Research

15 pages, 2049 KiB

Open AccessArticle

Effects of Vegetation Types and Soil Properties on Regional Soil Carbon and Nitrogen in Salinized Reservoir Wetland, Northeast China

by Yuchen Wang, Heng Bao, David J. Kavana, Yuncong Li, Xiaoyu Li, Linlu Yan, Wenjing Xu and Bing Yu

Plants 2023, 12(21), 3767; https://doi.org/10.3390/plants12213767 - 03 Nov 2023

Viewed by 753

Abstract

This study investigated the spatial variability in soil organic carbon (SOC), total nitrogen (TN), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) and their possible relationships with other soil properties in the Hongqipao reservoir, which is dominated by different vegetation types. [...] Read more.

This study investigated the spatial variability in soil organic carbon (SOC), total nitrogen (TN), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) and their possible relationships with other soil properties in the Hongqipao reservoir, which is dominated by different vegetation types. The results showed that there were high spatial variabilities in SOC, TN, SMBC and SMBN, and that the SOC, TN, SMBC and SMBN contents decreased with increasing soil depth in the Hongqipao reservoir. The SOC was significantly positively correlated with TN, SMBC, moisture content (MC) and negatively correlated with carbon to nitrogen ratio (C:N ratio) and bulk density (BD). Soil TN was significantly positively correlated with SMBC, SMBN, MC and negatively correlated with the C:N ratio, BD and pH. The SMBC was significantly positively correlated with SMBN, MC and negatively correlated with the C:N ratio, BD and pH. The SMBN was significantly negatively correlated with the C:N ratio and BD. All of the measures of soil properties in this study could explain the higher significant variability in the response variables (SOC, TN, SMBC and SMBN contents). The generalized additive model (GAM) showed that SOC and TN had different influencing factors in different soil depths. The structural equation model (SEM) showed that vegetation types had a significantly positive effect on TN and SMBN, and the soil depths had a significantly positive effect on SOC and a significantly negative effect on TN and SMBC. This study further suggests that vegetation types play a major role in determining the spatial characteristics of soil carbon and nitrogen, and any changes in the vegetation types in the reservoir may influence the distributions of soil carbon and nitrogen. This may affect the global carbon and nitrogen budgets and the atmospheric greenhouse gas concentration significantly. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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15 pages, 2336 KiB

Open AccessArticle

Control of Mosses on Water Flux in an Alpine Shrub Site on the Qilian Mountains, Northwest China

by Zhangwen Liu, Rensheng Chen, Jinxian Qi, Zhiying Dang, Chuntan Han and Yong Yang

Plants 2022, 11(22), 3111; https://doi.org/10.3390/plants11223111 - 15 Nov 2022

Cited by 1 | Viewed by 1422

Abstract

Mosses are an important component of the alpine shrub, but little is known about their contribution to ecosystem water and energy exchange, especially potential opportunities for alpine shrub expansion under a warming climate. We studied the role of mosses in alpine shrub evapotranspiration [...] Read more.

Mosses are an important component of the alpine shrub, but little is known about their contribution to ecosystem water and energy exchange, especially potential opportunities for alpine shrub expansion under a warming climate. We studied the role of mosses in alpine shrub evapotranspiration by conducting herb and moss removal experiments with different Potentilla fruticosa L. shrub coverage in the Qilian Mountains, Northwest China. The understory evapotranspiration was measured using lysimeters in different shrub coverage (dense shrub cover, medium shrub cover, and thin shrub cover) during the growing season of 2012. The understory evapotranspiration is about 1.61 mm per day in the control treatment (intact moss and herbs) during the growing season, and the evapotranspiration rates differed significantly between canopy covers. We found a 22% increase in evapotranspiration losses after removing the moss layer compared to the control treatment lysimeter with an intact moss layer in the shrub site. This suggests that most of the understory evaporation originated from the organic layer underlying the moss layer. Given this study’s large moss evaporation rates, understory contributions cannot be ignored when interpreting eddy covariance data for the whole alpine ecosystem. Our results show that mosses may exert strong controls on understory water fluxes in alpine shrub meadow ecosystems and suggest that changes in moss cover may have significant consequences for season frozen soil thaw. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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8 pages, 266 KiB

Open AccessArticle

UV-B Radiation Effects on the Alpine Plant Kobresia humilis in a Qinghai-Tibet Alpine Meadow

by Shengbo Shi, Rui Shi, Tiancai Li and Dangwei Zhou

Plants 2022, 11(22), 3102; https://doi.org/10.3390/plants11223102 - 15 Nov 2022

Cited by 1 | Viewed by 936

Abstract

Enhanced UV-B radiation resulting from stratospheric ozone depletion has been documented both globally and on the Qinghai-Tibet Plateau in China. The response of Kobresia humilis, an important alpine meadow plant species, to enhanced UV-B radiation was experimentally investigated at the Haibei Alpine [...] Read more.

