Central Mountain Range Research Articles

An Innovative Dynamic Model for Predicting Typhoon Track Deflections over Complex Terrain

This study presents an innovative, dynamic model for predicting typhoon track deflections over complex terrain. Based on potential vorticity conservation, the model incorporates a topographic adjusting parameter (α) and a meridional adjusting velocity (MAV) to capture the vortex’s response to terrain variations. Simulations using an idealized bell-shaped mountain and Taiwan’s realistic topography reveal that steeper terrain gradients consistently deflect typhoon tracks southward. This steering effect intensifies with increasing vortex strength due to a larger α, leading to enhanced MAV. Shallower approach angles also amplify deflections due to prolonged terrain interaction. Results highlight the significant role of Taiwan’s Central Mountain Range in shaping typhoon trajectories. This model offers a refined approach for predicting typhoon behavior near complex terrain, advancing forecasting capabilities, and enhancing disaster preparedness strategies.

Effects of Topography and Geography on Solar Diffuse Fraction Modeling in Taiwan

A correlation model for the diffuse fraction was recently developed on the basis of a data set obtained in the western part of the Taiwanese mainland. However, it is widely agreed that no existing diffuse fraction correlation model is applicable to all geographical regions and climatic conditions, which is a viewpoint stated from a macro perspective. This study re-justifies this viewpoint through the consideration of a rather small geographical region: Taiwan. The topographic profile of the Taiwanese mainland primarily comprises the high-rise Central Mountain Ranges running from north–northeast to south–southwest, which separate the mainland into eastern and western parts. Furthermore, there are a number of small, remote islands around the Taiwanese mainland. The humidity over the sky dome of these small islands, carried from the moist sea (or ocean) air, is usually greater than that of the Taiwanese mainland. This results in different diffuse fraction patterns between these two geographical regions due to the climatic factor of atmospheric constituents. Two diffuse fraction correlation models for Taiwan were developed using in situ data sets for the eastern part of the Taiwanese mainland and an island in the Penghu archipelago, respectively. In particular, one case considered the topographic effect on modeling the diffuse fraction in Taiwan, while the other considered the geographical effect. Statistical assessments indicate that each correlation model developed in the present study performed better than the previous one developed using the in situ data set for the western part of the Taiwanese mainland, with both applied to the specific site where the data set was used for the model’s development. This work demonstrates the need to consider the effects of topography and geography when modeling the diffuse fraction in Taiwan.

First record of Plectrohyla guatemalensis Brocchi, 1877 (Anura, Hylidae) from Nicaragua

We confirm the presence of the genus Plectrohyla Brocchi, 1877 in Nicaragua and report the first records of Plectrohyla guatemalensis Brocchi, 1877 in the country based on three specimens collected in 1983 from the central mountain range of Matagalpa department. These specimens collected over 40 years ago are the southernmost records for the species and expand its geographic distribution by approximately 175 km southeast from its nearest recorded locality in Honduras.

Enhanced shear and veer in the Taiwan Strait during typhoon passage

During typhoon passage extreme wind conditions pose a challenge to the structural integrity of wind turbines. Particularly, wind shear and wind veer can influence wind turbine loads. This study investigates how Taiwan’s central mountain range affects wind shear and wind veer in the Taiwan Strait during three westward-moving typhoon cases. The typhoons are simulated with the Weather Research and Forecasting (WRF) model. We find that wind speed, shear, and veer vary over different regions in the Taiwan Strait. In large areas, the simulated wind shear is larger than modeled over the open ocean. In particular, mountain blockage leads to a spatially confined area of several 1000 km2 downstream of Taiwan, that exhibits over several hours strongly modified shear and veer in all three analyzed cases. Shear exponents up to 0.75 and veer between 0.2 and 0.6° m−1 suggest that turbine loads are impacted by the vertical change in the wind field in this area. The shear exponent and wind veer vary strongly with height in the downstream area of Taiwan’s central mountain range. The location of the area with large wind shear and wind veer differs between the three simulated typhoon cases and primarily depends on the latitude of the typhoon track relative to the central mountain range.

