) of herbaceous plants than other communities. Catophractes alexandri-Stipagrostis uniplumis community had the highest cover (%) of shrubs. There was no statistically significant difference in plant species diversity (Shannon-Wienner Index) and species evenness between plant communities, but there was a statistically significant difference in plant species richness between the different plant communities. Dichrostachys cinerea-Grewia flava community, Senegalia mellifera subsp. detinens-Maytenus species community and Catophractes alexandri-Stipagrostis uniplumis community had lower number of species, whereas Vachellia luederitzii var. retinens-Grewia flava community had the highest number (46) of plant species. This study will help the Department of Wildlife and National Parks (DWNP) to develop an updated and informed Management Plan for the reserve, which takes cognizance of the plant ecology of the reserve.

scholarly journals Soil Moisture but Not Warming Dominates Nitrous Oxide Emissions During Freeze–Thaw Cycles in a Qinghai–Tibetan Plateau Alpine Meadow With Discontinuous Permafrost

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhe Chen ◽  
Shidong Ge ◽  
Zhenhua Zhang ◽  
Yangong Du ◽  
Buqing Yao ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Moisture ◽  
Tibetan Plateau ◽  
Active Layer ◽  
Alpine Meadow ◽  
Nitrous Oxide Emissions ◽  
Freeze Thaw ◽  
Discontinuous Permafrost ◽  
Significant Difference

Large quantities of organic matter are stored in frozen soils (permafrost) within the Qinghai–Tibetan Plateau (QTP). The most of QTP regions in particular have experienced significant warming and wetting over the past 50 years, and this warming trend is projected to intensify in the future. Such climate change will likely alter the soil freeze–thaw pattern in permafrost active layer and toward significant greenhouse gas nitrous oxide (N2O) release. However, the interaction effect of warming and altered soil moisture on N2O emission during freezing and thawing is unclear. Here, we used simulation experiments to test how changes in N2O flux relate to different thawing temperatures (T5–5°C, T10–10°C, and T20–20°C) and soil volumetric water contents (VWCs, W15–15%, W30–30%, and W45–45%) under 165 F–T cycles in topsoil (0–20 cm) of an alpine meadow with discontinuous permafrost in the QTP. First, in contrast to the prevailing view, soil moisture but not thawing temperature dominated the large N2O pulses during F–T events. The maximum emissions, 1,123.16–5,849.54 μg m–2 h–1, appeared in the range of soil VWC from 17% to 38%. However, the mean N2O fluxes had no significant difference between different thawing temperatures when soil was dry or waterlogged. Second, in medium soil moisture, low thawing temperature is more able to promote soil N2O emission than high temperature. For example, the peak value (5,849.54 μg m–2 h–1) and cumulative emissions (366.6 mg m–2) of W30T5 treatment were five times and two to four times higher than W30T10 and W30T20, respectively. Third, during long-term freeze–thaw cycles, the patterns of cumulative N2O emissions were related to soil moisture. treatments; on the contrary, the cumulative emissions of W45 treatments slowly increased until more than 80 cycles. Finally, long-term freeze–thaw cycles could improve nitrogen availability, prolong N2O release time, and increase N2O cumulative emission in permafrost active layer. Particularly, the high emission was concentrated in the first 27 and 48 cycles in W15 and W30, respectively. Overall, our study highlighted that large emissions of N2O in F–T events tend to occur in medium moisture soil at lower thawing temperature; the increased number of F–T cycles may enhance N2O emission and nitrogen mineralization in permafrost active layer.

scholarly journals Concurrent and Lagged Effects of Extreme Drought Induce Net Reduction in Vegetation Carbon Uptake on Tibetan Plateau

2020 ◽  
Vol 12 (15) ◽  
pp. 2347
Author(s):  
Chongchong Ye ◽  
Jian Sun ◽  
Miao Liu ◽  
Junnan Xiong ◽  
Ning Zong ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Qaidam Basin ◽  
Extreme Drought ◽  
Spatiotemporal Variability ◽  
Carbon Uptake ◽  
Significant Downward Trend ◽  
Significant Difference ◽  
Annual Total ◽  
Vegetation Carbon ◽  
Lagged Effects

