Correction to “Pedogenesis of a coastal climosequence and a volcanic ash‐influenced elevational transect of western Haleakalā, Maui”

Tropical mountain rainforests extend over large elevational gradients with diverse climatic conditions. They are characterised by a decrease of above ground biomass, and a pronounced increase of fine root biomass with increasing elevation. Forest stands at higher elevations are further characterised by thick organic layers and very moist soil conditions. The turnover of fine roots plays an important role in the cycling of carbon and nutrients in theses ecosystems. However, the knowledge about the patterns of fine root dynamics in tropical mountain rainforests is still scarce. Likewise, not much is known about water and nutrient uptake capacities of roots at different elevations.The present study was conducted in five forests stands along an elevational transect between 1050 and 3060 m asl in a mountain rainforest of South Ecuador. It aimed (1) to analyse the effect of temperature and soil conditions on fine root turnover along the elevational transect by means of minirhizotrons; (2) to assess the role of nutrient limitation and water-logging for fine root activity by means of a fertilization and throughfall exclusion experiment, respectively; as well as to examine nitrogen uptake capacity of fine roots by 15N tracer application; and (3) to investigate the dependence of root sap flow on environmental variables by means of miniature heat balance sap flow gauges, and to analyse related anatomical characteristics of root cross sections.Fine root turnover (d < 2 mm) was significantly higher in the lowermost and the uppermost stand (0.9 cm cm-1 yr-1) than in the three mid-elevation stands (0.6 cm cm-1 yr-1). The turnover of finest roots (d < 0.5 mm) was higher compared to the root cohort with d < 2 mm, and exceeded 1.0 cm cm-1 yr-1 at the lower and upper elevations of the transect. Hence fine root turnover decreased from pre-montane to mid-montane forests as would be expected from an effect of low temperature on root turnover, but it decreased further upslope despite colder temperatures. It is assumed that this non linear altitudinal trend of fine root turnover originates from an overlapping of a temperature effect with other environmental gradients in the upper part of the transect. Adverse soil conditions may reduce root longevity at high elevations, and are thus additional factors besides temperature that control root dynamics in tropical mountain forests. The fast replacement of fine roots is possibly used as an adaptive mechanism by trees to cope with limiting environmental conditions.The fertilizer study revealed highest root growth stimulation after P addition at 1050 m, and after N addition at 3060 m, thus pre-montane forests may be presumably limited by the availability of P, whereas upper montane forests are rather limited by the availability of N. The concentrations of major nutrients in fine root tissue dropped significantly along the elevational transect, with strongest reductions observed for N. This may support the assumption of a decreased nutrient availability with increasing altitude. Throughfall exclusion at 3060 m did not reduce fine root mortality in this forest stand, hence high soil moisture contents do not seem to be a main stressor leading to high fine root turnover rates in upper montane forests. The 15NO315NH4 uptake study yielded a constantly high nitrate and ammonium uptake capacity of fine roots at altitudes at 1050, 1890 and 3060 m, suggesting that fine roots in upper montane forests compensate for low nutrient supplies with high nutrient uptake capacities.Root sap flow followed marked diurnal and seasonal courses in the forest stands at 1050, 1890 and 3060 m. Sap flow decreased roughly by a factor of three between the lowermost and the uppermost forest stand. A reduced sap flow was observed when VPD was above average for several days. VPD was identified as the most influential environmental factor controlling root water uptake, but its significance decreased with increasing altitude. In contrast, the influence of temperature increased along the elevational transect, and was identified as the most influential factor determining root sap flow at 3060 m. Anatomical analyses of root cross-sections provided evidence for decreasing vessel diameters with increasing altitude. Theoretical hydraulic conductivity was found to decrease more than ten fold from 50.2 m² MPa-1 s-1 at 1050 m to 4.0 m² MPa-1 s-1 at 3060 m. It is concluded that the temperature decrease with increasing altitude acts on water uptake through several pathways, (i) on the physics of water flow in the soil-plant-atmosphere continuum (increasing viscosity of water, decreasing VPD), (ii) by reducing vessel cell growth, (iii) by restricting nutrient availability (which may lead to smaller vessels), and (iv) possibly by lowering aquaporine activity in the roots.