Species-specific dynamics may cause deviations from general biogeographical predictions - evidence from a population genomics study of a New Guinean endemic passerine bird family (Melampittidae).

The family Melampittidae is endemic to New Guinea and consists of two monotypic genera: Melampitta lugubris (Lesser Melampitta) and Megalampitta gigantea (Greater Melampitta). Both Melampitta species have scattered and disconnected distributions across New Guinea in the central mountain range and in some of the outlying ranges. While M. lugubris is common and found in most montane regions of the island, M. gigantaea is elusive and known from only six localities in isolated pockets on New Guinea with very specific habitats of limestone and sinkholes. In this project, we apply museomics to determine the population structure and demographic history of these two species. We re-sequenced the genomes of all seven known M. gigantaea samples housed in museum collections as well as 24 M. lugubris samples from across its distribution. By comparing population structure between the two species, we investigate to what extent habitat dependence, such as in M. gigantaea, may affect population connectivity. Phylogenetic and population genomic analyses, as well as acoustic variation revealed that M. gigantaea consists of a single population in contrast to M. lugubris that shows much stronger population structure across the island. We suggest a recent collapse of M. gigantaea into its fragmented habitats as an explanation to its unexpected low diversity and lack of population structure. The deep genetic divergences between the M. lugubris populations on the Vogelkop region, in the western central range and the eastern central range, respectively, suggests that these three populations should be elevated to full species level. This work sheds new light on the mechanisms that have shaped the intriguing distribution of the two species within this family and is a prime example of the importance of museum collections for genomic studies of poorly known and rare species.

Orographic Controls on Extreme Precipitation Associated with a Mei-Yu Front

Abstract Taiwan regularly receives extreme rainfall due to seasonal mei-yu fronts that are modified by Taiwan’s complex topography. One such case occurred between 1 and 3 June 2017 when a mei-yu front contributed to flooding and landslides from over 600 mm of rainfall in 12 h near the Taipei basin, and over 1500 mm of rainfall in 2 days near the Central Mountain Range (CMR). This mei-yu event is simulated using the Weather Research and Forecasting (WRF) Model with halved terrain as a sensitivity test to investigate the orographic mechanisms that modify the intensity, duration, and location of extreme rainfall. The reduction in WRF terrain height produced a decrease in rainfall duration and accumulation in northern Taiwan and a decrease in rainfall duration, intensity, and accumulation over the CMR. The reductions in northern Taiwan are linked to a weaker orographic barrier jet resulting from a lowered terrain height. The reductions in rainfall intensity and duration over the CMR are partially explained by a lack of orographic enhancements to mei-yu frontal convergence near the terrain. A prominent feature missing with the reduced terrain is a redirection of postfrontal westerly winds attributed to orographic deformation, i.e., the redirection of flow due to upstream topography. Orographically deforming winds converge with prefrontal flow to maintain the mei-yu front. In both regions, the decrease in mei-yu front propagation speed is linked to increased rainfall duration. These orographic features will be further explored using observations captured during the 2022 Prediction of Rainfall Extremes Campaign in the Pacific (PRECIP) field campaign. Significance Statement This study examines the impact of terrain on rainfall intensity, duration, and location. A mei-yu front, an East Asian weather front known for producing heavy, long-lasting rainfall, was simulated for an extreme rain event in Taiwan with mountain heights halved as a sensitivity test. Reducing terrain decreased rainfall duration in northern and central Taiwan. Decreases in rainfall duration for both regions is attributed to increased mei-yu front propagation speed. This increase in northern Taiwan is attributed to a weakened barrier jet, a low-level jet induced by flow blocked by the steep mountains of Taiwan. A unique finding of this work is a change in winds north of the front controlling movement of the front near the mountains in central Taiwan.