Enhanced UV-B radiation resulting from stratospheric ozone depletion has been documented both globally and on the Qinghai-Tibet Plateau in China. The response of Kobresia humilis, an important alpine meadow plant species, to enhanced UV-B radiation was experimentally investigated at the Haibei Alpine Meadow Ecosystem Research Station (37°29′–37°45′ N, 101°12′–101°23′ E; alt. 3200 m). K. humilis was exposed to UV-B radiation including ambient UV-B and enhanced UV-B (simulating a 14% reduction in the ozone layer) in a randomized design with three replications of each treatment. Enhanced UV-B radiation resulted in a significant increase of both leaf area and fresh weight chlorophyll and carotenoid but had no effect on UV-B absorbing pigments. Similarly, enhanced UV-B radiation did not significantly change the photosynthetic O₂ elevation rate while leaf thickness, width, and length significantly increased (p < 0.01). The enhanced UV-B radiation was associated with 2–3 days earlier flowering and a larger number of flowers per spikelet. The enhanced UV-B generally resulted in larger leaves and more flowers but earlier phenology. In summary, these findings suggest that alpine species of K. humilis have adapted to the strong solar UV-B radiation intensity presented on the Qinghai-Tibet Plateau, but the interspecies differences and their influence on trophic level should be more concerning. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

14 pages, 4542 KiB

Open AccessArticle

Soil Fungal Composition Drives Ecosystem Multifunctionality after Long-Term Field Nitrogen and Phosphorus Addition in Alpine Meadows on the Tibetan Plateau

by Bingheng Cheng, Hongyan Liu, Juan Bai and Jinhua Li

Plants 2022, 11(21), 2893; https://doi.org/10.3390/plants11212893 - 28 Oct 2022

Cited by 2 | Viewed by 1330

Abstract

An ecosystem can provide multiple functions and services at the same time, i.e., ecosystem multifunctionality (EMF). Above- and belowground biodiversity and abiotic factors have different effects on EMF. Human activities increase atmospheric nitrogen (N) and phosphorus (P) deposition, but the mechanism of how [...] Read more.

An ecosystem can provide multiple functions and services at the same time, i.e., ecosystem multifunctionality (EMF). Above- and belowground biodiversity and abiotic factors have different effects on EMF. Human activities increase atmospheric nitrogen (N) and phosphorus (P) deposition, but the mechanism of how atmospheric N and P deposition affect EMF in alpine meadows on the Tibetan Plateau is still unclear. Here, we measured eleven ecosystem parameters to quantify EMF by averaging method and explored the impact of plant and microbial species diversity and abiotic factors on EMF after long-term field N and P addition in alpine meadows on the Tibetan Plateau. Results showed that N addition reduced EMF by 15%, NP increased EMF by 20%, and there was no change due to P addition. N and P addition reduced pH, relative light conditions (RLC), and plant species richness and modified plant and fungal community composition. Structural equation model (SEM) analysis confirmed that fungal community composition was an important and positive driver on EMF. These results provided an understanding of how N and P addition affect EMF directly and indirectly through biotic and abiotic pathways, which was important for predicting the response of EMF to atmospheric N and P deposition in the future. Furthermore, the findings suggested that soil fungal composition was more important driving factors than abiotic factors in the response of EMF to N and P addition and the importance of the interactions between plant and soil microbial species diversity in supporting greater EMF. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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15 pages, 2597 KiB

Open AccessArticle

Spatial and Temporal Variability and Driving Factors of Carbon Dioxide and Nitrous Oxide Fluxes in Alpine Wetland Ecosystems

by Bing Yu, Wenjing Xu, Linlu Yan, Heng Bao and Hongxian Yu

Plants 2022, 11(21), 2823; https://doi.org/10.3390/plants11212823 - 24 Oct 2022

Viewed by 1290

Abstract

Plants regulate greenhouse gas (GHG) fluxes in wetland ecosystems, but the mechanisms of plant removal and plant species that contribute to GHG emissions remain unclear. In this study, the fluxes of carbon dioxide (CO₂) and nitrous oxide (N₂O) were [...] Read more.

