scholarly journals Contrasting growth response of evergreen and deciduous arctic‐alpine shrub species to climate variability

Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Svenja Dobbert ◽  
Roland Pape ◽  
Jörg Löffler
Keyword(s):  
Climate Variability ◽  
Growth Response ◽  
Shrub Species ◽  
Alpine Shrub

Patch mosaic cyclic succession associated with the growth and senescence of an alpine shrub

2016 ◽  
Vol 64 (2) ◽  
pp. 111 ◽  
Author(s):  
Danielle C. McPhail ◽  
Jamie B. Kirkpatrick
Keyword(s):  
Vegetation Change ◽  
Root Competition ◽  
Shrub Species ◽  
Central Plateau ◽  
Clear Sky ◽  
Patch Mosaic ◽  
Dead Material ◽  
Alpine Shrub ◽  
Floristic Variation ◽  
Sky Conditions

Endogenously-induced cyclic vegetation change has been associated with the life cycle of shrub species, resulting in mosaic or linear patterning in vegetation. We investigated whether mosaic cyclic succession was taking place in Richea acerosa (Lindley) F.Muell. alpine heath on the Central Plateau of Tasmania, Australia by determining the variation in species composition associated with different growth characteristics of the shrub and by monitoring shrubs in plots over 11 years. Temperatures below and adjacent to shrubs were measured in clear sky conditions to determine if microclimatic variation was associated with structural and floristic variation. Species richness was higher outside than inside the shrubs, and was further depressed by an increasing proportion of dead material in the shrub. However, Poa saxicola R.Br. appeared to be protected by the prickly foliage of R. acerosa and also preferentially occurred among the mass of dead stems that characterised the centre of older plants. There was a strong floristic shift associated with the development of the shrub. The live cover of individual shrubs remained constant in all plots over the 11 years, while plots initially dominated by senescent plants contained young plants and vice-versa. The live part of the shrubs moderated temperatures. However, root competition and protection from grazing seem likely to have made a major contribution to the shifting conditions associated with the mosaic cyclic succession.

Growth response of Great Basin limber pine populations to climate variability over the past 4002 years

2021 ◽  
pp. 1-22
Author(s):  
Constance I. Millar ◽  
Diane L. Delany ◽  
John C. King ◽  
Robert D. Westfall
Keyword(s):  
Climate Variability ◽  
Great Basin ◽  
Growth Response ◽  
High Growth ◽  
Cumulative Record ◽  
Growth Period ◽  
Atlantic Multidecadal Oscillation ◽  
Ice Age ◽  
Individual Site ◽  
Summer Temperatures

Abstract Tree-rings representing annual dates from live and deadwood Pinus flexilis at ten sites across the central Great Basin (~38°N) yielded a cumulative record across 4002 years (1983 BC–AD 2019). Individual site chronologies ranged in length from 861–4002 years; all were continuous over their sample depths. Correlations of growth with climate were positive for water relations and mostly negative for summer temperatures. Growth was generally correlated across sites, with the central Nevada stands most distinct. Although growth was low during the Late Holocene Dry Period, variability marked this interval, suggesting that it was not pervasively dry. All sites had low growth during the first half of the Medieval Climate Anomaly, high growth during the mid-interval pluvial, and low growth subsequently. Little synchrony occurred across sites for the early Little Ice Age. After AD 1650, growth was depressed until the early twentieth century. Growth at all sites declined markedly ca. AD 1985, was similar to the lowest growth period of the full records, and indicative of recent severe droughts. A small rebound in growth occurred after ca. AD 2010. A strong signal for Atlantic Multidecadal Oscillation (AMO) occurred in growth response at most sites. The persistence of all stands despite climate variability indicates high resilience of this species.

Strategies of light energy utilisation, dissipation and attenuation in sixco-occurring alpine heath species in Tasmania

2003 ◽  
Vol 30 (12) ◽  
pp. 1205 ◽  
Author(s):  
Erica L. Williams ◽  
Mark J. Hovenden ◽  
Dugald C. Close
Keyword(s):  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Distinct Species ◽  
High Light ◽  
Light Energy ◽  
Shrub Species ◽  
High Light Stress ◽  
Thermal Energy Dissipation ◽  
Alpine Shrub ◽  
Cycle Dependent

Alpine environments are characterised by low temperatures and high light intensities. This combination leads to high light stress owing to the imbalance between light energy harvesting and its use in photochemistry. In extreme cases, high light stress can lead to the level of photo-oxidative damage exceeding the rate of repair to the photosynthetic apparatus. Plant species may vary in the mechanisms they use to prevent photodamage, but most comparisons are of geographically and ecologically distinct species. Differences in leaf colouration suggested that photoprotective strategies might differ among Tasmanian evergreen alpine shrub species. We compared chlorophyll fluorescence and leaf pigment composition in six co-occurring alpine shrub species on the summit of Mt Wellington, southern Tasmania, Australia, during spring and autumn. We found marked differences among species in light energy utilisation, attenuation and dissipation. Ozothamnus ledifolius maintained a large capacity for photosynthetic light utilisation and thus, had a low requirement for light dissipation. All five of the other species relied on xanthophyll-cycle-dependent thermal energy dissipation. In addition Epacris serpyllifolia, Richea sprengelioides and Leptospermum rupestre had foliar anthocyanins that would attenuate photosynthetically active light in the leaf. During spring, all species retained de-epoxidised xanthophylls through the night and the pre-dawn concentration of antheraxanthin and zeaxanthin was significantly correlated with reductions in pre-dawn Fv / Fm. We propose that these species use three photoprotective strategies to cope with the combination of high light and low temperature.