Why Does Japan’s South Foehn, “Jintsu-Oroshi,” Tend to Onset during the Night?: An Investigation Based on Two Case Studies

Abstract The Jintsu-oroshi refers to Japan’s south foehn, which blows over the Toyama Plain in the Hokuriku region. This region faces the Sea of Japan to the north and the central mountain range to the south. The Jintsu-oroshi occurs more frequently at night than during the day. In this study, we determined the primary factors causing this feature using the Weather Research and Forecasting (WRF) Model. We selected a typical Jintsu-oroshi case in May 2016 for analysis. An extratropical cyclone traversed the Sea of Japan during the event, leading to a temporal change in the synoptic-scale pressure pattern. The observations and numerical simulation results showed that the collapse of the mixed layer over the mountains and the end of the sea breeze are key factors for the nighttime onset of the Jintsu-oroshi. Indeed, mountain waves and their resulting downslope winds did not occur under near-neutral atmospheric stability conditions over the mountains during the daytime. After sunset, the atmospheric stability changed to stable conditions, which caused the downslope winds to blow. However, the downslope winds did not reach the plains because of the sea breeze. After several hours, the sea breeze disappeared, and the downslope winds reached the leeward plains and increased the temperature there. Similar features were confirmed in August 2013 for another typical Jintsu-oroshi case under atmospheric conditions, without temporal changes in the synoptic-scale pressure pattern. We expect the results obtained in this study to advance our understanding of foehn occurrence in regions where mountains adjoin seas, similar to the coastal areas adjacent to the Sea of Japan. Significance Statement The Jintsu-oroshi refers to Japan’s south foehn, which blows over the Toyama Plain in the Hokuriku region. This foehn occurs more frequently at night than during the day. Strong foehns enhance the risk of fire. Nocturnal high temperatures due to foehns can cause sleeplessness in people. Nighttime foehns cause damage to paddy rice. Analyses of observations and numerical simulations for the two typical cases showed that Jintsu-oroshi did not tend to occur during the daytime because the development of a convective boundary layer over the mountains and sea breezes in the leeward plain inhibited the occurrence of the downslope winds. We expect the results obtained in this study to advance our understanding of foehn occurrence in regions where mountains adjoin seas, similar to the coastal areas adjacent to the Sea of Japan.

Expanding the simulation of East Asian super dust storms: physical transport mechanisms impacting the western Pacific

Abstract. Dust models are widely applied over the East Asian region for the simulation of dust emission, transport, and deposition. However, due to the uncertainties in estimates of dust transport, these methods still lack the necessary precision to capture the complexity of transboundary dust events. This study demonstrates an improvement in the Community Multiscale Air Quality (CMAQ) model dust treatment during long-range transport of dust from northwestern China to the South China Sea (SCS). To accomplish this, we considered a super dust storm (SDS) event in March 2010 and evaluated the dust scheme by including adjustments to the recent calibration (Dust_Refined_1) and bulk density (Dust_Refined_2) refinements individually and in combination (Dust_Refined_3). The Dust_Refined_3 normalized mean bias of PM10 was −30.65 % for the 2010 SDS event, which was lower in magnitude compared to Dust_Refined_1 (−41.18 %) and Dust_Refined_2 (−49.88 %). Indeed, Dust_Refined_3 improved the simulated aerosol optical depth (AOD) value during significant dust cases, e.g., in March 2005, March 2006, and April 2009. Dust_Refined_3 also showed more clearly that, in March 2010, a “double plume” (i.e., one plume originating from the Taiwan Strait and the other from the western Pacific) separated by the Central Mountain Range (CMR) of Taiwan affected dust transport on the island of Dongsha in the SCS. On 15–21 April 2021, both CMAQ simulations and satellite data highlighted the influence of Typhoon Surigae on dust transport to downwind Taiwan and the western Pacific Ocean (WPO). The CMAQ Dust_Refined_3 simulations further revealed that many dust aerosols were removed over the WPO due to Typhoon Surigae. Hence, the model indicated a near-zero dust particle concentration over the WPO, which was significantly different from previous dust transport episodes over the Taiwan region. Therefore, our study suggested an effective method to improve dust management of CMAQ under unique topographical and meteorological conditions.

