Recent Growth Rates Research Articles

ADVANTAGES AND CHALLENGES OF E-COMMERCE CUSTOMERS AND BUSINESSES: IN INDIAN PERSPECTIVE

E - Commerce allows consumers to electronically exchange goods and services with no barriers of time or distance. Electronic commerce has expanded rapidly over the past five years and is predicted to continue at this rate, or even accelerate. In the near future the boundaries between "conventional" and "electronic" commerce will become increasingly blurred as more and more businesses move sections of their operations onto the Internet. The e-commerce industry in India is growing at a remarkable pace due to high penetration of internet and sophisticated electronic devices. However, the recent growth rate of e-commerce in India is far lagging behind than other developed countries. The advantages of e- commerce are convenience, Time saving, Options, Easy to compare, Easy to find reviews, Coupons and deals, Increasing customer base, Rise in sales, 24/7, 365 days, Expand business reach, Recurring payments made easy, Instant transactions. There are many big problems and challenged on the way of an online merchant. Factors like safety and security of online money transaction being the biggest problem along with others have curbed the smooth expansion of the online industry in the country.

Crecimiento somático y relación ARN/ADN en estadios juveniles de <i>Eucinostomus argenteus</i> (Pisces: Gerreidae) en dos localidades del Caribe de Venezuela

Con la finalidad de evaluar la asociación de índices de crecimiento en estadios tempranos de peces marinos, se estimó la tasa de crecimiento somático y las condiciones fisiológicas de <em>Eucinostomus argenteus</em> en dos zonas del nor-oriente venezolano: Bahía de Mochima y Golfo de Cariaco. La edad y el crecimiento fueron estimados basados en análisis de otolitos sagitta. Las condiciones fisiológicas fueron evaluadas por medio de las concentraciones de proteínas y la relación ARN/ADN, empleando técnicas espectofotométricas y fluorométricas sobre tejido muscular. Las relaciones entre tallas con la edad y el diámetro de los otolitos resultaron positivas, significativas y ajustadas a un modelo de regresión lineal. Los valores de la tasa de crecimiento reciente oscilaron entre 0.178 y 0.418mm día-1, la tasa de crecimiento retrocalculado varió entre 0.295 y 0.393mm día-1, y la tasa ARN/ADN osciló entre 1.65 y 6.97. No se registraron diferencias entre las zonas de estudio, sin embargo se reportaron diferencias entre localidades. A pesar de no encontrarse correlación entre la tasa de crecimiento y la relación ARN/ADN, los valores reportados sugieren crecimiento positivo de los individuos silvestres en las localidades evaluadas. No obstante, ciertas localidades mostraron valores que indican pobres condiciones nutricionales, pudiendo afectarse a futuro otras tasas vitales.

‘Growth rings’ in crustose lichens: Comparison with directly measured growth rates and implications for lichenometry

Some species of crustose lichens, such as Ochrolechia parella (L.) Massal., exhibit concentric marginal rings, which may represent an alternative technique of measuring growth rates and potentially, a new lichenometric dating method. To examine this hypothesis, the agreement and correlation between ring widths and directly measured annual radial growth rates (RaGR, mm a−1) were studied in 24 thalli of O. parella in north Wales, UK, using digital photography and image analysis. Variation in ring width was observed at different locations around a thallus, between thalli, and from year to year. The best agreement and correlation between ring width and lichen growth rates was between mean width of the outer two rings (measured in 2011) and mean RaGR (in 2009/10). The O. parella data suggest that mean width of the youngest two growth rings, averaged over a sample of thalli, is a predictor of recent growth rates and therefore could be used in lichenometry. Potential applications include as a convenient method of comparing lichen growth rates on surfaces in different environmental settings; and as an alternative method of constructing lichen growth-rate curves, without having to revisit the same lichen thalli over many years. However, care is needed when using growth rings to estimate growth rates as: growth ring widths may not be stable; ring widths exhibit spatial and temporal variation; rings may not represent 1-year's growth in all thalli; and adjacent rings may not always represent successive year's growth.

Africa's Leadership Challenges in the 21st Century: What Can Leaders Learn from Africa's Pre-Colonial Leadership and Governance?

