Influence Of Climate Oscillations Research Articles

A 20-Year Ecotone Study of Pacific Northwest Mountain Forest Vulnerability to Changing Snow Conditions

(1) Background: Global climate change is expected to significantly alter growing conditions along mountain gradients. Landscape ecological patterns are likely to shift significantly as species attempt to adapt to these changes. We evaluated the extent to which spatial (elevation and canopy cover) and temporal (decadal trend and El Niño–Southern Oscillation/Pacific Decadal Oscillation) factors impact seasonal snowmelt and forest community dynamics in the Western Hemlock–True Fir ecotone region of the Oregon Western Cascades, USA. (2) Methods: Tsuga heterophylla and Abies amabilis seedling locations were mapped three times over 20 years (2002–2022) on five sample transects strategically placed to cross the ecotone. Additionally, daily ground temperature readings were collected over 10 years for the five transects using 123 data loggers to estimate below-canopy snow metrics. (3) Results: Based on validation using time-lapse cameras, the data loggers proved highly reliable for estimating snow cover. The method reported fewer days of snow cover as compared to meteorological station-based snow products for the region, emphasizing the importance of direct under-canopy field observations of snow. Snow season variability was most significantly impacted temporally by cyclical ENSO/PDO climate patterns and spatially by differences in canopy cover within the ecotone. The associated seedling analysis identified clear sorting of species by elevation within the ecotone but reflected a lack of a long-term trend, as species dominance in the seedling strata did not significantly shift along the elevation gradient over the 20-year study. (4) Conclusions: The data logger-based approach provided estimates of snow cover at ecologically significant locations and fine enough spatial resolutions to allow for the study of forest regeneration dynamics. The results highlight the importance of long-term, understory snow measurements and the influence of climatic oscillations in understanding the vulnerability of mountain areas to the changing climate.

The influence of climate oscillations and geological events on population differentiation of Camponotus japonicus in the Chinese mainland.

Camponotus japonicus (Hymenoptera: Formicidae) is an omnivorous social insect which builds sizable colonies in sparse woodlands or cropland and spreads across multiple climatic zones in the Chinese mainland. This study aims to reveal the role of climate changes and geological events in driving the genetic structure of social insect populations by investigating the phylogenetics and historical demography of C. japonicus in the Chinese mainland. Phylogenetic analyses were conducted based on the mitochondria DNA dataset using MrBayes and IQ-TREE. We constructed a haplotype network, calculated analyses of molecular variance, estimated the divergence time, and reconstructed the maximum clade credibility tree. Mismatch distribution and Bayesian skyline plots were used to infer historical population fluctuations. Additionally, ecological niche modeling was employed to predict the potential distribution of the species during the present, mid-holocene, and last glacial maximum periods in the Chinese mainland. The phylogenetic tree and median-joining network analyses support the presence of four distinct lineages in C. japonicus. These lineages exhibit significant genetic differentiation and limited gene flow. The divergence among the four lineages began in the early Pleistocene, approximately 1.41 million years ago (Ma). Subsequently, the central lineage diverged from both the northern and southern lineages around 1.16 Ma, while the northern and southern lineages diverged from each other at approximately 1.07 Ma. Population expansion was observed in the southern, central, and northern lineages prior to the last glacial maximum, while the Yunnan-Sichuan lineage experienced a slight increase in population size in more recent times. The predicted distribution of the species corresponds well with the actual distribution. Furthermore, the current suitable habitat areas in northern Xinjiang, southern Tibet, and the southeast coastal regions have significantly decreased compared to the last glacial maximum and the mid-holocene periods. Our results suggest that climate oscillations and geological events play an important role in driving genetic patterns and differentiation of C. japonicus. Mountain barriers isolate populations from each other, hinder the flow of genes, and effectively prevent the spread of this species. But at the same time, it also formed refugia at low altitudes areas such as Qinling-Bashan Mountains and Yanshan-Taihang Mountains and provide suitable habitats during glaciation. This study provides a good model for understanding how complex climate changes and geological events affect population genetic differentiation of social insects in the Chinese mainland.