Plants regulate greenhouse gas (GHG) fluxes in wetland ecosystems, but the mechanisms of plant removal and plant species that contribute to GHG emissions remain unclear. In this study, the fluxes of carbon dioxide (CO₂) and nitrous oxide (N₂O) were measured using the static chamber method from an island forest dominated by two different species, namely Betula platyphylla (BP) and Larix gmelinii (LG), in a marsh wetland in the Great Xing’an Mountains. Four sub-plots were established in this study: (1) bare soil after removing vegetation under BP (SBP); (2) bare soil after removing vegetation under LG (SLG); (3) soil with vegetation under BP (VSBP); and (4) soil with vegetation under LG (VSLG). Additionally, the contributions of the dark respiration from plant aerial parts under BP (VBP) and LG (VLG) to GHG fluxes were calculated. We found that the substantial spatial variability of CO₂ fluxes ranged from −25.32 ± 15.45 to 187.20 ± 74.76 mg m⁻² h⁻¹ during the study period. The CO₂ fluxes decreased in the order of SBP > VSLG > VSBP > SLG > VLG > VBP, indicating that vegetation species had a great impact on CO₂ emissions. Particularly, the absence of vegetation promoted CO₂ emission in both BP and LG. Additionally, CO₂ fluxes showed dramatically seasonal variations, with high CO₂ fluxes in late spring (May) and summer (June, July, and August), but low fluxes in late summer (August) and early autumn (September). Soil temperatures at 0–20 cm depth were better predictors of CO₂ fluxes than deeper soil temperatures. N₂O fluxes were varied in different treatments with the highest N₂O fluxes in SLG and the lowest N₂O fluxes in VBP. Meanwhile, no significant correlation was found between N₂O fluxes and air or soil temperatures. Temporally, negative N₂O fluxes were observed from June to October, indicating that soil N₂O fluxes were reduced and emitted as N₂, which was the terminal step of the microbial denitrification process. Most of the study sites were CO₂ sources during the warm season and CO₂ sinks in the cold season. Thus, soil temperature plays an important role in CO₂ fluxes. We also found that the CO₂ flux was positively related to pH in a 10 cm soil layer and positively related to moisture content (MC) in a 50 cm soil layer in VSBP and VSLG. However, the CO₂ flux was negatively related to pH in a 30 cm soil layer in SBP and SLG. Our findings highlight the effects of vegetation removal on GHG fluxes, and aid in the scientific management of wetland plants. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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16 pages, 2178 KiB

Open AccessArticle

Alchemilla monticola Opiz. Functional Traits Respond to Diverse Alpine Environmental Conditions in Karavanke, Slovenia

by Tadeja Trošt Sedej and Tajda Turk

Plants 2022, 11(19), 2527; https://doi.org/10.3390/plants11192527 - 27 Sep 2022

Viewed by 1125

Abstract

Alpine plants are exposed to demanding environmental conditions, such as high ultraviolet (UV) and photosynthetic radiation, extreme temperatures, drought, and nutrient deficiencies. Alpine plants adapt and acclimate to harsh conditions, developing several strategies, including biochemical, physiological, and optical responses. However, alpine plants’ survival [...] Read more.