Research Article| April 01, 1989 Systematic variations in the carbon and oxygen isotopic composition of pedogenic carbonate along elevation transects in the southern Great Basin, United States JAY QUADE; JAY QUADE 1Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar THURE E. CERLING; THURE E. CERLING 1Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar JOHN R. BOWMAN JOHN R. BOWMAN 1Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1989) 101 (4): 464–475. https://doi.org/10.1130/0016-7606(1989)101<0464:SVITCA>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JAY QUADE, THURE E. CERLING, JOHN R. BOWMAN; Systematic variations in the carbon and oxygen isotopic composition of pedogenic carbonate along elevation transects in the southern Great Basin, United States. GSA Bulletin 1989;; 101 (4): 464–475. doi: https://doi.org/10.1130/0016-7606(1989)101<0464:SVITCA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Stable carbon- and oxygen-isotope variations in Holocene soil carbonates that formed in the unsaturated zone were examined along several elevation transects in the southern Great Basin, United States, a region with a semi-arid climate. Our intent was to study the relationship between the stable isotopic composition of pedogenic carbonates and climate, ecological variations, differences in parent material, and soil depth.δ13C of pedogenic carbonate in three different soil profiles from different elevations decreases with soil depth, indicating a decrease in the ratio of atmospheric to plantderived CO2 downprofile. Pedogenic carbonate at the soil-air interface approaches a δ13C value in equilibrium with atmospheric CO2 in all three soils. Observed δ13C profiles for pedogenic carbonate can be described using a one-dimensional model for 12CO2 and 13CO2, assuming isotopic equilibrium between soil CO2 and soil carbonate. The modeled best fit to observed isotopic profiles suggests that the profile differences in part result from differing soil-respiration rates at each site.δ13C in deep pedogenic carbonate (>50 cm) varies by about 12 per mil over a 2,440-m elevation range, being enriched in 13C at the lowest elevations. The slope of δ13C for these carbonates versus elevation is very similar for soils developed on carbonate and on noncarbonate parent materials: depletion by 4.6 to 4.7 per mil per 1,000 m increase in altitude between 300 to 2,740 m above mean sea level for the localities studied. This concordance makes it likely that there has been complete isotopic exchange between HCO3- in solution and soil CO2 prior to carbonate precipitation.Soil CO2 and soil-respiration rates increase systematically with elevation. The plantderived component of soil CO2 indicates that C3 plants dominate the biomass at most measured sites, in agreement with plant surveys. Calculated equilibrium fractionation factors between soil CO2 and soil carbonate are very similar to those observed, again indicating complete isotopic exchange between carbon species. In all, the soil CO2 and soil-carbonate data suggest that the δ13C variation with elevation observed in the soil carbonates results from differing soil-respiration rates at each site, as well as from variations in the proportion of C3 to C4 and CAM plants in each site's surface biomass.δ18O values in pedogenic carbonates are higher at lower elevations, due in part to the more positive δ18O values for meteoric waters at lower elevations. The average δ18O value of deep (>50 cm) pedogenic carbonate at all sites, however, is enriched 2.4 to 3.7 per mil with respect to values we predict should be in equilibrium with the isotopic composition of local meteoric waters. This suggests that evaporative isotopic enrichment of soil waters may have occurred at all elevations prior to precipitation of carbonate, or that seasonal differences in the isotopic composition of meteoric waters coupled with differential infiltration may be taking place. One or both of these processes also may explain the δ18O decrease in soil carbonate with depth observed in two of three soil profiles. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The western slope of Haleakalā, Maui, demonstrates a wide range in soil development (eight mapped soil orders), thus providing a unique opportunity to investigate how climate and volcanic ash deposition influence soil development on basalt. The objective of this study was to examine soil chemical and physical properties across climatic gradients and elevation to address how climate and relatively recent volcanic ash deposition affect pedogenesis across western Haleakalā. Sixteen pedons were sampled: five in a coastal climosequence uninfluenced by volcanic ash (15–224 m elevation; 461–2768 mm mean annual precipitation [MAP]; 22°C–23°C mean annual temperature [MAT]; 3357–5577 mm potential evapotranspiration [PET]), and eleven in an elevational transect variably influenced by volcanic ash (73–1362 m elevation; 283–2267 mm MAP; 13°C–24°C MAT; 1555–2704 mm PET). Pedogenic thresholds for dynamic soil properties (base saturation [BS], pH, organic C, and Al/Si extracted by ammonium oxalate) occurred at about 0.4 MAP/PET (1500 mm MAP) along the coastal climosequence and at about 0.8 MAP/PET (1600 mm MAP) along the elevational transect due to an increase in soil moisture availability and leaching potential. Greater clay/Fe (extracted by citrate dithionite [CD]) and crystalline Fe (CD minus hydroxylamine hydrochloride‐hydrochloric acid [HH]) in drier lowland soils more distant from the summit indicate they are likely older and occur on older landforms. The ratio MAP/PET is an effective climatic index for understanding trends in pedogenesis and indicating pedogenic thresholds in climosequences and elevational transects in Hawaiian ecosystems.