Influence of climate oscillations on urban and rural temperature variability in the Kanto region of Japan

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 75:65-80 (2018) - DOI: https://doi.org/10.3354/cr01507 Influence of climate oscillations on urban and rural temperature variability in the Kanto region of Japan M. X. C. Seow1,*, M. Roth2 1Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 2Department of Geography, National University of Singapore, 117570, Singapore *Corresponding author: xcmarvin@eps.s.u-tokyo.ac.jp ABSTRACT: Climate oscillations of air and sea-surface temperatures are known to influence surface temperature and precipitation variability. Intraseasonal (4 to 12 mo) and interannual (>12 to 120 mo) variability is investigated using monthly mean temperature data from 4 urban and 3 rural weather stations located in the Kanto region of Japan, during the period January 1973-August 2015. Indices of 6 climate oscillations (El Niño-Southern Oscillation, Indian Ocean Dipole, Quasi-Biennial Oscillation, Arctic Oscillation, Pacific North American Pattern and West Pacific Pattern) known to influence Japan’s climate are investigated using wavelet analysis to identify oscillations in temperature data and climate mode indices at various periods. Continuous wavelet transform analysis shows that temperature variability is more pronounced at the intraseasonal than interannual timescale and urbanisation has no influence on temperature variability. Using the wavelet transform coherence analysis, all climate oscillations except El Niño-Southern Oscillation significantly covary with the temperature at certain periods and years, with the West Pacific Pattern having the highest coherence on average across the whole study period and analysed timescales. On average across the study period, using the multiple linear regression technique, only the Arctic Oscillation and West Pacific Pattern are found to significantly contribute to both intraseasonal and interannual temperature variability. KEY WORDS: Climate variability · Air temperature · Urban-rural stations · Wavelet analysis · Japan’s climate Full text in pdf format PreviousNextCite this article as: Seow MXC, Roth M (2018) Influence of climate oscillations on urban and rural temperature variability in the Kanto region of Japan. Clim Res 75:65-80. https://doi.org/10.3354/cr01507 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 75, No. 1. Online publication date: April 18, 2018 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2018 Inter-Research.

Influence of climate oscillations on temperature and precipitation over the United Arab Emirates

In this study, we investigate the influence of global climate oscillations on the local temperature and precipitation over the United Arab Emirates (UAE), which is one of the driest regions in the world with very high temperatures and low precipitation. The identification and assessment of remote interactions (teleconnections) are carried out by using ground station and gridded data sets. Monthly rainfall data from six ground stations over the UAE for the period of 1982–2010 is used in this study along with the long-term gridded precipitation and temperature data from the Global Precipitation Climatology Center and Global Historic Climatic Network. Linear correlations, wavelet analysis, and cross-wavelet analysis have been applied to identify the relation between climate indices and precipitation (temperature). The analysis reveals that the strong variability in precipitation is closely associated with the Southern Oscillation Index (SOI) and the Indian Ocean Dipole Index (IOD) during the months of August–March, September–January, respectively. In case of temperature, the strong variability is associated with the North Atlantic Oscillation Index (NAO) and the East Atlantic Oscillation Index (EAO) during the months of April–October, July–December. Spatial analysis of cross-wavelet reveals that the winter precipitation is significantly influenced by SOI and temperature during summer by the NAO. This research concludes that the negative phases of SOI (NAO) play a significant role in the increase of precipitation (decrease in summer temperatures) over the UAE region.

Changes in deep-sea fish and crustacean communities at 1000–2200 m in the Western Mediterranean after 25 years: Relation to hydro-climatic conditions

