Interactions between topsoil properties and ecophysiological responses of mangroves (Avicennia marina) along the tidal gradient in an arid region in Qatar

This study investigated the interactions between topsoil properties and ecophysiological responses of Avicennia marina along the tidal gradient in an arid region in Qatar. In February 2017, three plots were established, each at a distance of 0 m (D0), 50 m (D50), and 100 m (D100) from the inland boundary of a mangrove forest. Soil samples were collected at 0–10-cm depth in each plot to determine the chemical properties, and the density of seedlings, saplings, and trees was measured. Moreover, above- (AGB) and below-ground biomass (BGB) were calculated using an allometric equation for A. marina with the measured diameter at breast height in February 2017. As an indicator of salt stress, chlorophyll fluorescence parameters were measured in October 2017. Salinity (45.60 ppt) and exchangeable sodium percentage (ESP; 29.02%) at D100 were significantly highest. AGB was higher at D100 (41.44 Mg ha–1) than at D0 (0 Mg ha–1) and D50 (7.33 Mg ha–1), and BGB was higher at D100 (44.91 Mg ha–1) than only at D0 (0 Mg ha–1). There was no significant difference in the density of seedlings, saplings, or trees or the chlorophyll fluorescence parameters among the plots. Salt stress was not induced despite the hypersalinity at this site, since A. marina growing in an arid climate can endure strong salinity. Soil pH was highest at D0, followed by at D50 and D100. Organic matter, total nitrogen, available phosphorus, and cation exchange capacity were significantly higher at D100 than at D0 and D50. Higher concentrations of nutrients on the seaward side might result from the tidal gradient and a large input of organic matter and low soil alkalinity.Qatar University Grant (QUUG-CAS-DBES-15/16-5); the Biodiversity Conservation Fund of Kazakhstan (Q1727701); the Korean Ministry of Environment (2014001310008

Species specific physiological responses of Pinus densiflora and Larix kaempferi seedlings to open-field experimental warming and precipitation manipulation

Physiological responses of 1-year-old Pinus densiflora and Larix kaempferi seedlings were measured under open-field warming and precipitation manipulation. Air temperature of warming plots was 3 °C higher, while precipitation manipulation plots received ±40% of the precipitation than control plots. Seedlings were planted in May, and temperature and precipitation were manipulated from June 2017. Total chlorophyll content (Chlt), net photosynthetic rate (Pn), transpiration rate (E), and stomatal conductance (gs) were measured between July and September 2017. For P. densiflora and L. kaempferi, Chlt increased by 11.75% and 11.64%, and Pn decreased by 9.14% and 2.17% under warming, respectively. E and gs were lower under warming in P. densiflora, but higher in L. kaempferi. The lower Pn in P. densiflora resulted from stomatal closure, while that of L. kaempferi resulted from reduced vitality. Lower precipitation increased Chlt and Pn by 11.64% and 2.66% for P. densiflora, and by 6.40% and 4.32% for L. kaempferi, respectively. Conversely, higher precipitation decreased Pn of P. densiflora by 5.72%, and decreased Chlt and Pn of L. kaempferi by 8.24% and 4.55%, respectively. These results can be attributed to concentrated precipitation. In this study, two species responded differently even when they were exposed to the same environmental conditions, and this was due to the species-specific mechanisms to water stress derived from the high temperature

Effects of Warming and Precipitation Manipulation on Fine Root Dynamics of Pinus densiflora Sieb. et Zucc. Seedlings

Air warming (TC: control; TW: +3 °C) and precipitation manipulation (PC: control; PD: −30%; PI: +30%) were established to examine effects of these treatments on fine root production (FRP), fine root mortality (FRM), and total root (coarse and fine root) biomass in 33- to 59-month-old Pinus densiflora Sieb. et Zucc. seedlings for two years. We hypothesized that warming and altered precipitation would affect the growth, death, and biomass of fine roots by changing soil temperature and soil water availability. Mean annual FRP and total root biomass were significantly altered by only precipitation manipulation: they were 29.3% (during the two-year period) and 69.0% (after the entire two years) higher, respectively, in PD plots than in PC plots, respectively. In contrast, only warming had a significant effect on mean annual FRM, being 13.2% lower in TW plots than TC plots during the two-year period. Meanwhile, fine root biomass was affected negatively and simultaneously by both soil temperature and soil moisture. It seemed that fine root dynamics have changed so that they maintain their systems in response to the altered soil temperature and moisture. The current study adds significant knowledge for understanding the fine root dynamics of P. densiflora seedlings under altered temperature and precipitation regimes

Endangered plant species under differing anthropogenic interventions: how to preserve Pterygopleurum neurophyllum in Wondong wetland?