Bacteria are essential regulators of soil biogeochemical cycles. While several studies of bacterial elevational patterns have been performed in recent years, the drivers of these patterns remain incompletely understood. To clarify bacterial distribution patterns and diversity across narrow- and broad-scale elevational gradients, we collected soil samples from 22 sites in the grasslands of Mt. Tianshan in China along three elevational transects and the overall elevation transect: (1) 6 sites at elevations of 1047–1587 m, (2) 8 sites at 876–3070 m, and (3) 8 sites at 1602–2110 m. The bacterial community diversity across the overall elevation transects exhibited a hump-like pattern, whereas consistent patterns were not observed in the separate elevational transects. The bacterial community composition at the phylum level differed across the transects and elevation sites. The Actinobacteria was the most abundant phylum overall (41.76%) but showed clear variations in the different transects. Furthermore, heatmap analyses revealed that both pH and mean annual temperature (MAT) were significantly (P < 0.05) correlated with bacterial community composition as well as the dominant bacterial phyla, classes, and genera. These findings provide an inclusive view of bacterial community structures in relation to the environmental factors of the different elevational patterns.

Comparison of ozone concentrations on a surface elevation gradient with balloon-borne ozonesonde measurements

Environment and genetics combine to influence tree growth and should therefore be jointly considered when evaluating forest responses in a warming climate. Here, we combine dendroclimatology and population genetic approaches with the aim of attributing climatic influences on growth of European larch (Larix decidua) and Norway spruce (Picea abies). Increment cores and genomic DNA samples were collected from populations along a ~900-m elevational transect where the air temperature gradient encompasses a ~4 °C temperature difference. We found that low genetic differentiation among populations indicates gene flow is high, suggesting that migration rate is high enough to counteract the selective pressures of local environmental variation. We observed lower growth rates towards higher elevations and a transition from negative to positive correlations with growing season temperature upward along the elevational transect. With increasing elevation there was also a clear increase in the explained variance of growth due to summer temperatures. Comparisons between climate sensitivity patterns observed along this elevational transect with those from Larix and Picea sites distributed across the Alps reveal good agreement, and suggest that tree-ring width (TRW) variations are more climate-driven than genetics-driven at regional and larger scales. We conclude that elevational transects are an extremely valuable platform for understanding climatic-driven changes over time and can be especially powerful when working within an assessed genetic framework.

Elevation does not matter? Genome screening using AFLP fails to reveal selection along elevational transects: a case study of Caucasian Primula vulgaris Huds. (Primulaceae)

Leaf carbon isotope discrimination (Δ), seasonal estimates of the leaf-to-air water vapor gradient on a molar basis (ω), and leaf nitrogen contents were examined in three riparian tree species (Populus fremontii, P. angustifolia, and Salix exigua) along elevational transects in northern and southern Utah USA (1500-2670 m and 600-1820 m elevational gradients, respectively). The ω values decreased with elevation for all species along transects. Plants growing at higher elevations exhibited lower Δ values than plants at lower elevations (P. fremontii, 22.9‰ and 19.5‰, respectively; P. angustifolia, 23.2‰ and 19.2‰, respectively; and S.␣exigua, 21.1‰ and 19.1‰, respectively). Leaf nitrogen content increased with elevation for all species, suggesting that photosynthetic capacity at a given intercellular carbon dioxide concentration was greater at higher elevations. Leaf Δ and nitrogen content values were highly correlated, implying that leaves with higher photosynthetic capacities also had lower intercellular carbon dioxide concentrations. No significant interannual differences were detected in carbon isotope discrimination.

Several wood structural characteristics were measured in 15-year-old Abiesconcolor (white fir) from four populations along an elevational transect in the central Sierra Nevada region. The trees had been growing in a plantation near Placerville, California. Growth rings were narrower at breast height, latewood percentage tended to be greater, and tracheids were shorter in trees from higher elevation populations. Proportion of family variance components was greater than population for specific gravity and spiral grain angle. The characteristics that showed greatest population components of variation would be largely determined by durations and rates of shoot and radial growth. Presumably, length of the growing season would exert stronger selection pressure on these variables than on other characteristics of wood structure.

