Mid Elevations Research Articles

Altitudinal biodiversity patterns of seed plants along Gongga Mountain in the southeastern Qinghai-Tibetan Plateau.

The mechanisms underlying elevation patterns in species and phylogenetic diversity remain a central issue in ecology and are vital for effective biodiversity conservation in the mountains. Gongga Mountain, located in the southeastern Qinghai–Tibetan Plateau, represents one of the longest elevational gradients (ca. 6,500 m, from ca. 1,000 to 7,556 m) in the world for studying species diversity patterns. However, the elevational gradient and conservation of plant species diversity and phylogenetic diversity in this mountain remain poorly studied. Here, we compiled the elevational distributions of 2,667 native seed plant species occurring in Gongga Mountain, and estimated the species diversity, phylogenetic diversity, species density, and phylogenetic relatedness across ten elevation belts and five vegetation zones. The results indicated that species diversity and phylogenetic diversity of all seed plants showed a hump‐shaped pattern, peaking at 1,800–2,200 m. Species diversity was significantly correlated with phylogenetic diversity and species density. The floras in temperate coniferous broad‐leaved mixed forests, subalpine coniferous forests, and alpine shrublands and meadows were significantly phylogenetically clustered, whereas the floras in evergreen broad‐leaved forests had phylogenetically random structure. Both climate and human pressure had strong correlation with species diversity, phylogenetic diversity, and phylogenetic structure of seed plants. Our results suggest that the evergreen broad‐leaved forests and coniferous broad‐leaved mixed forests at low to mid elevations deserve more conservation efforts. This study improves our understanding on the elevational gradients of species and phylogenetic diversity and their determinants and provides support for improvement of seed plant conservation in Gongga Mountain.

Reply to the comment by Bailey et al. on “Long-term decline of sugar maple following forest harvest, Hubbard Brook Experimental Forest, New Hampshire”

Sugar maple decline in eastern North America is caused by a complex combination of factors, with soil nutrition being one of several important determinants. Given the complexity of sugar maple population dynamics and the geographic extent of the species, we support Bailey et al.’s (2019, Can. J. For. Res. 49(7), doi: 10.1139/cjfr-2018-0207 ) argument to interpret results from Cleavitt et al. (2018, Can. J. For. Res. 48(1): 23–31, doi: 10.1139/cjfr-2017-0233 ) with due caution. The experiment at Hubbard Brook Experimental Forest represents an atypical application of contemporary forest practice in the White Mountain National Forest; however, some comments in Bailey et al. (2019) missed the point; others inaccurately characterized our paper. Cleavitt et al.’s (2018) 30-year record of vegetation recovery following whole-tree harvest documented a worrisome inability of a sugar maple population that successfully established after harvest to maintain its position in the understory. This lack of persistence on base-poor soils such as those in the mid and upper elevations of Hubbard Brook Experimental Forest suggests that the successful recruitment of sugar maple is not guaranteed.

Assessing suitability of modified center pivot irrigation systems in corn production using low altitude aerial imaging techniques

This study evaluated corn (Zea mays var. indentata) canopy vigor and temperature variations using small unmanned aerial system (UAS) based spatiotemporal imagery data. The key objective was to develop understanding on site-specific suitability of the Mid Elevation Spray Application (MESA) and Low Elevation Spray Application (LESA) sprinkler systems in irrigating corn crop and potential water as well as energy savings. Aerial data was collected through small UAS flights at 100 m height above ground level and on 49, 59, 65, 77, 105, 114, 134 days after planting (DAP). Small UAS had 5-band multispectral and radiometric thermal imager on-board the platform. Custom image processing algorithms were developed to extract various vegetation indices (Normalized difference vegetation index [NDVI], Green NDVI [GNDVI] and Normalized difference red edge [NDRE]) and canopy temperature maps from the imagery data. Two sample T-test was performed on extracted data to understand significant difference, at 5% level, within the LESA and MESA treatments. For both the irrigation techniques, the crop vigor increased in the early growth stage (49, 65 DAP), peaked in the mid growth stage (77, 105, 114 DAP) and then decreased in the late growth stage (134 DAP). The MESA irrigated sections had higher vigor (NDVI, GNDVI, NDRE), but not significant, compared to LESA throughout the season. Similarly, the MESA irrigated areas had significantly (0.61–2.07 °C) cooler canopies than LESA. Such results were anticipated, in part due to the issues with the sprinkler heads used in LESA. The heads were being pulled off in the corn field, causing the weighted hose to damage the crop. A different kind of sprinkler head was used after this incident. However, some strips of corn had already been damaged. Overall, this study results confirm suitability of aerial imagery data in evaluating pertinent irrigation treatments. Additional season’s data would be needed to clearly understand which technique (LESA or MESA) is more suitable for irrigating corn crop in the central part of state of Washington.