A taxonomic revision of the genus Angelica (Apiaceae) in Taiwan with a new species A. aliensis

BackgroundAngelica L. sensu lato is a taxonomically complex genus, and many studies have utilized morphological and molecular features to resolve its classification issues. In Taiwan, there are six taxa within Angelica, and their taxonomic treatments have been a subject of controversy. In this study, we conducted a comprehensive analysis incorporating morphological and molecular (cpDNA and nrDNA) characteristics to revise the taxonomic treatments of Angelica in Taiwan.ResultsAs a result of our research, we have revised the classification between A. dahurica var. formosana and A. pubescens and merged two varieties of A. morrisonicola into a single taxon. A new taxon, A. aliensis, has been identified and found to share a close relationship with A. tarokoensis. Based on the morphological and molecular characteristics data, it has been determined that the former three taxa should be grouped into the Eurasian Angelica clade, while the remaining four taxa should belong to the littoral Angelica clade. Furthermore, Angelica species in Taiwan distributed at higher altitudes displayed higher genetic diversity, implying that the central mountain range of Taiwan serves as a significant reservoir of plant biodiversity. Genetic drift, such as bottlenecks, has been identified as a potential factor leading to the fixation or reduction of genetic diversity of populations in most Angelica species. We provide key to taxa, synopsis, phenology, and distribution for each taxon of Taiwan.ConclusionsOur comprehensive analysis of morphological and molecular features has shed light on the taxonomic complexities within Angelica in Taiwan, resolving taxonomic issues and providing valuable insights into the phylogenetic relationships of Angelica in Taiwan.

Identification of potential source regions and long-range transport routes/channels of marine PM2.5 at remote sites in East Asia

Long-range transport (LRT) of air masses in East Asia and their impacts on marine PM2.5 were explored. Situated in the leeward region of East Asia, Taiwan Island marked by its elevated Central Mountain Range (CMR) separates air masses into two distinct air currents. This study aims to investigate the transport of PM2.5 from the north to the leeward region. Six transport routes (A-F) were identified and further classified them into three main channels (i.e. East, West, and South Channels) based on their transport routes and potential sources. Green Island (Site GR) and Hengchun Peninsula (Site HC) exhibited similarities in their transport routes, with Central China, North China, and Korean Peninsula being the major source regions of PM2.5, particularly during the Asian Northeastern Monsoons (ANMs). Dongsha Island (Site DS) was influenced by both Central China and coastal regions of East China, indicating Asian continental outflow (ACO) as the major source of PM2.5. The positive matrix factorization (PMF) analysis of PM2.5 resolved that soil dust, sea salts, biomass burning, ship emissions, and secondary aerosols were the major sources. Northerly Channels (i.e. East and West Channels) were primarily influenced by ship emissions and secondary aerosols, while South Channel was dominated by oceanic spray and soil dust. The results of W-PSCF and W-CWT analysis indicated that three remote sites experienced significant contributions from Central China in the highest PM2.5 concentration range (75–100%). In contrast, PM2.5 in the 0–25% and 25–50% ranges primarily originated from the open seas, with ship emissions being the prominent source. It suggested that northern regions with heavy industrialization and urbanization have impacts on high PM2.5 concentrations, while open seas are the main sources of low PM2.5 concentrations.

Transcriptome data from silica-preserved leaf tissue reveal gene flow patterns in a Caribbean bromeliad.