Alpine plants are exposed to demanding environmental conditions, such as high ultraviolet (UV) and photosynthetic radiation, extreme temperatures, drought, and nutrient deficiencies. Alpine plants adapt and acclimate to harsh conditions, developing several strategies, including biochemical, physiological, and optical responses. However, alpine plants’ survival strategies are hardly researched due to time-consuming and complex experimental conditions, which are supported by scarce studies. Our study focused on the functional traits of the alpine plant Alchemilla monticola Opiz (hairy lady’s mantle) growing at two different altitudes (1500, 2000 m a.s.l.) and two different UV exposures per altitude. Near-ambient (UV) and reduced (UV-) UV radiations were provided by using two sorts of UV absorbing filters; temperatures were monitored hourly. The experimental plots were located at Tegoška Gora, Karavanke, Slovenia. Functional traits: physiological, biochemical, and optical characteristics were recorded three times during the growing season. A. monticola showed high maximum photochemical efficiency at both altitudes throughout the season, which confirms good adaptation and acclimatization of the plant. Furthermore, significantly higher maximum photochemical efficiency at the subalpine altitude coincided with significantly higher UV absorbing compounds (UV AC) contents at the subalpine compared to the montane altitude in August. A. monticola manifested high UV AC contents throughout the season, with significantly increased synthesis of UV AC contents in the subalpine conditions in August and September. The stomatal conductance rate increased with altitude and was correlated mostly to a lower temperature. A. monticola leaves did not transmit any UV spectrum, which corresponded to high total UV AC contents. The leaf transmittance of the photosynthetic spectrum increased at the subalpine altitude, while the transmittance of the green and yellow spectra increased under the reduced UV radiation in the autumn. A. monticola’s high photosynthetic spectrum transmittance at the subalpine altitude in the autumn might therefore be due to subalpine harsh environmental conditions, as well as plant ontogenetical phase. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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19 pages, 14810 KiB

Open AccessArticle

Functional Traits of Male and Female Leaves of Hippophae tibetana on the Eastern Edge of the Tibetan Plateau and Their Altitudinal Variability

by Baoli Fan, Zongqi Ma, Pengfei Gao, Jing Lu, Nana Ding and Kun Sun

Plants 2022, 11(19), 2484; https://doi.org/10.3390/plants11192484 - 22 Sep 2022

Cited by 3 | Viewed by 1392

Abstract

To date, there have been few studies of the functional traits of the dioecious Hippophae tibetana Schlecht leaves, either male or female, in response to ecological factors such as altitude. Elucidating these relationships will establish an important scientific basis for vegetation restoration and [...] Read more.

To date, there have been few studies of the functional traits of the dioecious Hippophae tibetana Schlecht leaves, either male or female, in response to ecological factors such as altitude. Elucidating these relationships will establish an important scientific basis for vegetation restoration and reconstruction of the Tibetan Plateau ecosystem. The natural populations of H. tibetana, distributed across three field sites, at 2868 m, 3012 m and 3244 m, in Tianzhu, Gansu, were studied by field survey sampling and laboratory analysis. In particular, the adaptions of leaf functional traits to elevation in these dioecious plants were analyzed. The results show that: (1) there is no “midday depression” of photosynthetic activity in either male or female plants. Over a one-day period, the net photosynthetic rate (Pn) and transpiration rate (Tr) of H. tibetana female plants were higher than those of male plants (p < 0.05). This correlated to the period of vigorous fruit growth in the female plant. The measured Pn and Tr were maximal at the intermediate altitude (3012 m). The light compensation point (LCP) of the leaves of male and female plants were 57.6 and 43.2 μmol·m⁻²·s⁻¹, respectively, and the light saturation points (LSP) of the leaves were 1857.6 and 1596.8 μmol·m⁻²·s⁻¹. (2) Altitude had a significant effect on plant and leaf functional traits of male and female H. tibetana (p < 0.05), and no significant difference was noted between plants at the same altitude. The values for leaf area (LA), specific leaf weight (LMA), leaf phosphorus content per unit mass (Pmass) and leaf phosphorus content per unit area (Parea) were also maximal at the intermediate altitude. Leaf nitrogen content per unit area (Narea) and leaf nitrogen content per unit mass (Nmass) increased with altitude. This indicated that the functional traits of male and female plants and leaves of H. tibetana showed a strong “trade-off relationship” with altitude. (3) Pearson correlation analysis showed that there were significant correlations among functional traits of H. tibetana leaves. Redundancy analysis (RDA) showed that soil water content (SWC), altitude (Alt) and soil organic carbon (SOC) had significant effects on the functional traits of H. tibetana leaves (p < 0.05). Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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13 pages, 1994 KiB

Open AccessArticle

The Upper Range Limit of Alien Plants Is Not in Equilibrium with Climate in the Andes of Central Chile

by Estefany Goncalves, Ileana Herrera, Jake Alexander, Milen Duarte, Lohengrin A. Cavieres, Luis Morales-Salinas and Ramiro O. Bustamante

Plants 2022, 11(18), 2345; https://doi.org/10.3390/plants11182345 - 08 Sep 2022

Viewed by 1259

Abstract

Alien plant species are colonizing high-elevation areas along roadsides. In this study, we evaluated whether the distributions of alien plants in the central Chilean mountains have reached climatic equilibrium (i.e., upper distribution limits consistent with their climatic requirements). First, we evaluated whether the [...] Read more.