Microclimatic variations and their effects on photosynthetic efficiencies and lichen species distribution along elevational gradients in Garhwal Himalayas

Climate change effects on Himalayas are expectedly more pronounced than any other mountainous ecoregion of the world with expected threat of meltdown by the year 2100 if effective checks are not imposed. The impacts of this climate warming in the geologically fragile Himalayas has started to show its effects on shifting precipitation patterns, increasing temperatures, glaciers meltdown, species richness patterns and overall unpredictable microclimatic conditions. For measuring such impacts of current climate warming in Himalayan ecosystems, need of ecological substitutes has been stressed on by different United Nation conventions. Lichens in contrast to vascular flora have long been proved to act as cost effective global indicators for measuring ecosystems responses to environmental climate. The variations in microclimatic attributes and their effects on photosynthetic efficiency and distribution were studied in geologically fragile ecosystem of Govind Pashu Vihar National Park in Garhwal Himalayas. Total 217 species of lichens comprising 80 genera and 35 families were found along different elevations. Among the different habitat groups, corticolous lichens showed their dominance (123 species) followed by saxicolous (65 species) and terricolous (29 species) lichens. Corticolous forms were dominated by crustose while saxicolous and terricolous were mostly fruticose growth forms. Mostly large number of species showed a narrow distribution with maximum species richness observed in mid elevation zones (1950–2200 m) followed by a gradual decline towards higher elevations. Phaeophyscia hispidula, Parmotrema reticulatum and Flavoparmelia caperata showed wider ecological amplitude. Out of these species, P. hispidula and F. caperata were further subjected to chlorophyll fluorescence measurements with a pulse amplified modulated fluorometer to access photosynthetic quenching efficiencies. Maximum electron transport rates (ETR; 96 ± 5.76 μmol e− m−2 s−1) were observed in Phaeophyscia hispidula (1550 m) while F. caperata showed nearly 21% lower ETR. Photochemical quenching (qP; 0.5 ± 0.01) was maximum at 1550 m elevation in F. caperata while P. hispidula showed maximum qP values at 2200 m elevation, showing it’s higher tolerances towards extreme light stresses. F. caperata showed higher (0.102 ± 0.003) non photochemical quenching (NPQ) in comparison to P. hispidula (0.062 ± 0.001) at extreme elevations of 3508 m. P. hispidula overall showed more toxitolerant nature towards abiotic stresses as compared to F. caperata. Higher photosynthetically active radiation (PAR; 1600–2350 µmol m−2 s−1), thallus hydration levels and extreme variations in air temperature (5.75–31.65 °C), ambient humidity along elevations were imperative in controlling species richness, distribution and photosynthetic quenching of lichen flora in the region.

Elevation affects extra-pair paternity but not a sexually selected plumage trait in dark-eyed juncos

Differences in environmental conditions are expected to generate distinct selective pressures favoring different phenotypes. For example, environmental conditions that affect the timing of breeding may influence opportunities for extra-pair copulations and thus the strength of sexual selection on males. To explore these relationships quantitatively, we compared breeding synchrony, rates of extra-pair paternity, and expression of a sexually selected plumage trait (the amount of white on the tail feathers) in populations of dark-eyed junco (Junco hyemalis) breeding at elevations from 1960 to 2660 m in California. Microsatellite parentage analysis revealed that extra-pair paternity rates varied by elevation, with intermediate elevations having the highest rate. Differences in breeding synchrony could not explain this variation. Extra-pair males had more tail white than the social males they cuckolded, consistent with tail white being a sexually selected trait. Although the observed differences in rates of extra-pair paternity suggested that sexually selected traits should also vary with elevation, there were no differences among elevations in the amount of white on male tails or in the correlation between tail white and proxies for male condition. Multiple factors may have contributed to this result, including persistent gene flow among elevations, which may counter the effects of local differences in selective pressures. These findings demonstrate the complexity of interactions among environmental conditions, selective pressures, and variation in phenotypic traits, and underscore the importance of assessing the impacts of sexual selection in the larger context of population genetic structure. SIGNIFICANCE STATEMENT: Environmental differences, such as those occurring along elevation gradients, can lead to differences in sexual selection. We found that juncos at mid elevations had higher rates of extra-pair paternity than juncos at high and low elevations. Our results also provide evidence that male tail plumage is sexually selected, as females preferred to copulate with males with more white on their tail plumage than the females’ social mates. This suggests that male tail white should differ among elevations, as the reproductive rewards of having an attractive tail would be greater at mid elevations. However, we found no differences in male tail white among elevations. This may be due to the birds breeding freely across elevations, as evidenced by a lack of genetic structure, i.e., gene flow swamping out any differences that might otherwise form.

