Juniperus Pingii Research Articles

Endemic Juniperus Montane Species Facing Extinction Risk under Climate Change in Southwest China: Integrative Approach for Conservation Assessment and Prioritization.

Simple SummaryClimate change is one of the most significant drivers of habitat loss and species extinction, particularly montane endemic species such as Juniper trees, which are restricted to unique habitats. Therefore, assessing the impact of climate change on the extinction risk of species is a promising tool or guide for species conservation planning. The loss in species habitat due to global warming indicates the level of extinction or endangerment. Predictions of suitable habitats are outputs from assessment analysis. This will help conservationists discover new populations of endemic species and help raise the awareness of local people to save and rescue these endangered species.Climate change is an important driver of biodiversity loss and extinction of endemic montane species. In China, three endemic Juniperus spp. (Juniperus pingii var. pingii, J. tibetica, and J. komarovii) are threatened and subjected to the risk of extinction. This study aimed to predict the potential distribution of these three Juniperus species under climate change and dispersal scenarios, to identify critical drivers explaining their potential distributions, to assess the extinction risk by estimating the loss percentage in their area of occupancy (AOO), and to identify priority areas for their conservation in China. We used ensemble modeling to evaluate the impact of climate change and project AOO. Our results revealed that the projected AOOs followed a similar trend in the three Juniperus species, which predicted an entire loss of their suitable habitats under both climate and dispersal scenarios. Temperature annual range and isothermality were the most critical key variables explaining the potential distribution of these three Juniperus species; they contribute by 16–56.1% and 20.4–38.3%, respectively. Accounting for the use of different thresholds provides a balanced approach for species distribution models’ applications in conservation assessment when the goal is to assess potential climatic suitability in new geographical areas. Therefore, south Sichuan and north Yunnan could be considered important priority conservation areas for in situ conservation and search for unknown populations of these three Juniperus species.

Spring Hydroclimate Reconstruction on the South‐Central Tibetan Plateau Inferred From Juniperus Pingii Var. Wilsonii Shrub Rings Since 1605

AbstractAlpine regions on the Tibetan Plateau are sensitive to climate change, however, little is known about their long‐term hydroclimate variability due to short and few instrumental records. Alpine shrub provides a rare opportunity to reconstruct past high‐resolution hydroclimate conditions. Here, we used living and dead juniper shrubs (Juniperus pingii var. wilsonii) to develop a 537‐year ring width chronology nearby the Nam Co Lake (4,725 m a.s.l.). The chronology explained 46% of variance in May–June Standardized Moisture Anomaly Index (SZI) in the period from 1970 to 2010. We reconstructed May–June SZI since 1605. The reconstructed SZI matched well with several tree‐ring based moisture or drought reconstructions for the Tibetan Plateau. In particular, two long dry May–June periods of 1637–1683 and 1708–1785 during the Little Ice Age (LIA) implied that long‐term cold temperature tends to slow down hydrological cycle in the margin areas of the Indian summer monsoon.

Air moisture signals in a stable oxygen isotope chronology of dwarf shrubs from the central Tibetan Plateau.

Annually resolved biological climate proxies beyond the altitudinal and latitudinal distribution limit of trees are rare. In such regions, several studies have demonstrated that annual growth rings of dwarf shrubs are suitable proxies for palaeoclimatic investigations. In High Asia, the pioneer work of Liang et al. (Liang E, Lu X, Ren P, Li X, Zhu L, Eckstein D, 2012. Annual increments of juniper dwarf shrubs above the tree line on the central Tibetan Plateau: a useful climatic proxy. Annals of Botany109: 721-728) confirmed the suitability of shrub growth-ring chronologies for palaeoclimatic research. This study presents the first sensitivity study of an annually resolved δ18O time series inferred from Wilson juniper (Juniperus pingii var. wilsonii) from the northern shoreline of lake Nam Co (Tibetan Plateau). Based on five individual dwarf shrub discs, a statistically reliable δ18O chronology covering the period 1957-2009 was achieved (expressed population signal = 0.80). Spearman's correlation analysis between the δ18O chronology and climate variables from different sources was applied. In a first step, the suitability of various climate data was evaluated. Examinations of climate-proxy relationships revealed significant negative correlations between the δ18O shrub chronology and summer season moisture variability of the previous and current year. In particular, relative humidity of the previous and current vegetation period significantly determined the proxy variability (ρ = -0.48, P < 0.01). Furthermore, the δ18O variability of the developed shrub chronology significantly coincided with a nearby tree-ring δ18O chronology of the same genus (r = 0.62, P < 0.01). The δ18O shrub chronology reliably recorded humidity variations in the Nam Co region. The chronology was significantly correlated with a nearby moisture-sensitive tree-ring δ18O chronology, indicating a common climate signal in the two chronologies. This climate signal was likely determined by moisture variations of the Asian summer monsoon. Local climate effects were superimposed on the supra-regional climate signature of the monsoon circulation. Opposing δ18O values between the two chronologies were interpreted as plant-physiological differences during isotopic fractionation processes.