Transcriptome sequencing is a cost-effective approach that allows researchers to study a broad range of questions. However, to preserve RNA for transcriptome sequencing, tissue is often kept in special conditions, such as immediate ultracold freezing. Here, we demonstrate that RNA can be obtained from 6-month-old, field-collected samples stored in silica gel at room temperature. Using these transcriptomes, we explore the evolutionary relationships of the genus Pitcairnia (Bromeliaceae) in the Dominican Republic and infer barriers to gene flow. We extracted RNA from silica-dried leaf tissue from 19 Pitcairnia individuals collected across the Dominican Republic. We used a series of macro- and micro-evolutionary approaches to examine the relationships and patterns of gene flow among individuals. We produced high-quality transcriptomes from silica-dried material and demonstrated that evolutionary relationships on the island match geography more closely than species delimitation methods. A population genetic examination indicates that a combination of ecological and geographical features presents barriers to gene flow in Pitcairnia. Transcriptomes can be obtained from silica-preserved tissue. The genetic diversity among Pitcairnia populations does not warrant classification as separate species, but the Dominican Republic contains several barriers to gene flow, notably the Cordillera Central mountain range.

Fractionation of rare earth elements in soil profiles along an elevation gradient in central Taiwan

The distribution of rare earth elements (REEs) in soils is affected by climate, which is one of the main factors controlling soil formation. However, variations in the geochemical behavior of soil REEs with pedoclimatic changes have rarely been investigated. This study determined the mobilization/retention and fractionation of REEs in nine soil profiles derived from sandy shale along an elevation gradient from 49 m to 2394 m above sea level in the Central Mountain Range of Taiwan. The experimental results indicated a gradually decreased ΣREEs trend with increasing elevation/rainfall. Clay content significantly (p < 0.05) correlated with REEs, which accumulated in argillic horizons. Moreover, a decreasing GdN/YbN ratio with increasing secondary minerals (i.e., clay and pedogenic Fe and Al oxides) implied their preferential sequestration tendency for heavy REEs over light REEs. This preferential association coupled with intensifying illuviation along the climatic gradient, resulted in increasing LaN/SmN and decreasing GdN/YbN ratios with increasing weathering degree and elevation (p < 0.01). Our results demonstrate that in the studied humid tropical region, increasing moisture availability caused by higher rainfall and lower air temperatures with rising elevation has led to stronger illuviation and more advanced soil development, which is reflected in REE fractionation and can be quantified by the ratios GdN/YbN and LaN/SmN.

A compilation of common crossbill Loxia curvirostraL., 1758 ring-recovery data from the Iberian Peninsula and other European regions

In November 2021, a female common crossbill ringed in Switzerland was found in the Sistema Central mountain range, within the administrative border of the Community of Madrid (Spain). This is an unusal record due to the lack of data on irruptions of this species from central or northern Europe in the centre of the Iberian Peninsula. In this study, we have compiled all the existing common crossbill ring-recovery data from Iberia and other European regions. Our results show that common crossbill populations in the Iberian Peninsula are mainly sedentary, with limited movements across the different pine forest masses in search of food. In contrast, northern European common crossbill populations develop long distance migratory movements that may involve a large number of individuals following a NE-SW axis that, in an irregular manner and depending on the year, can arrive in the Iberian Peninsula in mid-August or September, where they may remain for several years before returning to their places of origin. In the Iberian Peninsula, these crossbills seem to use the pine species available as a trophic resource according to their ecological speciation, including species not present in their regions of origin.

New potential distribution and overlap areas of woolly opossum, genus Caluromys (Didelphimorphia: Didelphidae), in Colombia