Ashes to ashes: Characterization of organic matter in Andosols along a 3400 m elevation transect at Mount Kilimanjaro using analytical pyrolysis

Tropical mountain ecosystems cover a broad variety of climatic and vegetation zones and are global hotspots of biodiversity. These ecosystems are severely threatened by climate and land-use change, which also strongly affect soil properties. Mt. Kilimanjaro, with its large elevation gradient and relatively homogeneous geology of volcanic rocks and ashes, provides a unique opportunity to study and interpret soil organic matter (SOM) responses to climatic changes.Our objectives were to identify key SOM compounds in six elevation zones (covering ecosystems from tropical dry-lowland, through montane forest, up to alpine heathlands) that are affected by the climatic changes along a 3400 m transect, and to relate these SOM changes to ecosystem specific characteristics. The SOM composition in four topsoils (0–10 cm) samples per ecosystem was characterized by analytical double-shot pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS). Evolving-gas analysis-mass spectrometry (EGA-MS) was used to quantitatively compare the thermal desorption (first shot: <280 °C) and pyrolysis step (second shot: 280–600 °C).The percentage of thermally desorbed compounds increased 10 fold from lowland (<900 m) to mountain forest soils (>2000 m), followed by a 40% decrease in alpine ecosystems (>4000 m). Alkanes/-enes/-ols contributed between 4% and 30% to the identified SOM composition, with a maximum at mid elevation (2120 m). Fatty acids and fatty acid esters contributed with <3% to SOM composition and decreased to a minimum of <1% at Podocarpus forest soils (2900 m), followed by a re-increase at higher elevation. The percentage of lignin-derived compounds followed a similar pattern but also responded to reduced woody inputs above the tree line.Two main factors that seem to affect SOM quality and composition at Mt. Kilimanjaro were: 1) the rate and composition of organic matter inputs that in turn are controlled by climatic characteristics and the vegetation type and 2) the decomposition rate and efficiency, mainly controlled by soil pH, temperature and water availability. High forest productivity at mid elevations (2200 m) leads to high amounts of volatile compounds and increases stable SOM pools. The overall carbon accumulation in Andosols of Mt. Kilimanjaro is linked to the percentage of bound lipids (mainly alkanes, alkenes and alcohols), while site specific input patterns (e.g. vegetation or wild fires) are strongly reflected by sterols, lignin derived compounds or polycyclic aromatic compounds in SOM.

Purple Passion Fruit, Passiflora edulis Sims f. edulis, Variability for Photosynthetic and Physiological Adaptation in Contrasting Environments

Purple passion fruit (Passiflora edulis Sims f. edulis) is a tropical juice source. The goal of this project was to evaluate photosynthetic and physiological variability for the crop with the hypotheses that landraces contain the diversity to adapt to higher elevation nontraditional growing environments and this is dependent on specific parameters of ecological adaptation. A total of 50 genotypes of this crop were chosen from divergent sources for evaluations of their eco-physiological responses in two equatorial locations at different altitudes in the Andes Mountains, a center of diversity for the species. The germplasm included 34 landraces, 8 commercial cultivars, and 8 genebank accessions. The two locations were contrasting in climates, representing mid and high elevations in Colombia. Mid-elevation valleys are typical regions of production for passion fruit while high elevation sites are not traditional. The location effects and variables that differentiated genotypes were determined. Results showed statistically significant differences between locations and importance of physiological parameters related to photosynthesis and water use efficiency. Some landraces exhibited better water status and gas exchange than commercial types. Parameters like maximum photosynthesis, points of light saturation and compensation, darkness respiratory rate, and apparent quantum yield varied between genotype groups. The landraces, commercial types, and genebank entries also differed in content of carotenoids and chlorophylls a and b. Meanwhile, photosynthesis measurements showed that altitudinal difference had an effect on genotype-specific plant growth and adaptation. An important conclusion was that landraces contained the diversity to adapt to the new growing environment at higher altitudes.