Alien plant species are colonizing high-elevation areas along roadsides. In this study, we evaluated whether the distributions of alien plants in the central Chilean mountains have reached climatic equilibrium (i.e., upper distribution limits consistent with their climatic requirements). First, we evaluated whether the upper elevational limits of alien plants changed between 2008 and 2018 based on the Mountain Invasion Research Network (MIREN) database. Second, we compared the observed upper elevational limits with the upper limits predicted by each species’ global climatic niche. On average across species, the upper elevation limit did not change between 2008 and 2018. However, most species maintained the same limit or shifted downward, while only 23% of the species shifted upwards. This lack of change does not mean that the species’ distributions are in equilibrium with the climate, because the observed upper limit was lower than the limit predicted by the global niche model for 87% of species. Our results suggest that alien species in this study region may not only be climate-limited, but could also be limited by other local-scale factors, such as seed dispersal, intermittent disturbance rates, soil type and biotic interactions. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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20 pages, 6330 KiB

Open AccessArticle

Spatial Autocorrelation Analysis of Land Use and Ecosystem Service Value in the Huangshui River Basin at the Grid Scale

by Feifei Shi, Bingrong Zhou, Huakun Zhou, Hao Zhang, Hongda Li, Runxiang Li, Zhuanzhuan Guo and Xiaohong Gao

Plants 2022, 11(17), 2294; https://doi.org/10.3390/plants11172294 - 02 Sep 2022

Cited by 5 | Viewed by 1453

Abstract

The Huangshui River Basin is one of the most densely populated areas on the Qinghai–Tibet Plateau and is characterized by a high level of human activity. The contradiction between ecological protection and socioeconomic development has become increasingly prominent; determining how to achieve the [...] Read more.

The Huangshui River Basin is one of the most densely populated areas on the Qinghai–Tibet Plateau and is characterized by a high level of human activity. The contradiction between ecological protection and socioeconomic development has become increasingly prominent; determining how to achieve the balanced and coordinated development of the Huangshui River Basin is an important task. Thus, this study used the Google Earth Engine (GEE) cloud-computing platform and Sentinel-1/2 data, supplemented with an ALOS digital elevation model (ALOS DEM) and field survey data, and combined a remote sensing classification method, grid method, and ecosystem service value (ESV) evaluation method to study the spatial correlation and interaction between land use (LU) and ESV in the Huangshui River Basin. The following results were obtained: (1) on the GEE platform, Sentinel-1/2 active and passive remote sensing data, combined with the gradient tree-boosting algorithm, can efficiently produce highly accurate LU data with a spatial resolution of 10 m in the Huangshui River Basin; the overall accuracy (OA) reached 88%. (2) The total ESV in the Huangshui River Basin in 2020 was CNY 33.18 billion (USD 4867.2 million), of which woodland and grassland were the main contributors to ESV. In the Huangshui River Basin, the LU type, LU degree, and ESV have significant positive spatial correlations, with urban and agricultural areas showing an H-H agglomeration in terms of LU degree, with woodlands, grasslands, reservoirs, and wetlands showing an H-H agglomeration in terms of ESV. (3) There is a significant negative spatial correlation between the LU degree and ESV in the Huangshui River Basin, indicating that the enhancement of the LU degree in the basin could have a negative spatial spillover effect on the ESV of surrounding areas. Thus, green development should be the future direction of progress in the Huangshui River Basin, i.e., while maintaining and expanding the land for ecological protection and restoration, and the LU structure should be actively adjusted to ensure ecological security and coordinated and sustainable socioeconomic development in the Basin. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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12 pages, 1344 KiB

Open AccessArticle

Effect of Plateau Pika Disturbance on Plant Aboveground Biomass of Alpine Meadows at Two Different Scales

by Xiaoxing Wei and Zhenggang Guo

Plants 2022, 11(17), 2266; https://doi.org/10.3390/plants11172266 - 31 Aug 2022

Cited by 5 | Viewed by 1128

Abstract

Disturbance by small burrowing herbivores often has an impact on plant aboveground biomass of grassland because it makes grasslands into a mosaic of discrete vegetated surfaces and bare soil patches. This study focuses on the plateau pika (Ochotona curzoniae) to investigate [...] Read more.