Africa continues to face serious development challenges despite recent record growth rates. Such challenges as dependency, corruption, underdeveloped infrastructure and production sectors, and leadership and governance are some of the impediments to Africa’s quest for sustainable and equitable development. Explaining such development challenges has continued to elude scholars. To the radical leftist scholars, Africa’s underdevelopment can adequately be explained by its forceful and uneven integration into the global economic system. However, with over fifty years of independence, the debate is increasingly focusing on Africa’s leadership as good explanation for its poverty and underdevelopment. This paper argues that the current poverty and underdevelopment of Africa have much to do with enabling conditions created by African leaders and proposes that addressing this requires Africans to go back to pre-colonial history where they can tap good lessons rather than continuing importing Western based models which may not necessarily fit into Africa’s unique characteristics.

Volatility and co-movement: an analysis of stock markets behavior of selected emerging and developed countries

Financial markets around the world suffer significantly during the GFC and European debt crisis. Although the GFC is over, but the after-effect is still visible in most of the developed and emerging countries and stock markets remained volatile. In this paper, we analyse historical stock market volatility and co-movement behavior of three emerging markets and three developed economies from January 2001 to December 2012. We investigate whether the stock market volatilities and co-movement behaviors are correlated and affected by the GFC during the observation period. Our analysis of stock market behavior and co-movement analysis includes the standard historical volatility model and R-square estimates. We use the standard historical volatility model followed by Jones et al. (1998), Andersen and Bollerslev (1997) and Andersen and Bollerslev (1998); and the R-square metrics were suggested by Morck et al. (2000), Khandaker and Heaney (2009) and Alves et al. (2010). The selection criteria for the developed economies include geographical location, availability of stock return data and size of the equity market; and emerging markets are taken from the emerging Asian markets based on their recent market performance, growth rate and market capitalisation. We find evidence that the sample of emerging markets, exhibits higher stock market volatility during the sample period and these volatilities increases during the GFC. There is also evidence that the sample emerging countries exhibit a higher level of stock market co-movement behavior, and these markets were highly synchronous during the GFC. For example, China exhibits higher stock return co-movement behavior and, this behavior increase during the GFC. Further, we do not find any evidence of a statistically significant correlation coefficient between the volatility measures and stock return co-movement measures for our sample developed countries. However, these measures are statistically significant for the emerging country group. The example includes China and Malaysia. Our result provides evidence that stock market co-movement behavior or the R-squared matrix captures somewhat different aspects of stock market behavior other than the stock market volatility for the developed economies. Therefore, it is concluded that both these market models capture somewhat different aspects of stock market behavior and should be carefully used.

Stand history is more important than climate in controlling red maple (Acer rubrumL.) growth at its northern distribution limit in western Quebec, Canada

Aims: We examined growth of red maple (Acer rubrum L.) to evaluate environmental controls of its northern distributional limit in Eastern North America and its potential response to future climate change. Methods: We collected growth data from nine sites located along a 300-km transect (47-49 degrees N), which included frontier population of red maple and covered three bioclimatic domains in western Quebec. We analyzed three growth variables: growth rates during the first 30 years of maple lifespan, cumulative basal area increment (BA I) over the most recent decade (2000-2009) and annual growth rate over the whole tree lifespan ranging from 58 to 112 years. We also examined growth sensitivity to climate by using response function analysis. Important Findings: Three different proxies of maple absolute growth (initial growth rate, BA I during 2000-09 and mean diameter growth rate) indicated a better growth with an increase in latitude. We speculate that stand history effectively overrode the direct effects of colder climate on maple growth along the S-N gradient. Regeneration of maple in the southern sites likely occurred in canopy gaps, whereas in the north it was contingent upon large disturbances such as stand-replacing fires, which apparently provided more favorable light environment for maple growth than canopy gaps. The annual growth variability, which reflects effects of annual weather on growth and is largely independent from the absolute growth rate, was significantly affected by monthly climate, suggesting a positive effect of higher summer temperature in the northern part of the transect (48-49 degrees N) and a negative effect of summer drought in the south (47-48 degrees N). In the future, the natural and human disturbance regimes will be dominant controls of the actual biomass productivity of red maple at the northern limit of its present distribution range. Direct effects of climate on maple growth would likely be less important in this context, and will likely entail negative effect of increased summer drought in the southern part of the study area and positive effects of increased temperatures in the north.