Beneficial effects on H1N1-induced acute lung injury and structure characterization of anti-complementary acidic polysaccharides from Juniperus pingii var. wilsonii.

Juniperus pingii var. wilsonii has been traditionally used in Tibetan medicine for the treatment of inflammatory diseases. In the present study, J. pingii var. wilsonii polysaccharides (JPWP), with high content of d‑galacturonic acid, showed potent anti-complementary activity in vitro and significantly attenuated acute lung injury (ALI) induced by H1N1 influenza virus in vivo through reducing the inflammatory responses, alleviating oxidative stress and inhibiting the activation of complement. Thus, anti-complementary activity-guided fractionation of JPWP led to the isolation of an acidic homogeneous polysaccharide, JPWP-PS, whose structure was further elucidated by acid hydrolysis, PMP derivation, methylation and NMR analysis. JPWP-PS had potent anti-complementary activity with the CH50 value of 0.073 ± 0.009 mg/mL, and was characterized by the residues of T-Araf-(1→, →3)-Araf-(1→, →3,5)-Araf-(1→, →3)-Galp-(1→ and →4)-GalpA-(1→.

Past the climate optimum: Recruitment is declining at the world's highest juniper shrublines on the Tibetan Plateau.

Alpine biomes are climate change hotspots, and treeline dynamics in particular have received much attention as visible evidence of climate-induced shifts in species distributions. Comparatively little is known, however, about the effects of climate change on alpine shrubline dynamics. Here, we reconstruct decadally resolved shrub recruitment history (age structure) through the combination of field surveys and dendroecology methods at the world's highest juniper (Juniperus pingii var. wilsonii) shrublines on the south-central Tibetan Plateau. A total of 1,899 shrubs were surveyed at 12 plots located in four regions along an east-to-west declining precipitation gradient. We detected synchronous recruitment with 9 out of 12 plots showing a gradual increase from 1600 to 1900, a peak at 1900-1940, and a subsequent decrease from the 1930s onward. Shrub recruitment was significantly and positively correlated with reconstructed summer temperature from 1600 to 1940, whereas it was negatively associated with temperature in recent decades (1930-2000). Recruitment was also positively correlated with precipitation, except in the 1780-1830 period, when a trend toward wetter climate conditions began. Warming-induced drought limitation has likely reduced the recruitment potential of alpine juniper shrubs in recent decades. Ongoing warming without a simultaneous increase in precipitation is expected to further impair recruitment at the world's highest juniper shrublines and alter the dynamics and competitive balance between woody plant species throughout these alpine biomes.

Volatile Composition of Juniperus pingii var. wilsonii and Its Inhibitory Effect on Nitric Oxide Production of Macrophage Cells

The leaves and twigs of Juniperus pingii var. wilsonii (Cupressaceae) smell aromatic and are traditionally used as the Tibetan medicine Xuba. Their essential oil obtained by ultrasonic-assisted hydrodistillation and volatiles collected by GC headspace technique were analyzed and compared by GC-MS. The analyses revealed the presence of thirty-nine components in the essential oil, representing 95.8% in content of the total oil, mainly including sabinene (22.6%), elemol (15.5%) and (-)-terpinen-4-ol (9.6%). Thirty-eight components accounting for 99.4% of the headspace volatiles were identified, mainly including sabinene (32.5%), β-pinene (21.9%) and α-thujene (10.3%). The compositions of the oil and headspace volatiles were quite similar, and twenty-five compounds identified were in common, which was 91.3% of the oil and 96.0% of the headspace volatiles in content. The essential oil could obviously inhibit Nitric oxide production in LPS-stimulated RAW 264.7 cells with no significant effect on cell viability, indicating its good anti-inflammatory activity.