Long-term changes in the biomass, diversity and composition of deep-living fish and decapods from the Balearic Basin (western Mediterranean) have been compared between two periods, 1985–1992 vs. 2007–2012, based on 106 bottom trawls performed at 1000–2250m. Relationships have been identified between the changes in community composition and the hydroclimatic conditions (e.g. NAO, temperature, salinity and dissolved O2) of the area. We found a generalized deepening of middle-slope communities (950–1250m), especially among decapods, which is suggested (from GLM results) to have been a response to the long-term increase in salinity of the Levantine Intermediate Waters (LIW), located above the level sampled to ca. 700m. Even more pronounced was the shallowing of all of the lower slope species (1600–2250m), accompanied by a significant decrease of biomass from 1985–1992 to 2007–2012. This last tendency would be done to a combination of factors: long-term decrease of O2 in the bottom-boundary layer, greater degradation of POM arriving on the bottom due to temperature increase in the Western Mediterranean Deep Waters (WMDW) and probably a decrease of Chl a at the surface and, thus, of production. The influence of climatic oscillations (NAO) on differences found between 1985–1992 and 2007–2012 seems secondary, likely because the NAO did not show significant differences between the two periods. Some plankton-feeding species showed an increase of density during high/positive NAO (e.g. Alepocephalus rostratus), while some benthos feeders increased during low/negative NAO (e.g. Aristeus antennatus, mainly juveniles). The increase of rainfall and advective fluxes under low/negative NAO (i.e., in 2007–2012) may increase the formation of the nepheloid layer identified over 1200–1400m in the area (Cartes et al., 2013a), linked to zooplankton aggregation in that depth range. Greater food availability could explain the generalized migration by both middle and lower slope species toward these intermediate depths that acquired greater trophic resources. Deep-sea Mediterranean fish and invertebrates, including important commercial species, seemed to undergo long-term changes in its distribution and biomass due to changes in hydro-climatic conditions, mainly a decrease of O2 in the bottom-boundary layer.

A range wide geographic pattern of genetic diversity and population structure of Hexinia polydichotoma (Asteraceae) in Tarim Basin and adjacent areas

In order to investigate the genetic diversity and influence of climate oscillations on evolutionary processes of organisms in northwest China, we selected Hexinia polydichotoma, a species endemic to China, and examined the geographic pattern of genetic variation in its entire cover range, Tarim Basin and adjacent areas. In the study, 22 chloroplast (cp) haplotypes were identified based on two cpDNA sequences (trnH–psbA and ycf6–psbM), and five ITS sequence variations were found. Shown in the cp haplotype network, the two common cp haplotypes mainly distributed along the northern and southern rims of the basin respectively and intersected in the center of the basin, whereas in the ITS network, ITS genotype 1 was widespread across the whole distribution area, and rare genotypes were concentrated in the western rim of the basin. Genetic variation primarily occurred among populations and SAMOVA groups. Fragmented desert habitat may have caused gene flow barrier among populations or groups far from each other, leading to significant genetic differentiation at these levels. It appears that expansion and contraction cycles of river systems and oases during the middle Pleistocene was the source of the observed fragmentation. Geographic range expansion in H. polydichotoma was supported by the significant value for Tajima's D, Fu's FS, and by a unimodal mismatch distribution. It was possible that the enlargement of the Taklimakan Desert during the middle Pleistocene may have provided appropriate conditions for the range dispersal. We identified western rim of the basin as the center of genetic diversity of H. polydichotoma based on the present dataset.

Phylogeographic and demographic effects of Quaternary climate oscillations in Hexinia polydichotoma (Asteraceae) in Tarim Basin and adjacent areas

In order to investigate the genetic diversity and influence of climate oscillations on evolutionary processes of organisms in Northwest China, we selected Hexinia polydichotoma, a species endemic to China, and examined the phylogeographic structure and historical factors that influenced the evolutionary history of this species in its entire cover range, Tarim Basin and adjacent areas. In the study, 17 haplotypes were identified in H. polydichotoma on the basis of two chloroplast DNA sequences (trnH–psbA and ycf6–psbM). Shown in the network, the two common haplotypes, A and D, respectively, mainly distribute along the northern and southern rims of the basin. The analyses of molecular variance analysis suggest that genetic variation primarily occurs among populations, and all populations were subdivided into five groups by SAMOVA. Geographic range expansion along the southern and northern rims of the basin was supported by the significant value for Tajima’s D and by the unimodal mismatch distribution. It is possible that during the interglacial period of the middle Pleistocene, a large amount of snow and glacial ice melted from the mountains surrounding Tarim Basin. This increased water, the expanding desert, and the dispersal ability of H.polydichotoma were important factors driving not only geographic range expansion, but also the current phylogeographic structure of this species. It is possible that during the middle Pleistocene, the climatic fluctuations resulted in expansion and contraction cycles of river systems and oases, and may consequently have caused population fragmentation.