Evaluating water application efficiency of low and mid elevation spray application under changing weather conditions

Over half of the irrigated land in the US, 11.5 million ha, is irrigated with center pivot and linear move systems. Because of this, minor changes in the operation efficiency of these systems can have large impact on overall water conservation. The objective of this study was to evaluate the water application efficiency (WAE) of low and of mid elevation spray application (LESA and MESA) using catch can test and drainage lysimeters, and develop governing equations based on the weather variables. A three-year (2015–2017) field study was conducted at the Washington State University Research and Extension Center, near Prosser. Catch cans were used to collect the fraction of total irrigation-water applied that reached the ground surface as WAE and drainage lysimeters to measure the overall water loss (OAWL) and wind drift and evaporation losses (WDEL), (WDEL = 100-WAE). Air temperature (Ta), relative humidity (RH), short-wave global irradiance (Rg), wind speed (WS), and calculated vapor pressure deficit (VPD) were used as the input weather variables to mixed modeling technique. Results showed that on average 21% more irrigation-water reached the ground with LESA than with MESA systems. Lysimetric measurements showed on average a 16% efficiency difference between MESA and LESA. The monthly WAE differences between MESA and LESA increased from 12 to 30% during the hot summer months and thereafter decreased, from 30 to 9%. The warmer and drier year of 2015 had the highest annual average values of WDEL of 17% for LESA and 19% for MESA. Results indicated a relatively constant WAE for LESA regardless of weather conditions. Mixed modelling showed that VPD was the only significant predictor (P < 0.05) of WAE for LESA, while VPD and WS for MESA. Our results might be used to adjust center pivot travel speed (% settings) to compensate for variations in WAE as the weather changes.

Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand.

This study is based on more than 25,000 specimens of the superfamily Empidoidea (Diptera) collected throughout a full year on a 2000 m elevational habitat succession gradient along a 21 km transect on Doi Inthanon, the highest mountain in Thailand. The samples were sorted to 58 genera and 458 morphospecies (Empididae, 73; Hybotidae, 203; Dolichopodidae, 179; Brachystomatidae, 3). The data were used to prepare the first thorough taxon-focussed description of how diversity of a major group of Diptera is structured in tropical forest biotopes. We found significant spatial (elevation / habitat) and temporal (seasonal) variations in richness (α-diversity) and abundance at family-level. α-Diversity of the four families was maximal in damp evergreen forests at higher elevation (1500-2500 m), but Dolichopodidae also had a major subsidiary peak in lowland dry evergreen forest at 500-1000 m. Genus-, tribe- and subfamily level α-diversity / elevation profiles were varied, indicating that overall family-level richness is a composite of many taxa that contribute low, high or mid-elevation specialisms. We provide a detailed analysis of these specialisms for each of the 58 genera. Adult phenology was correlated with the monsoon and had three characteristic phases: (i) pre-monsoon commencement during the latter part of the hot dry season, (ii) a 'flush' of maximal richness during the early-monsoon, and (iii) a secondary richness maximum associated with the late-monsoon. Maximum α-diversity occurred in phases (i) and (ii) but communities in phase (iii) had characteristically low evenness in which a few abundant species were dominant. Cluster analysis and ordination resolved three well-founded communities with different species-abundance distributions, high levels of species-level specialism and habitat-fidelity associated with moist hill evergreen forest (MHE) at >2000 m; mid elevation evergreen forests (EM) at 1000-2000 m and dry lowland forest (DL) at 1000 m. The three forest types with which these communities are associated are widespread and typical of northern Thailand and the diversity characteristics of each habitat are likely scalable to larger geographic areas. The transition from lowland DL through to upper montane MHE communities was generally characterised by increasing abundance, lower evenness (higher dominance), slower temporal turnover of community composition (relaxation of seasonality), longer periods of adult flight activity and rare species contributing less to species richness. Oriental biogeographic influences are strong at lower elevations but Palaearctic influences are increasingly important at higher elevations. The mixing of Oriental and Palaearctic elements in MHE forests is thought to explain the greater phylogenetic complexity at higher elevation (as measured by taxonomic distinctness).