Climatic extremes have adverse concurrent and lagged effects on terrestrial carbon cycles. Here, a concurrent effect refers to the occurrence of a latent impact during climate extremes, and a lagged effect appears sometime thereafter. Nevertheless, the uncertainties of these extreme drought effects on net carbon uptake and the recovery processes of vegetation in different Tibetan Plateau (TP) ecosystems are poorly understood. In this study, we calculated the Standardised Precipitation–Evapotranspiration Index (SPEI) based on meteorological datasets with an improved spatial resolution, and we adopted the Carnegie–Ames–Stanford approach model to develop a net primary production (NPP) dataset based on multiple datasets across the TP during 1982–2015. On this basis, we quantised the net reduction in vegetation carbon uptake (NRVCU) on the TP, investigated the spatiotemporal variability of the NPP, NRVCU and SPEI, and analysed the NRVCUs that are caused by the concurrent and lagged effects of extreme drought and the recovery times in different ecosystems. According to our results, the Qaidam Basin and most forest regions possessed a significant trend towards drought during 1982–2015 (with Slope of SPEI < 0, P < 0.05), and the highest frequency of extreme drought events was principally distributed in the Qaidam Basin, with three to six events. The annual total net reduction in vegetation carbon uptake on the TP experienced a significant downward trend from 1982 to 2015 (−0.0018 ± 0.0002 PgC year−1, P < 0.001), which was negatively correlated with annual total precipitation and annual mean temperature (P < 0.05). In spatial scale, the NRVCU decrement was widely spread (approximately 55% of grids) with 17.86% of the area displaying significant declining trends (P < 0.05), and the sharpest declining trend (Slope ≤ −2) was mainly concentrated in southeastern TP. For the alpine steppe and alpine meadow ecosystems, the concurrent and lagged effects of extreme drought induced a significant difference in NRVCU (P < 0.05), while forests presented the opposite results. The recovery time comparisons from extreme drought suggest that forests require more time (27.62% of grids ≥ 6 years) to recover their net carbon uptakes compared to grasslands. Therefore, our results emphasise that extreme drought events have stronger lagged effects on forests than on grasslands on the TP. The improved resilience of forests in coping with extreme drought should also be considered in future research.

scholarly journals Species interactions involving cushion plants in high-elevation environments under a changing climate

Ecosistemas ◽  
2021 ◽  
Vol 30 (1) ◽  
pp. 2186
Author(s):  
Francisco I. Pugnaire ◽  
Gianalberto Losapio ◽  
Christian Schöb
Keyword(s):  
Global Warming ◽  
Plant Species ◽  
Species Interactions ◽  
High Elevation ◽  
Plant Ecology ◽  
Plant Interactions ◽  
Mountain Ranges ◽  
Cushion Plant ◽  
Cushion Plants ◽  
Negative Impacts

The effects of global warming are stronger in high-elevation environments than elsewhere. Here, we review recent advances in alpine plant ecology with a focus on dry mountain ranges, mainly in Mediterranean-type climate, with a global change perspective. Raising temperatures and changes in precipitation influence both plant growth and reproduction, and therefore the spatial distribution of species. Research in high-elevation systems evidenced that plant–plant interactions involving cushion plants play a crucial role in the assembly of plant communities, influencing species richness, genetic and phylogenetic diversity, and species persistence. By buffering environmental extremes and ameliorating biophysical conditions, cushion plant species acting as ecosystem engineers are fundamental in the response of alpine ecosystems to global warming, mitigating negative impacts on different plant species with narrow niche and small distribution range.