Genetic variation in reproductive phenology among clones in a seed orchard affects the genetic efficiency of the orchard. Our objective was to evaluate genetic variation in reproductive phenology of Pinus patula clones in a seed orchard and the amount of overlap with pollen dispersal in natural stands. In 2014 and 2015, phenology of female and male strobili was recorded on 31 clones in the orchard, and phenology of male strobili was measured on 10 trees in each of four nearby natural stands along an elevational transect. Onset and end dates, and length of female receptivity (F_onset, F_end and F_length) and pollen dispersal (M_onset, M_end and M_length) were calculated, and genetic parameters were estimated. Differences between years in M_onset were larger in the natural stands than in the orchard, but there was a large overlap between the orchard and natural stands. A negative linear relationship with elevation was found for M_end and M_length in natural stands along the elevation transect. Genetic variation was detected for most reproductive phenology traits in the orchard. Genetic control was stronger for M_onset and M_length ( $$H_{c}^{2}$$ ≥ 0.54) than for female receptivity traits ( $$H_{c}^{2}$$ ≤ 0.38). Most phenological traits showed high genetic stability in both years (rB ≥ 0.76). We found a positive genetic correlation (r = 0.67) between F_onset and M_onset, suggesting there is a risk of selfing among clonal ramets. Moreover, the overlap between female receptivity in the orchard and pollen dispersal in neighboring natural stands indicates a risk of genetic contamination in the orchard, particularly for late-phenology clones.

Soil properties and microbial activity across a 500 m elevation gradient in a semi-arid environment

Fine root turnover plays an important role in the cycling of carbon and nutrients in ecosystems. Not much is known about fine root dynamics in tropical montane rainforests, which are characterized by steep temperature gradients over short distances. We applied the minirhizotron technique in five forest stands along an elevational transect between 1,050 and 3,060 m above sea level in a South Ecuadorian montane rainforest in order to test the influence of climate and soil parameters on fine root turnover. Turnover of roots with diameter < 2.0 mm was significantly higher in the lowermost and the uppermost stand (0.9 cm cm−1 year−1) than in the three mid-elevation stands (0.6 cm cm−1 year−1). Root turnover of finest roots (d < 0.5 mm) was higher compared to the root cohort with d < 2.0 mm, and exceeded 1.0 cm cm−1 year−1 at the lower and upper elevations of the transect. We propose that the non linear altitudinal trend of fine root turnover originates from an overlapping of a temperature effect with other environmental gradients (e.g. adverse soil conditions) in the upper part of the transect and that the fast replacement of fine roots is used as an adaptive mechanism by trees to cope with limiting environmental conditions.

Soil development along an elevational transect in the western Sierra Nevada, California

Aims: Quantifying the relative importance of the mechanisms that drive community assembly in forests is a crucial issue in community ecology. The present study aims to understand the ways in which niche-based and spatially based processes influence community assembly in areas in different climatic conditions and how these processes change during the transition from seedling to adult. Methods: In this study, we investigated how taxonomic and phylogenetic beta diversity in seedling and adult stages of forest trees change across three elevational transects in tropical, subtropical and subalpine forests in Southwest China, and the relationships of these changes to the environment and inter-site distances. We quantified the relative contribution of environmental conditions and spatial distribution to taxonomic and phylogenetic beta diversity of both seedling and adult life stages along each elevational transect. We also quantified the taxonomic and phylogenetic similarity between seedlings and adult trees along elevations. Important Findings: Taxonomic and phylogenetic beta diversity of both seedlings and adult trees increased with an increase in both environmental distance and spatial distance in all three transects. On both taxonomic and phylogenetic levels, the effects of environmental filtering and spatial disposition varied between life stages and among forest types. Phylogenetic similarity between seedlings and adult trees increased with elevation, although the taxonomic similarity did not show clear elevational patterns. Our results suggest that the relative contribution of niche-based and space-based processes to taxonomic and phylogenetic assemblages varies across major plant life stages and among forest types. Our findings also highlight the importance of ontogenetic stages for fully understanding community assembly of long-lived tree species.

Hydrologic processes that control river flow in Bhutan’s Chamkhar Chhu basin are important for understanding water supply vulnerability to downstream populations in a changing climate. Seasonal source waters and flow paths of streamflow of the basin were determined using isotopic and geochemical tracers for water year 2016. Samples including surface water, groundwater, glacier meltwater, and precipitation were collected in premonsoon, monsoon, and postmonsoon seasons along an elevation transect from 2,538 to 5,158 m. Solute trends in surface waters demonstrate the major influence that tributaries can have on main stem hydrochemistry and the increasingly important role of groundwater below 3,500 m. Groundwater’s role in flow is supported by a two-component hydrograph separation using SO4 2− as a tracer and shows that groundwater is especially important to river flow in the premonsoon. Source waters to river flow were calculated using δ18O as a tracer, indicating that rain and meltwater are more evenly important across the elevation transect in the early monsoon period than in the postmonsoon period when ice melt contributions rapidly wane with distance from the glacier.