The woolly opossums of the genus Caluromys, despite their wide distribution range, are poorly known species. In Colombia, the presence of C. derbianus and C. lanatus is recognized, and the presence of C. philander has been proposed. This study sought to update the distribution and know overlapping areas of the species of the genus Caluromys in Colombia. We modeled the current and potential distribution of C. derbianus and C. lanatus, and discussed the potential presence of C. philander. We extend the distribution range for C. derbianus and C. lanatus by obtaining new records mainly in the Colombian Caribbean region. For C. derbianus, we found that the estimated model area was 177,337 km2, with the most suitable areas in the Caribbean region in the department of Córdoba and the coast of the department of Sucre, in the north and south of the Pacific region, and in the Andean region on the western mountain range, associated with forest cover. For C. lanatus, the estimated model area was 940,007 km2 with the greatest habitat suitability in the forest cover of the Sierra Nevada de Santa Marta, the central mountain range, the Magdalena River valleys and the Andean-Orinosence piedmont. The areas of occupancy (AOO) and extent of occurrence (EOO) in Colombia are 268 km2 and 182,741 km2 for C. derbianus, 652 km2 and 1,036,486 km2 for C. lanatus, with an overlap area of 37,889 km2. Although we found high uncertainty in the records for C. philander in Colombia, we consider that the species probably has representation in the eastern Amazon and Orinoquia regions. This information could be useful to provide new perspectives for the study of the ecological interactions of these Neotropical marsupials, as well as for assessing threats to woolly opossums in Colombia.

A new species of Stelis subgen. Unciferia (Orchidaceae: Pleurothallidinae) from Costa Rica

A new species of Stelis recorded in the middle lands of the Tilarán mountain range and the Volcanic Central mountain range of Costa Rica is described based on living material. Distribution map, line drawing and a Lankester Digital Composite Plate of the new species is provided. The new species Stelis luz-marinae belongs to the Stelis subgen. Unciferia and is related to the Stelis segoviensis group, a group of a dozen species distributed from Mexico to Ecuador, but with its highest diversity in Costa Rica and Panama. The new species is compared to its similar species, as Stelis psilantha, S. segoviensis and S. werckleana, but it can be distinguished by its short coflorescences generally as long as the leaf lenght, its rachis with short internodes, and its yellow-brownish flowers with the adaxial edges of the sepals covered by white or brownish trichomes.

Limbodessus moni sp. nov., a new high altitudinal diving beetle from the Grasberg in West Papua, Indonesia (Coleoptera: Dytiscidae, Bidessini).

Limbodessus moni sp. nov. is described from Lake Anderson and from small, richly vegetated swampy areas around alpine lakes at 3,970 m a.s.l. near the Grasberg Mine (Carstensz Pyramid) in the Central Mountain Range of New Guinea. The record of the new species marks the altitudinal maximum of a diving beetle in New Guinea. The new species is morphologically similar to L. alexanderi Balke & Hendrich, 2015 in terms of body size and dark coloration; however, both species can be easily separated by the shape of the median lobe and the more moniliform female antennomeres, not forming a conspicuous club as in L. alexanderi. A modified key for all five Limbodessus species from New Guinea and adjacent islands is presented.

Integrative systematics and conservation of endangered Carabus nankotaizanus (Coleoptera: Carabidae) in Taiwan

Abstract The endangered endemic ground beetle, Carabus nankotaizanus Kano, 1932 (Coleoptera: Carabidae), consists of 4 subspecies distributed across the lowlands to mountain forests of Taiwan. However, continuous morphological variation among the subspecies and large altitudinal range gaps between lowland and mountain populations of C. nankotaizanus raise questions concerning its species boundaries. We assessed the species boundaries between lowland and mountain populations of C. nankotaizanus using an integrative approach combining morphological, molecular, life-history, and ecological traits. Future suitable habitats were predicted using ecological niche models to evaluate the effect of range shifts driven by climate warming. The analyses of morphological and ecological traits indicate that the lowland and mountain populations of C. nankotaizanus are 2 distinct phenetic and ecological species. The molecular phylogeny further supported 4 divergent groups (paraphyletic C. nankotaizanus sp. 1 of the northern lowland + monophyletic C. nankotaizanus sp. 2 of the northern mountain, paraphyletic C. nankotaizanus sp. 3 of the southeastern lowland + monophyletic C. nankotaizanus sp. 4 of the mountain groups). We recommend the designation of the 4 cryptic C. nankotaizanus as candidate species and officially protected evolutionary lineages. Future range shifts of C. nankotaizanus sp. 1 to higher latitudinal lowlands of northern Taiwan may pose significant challenges to its conservation due to urban development and island boundary. By contrast, upcoming range shifts of the mountain C. nankotaizanus species to higher altitudes of protected national parks and forest reserves in the Central Mountain Range may not represent a major threat to its survival.