Biochemical indices and life traits of loggerhead turtles (Caretta caretta) from Cape Verde Islands.

The loggerhead turtle (Caretta caretta) is an endangered marine reptile for whom assessing population health requires knowledge of demographic parameters such as individual growth rate. In Cape Verde, as within several populations, adult female loggerhead sea turtles show a size-related behavioral and trophic dichotomy. While smaller females are associated with oceanic habitats, larger females tend to feed in neritic habitats, which is reflected in their physiological condition and in their offspring. The ratio of RNA/DNA provides a measure of cellular protein synthesis capacity, which varies depending on changes in environmental conditions such as temperature and food availability. The purpose of this study was to evaluate the combined use of morphometric data and biochemical indices as predictors of the physiological condition of the females of distinct sizes and hatchlings during their nesting season and how temperature may influence the physiological condition on the offspring. Here we employed biochemical indices based on nucleic acid derived indices (standardized RNA/DNA ratio-sRD, RNA concentration and DNA concentration) in skin tissue as a potential predictor of recent growth rate in nesting females and hatchling loggerhead turtles. Our major findings were that the physiological condition of all nesting females (sRD) decreased during the nesting season, but that females associated with neritic habitats had a higher physiological condition than females associated with oceanic habitats. In addition, the amount of time required for a hatchling to right itself was negatively correlated with its physiological condition (sRD) and shaded nests produced hatchlings with lower sRD. Overall, our results showed that nucleic acid concentrations and ratios of RNA to DNA are an important tool as potential biomarkers of recent growth in marine turtles. Hence, as biochemical indices of instantaneous growth are likely temperature-, size- and age-dependent, the utility and validation of these indices on marine turtles stocks deserves further study.

Corporate Investment in Sport Sponsorship and its Evaluation

Corporate investment in sponsorship has increased dramatically in recent decades and growth rate in sponsorship has exceeded any other marketing communications tool. Although spending on sponsorship is expected to increase more in the future and sport dominates the pie of sponsorship revenue, the relationship between sponsorship and purchase intentions of consumers is still vague and needs elaborate research. Current study is an attempt to contribute understanding of sponsorship in sport context and aims to evaluate sport sponsorship effectiveness by investigating antecedents of attitudes towards sponsor and purchase intentions. A conceptual model was developed to examine the effects of factors such as perceived sincerity, perceived fit between the sponsor and sport team and team attachment on attitude towards sponsor and intentions to purchase sponsor’s products. The measurement model was tested using confirmatory factor analysis and hypothesized model was tested by using Structural equation modeling (SEM). The data were collected from spectators of a Turkish basketball game in the arena before the start of game. The results suggest that perceived fit and team attachment have positive influence on sincerity perceptions which in turn create positive attitudes toward sponsor and greater purchase intentions for products of sponsor. Findings of the study have important implications for sponsors and future research.

Differential growth in estuarine and freshwater habitats indicated by plasma IGF1 concentrations and otolith chemistry in Dolly Varden Salvelinus malma.

This study employed a combination of otolith microchemistry to indicate the recent habitat use, and plasma concentrations of the hormone insulin-like growth factor 1 (IGF1) as an index of recent growth rate, to demonstrate differences in growth and habitat use by Dolly Varden Salvelinus malma occupying both freshwater and estuarine habitats in south-west Alaska. Extensive sampling in all habitats revealed that fish had higher IGF1 levels in estuarine compared to lake habitats throughout the summer, and that the growth rates in different habitats within the estuary varied seasonally. In addition, otolith microchemistry indicated differentiation in estuarine habitat use among individual S. malma throughout summer months. Although growth in the estuary was higher than in fresh water in nearly all sites and months, the benefits and use of the estuarine habitats varied on finer spatial scales. Therefore, this study further illustrates the diverse life histories of S. malma and indicates an evaluation of the benefits of marine waters needs to include sub-estuary scale habitat use.