Assemblage Patterns of Hymenoptera at Different Elevations of Gunung Datuk, Rembau

2017 ◽  
Vol 14 (2) ◽  
pp. 1 ◽  
Author(s):  
Noor Nasuha Abd Aziz ◽  
Siti Khairiyah Mohd Hatta ◽  
Idris Abd Ghani ◽  
Saiyid Jalaluddin Saiyid Shaifuddin
Keyword(s):  
Species Richness ◽  
Diversity Index ◽  
High Elevation ◽  
Significant Difference ◽  
Index Site ◽  
Evenness Index ◽  
Abundance And Diversity ◽  
Richness Index ◽  
Paired T Test ◽  
Malaise Traps

A study on abundance and diversity of Hymenoptera was conducted in Gunung Datuk, Rembau. Samplings were conducted from November 2014 to February 2015 using six Malaise traps. Three traps were placed at Site 1 at 700m height for high elevation and the remaining traps were placed at Site 2 at 200m height for low elevation. A total number of 221 Hymenopteran were collected which consist of nine families namely Ichneumonidae, Formicidae, Braconidae, Bethylidae, Evaniidae, Tiphiidae, Vespidae, Pompilidae and Apidae. In this study, 93 individuals were obtained from Site 1, comprising nine families and 43 morphospecies while 127 individuals were obtained from Site 2 with nine families and 45 morphospecies. Formicidae was the most dominant family collected from both sites with a total of 104 individuals while the least family recorded was Apidae with only one individual. Shannon’s Weiner Diversity Index (H’) showed Site 1 had the higher diversity value with H’ = 3.17 compared to Site 2 with value H’ = 3.12. For Evenness Index, Site 1 had higher value compared to Site 2 with E’ = 0.84 and E’ = 0.82 respectively. Moreover, for Margalef Richness Index, Site 1 recorded R’ = 9.24 while site two recorded R’ = 9.08 which concluded that Site 1 had higher species richness compared to Site 2. Paired t-test showed that both sites had no significant difference with p>0.05. Overall study showed that the diversity and abundance of Hymenoptera in Gunung Datuk were low since the value of H’ is less than 3.50.

scholarly journals Multi-Year NDVI Values as Indicator of the Relationship between Spatiotemporal Vegetation Dynamics and Environmental Factors in the Qaidam Basin, China

2021 ◽  
Vol 13 (7) ◽  
pp. 1240
Author(s):  
Junpeng Lou ◽  
Guoyin Xu ◽  
Zhongjing Wang ◽  
Zhigang Yang ◽  
Sanchuan Ni
Keyword(s):  
Environmental Factors ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Qaidam Basin ◽  
Elevation Gradient ◽  
Practical Significance ◽  
Elevation Gradients ◽  
Relative Contribution ◽  
Significant Difference ◽  
Different Altitudes

The Qaidam Basin is a unique and complex ecosystem, wherein elevation gradients lead to high spatial heterogeneity in vegetation dynamics and responses to environmental factors. Based on the remote sensing data of Moderate Resolution Imaging Spectroradiometer (MODIS), Tropical Rainfall Measuring Mission (TRMM) and Global Land Data Assimilation System (GLDAS), we analyzed the spatiotemporal variations of vegetation dynamics and responses to precipitation, accumulative temperature (AT) and soil moisture (SM) in the Qaidam Basin from 2001 to 2016. Moreover, the contribution of those factors to vegetation dynamics at different altitudes was analyzed via an artificial neural network (ANN) model. The results indicated that the Normalized Difference Vegetation Index (NDVI) values in the growing season showed an overall upward trend, with an increased rate of 0.001/year. The values of NDVI in low-altitude areas were higher than that in high-altitude areas, and the peak values of NDVI appeared along the elevation gradient at 4400–4600 m. Thanks to the use of ANN, we were able to detect the relative contribution of various environmental factors; the relative contribution rate of AT to the NDVI dynamic was the most significant (35.17%) in the low-elevation region (< 2900 m). In the mid-elevation area (2900–3900 m), precipitation contributed 44.76% of the NDVI dynamics. When the altitude was higher than 3900 m, the relative contribution rates of AT (39.50%) and SM (38.53%) had no significant difference but were significantly higher than that of precipitation (21.97%). The results highlight that the different environmental factors have various contributions to vegetation dynamics at different altitudes, which has important theoretical and practical significance for regulating ecological processes.

Sign in / Sign up

Export Citation Format

Share Document