Disturbance by small burrowing herbivores often has an impact on plant aboveground biomass of grassland because it makes grasslands into a mosaic of discrete vegetated surfaces and bare soil patches. This study focuses on the plateau pika (Ochotona curzoniae) to investigate the effect of the disturbance by a small burrowing herbivore on plant aboveground biomass through upscaling the quadrat scale to the plot scale across five sites. This study showed that the plateau pika disturbance reduced sedge biomass and increased forb biomass. In contrast, they did not affect plant community biomass, grass biomass and legume biomass at the quadrat scale across the five sites. At the plot scale, that is, when the bare soil patches with a lack of plants were considered, plateau pika disturbance induced lower aboveground biomass of the plant community, sedge and legumes, while it had no relationship with grass biomass and forb biomass. As the disturbance intensity increased, the aboveground biomass of the plant community and sedge decreased, whereas the grass biomass showed a hump-shaped trend. These results indicate that plateau pika disturbance might be not beneficial to alpine meadows given the aboveground biomass of the plant community at the plot scale. In contrast, the intermediate disturbance intensity improves the grazing quality of alpine meadows through the higher grass biomass. The findings of this study imply that the plot scale is better than the quadrat scale to investigate the influence of the disturbance by a small burrowing herbivore on the plant aboveground biomass, and that management of a small burrowing herbivore needs to consider its disturbance intensity. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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11 pages, 2441 KiB

Open AccessArticle

Seed Germination Ecology of Semiparasitic Weed Pedicularis kansuensis in Alpine Grasslands

by Jiedong Hu, Kaihui Li, Chengjun Deng, Yanming Gong, Yanyan Liu and Lei Wang

Plants 2022, 11(13), 1777; https://doi.org/10.3390/plants11131777 - 05 Jul 2022

Cited by 4 | Viewed by 1507

Abstract

The semiparasitic weed Pedicularis kansuensis Maxim. has rapidly spread in the alpine grasslands of northern China over the past twenty years and has caused serious ecological problems. In order to effectively halt the spread of this weed, a thorough understanding of the dormancy [...] Read more.

The semiparasitic weed Pedicularis kansuensis Maxim. has rapidly spread in the alpine grasslands of northern China over the past twenty years and has caused serious ecological problems. In order to effectively halt the spread of this weed, a thorough understanding of the dormancy type and the seed-germination ecology of P. kansuensis is required. We have conducted a series of experiments to investigate the effects of plant growth regulators (gibberellin (GA₃) and strigolactone synthesis (GR24)), as well as different abiotic (temperature, light, cold stratification, and drought) and biotic (aqueous extracts of three native dominant plants) factors on the seed-germination characteristics of P. kansuensis. The seed-germination percentages ranged from 2% to 62% at all of the temperatures that were examined, with the highest occurring at 25/10 °C. The light conditions did not significantly affect the germination percentage. The seed germination was greatly improved after two to eight weeks of cold stratification. The seed germination decreased dramatically with an increasing polyethylene glycol (PEG-6000) concentration, from 55% to 0%, under 10% and 20% PEG-6000. The seed germination was improved at a proper concentration of GA₃, GR24, and the aqueous extracts of Festuca ovina L., Stipa purpurea L., and Leymus secalinus (Georgi) Tzvel. Furthermore, in the pot experiment, the seedling emergence of P. kansuensis was also improved by the cultivation of these three dominant grasses. These findings indicate that the dormancy type of P. kansuensis seeds is non-deep physiological dormancy, and such findings will help in paving the way for the creation of effective weed management strategies, based on a thorough knowledge of germination ecology. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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12 pages, 2660 KiB

Open AccessArticle

Effects of Pedicularis kansuensis Expansion on Plant Community Characteristics and Soil Nutrients in an Alpine Grassland

by Ruimin Qin, Jingjing Wei, Li Ma, Zhonghua Zhang, Yandi She, Hongye Su, Tao Chang, Beilong Xie, Honglin Li, Wenying Wang, Guoxi Shi and Huakun Zhou

Plants 2022, 11(13), 1673; https://doi.org/10.3390/plants11131673 - 24 Jun 2022

Cited by 3 | Viewed by 2548

Abstract

Pedicularis kansuensis is an indicator species of grassland degradation. Its population expansion dramatically impacts the production and service function of the grassland ecosystem, but the effects and mechanisms of the expansion are still unclear. In order to understand the ecological effects of P. [...] Read more.