Slow lifelong growth predisposes Populus tremuloides trees to mortality.

Widespread dieback of aspen forests, sometimes called sudden aspen decline, has been observed throughout much of western North America, with the highest mortality rates in the southwestern United States. Recent aspen mortality has been linked to drought stress and elevated temperatures characteristic of conditions expected under climate change, but the role of individual aspen tree growth patterns in contributing to recent tree mortality is less well known. We used tree-ring data to investigate the relationship between an individual aspen tree's lifetime growth patterns and mortality. Surviving aspen trees had consistently higher average growth rates for at least 100 years than dead trees. Contrary to observations from late successional species, slow initial growth rates were not associated with a longer lifespan in aspen. Aspen trees that died had slower lifetime growth and slower growth at various stages of their lives than those that survived. Differences in average diameter growth between live and dead trees were significant (α = 0.05) across all time periods tested. Our best logistical model of aspen mortality indicates that younger aspen trees with lower recent growth rates and higher frequencies of abrupt growth declines had an increased risk of mortality. Our findings highlight the need for species-specific mortality functions in forest succession models. Size-dependent mortality functions suitable for late successional species may not be appropriate for species with different life history strategies. For some early successional species, like aspen, slow growth at various stages of the tree's life is associated with increased mortality risk.

Mortality in relation to growth rate and soil resistance varies by species for underplanted Nothofagus seedlings in scarified shelterwoods

This study evaluated early mortality patterns of planted Nothofagus dombeyi (Mirb.) Blume (evergreen, shade intolerant) and Nothofagus alpina (P. et E.) Oerst. (deciduous, mid-tolerant to shade) seedlings established in scarified gaps in a Nothofagus old-growth forest in the Chilean Andes that was subjected to a shelterwood cut. Soils were scarified with heavy machinery that removed up to 40 cm of the upper horizons (e.g. it completely removed the litter layer and organic horizon, and in some cases partially the A horizon) to eliminate bamboo (Chusquea culeou E. Desv) shoots and rhizomes from the scarified areas. Two years after planting, seedlings were growing free of understory competition and mortality patterns were assessed using logistic regression models with the following predictor variables: (1) basal diameter growth in the prior year, and (2) soil strength measured as resistance to penetration. The probability of mortality of both species was highly predictable based on recent basal diameter growth. N. dombeyi seedlings appeared to be less affected by mortality, as reflected in lower sensitivity of mortality at lower growth rates compared to N. alpina. High values of resistance to penetration (>2,000 kPa) induced a higher probability of mortality in N. alpina (up to 40 % at 3,500 kPa). In contrast, N. dombeyi mortality was not significantly influenced by soil strength, which illustrates the more stress-resistant and pioneer character of this species. This study showed that recent growth rates can be used as a predictor of future mortality, but these relationships need to be calibrated for each species. In addition, our results suggest that species characteristics that relate to resource limitations, such as shade tolerance, are not adequate to understand effects of other stressors, such as soil disturbance, on mortality patterns.

Elucidating Metabolic Variability in Isogenic Microbial Populations Arising due to Noise in Protein Expression

Members of a population of isogenic microbes vary in their protein expression states because of stochastic gene expression. Advances in single-cell proteomics on model organisms like E. coli and S. cerevisiae are uncovering this heterogeneity in protein copy numbers. Here we use genome-scale flux balance models to study the effect of heterogeneity in protein expression on metabolic behavior. We predict wide distribution in specific growth rates among the members of the population in accordance with recent single-cell growth rate measurements. Using flux balance analysis along with principal component analysis enables us to identify sub-populations which differ in their metabolic pathway usage. In case of E. coli grown in a minimal medium, we predict presence of slow-growing acetate secreting cells, fast-growing CO2 secreting cells and shifting preference between glycolysis and ED pathway to metabolize glucose. Preliminary population-level measurements support our prediction of acetate secreting cells in aerobic growth conditions. We also find that variability in expression of few genes may be sufficient to capture most of the metabolic variability of the entire population. We extend this study to S. cerevisiae for which the requisite data is becoming available.