Facilitation stabilizes moisture-controlled alpine juniper shrublines in the central Tibetan Plateau

The Tibetan Plateau hosts one of the world's highest undisturbed alpine juniper shrublines. However, little is known about the dynamics of these shrublines in response to climate warming and shrub-to-shrub interactions. Since growth of shrubline junipers is limited more by moisture availability than by low temperatures, we tested if upslope advancement of alpine juniper shrublines was constrained by warmer temperatures and related recent droughts. We also evaluated whether facilitation among neighboring shrubs, as inferred from spatial analyses, influenced shrubline dynamics. Three rectangular plots crossing the Juniperus pingii var. wilsonii shrubline were sampled at elevations from 4810 to 4917ma.s.l. near the Nam Co Lake, central Tibetan Plateau. Location of each stem and its diameter at the root collar and age were measured. We reconstructed the spatial and temporal shrubline dynamics during the past 350years using standard dendrochronological methods. Independent, long-term summer temperature reconstructions also were associated with shrub recruitment. Point-pattern analyses were used to characterize spatial patterns of different size classes of shrubs. The three shrublines showed little long-term changes despite ongoing warming; no upward shift has occurred in the past 100years. Recruitment was negatively associated with summer temperatures and drought occurrence since the 1920s. Spatial patterns were characterized by clustering at local scales and attraction between the different size classes, suggesting facilitation. We conclude that moisture availability limits the recruitment and elevational advance of junipers in this area of the Tibetan Plateau. Dynamics of alpine shrublines are more contingent on positive interactions and local environmental factors than on regional climatic variability.

Isolation and characterization of polymorphic microsatellite loci in Ping’s juniper Juniperus pingii

Juniperus pingii (Ping's juniper) is a threatened conifer species endemic to China, and a good knowledge of its population genetics would be essential to formulate effective conservation strategies. In this study, ten polymorphic microsatellite loci were isolated, and characterized for their utility using 58 individuals from two geographically distinct populations. In population XGLL, the number of alleles per locus (N (A)) ranged from four to 11, with an average of 6.2 per locus; the observed (H (O)) and expected heterozygosity (H (E)) ranged from 0.205 to 0.854 and from 0.423 to 0.754, with an average of 0.347 and 0.527, respectively. In population BM, N (A), H (O) and H (E) ranged from four to eight, from 0.198 to 0.454 and from 0.339 to 0.853, with an average of 5.8, 0.294 and 0.556, respectively. Following the sequential Bonferroni correction, only one locus (Jp07) was found to deviate significantly from Hardy-Weinberg equilibrium within population XGLL, and no significant linkage disequilibrium was detected in any of these loci within either population. These polymorphic microsatellite loci would be useful for population genetic studies of this conifer species.

Annual increments of juniper dwarf shrubs above the tree line on the central Tibetan Plateau: a useful climatic proxy

Dendroclimatology is playing an important role in understanding past climatic changes on the Tibetan Plateau. Forests, however, are mainly confined to the eastern Tibetan Plateau. On the central Tibetan Plateau, in contrast, shrubs and dwarf shrubs need to be studied instead of trees as a source of climate information. The objectives of this study were to check the dendrochronological potential of the dwarf shrub Wilson juniper (Juniperus pingii var. wilsonii) growing from 4740 to 4780 m a.s.l. and to identify the climatic factors controlling its radial growth. Forty-three discs from 33 stems of Wilson juniper were sampled near the north-eastern shore of the Nam Co (Heavenly Lake). Cross-dating was performed along two directions of each stem, avoiding the compression-wood side as far as possible. A ring-width chronology was developed after a negative exponential function or a straight line of any slope had been fit to the raw measurements. Then, correlations were calculated between the standard ring-width chronology and monthly climate data recorded by a weather station around 100 km away. Our study has shown high dendrochronological potential of Wilson juniper, based on its longevity (one individual was 324 years old), well-defined growth rings, reliable cross-dating between individuals and distinct climatic signals reflected by the ring-width variability. Unlike dwarf shrubs in the circum-arctic tundra ecosystem which positively responded to above-average temperature in the growing season, moisture turned out to be growth limiting for Wilson juniper, particularly the loss of moisture caused by high maximum temperatures in May-June. Because of the wide distribution of shrub and dwarf shrub species on the central Tibetan Plateau, an exciting prospect was opened up to extend the presently existing tree-ring networks far up into one of the largest tundra regions of the world.