Pedicularis kansuensis is an indicator species of grassland degradation. Its population expansion dramatically impacts the production and service function of the grassland ecosystem, but the effects and mechanisms of the expansion are still unclear. In order to understand the ecological effects of P. kansuensis, three P. kansuensis patches of different densities were selected in an alpine grassland, and species diversity indexes, biomasses, soil physicochemical properties, and the mechanism among them were analyzed. The results showed that P. kansuensis expansion increased the richness index, the Shannon–Wiener index significantly, and the aboveground biomass ratio (ABR) of the Weed group (p < 0.05), but reduced the total biomass of the community and the ABR of the Gramineae and Cyperaceae decreased insignificantly (p > 0.05); soil moisture, soil AOC, and NO₃⁻·N decreased significantly (p < 0.05), while soil pH and total soil nutrients did not change significantly, and available phosphorus (AP) decreased at first and then increased (p < 0.05). The structural equation model (SEM) showed that P. kansuensis expansion had a significant positive effect on the community richness index, and a significant negative effect followed on the soil AOC from the increase of the index; the increase of pH had a significant negative effect on the soil AOC, NO₃⁻·N, and AP. It indicated that P. kansuensis expansion resulted in the increase of species richness, the ABR of the Weed group, and the community’s water demand, which promoted the over-utilization of soil available nutrients in turn, and finally caused the decline of soil quality. This study elucidated a possible mechanism of poisonous weeds expansion, and provided a scientific and theoretical basis for grassland management. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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24 pages, 3607 KiB

Open AccessArticle

Vegetation Classification and Distribution Patterns in the South Slope of Yarlung Zangbo Grand Canyon National Nature Reserve, Eastern Himalayas

by Po-Po Wu, Zi Wang, Ning-Xia Jia, Shao-Qiong Dong, Xiao-Yun Qu, Xian-Guo Qiao, Chang-Cheng Liu and Ke Guo

Plants 2022, 11(9), 1194; https://doi.org/10.3390/plants11091194 - 28 Apr 2022

Cited by 5 | Viewed by 2438

Abstract

Yarlung Zangbo Grand Canyon National Nature Reserve has the most complete vertical vegetation belts in China. However, identification and distribution of vertical vegetation belts is still uncertain and in debate. To explore the above issues, 190 plots were surveyed within the reserve from [...] Read more.

Yarlung Zangbo Grand Canyon National Nature Reserve has the most complete vertical vegetation belts in China. However, identification and distribution of vertical vegetation belts is still uncertain and in debate. To explore the above issues, 190 plots were surveyed within the reserve from 2019 to 2021. Based on the vegetation plot data, cluster analysis, ordination analysis, and biodiversity statistics were performed to reveal the structure of vertical vegetation belts–the driving factors of vegetation distribution–to describe the main biodiversity patterns. Five vertical vegetation belts were identified by clustering. NMDS ordination showed that the main factor of vegetation distribution is elevation. Based on the results of the analysis and previous literature, a new scheme of vertical vegetation belts in the south slope of the reserve was proposed. There was a lower montane seasonal rainforest belt (600–1100 m), a lower montane evergreen broadleaf forest belt (1100–1800 m), a middle montane semi-evergreen broadleaf forest belt (1800–2400 m), a subalpine evergreen needleleaf forest belt (2400–3800 m), a alpine shrubland and meadow belt (3800–4400 m), an alpine sparse vegetation belt (4400–4800 m), and a nival belt (4800–7782 m). Among them, the seasonal rainforest belts are the northernmost distribution of this type, and the semi-evergreen broadleaf forest belts exist only in the Eastern Himalayas. The study showed a unimodal pattern in plant species diversity, the peak of which is about 1900 m. The middle montane semi-evergreen broadleaf forest belt had the highest species diversity in the reserve. This study settled the issues regarding the vertical vegetation belts, the main drivers of vegetation and assessment of plant species diversity in the south slope of the Yarlung Zangbo Grand Canyon National Nature Reserve. It provides essential support for the management and conservation of these ecosystems in the reserve. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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17 pages, 2343 KiB

Open AccessArticle

Phenotypic Plasticity and Local Adaptation of Leaf Cuticular Waxes Favor Perennial Alpine Herbs under Climate Change

by Luhua Yao, Dengke Wang, Dangjun Wang, Shixiong Li, Youjun Chen and Yanjun Guo

Plants 2022, 11(1), 120; https://doi.org/10.3390/plants11010120 - 31 Dec 2021

Cited by 1 | Viewed by 1721

Abstract

Six perennial herbs (Plantago asiatica, Polygonum viviparum, Anaphalis lactea, Kobresia humilis, Leontopodium nanum and Potentilla chinensis) widely distributed in alpine meadows were reciprocally transplanted at two sites in eastern edge of Qinghai-Tibetan Plateau, Hongyuan (3434 m, 2.97 [...] Read more.