HYPOGLYCEMIC ACTIVITY OF THE METHANOLIC EXTRACT OF IMMATURE FRUITS OF Capsicum pubescens Ruiz et Pavón (PERON CHILI PEPPER) IN DIABETIC RATS

Capsicum pubescens is the least studied domesticated chili pepper, specifically in its antioxidant activity and hypoglycemic properties. It is cultivated on a small scale in family gardens and greenhouses in the central Mexico to the mid elevation Andes of Peru and Bolivia, where it probably originated. The fruits are called “peron” (pear‐shaped and yellow) or “manzano” (apple‐shaped and red) in Mexico and “rocoto” in Peru. In this research, the hypoglycemic effect of the methanolic extract of immature yellow chili fruit of C. pubescens (peron chili pepper), administered orally (100 μL) to diabetic rats treated with 40 mg of streptozotocin (STZ)/kg of body weight, was evaluated over 60 days in three doses (0.1, 1 and 10 mg/kg). During this time, the body weight and glucose levels were obtained every ten days and at 60 days, the rats were sacrificed (NOM‐062‐ZOO‐1999), determining the levels of blood glucose, urea, creatinine, uric acid, triacylglycerides, total lipids, total cholesterol and HDL‐cholesterol. In normoglycemic (non‐diabetic) rats, the extract did not show a negative effect on the parameters determined, maintaining blood glucose levels (90 mg/dL) and body weight (436.6 g) without significant differences in the three doses probed. However, in the diabetic rats treated with the extract, there was a significant decrease in the levels of blood glucose (&lt;110 mg/dL), uric acid, creatinine, triacylglycerides and total lipids, and a tendency to lower cholesterol levels total and cholesterol‐HDL doses‐dependent. These results demonstrate the hypoglycemic effect of the methanolic extract of immature fruits of the yellow genotype of C. pubescens, as well as a protective effect of kidney and liver damage, mainly at a dose of 10 mg/kg.Support or Funding InformationGrants: Financial support grant from CONACYT (ACC) and CIC/UMSNH (Project 2.10 RSG).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ecological consequences of anomalies in atmospheric moisture and snowpack.

Although increased frequency of extreme-weather events is one of the most secure predictions associated with contemporary climate change, effects of such events on distribution and abundance of climate-sensitive species remain poorly understood. Montane ecosystems may be especially sensitive to extreme weather because of complex abiotic and biotic interactions that propagate from climate-driven reductions in snowpack. Snowpack not only protects subnivean biotas from extreme cold, but also influences forage availability through timing of melt-off and water availability. We related relative abundances of an alpine mammal, the American pika (Ochotona princeps), to measures of weather and snowpack dynamics over an 8-yr period that included before and after a year of record-low snowpack in Washington, USA. We sought to (1) quantify any change in pika abundance associated with the snowpack anomaly and (2) identify aspects of weather and snowpack that influenced abundance of pikas. Pikas showed a 1-yr lag response to the snowpack anomaly and exhibited marked declines in abundance at elevations below 1,400m simultaneous with increased abundances at higher elevations. Atmospheric moisture, indexed by vapor pressure deficit (VPD), was especially important, evidenced by strong support for the top-ranked model that included the interaction of VPD with snowpack duration. Notably, our novel application of VPD from gridded climate data for analyses of animal abundances shows strong potential for improving species distribution models because VPD represents an important aspect of weather that influences the physiology and habitat of biota. Pikas were apparently affected by cold stress without snowpack at mid elevations, whereas changes to forage associated with snowpack andVPD were influential at high and low elevations. Our results reveal context dependency in pika responses to weather and illustrate how snow drought can lead to rapid change in the abundance of subnivean animals.

Composition, richness and floristic diversity along an elevational gradient in a semi-disturbed treeline ecotone, Bhaderwah, Jammu and Kashmir

The paper deals with plant species richness - diversity relationship along the rising elevation in a semi-disturbed tree line ecotone in upper Bhaderwah, a part of lesser Himalaya. 253 plant species distributed over 170 genera and 62 families were recorded during the intensive field surveys carried during May 2014 to September 2016. These included 11 trees, 29 shrubs and 213 herb species with 247 angiosperms and 6 gymnosperms. Family Asteraceae with 37 species dominated the study area. Maximum richness (179) was observed at sub-alpine zone (Site IV) while the trees (H'=1.74) and shrubs (H'=2.48) revealed maximum diversity at Site III and herbs at Site IV (H'=4.60). The maximum evenness for trees, shrubs and herbs was exhibited by sites III (J'=0.79), V (J'=0.87) and VI (J'=0.94), respectively. The diversity and evenness showed an incremental rise along the rising elevation reaching maxima at the mid elevation with Site-IV being the species rich and Site-VII species deficit, which implies that sub-alpine and alpine forests need effective monitoring and conservation.