scholarly journals Germination at Extreme Temperatures: Implications for Alpine Shrub Encroachment

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 327
Author(s):  
Susanna E. Venn ◽  
Rachael V. Gallagher ◽  
Adrienne B. Nicotra
Keyword(s):  
Geographic Distribution ◽  
Shrub Encroachment ◽  
Shrub Species ◽  
Ambient Temperatures ◽  
Average Temperature ◽  
Alpine Shrub ◽  
Maximum Temperatures ◽  
Gradient Plate ◽  
High Elevations ◽  
Germination Niche

Worldwide, shrub cover is increasing across alpine and tundra landscapes in response to warming ambient temperatures and declines in snowpack. With a changing climate, shrub encroachment may rely on recruitment from seed occurring outside of the optimum temperature range. We used a temperature gradient plate in order to determine the germination niche of 14 alpine shrub species. We then related the range in laboratory germination temperatures of each species to long-term average temperature conditions at: (1) the location of the seed accession site and (2) across each species geographic distribution. Seven of the species failed to germinate sufficiently to be included in the analyses. For the other species, the germination niche was broad, spanning a range in temperatures of up to 17 °C, despite very low germination rates in some species. Temperatures associated with the highest germination percentages were all above the range of temperatures present at each specific seed accession site. Optimum germination temperatures were consistently within or higher than the range of maximum temperatures modelled across the species’ geographic distribution. Our results indicate that while some shrub species germinate well at high temperatures, others are apparently constrained by an inherent seed dormancy. Shrub encroachment in alpine areas will likely depend on conditions that affect seed germination at the microsite-scale, despite overall conditions becoming more suitable for shrubs at high elevations.

scholarly journals Araucaria growth response to solar and climate variability in South Brazil

2018 ◽  
Vol 36 (3) ◽  
pp. 717-729 ◽  
Author(s):  
Alan Prestes ◽  
Virginia Klausner ◽  
Iuri Rojahn da Silva ◽  
Arian Ojeda-González ◽  
Caren Lorensi
Keyword(s):  
Climate Variability ◽  
Tree Ring ◽  
Growth Response ◽  
Classical Method ◽  
Southern Oscillation ◽  
Ring Width ◽  
The Sun ◽  
Local Climate ◽  
Climate Conditions ◽  
Growth Series

Abstract. In this work, the Sun–Earth–climate relationship is studied using tree growth rings of Araucaria angustifolia (Bertol.) O. Kuntze collected in the city of Passo Fundo, located in the state of Rio Grande do Sul (RS), Brazil. These samples were previously studied by Rigozo et al. (2008); however, their main interest was to search for the solar periodicities in the tree-ring width mean time series without interpreting the rest of the periodicities found. The question arises as to what are the drivers related to those periodicities. For this reason, the classical method of spectral analysis by iterative regression and wavelet methods are applied to find periodicities and trends present in each tree-ring growth, in Southern Oscillation Index (SOI), and in annual mean temperature anomaly between the 24 and 44∘ S. In order to address the aforementioned question, this paper discusses the correlation between the growth rate of the tree rings with temperature and SOI. In each tree-ring growth series, periods between 2 and 7 years were found, possibly related to the El Niño/La Niña phenomena, and a ∼ 23-year period was found, which may be related to temperature variation. These novel results might represent the tree-ring growth response to local climate conditions during its lifetime, and to nonlinear coupling between the Sun and the local climate variability responsible to the regional climate variations. Keywords. History of geophysics (solar–planetary relationships) – meteorology and atmospheric dynamics (climatology; palaeoclimatology)

Somatic growth of Atlantic bluefin tuna Thunnus thynnus under global climate variability: Evidence from over 60 years of daily resolved growth increments with a simulation study

2021 ◽  
Author(s):  
Can Zhou
Keyword(s):  
Measurement Error ◽  
Climate Variability ◽  
Simulation Study ◽  
Growth Response ◽  
Somatic Growth ◽  
Bluefin Tuna ◽  
Growth Responses ◽  
Atlantic Bluefin Tuna ◽  
Growth Increments ◽  
Highly Nonlinear

Somatic growth is integral to fishery stock productivity. Under climate variability, omitting growth variability renders fishery management strategies non-optimal. Based on a multidecadal tag-recapture database, a case study is presented to investigate the potential growth response of the Atlantic bluefin tuna to three regionally relevant large-scale climate patterns, i.e., the North Atlantic Oscillation, Arctic Oscillation, and Pacific North America pattern. An additional simulation study is conducted to explore the effect of the overall scale and the distribution of measurement error on the detection probability of extrinsic effects and the estimation of growth parameters. Results indicate significant growth response at an intra-annual scale to all three climate indices examined. Identified growth responses to climate variations are highly nonlinear. The projected growth shows increased growth in recent decades under climate variability with respect to the historical mean. Simulation results show a higher probability to detect climate signals when the overall measurement error is low. Substantial bias is expected when the measurement error at tag release is high, cautioning against careless integration of different types of growth data.

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