A New Species of Werauhia (Bromeliaceae: Tillandsioideae) from Montane Cloud Forests of Costa Rica

Werauhia oenophylla Cascante &amp; J. F. Morales (Bromeliaceae), a new species of Tillandsioid epiphytic bromeliad, is described from the montane forests of Costa Rica. The new species is related to W. umbrosa (L. B. Sm.) J. R. Grant by its compound inflorescence with several flowers in short (&lt; 10 cm) lateral branches and coriaceous floral bracts that are longer than the pedicel. Werauhia oenophylla is distinguished by the combination of reddish-wine coloration on the abaxial surface of leaves and peduncle bracts and reddish-rose floral bracts. This species is only known from the country’s cloud forests in the Central Volcanic Mountain Range.

Phylogenetic divergence associated with climate oscillations and topology illustrates the dispersal history of Formosan sambar deer (Rusa unicolor swinhoii) in Taiwan

The island of Taiwan represents an ideal context for studying the effects of climatic oscillations and topographic variation on large herbivores due to its varied tropical to sub-tropical climate zones at different elevational ranges. We explored the phylogenetics of Formosan sambar deer (Rusa unicolor swinhoii) using the control region of the mitochondrial genome. We detected 18 haplotypes among 454 sequences across the island and grouped them into six regions based on SAMOVA, with 68.78% variance among regions. A Bayesian phylogenetic dendrogram revealed two spatially segregated genetic clades. Neutrality tests and Bayesian skyline plots uncovered different demographic expansion histories for the two clades. We further tested divergence times and chronology to propose potential phylogenetic scenarios, which were examined using approximate Bayesian computation. Finally, we present a credible hypothesis for a glacial refugium in the northern part of the Central Mountain Range. Subsequent secondary contact between the two clades during interglacial periods has led to the extant genetic structure of Formosan sambar deer.

Ambient ozone – New threat to birds in mountain ecosystems?

Mountain ecosystems are inhabited by species with specific characteristics enabling survival at high altitudes, which make them at risk from various pressures. In order to study these pressures, birds represent excellent model organisms due to their high diversity and position at the top of food chains. The pressures upon mountain bird populations include climate change, human disturbance, land abandonment, and air pollution, whose impacts are little understood. Ambient ozone (O3) is one of the most important air pollutants occurring in elevated concentrations in mountain conditions. Although laboratory experiments and indirect course-scale evidence suggest its negative effects on birds, population-level impacts remain unknown. To fill this knowledge gap, we analysed a unique 25-years long time series of annual monitoring of bird populations conducted at fixed sites under constant effort in a Central European mountain range, the Giant Mountains, Czechia. We related annual population growth rates of 51 bird species to O3 concentrations measured during the breeding season and hypothesized (i) an overall negative relationship across all species, and (ii) more negative O3 effects at higher altitudes due to increasing O3 concentration along altitudinal gradient. After controlling for the influence of weather conditions on bird population growth rates, we found an indication of the overall negative effect of O3 concentration, but it was insignificant. However, the effect became stronger and significant when we performed a separate analysis of upland species occupying the alpine zone above treeline. In these species, populations growth rates were lower after the years experiencing higher O3 concentration indicating an adverse impact of O3 on bird breeding. This impact corresponds well to O3 behaviour and mountain bird ecology. Our study thus represents the first step towards mechanistic understanding of O3 impacts on animal populations in nature linking the experimental results with indirect indications at the country-level.