Mercury bioaccumulation in temperate forest food webs associated with headwater streams

The soils and food webs associated with mid to high elevation, forested, headwater streams in northeastern North America are potential hotspots for mercury (Hg) methylation and bioaccumulation, but are not well studied. Our goals were to quantify total Hg (THg) and methyl Hg (MeHg) concentrations in soils and terrestrial food webs associated with headwater streams of northern hardwood forests to identify predictors of small-scale spatial variation in Hg bioaccumulation. We sampled soil characteristics that promote Hg methylation including pH, sulfur and calcium content, and organic matter. To assess spatial variation, we sampled at high (~700 m asl) and mid elevations (~500 m asl), both adjacent to (<1 m) and away from (>75 m) three replicate headwater streams in each of two watersheds of the White Mountains region, New Hampshire, USA. Soils of these forested watersheds differed significantly in pH and the content of calcium, sulfur, organic matter and THg. Conditions for methylation were more favorable in the upland forest sites compared to streamside sites. Significant bioaccumulation of THg occurred in all measured components of the food web, including insects, spiders, salamanders, and birds. Trophic position, as determined by δ15N, was the best predictor of both THg and MeHg bioaccumulation across the sampled taxa and was also a better predictor than spatial location. However, the degree of bioaccumulation at which MeHg significantly affects animal behavior, reproduction or survival is unknown for most taxa in terrestrial habitats, particularly for invertebrates. These findings show that Hg methylation and bioaccumulation is not limited to areas traditionally classified as wetlands or to areas with exceptionally high THg inputs, but that it is a widespread and important phenomenon in the moist deciduous forests of eastern North America.

Differences in Soft-Sediment Infaunal Communities Between Shorelines with and Without Seawalls

Seawalls are an increasingly conspicuous component of coastlines, which may modify ecological communities through their effects on physical and biological processes. Effects of seawalls on ecological communities may vary spatially according to environmental conditions at the site of seawall placement, the local species pool, and the characteristics of the seawall itself. In the Austral Spring of 2014, we assessed how differences in infaunal communities between paired sedimentary sites with and without seawalls vary with tidal elevation and environmental conditions (i.e. sediment variables, benthic cover), at five locations within Brisbane Waters, New South Wales, Australia. Contrary to the prediction that differences in infaunal communities between sites with and without seawalls would be greatest at high intertidal elevation at which seawalls are built, we found greater differences at mid intertidal elevations. At muddy locations, characterised by high faunal abundance and richness, the abundance of mid intertidal infauna was less at sites with than without seawalls. By contrast, at sandy locations, which were characterised by low infaunal abundance and richness, the reverse pattern was seen. Although the structure of infaunal communities was correlated with sediment characteristics, sites with and without seawalls did not display consistent patterns of difference in sediment grain size or organic carbon content across locations. The greater difference in infaunal communities between sites with and without seawalls at mid than high or low intertidal elevations likely reflects an interaction between the proximity of habitat to seawalls and biological traits of the resident infaunal species that influence their susceptibility to perturbation.

A novel dendroecological method finds a non-linear relationship between elevation and seasonal growth continuity on an island with trade wind-influenced water availability.