Six perennial herbs (Plantago asiatica, Polygonum viviparum, Anaphalis lactea, Kobresia humilis, Leontopodium nanum and Potentilla chinensis) widely distributed in alpine meadows were reciprocally transplanted at two sites in eastern edge of Qinghai-Tibetan Plateau, Hongyuan (3434 m, 2.97 °C, 911 mm) and Qilian (3701 m, 2.52 °C, 472 mm), aiming to evaluate the responses of alpine plants to changing environments. When plants were transplanted from Hongyuan to Qilian, most plant species showed a decrease of total wax coverage in first year and reverse trend was observed for some plant species in second year. However, when plants were transplanted from Qilian to Hongyuan, the response of total wax coverage differed greatly between plant species. When compared with those in first year, plasticity index of average chain length of alkane decreased whereas carbon preference index of alkane increased at both Hongyuan and Qilian in second year. The total wax coverage differed between local and transplanted plants, suggesting both environmental and genetic factors controlled the wax depositions. Structural equation modeling indicated that co-variations existed between leaf cuticular waxes and leaf functional traits. These results suggest that alpine herbs adjust both wax depositions and chain length distributions to adapt to changing environment, showing climate adaptations. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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11 pages, 1496 KiB

Open AccessArticle

Biomass and Species Diversity of Different Alpine Plant Communities Respond Differently to Nitrogen Deposition and Experimental Warming

by Emmanuella A. Kwaku, Shikui Dong, Hao Shen, Wei Li, Wei Sha, Xukun Su, Yong Zhang, Shuai Li, Xiaoxia Gao, Shiliang Liu, Jianbin Shi, Xiaowen Li, Quanru Liu and Zhenzhen Zhao

Plants 2021, 10(12), 2719; https://doi.org/10.3390/plants10122719 - 10 Dec 2021

Cited by 6 | Viewed by 2735

Abstract

The ability of fragile ecosystems of alpine regions to adapt and thrive under warming and nitrogen deposition is a pressing conservation concern. The lack of information on how these ecosystems respond to the combined impacts of elevated levels of nitrogen and a warming [...] Read more.

The ability of fragile ecosystems of alpine regions to adapt and thrive under warming and nitrogen deposition is a pressing conservation concern. The lack of information on how these ecosystems respond to the combined impacts of elevated levels of nitrogen and a warming climate limits the sustainable management approaches of alpine grasslands. In this study, we experimented using a completely random blocked design to examine the effects of warming and nitrogen deposition on the aboveground biomass and diversity of alpine grassland plant communities. The experiment was carried out from 2015 to 2018 in four vegetation types, e.g., alpine desert, alpine desert steppe, alpine marsh, and alpine salinised meadow, in the Aerjin Mountain Nature Reserve (AMNR) on the Qinghai–Tibetan Plateau (QTP). We found that W (warming) and WN (warming plus N deposition) treatment significantly increased the aboveground biomass of all the vegetation types (p < 0.05) in 2018. However, W and WN treatment only significantly increased the Shannon diversity of salinised meadows in 2018 and had no significant effect on the Shannon diversity of other vegetation types. Such results suggested that long-term nitrogen deposition and warming can consistently stimulate biomass accumulation of the alpine plant communities. Compared with other vegetation types, the diversity of alpine salinised meadows are generally more susceptible to long-term warming and warming combined with N deposition. Warming accounts many of such variabilities, while short-term N deposition alone may not significantly have an evident effect on the productivity and diversity of alpine grasslands. Our findings suggested that the effects of short-term (≤4 years) N deposition on alpine vegetation productivity and diversity were minimal, while long-term warming (>4 years) will be much more favourable for alpine vegetation. Full article

(This article belongs to the Special Issue Alpine Ecosystems in a Changing World)

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