Endangered wetland plants are important as the potential keystone species and mediators for plant-soil interactions. Establishing conservation strategies for endangered plants is also prioritized because of the elevating extinction risk by human-induced wetland disturbances. The present study examined the factors controlling the incidence of Pterygopleurum neurophyllum, the endangered wetland plant experiencing severe habitat loss throughout Northeast Asia. Here, P. neurophyllum populations and their surrounding environments were addressed in the last natural Korean habitat to assess the possible influential factors (vegetation coverage, species richness, exotic plant species, coarse rock content, soil bulk density, and soil electroconductivity and pH) under anthropogenic wetland interventions (with or without soil disturbance). Our results showed that P. neurophyllum occurred 6 out of 32 plots in the study area. All P. neurophyllum were found in Miscanthus-dominated area, but preferred microhabitats featuring reduced vegetation coverage, increased species richness, and undisturbed soils under vegetation removal. Multimodel inference also indicated that vegetation coverage (relative importance = 1.00) and coarse rock content (relative importance = 0.70) were the major influential factors for P. neurophyllum population size, and the surviving P. neurophyllum were strictly limited to where both of them were kept lowered. Furthermore, the wetland intervention with soil disturbance had a negative effect on P. neurophyllum by creating the rocky and compacted soil surface as a result of land reclamation treatments. Conversely, the wetland intervention without soil disturbance enhanced the P. neurophyllum incidence by decreasing vegetation coverage of the overcrowding competitive plants. Overall findings reflect that the strategies to counteract habitat loss and manage the overly dense competitive plants should be necessary for conserving P. neurophyllum, as well as other wetland plants threatened by the human-induced disturbances and excessive competition intensities

Flora and Vegetation Characteristics of the Natural Habitat of the Endangered Plant Pterygopleurum neurophyllum

This study analyzed the flora, life form, and vegetation of the Nakdong River wetland. Vegetation analysis was performed on 37 plots using the phytosociological method of the Zürich-Montpellier School. PCA analysis was conducted by using the vegetation data (ground cover of class; 1~9) of 37 plots surveyed by phytosociological method. PCA (Principal Component Analysis) was used to statistically analyze the objectivity of the community classification and the character species. The traditional classification and mathematical statistic methods were used. A total of 82 taxa belonging to 28 families, 65 genera, 72 species, 2 subspecies, and 8 varieties were present in the vegetation of the survey area. The life form was analyzed to be the Th-R5-D4-e type. The communities were classified into seven communities: Miscanthus sacchariflorus community, Phragmites communis community, Phragmites communis–Carex dispalata community, Ulmus parvifolia community, Zizania latifolia community, Setaria viridis community, and Salix koriyanagi–Salix chaenomeloides community. As a result of PCA analysis, it was classified into seven communities. Seven communities were analyzed, where the most dominant species (M. sacchariflorus, P. communis, C. dispalata, U. parvifolia, Z. latifolia, S. viridis, S. koriyanagi, S. chaenomeloides) of each community were examined as character species. Another species is analyzed as Salix koreensis. Of the sixteen M. sacchariflorus communities, Pterygopleurum neurophyllum was present in six plots (A-2 group) but not in ten plots (A-1 group). These two groups showed differences in coverage and the number of occurring species. As for the relative net contribution degree (r-NCD) in the A-2 group, most species showed low r-NCD except for M. sacchariflorus, which showed an r-NCD of 100. The r-NCDs in the A-1 group were as follows: Miscanthus sacchariflorus (100), P. neurophyllum (21.74), and Persicaria perfoliata (10.14). Therefore, P. neurophyllum is difficult to grow in the A-1 group. As a result, it is thought that the high density of M. sacchariflorus affects the growth and distribution of P. neurophyllum. In order to expand and maintain P. neurophyllum, the habitat environment needs to be altered by adjusting the density of M. sacchariflorus

The Growth and Physiological Characteristics of the Endangered CAM Plant, Nadopungnan (Sedirea japonica), under Drought and Climate Change Scenarios

No natural habitat of Sedirea japonica has been found in Korea for the past 20 years. This study was conducted to provide basic physiological data for the conservation strategy of this endangered plant in response to climate change. Soil fruit daylight system (SFDS) chambers were used and four treatment groups (2.6LVPD, 2.6HVPD, 8.5LVPD, and 8.5HVPD) were designed based on the RCP scenario (RCP 2.6, and 8.5) and VPD conditions (low VPD; LVPD, and high VPD; HVPD). Air dryness was induced in the HVPD groups during the daytime by increasing the atmospheric vapor pressure deficit (VPD). There was no significant difference based on the RCP scenario. However, the difference between LVPD and HVPD was considerable. Total CO2 uptake and transpiration were lower than those of LVPD due to the duration decrease of Phase I in 2.6HVPD and 8.5HVPD. There was a reduction in total biomass, leaf thickness, length, and the number of leaves. ABS/RC, DI0/RC, φD0, VK, VJ, and other chlorophyll fluorescence markers increased. φP0, RE0/RC, φE0, ψE0, φR0, RC/CS0, Sm, N, PIabs, DFabs, SFIabs, and PIabs,Total declined. Daily drought stresses impact the physiological mechanisms occurring at nighttime. The defense mechanisms against drought stress occur by conserving water by controlling the stomata, inactivating the reaction center, and increasing the dissipated energy through heat. In summary, S. japonica is flexible against drought stress