Influence of climate oscillations on dentinal deposition in teeth of Commerson's dolphin

AbstractEffects of climatic oscillations on populations in marine environments are produced mainly through the lower trophic levels. Marine mammals, as top predators, are affected indirectly by these fluctuations, showing variations in their survival, growth and reproduction. The main objective of this study was to determine whether we could detect the effect of climatic oscillations on Commerson's dolphins (Cephalorhynchus c. commersonii) off Tierra del Fuego, Argentina, by examining the presence and proportion of anomalous dentinal growth layer groups (GLGs). The relative deposition of anomalous GLGs was determined using calendar years from 1960 to 2005, and related to the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) events, and to mean annual sea surface temperatures (SST). Then, growth parameters between animals that did and did not show anomalous dentinal growth layer patterns in one or more of their GLGs were compared. The presence of anomalous GLGs was related to the SAM, increasing in frequency with negative values of the SAM. No relationship was found among anomalous GLGs, ENSO, and SST. There were no significant differences in growth parameters between animals with and without anomalous GLGs. Using recording structures such as teeth provided a unique way of reconstructing time series to evaluate the effects of these climatic patterns on a top predator species in an area where no similar studies have been conducted, primarily due to a lack of suitable long‐term data sets.

Historical geographic dispersal of the golden snub‐nosed monkey (Rhinopithecus roxellana) and the influence of climatic oscillations

Current understanding of historic climate oscillations that have occurred over the past few million years has modified scientific views on evolution. Major climatic events have caused local and global extinction of plants and animals and have impacted the spatial distribution of many species. The endangered golden snub-nosed monkey (Rhinopithecus roxellana) currently inhabits three isolated regions of China: the Sichuan and Gansu provinces (SG), the Qinling Mountains in Shaanxi province (QL), and the Shennongjia Forestry District in Hubei province (SNJ). However, considerable uncertainty still exists about their historical dispersal routes under the influence of environment change. To date, two dispersal routes have been proposed: (1) the QL and SNJ populations originated from the SG population; and (2) the SG population recolonized from the QL and SNJ populations. We used the mitochondrial DNA complete control region to perform statistical assessments of the relative probability of alternative migration scenarios and the role of environmental change on the geographic dispersal of Rhinopithecus roxellana. Thirty haplotypes were identified from the three geographic regions and a high degree of genetic structure was observed. The most recent common ancestor among the mitochondrial DNA haplotypes was estimated to live around 0.47-1.88 million years ago and five notable haplotype clusters were found. Phylogenetic analysis and historical gene flow estimates suggested that the QL and SNJ populations originated from the SG population, with at least two dispersal events from the SG population occurring during the Pleistocene (1.17±0.70 and 0.53±0.30 Ma). Composite dispersal history of the golden snub-nosed monkey can be explained by both environmental change inducing global climate change and the influence of the Tibetan Plateau uplift. Such range shifts involved considerable demographic changes, as revealed in the dramatic decreases in population size during the last 25,000 years.

Differential effects of historical migration, glaciations and human impact on the genetic structure and diversity of the mountain pasture weed Veratrum album L.