Climatic seasonality drives ecosystem processes (e.g. productivity) and influences plant species distribution. However, it is poorly understood how different aspects of seasonality (especially regarding temperature and precipitation) affect growth continuity of trees in climates with low seasonality because seasonality is often only crudely measured. On islands, exceptionally wide elevational species distribution ranges allow the use of tree rings to identify how growth continuity and climate–growth relationships change with elevation. Here, we present a novel dendroecological method to measure stem growth continuity based on annual density fluctuations (ADFs) in tree rings of Pinus canariensis to indicate low climatic seasonality. The species ranges from 300 to >2000 m a.s.l. on the trade wind-influenced island of La Palma (Canary Islands), where we measured three decades of tree-ring data of 100 individuals distributed over 10 sites along the entire elevational range. The successfully implemented ADF approach revealed a major shift of stem growth continuity across the elevational gradient. In a remarkably clear pattern, stem growth continuity (percentage of ADFs) showed a hump-shaped relationship with elevation reaching a maximum at around 1000 m a.s.l. Low- to mid-elevation tree growth was positively correlated with the Palmer Drought Severity Index (PDSI; indicating aridity) and sea surface temperature (indicating trade wind-influenced moderation of water supply), while high-elevation tree growth was positively correlated with winter temperature (indicating a cold-induced dormancy period). We conclude that ADFs are a useful method to measure stem growth continuity in low-seasonality climates. Growth of P. canariensis on the Canary Islands is more frequently interrupted by winter cold at high elevations and by summer drought at low elevations than in the trade wind-influenced mid elevations, where growth sometimes continues throughout the year. Climate change-associated alterations in trade wind cloud formation might cause non-analogue growth limitations for many unique island species.

Spatiotemporal evidence of tree-growth resilience to climate variations for Yezo spruce (Picea jezoensis var. komarovii) on Changbai Mountain, Northeast China

Global warming-induced changes in tree-growth resilience to climate variations have been widely reported for mid- and high-latitude regions around the world. Most studies have focused on the spatial variability of trees in radial growth–climate relationships on Changbai Mountain in Northeast China, but little is known about temporal changes in tree growth in response to climate. We explored the stability of effect of climate variables on radial growth of Yezo spruce [Picea jezoensis Carr. var. komarovii (V.Vassil.) Cheng et L.K.Fu] at 1200, 1400, and 1600 m above sea level, representing low, middle, and upper ranges of the spruce–fir mixed forest on Changbai Mountain. The results showed that the relation between tree growth and climate did not vary with altitude, but the stability of the tree-growth–climate relationship did vary with altitude as the climate changed. Radial growth of Yezo spruce at all three elevations was influenced primarily by maximum temperature during May (Tmax5) and mean minimum temperature from January to March (Tmin1–3). More specifically, the relationship strengthened significantly at lower elevations, but weakened significantly at higher elevation, and fluctuated at mid elevations since 1980. Increase in Tmin1–3 and decrease in Tmax5 were the main reasons for the decrease in the radial growth at three altitudes. The findings of this study clarified that the decrease in radial growth on Changbai Mountain is not a “divergence problem” of an unexpected decrease in tree growth in response to an increase in mean temperature and provides a reference for using tree-ring data to reconstruct climate patterns and/or predict the growth of trees under various climate change scenarios.

Spatio-Temporal Analysis of Early Twenty-First Century Areal Changes in the Kabul River Basin Cryosphere

Climate change is a common concern globally and the Kabul River Basin, a transboundary basin between Pakistan and Afghanistan, is no exception. Rising temperatures cause snow and glaciers to melt rapidly, which increases the variability of river flows that may affect the water resource management between the two countries. For this purpose, it is necessary to study snow and glaciers, the main source of river flow. The goal of this research is to assess and analyze the basin-scale and elevation-zonal variation in the areal extent of snow and glacier cover for the years 2001–2016, on daily, monthly, seasonal and yearly basis. The basin was distributed into eight elevation zones; and snow cover for the whole basin and each elevation zone was then extracted by utilizing the Moderate Resolution Imaging Spectroradiometer (MODIS), Onboard TERRA Satellite, 8-daily, 500 m resolution images. As per average climatology of the basin, snow cover is minimum in August because of higher summer temperatures and maximum in February owing to lower winter temperatures and higher westerly precipitation in solid form. Based on the basin-scale analysis of changes in the daily snow-covered areal extents, it is found that snow cover significantly increases in the three lowest elevation zones, whereas in the mid elevation zones (Zone 4 and 5) and the highest elevation zone (Zone 8) a negligible decreasing trend is found. Moreover, non-significant but decreasing trend in Zone 8 may hint either at decrease in solid precipitation in the high elevation region or a slight retreat of the glaciers which may become significant in the coming years. In addition, there is a significant decreasing trend of snow covered area in Zones 6 and 7 which gives a similar indication. Our seasonal and annual analysis indicates that there is an overall slight increasing trend in the basin for all analyzed seasons and also on annual basis. The results concluded that a detailed hydro-climate modeling analysis should be carried out for this basin to find the changes in water availability under the future climate scenarios.

Scour depths at sites selected for spawning by brown trout (Salmo trutta) along a longitudinal gradient of a North American mountain river

AbstractIn the Intermountain West, USA, fry of fall‐spawning brown trout (Salmo trutta) are susceptible to scour‐related mortality because they are still in the gravel during spring snowmelt run‐off events. The goal of our research was to understand patterns of gravel scour on the Logan River, Utah, in relation to brown trout spawning and whether mobility of spawning gravels could explain the absence of brown trout from higher elevations. We collected data to characterize local entrainment potential at spawning gravels longitudinally on the Logan River during 2009 and 2010 spring flood events. We used scour chains to measure scour depth at spawning locations, and we also examined the position of redds in channel cross sections in relation to the centre line. The flood magnitude in both years approximated the 2‐year flood magnitude, but the flood in 2009 was much longer in duration. Scour at 27% of scour chain locations exceeded the estimated median upper limit of developing fry in 2009, whereas scour at 0% of locations exceeded this depth in 2010. Brown trout spawned in locations with similar entrainment potential at both mid and high elevations, which contributed to a lack of trend in scour depth with elevation. In addition, the majority of areas chosen for spawning were channel margins. The relationship between local entrainment potential at spawning gravels and scour depth was similar for the mid‐elevation canyon zone with medium brown trout density and the high‐elevation noncanyon zone with low brown trout density. In a low‐elevation backwater zone containing high densities of brown trout, scour was high despite low levels of entrainment potential. Overall, findings suggest that spawning gravel scour is not limiting brown trout abundance at high elevations in this system given shallow scour depths overall and a general lack of increase in scour depth with increasing elevation/distance upstream.

Variation in Tree Community Composition and Carbon Stock under Natural and Human Disturbances in Andean Forests, Peru

Deforestation and forest degradation in Andean forests is influenced by natural and social environments including a wide elevation range and anthropogenic disturbance. Tree community composition is receiving attention as a key indicator of forest degradation. However, difference in factors affecting community composition at different elevation zones remains unclear. We aimed at elucidating factors (natural and human disturbances, and forest characteristics) that influence the variations in community composition in Andean forests. We conducted a ground-based survey setting 45 plots across a wide elevation range (ca. 600 to 3500 m a.s.l.) in Cusco region, Peru. Above ground biomass (AGB) decreased with increasing elevation. The generalized linear models for multivariate abundance data suggested that a factor affecting community composition was natural disturbance (erosion) at low elevation (&lt;1000 m), while human disturbance (infrastructure such as sheds and trails) at high elevation (≥2400 m). Within each of the different elevation zones, the AGB affected community composition only at mid elevation (1000–2400 m), whereas mean tree height showed a consistent effect on community composition across the three elevations. Our results suggest that the effects of human disturbance on community composition were more prominent at higher elevation. The results also suggest that mean tree height may have a potential to be a key measure for evaluating variations in community composition in Andean forests.

Richness Patterns of Ferns Along an Elevational Gradient in the Sierra de Juárez, Oaxaca, Mexico: a Comparison with Central and South America

The transition zone from the tropics to the subtropics in Mexico is an outstanding and poorly explored area of biotic overlap, and as such very interesting to evaluate how species richness patterns change in the latitudinal context. In order to assess alpha diversity patterns of ferns in this zone, we analyzed changes in their assemblages along an elevational gradient from 300 m to 3,000 m in the Sierra de Juárez, Oaxaca, and compared the results with similar studies conducted in Central and South America. We report the most detailed plot-based elevational gradient study on ferns in the region and provide detailed data on species abundances and elevational ranges. In 121 plots of 20 × 20 m, we found 195 fern species, with the highest species numbers recorded at mid-elevations (1,100–2,200 m) and lower richness at both gradient extremes. This hump-shaped pattern was mainly driven by epiphytes, which contributed about 40% to the total species richness and had wider elevational ranges than terrestrial species, which contributed 38% to the total richness, and were more or less constant at low to mid elevations about 2,500 m, followed by a gradual decline. Overall, richness per plot was low compared to other elevational gradients within the tropics closer to the Equator. This decline of species richness towards the subtropics and temperate regions appears to be rather abrupt within Central America, but additional data are needed to close the remaining gap of knowledge between Costa Rica and Mexico.