Aim Today’s genetic population structure and diversity of species can be understood as the result of range expansion from the area of origin, past climatic oscillations and contemporary processes. We examined the relative importance of these factors in Veratrum album L., a toxic weed of mountain grasslands. Location Continental Europe. Methods Forty populations from the Asian border (Urals and Caucasus) to Portugal were studied using amplified fragment length polymorphisms (AFLPs) combined with selected plant and population measures. The data were analysed with phylogenetic, population genetic and regression methods inferring both genetic structure and diversity from geographic and ecological factors. Results Fragment frequency clines together with genetic distance clustering and principal coordinates analysis indicated an east–west direction in the genetic structure of V. album, suggesting ancient migration into Europe from a proposed Asian origin. However, the strong geographic pattern in the genetic structure, pronounced isolation by distance (R2 = 0.74) and moderate overall population differentiation (FST = 0.13) suggests high historical gene flow, possibly during glacials, and vicariance into mountainous regions during interglacials. Occurrence of V. album during the last glaciation in several areas along the periphery of the Alps and recolonization of this mountain range from both eastern and central–western areas was indicated. Genetic diversity was highest in central Europe, a pattern that did not agree with the expectations from east–west migration into Europe. Furthermore, managed habitats showed higher levels of genetic diversity compared to unmanaged habitats. Stepwise linear regression determined shoot density and soil phosphorus as the main predictors of within-population genetic diversity (R2 = 0.40). Main conclusions Our results showed that V. album retained genetic imprints of historical range expansion into Europe, although this was alleviated by the influence of climatic oscillations and contemporary processes. For example, genetic population structure was strongly affected by post-glacial vicariance while patterns of genetic diversity seemed mainly to be influenced by human land use. Our findings highlight the importance of applying a synthetic approach, testing the influence of both historical and contemporary processes on genetic structure and diversity in order to understand complex phylogeographic patterns. This may especially apply to widespread species, such as weeds. Implications of our findings for biological control are briefly discussed.

Relationship between fire, climate oscillations, and drought in British Columbia, Canada, 1920–2000

AbstractClimate oscillations such as El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) are known to affect temperature and precipitation regimes and fire in different regions of the world. Understanding the relationships between climate oscillations, drought, and area burned in the past is required for anticipating potential impacts of regional climate change and for effective wildfire‐hazard management. These relationships have been investigated for British Columbia (BC), Canada, either as part of national studies with coarse spatial resolution or for single ecosystems. Because of BC's complex terrain and strong climatic gradients, an investigation with higher spatial resolution may allow for a spatially complete but differentiated picture. In this study, we analyzed the annual proportion burned–climate oscillation–drought relationships for the province's 16 Biogeoclimatic Ecosystem Classification (BEC) zones. Analyses are based on a digital, spatially explicit fire database, climate oscillation indices, and monthly precipitation and temperature data with a spatial resolution of 400 m for the period 1920–2000. Results show that (1) fire variability is better related to summer drought than to climate oscillations, and that (2) fire variability is most strongly related to both, climate oscillations and summer drought in southeastern BC. The relationship of area burned and summer drought is strong for lower elevations in western BC as well. The influence of climate oscillations on drought is strongest and most extensive in winter and spring, with higher indices being related to drier conditions. Winter and spring PDO and additive winter and spring PDO+ENSO indices show BC's most extensive significant relationship to fire variability. Western BC is too wet to show a moisture deficit in summer that would increase annual area burned due to teleconnections.

The influence of climatic oscillations during the Quaternary Era on the genetic structure of Asian black bears in Japan

The Asian black bear (Ursus thibetanus) inhabits two of the main islands, Honshu and Shikoku, in Japan. To determine how climatic oscillations during the Quaternary Era affected the genetic structure of the black bear populations in Japan, we examined their phylogeographic relationships and compared their genetic structure. We analysed an approximately 700-bp sequence in the D-loop region of mitochondrial DNA collected from 589 bears in this study with 108 bears from a previous study. We observed a total of 57 haplotypes and categorized them into three clusters (Eastern, Western and Southern) based on the spatial distribution of the haplotypes. All but 2 of the 41 haplotypes in the Eastern cluster were distributed locally. Genetic diversity was generally low in northern Japan and high in central Japan. Demographic tests rejected the expansion model in northern populations. Haplotypes of the Western and Southern clusters were unique to local populations. We conclude that the extant genetic structure of the Asian black bear populations arose as follows: first, populations became small and genetic drift decreased genetic diversity in the northern area during the last glacial period, whereas large continuous populations existed in the southern part of central Japan. These patterns were essentially maintained until the present time. In western and southern Japan, the effects of climatic oscillations were smaller, and thus, local structure was maintained.