The relationship between nucleolar organizer size and growth inChironomus ripariuslarvae (Diptera:Chironomidae)

AbstractChironomid larvae possess giant polytene chromosomes. When genes on these chromosomes undergo transcription, they are visible as puffs. The nucleolar organizer region (NOR), visible as an especially large puff, shrinks when a larva is at particular developmental stages or is subjected to chemical stress. However, whether reduced NOR size is indicative of reduced growth is unknown. Therefore, we conducted 2 experiments to examine the relationship between NOR size and chironomid growth under controlled laboratory conditions. In the 1st experiment, we quantified the effect of ration quality on larval growth and NOR size. In the 2nd, we determined whether NOR size varied as a function of recent growth, independently of larval size. The combined results demonstrated that NOR size varied as a function of prepupal development and was positively correlated with a chironomid’s most recent growth rate, independently of its biomass. The finding that NOR size is related to growth validates its use as a biomar...

Analyzing determinants of bond yield spreads with Bayesian Model Averaging

This paper analyzes determinants of country default risk in emerging markets, reflected by sovereign yield spreads. The results reported so far in the literature are heterogeneous with respect to significant explanatory variables. This could indicate a high degree of uncertainty about the “true” regression model. We use Bayesian Model Averaging as the model selection method in order to find the variables which are most likely to determine credit risk. We document that total debt, history of recent default, currency depreciation, and growth rate of foreign currency reserves as well as market sentiments are the key drivers of yield spreads.

Modeling Young Stand Development towards the Old-Growth Reference Condition in Evergreen Mixed-Conifer Stands at Headwaters Forest Reserve, California

We sought to answer the question: How do we restore characteristics of old-growth evergreen mixed-conifer forests in young even-aged stands on upland terrain at Headwaters Forest Reserve (HFR)? We described the old-growth reference condition for three stands at HFR. In each old-growth stand, trees within a 1-ha plot were inventoried. We found coast Douglas-fir (Pseudotsuga menziesii var. menziesii) and tanoak (Notholithocarpus densiflorus) well represented while coast redwood (Sequoia sempervirens) dominated in terms of size. Numbers of understory and overstory trees ha−1 and average tree sizes were similar among sites, suggesting these were useful goals for restoration. Adjacent to each old-growth stand, we measured recent growth rates of second-growth trees and remnant old trees across a range of tree sizes, stand structures, and densities. The resultant growth models of redwood and Douglas-fir enabled us to project the development of precommercially thinned young stands at HFR forward in time under two silvicultural prescriptions: (i) no further management; and (ii) partial harvesting simulated before trees attained 30 cm dbh. The partial-harvesting prescription reduced stand density and set the young stand on a more rapid trajectory towards the reference condition found at HFR.

Body Condition Correlates with Instantaneous Growth in Stream‐Dwelling Rainbow Trout and Arctic Grayling

AbstractUnderstanding the growth response of fish to varying environmental and biological conditions is important for the management and conservation of populations and communities. However, obtaining growth data at time scales shorter than those provided by annual size‐at‐age relationships is costly and labor intensive and can be logistically impractical. We assessed the ability of a body condition index to serve as a proxy for individual instantaneous growth rates in two species of mostly subadult stream‐dwelling salmonids in southwestern Alaska. We found that relative body condition, as measured by the residuals around a length–mass regression, was strongly correlated with direct measures of individual instantaneous growth (day−1) from mark–recapture data. Further, body condition was significantly correlated with growth accumulated over a period of roughly 2–10 weeks in both Rainbow Trout Oncorhynchus mykiss and Arctic Grayling Thymallus arcticus, while the relationship was typically weaker for time periods of less than 2 weeks and greater than 1 year. Despite the limitations of using body condition indices to infer the physiological status of individuals, our results demonstrate that, when applied judiciously, body condition can be used as a surrogate for recent individual instantaneous growth rate.

Sulfate-nitrate-ammonium aerosols over China: response to 2000–2015 emission changes of sulfur dioxide, nitrogen oxides, and ammonia

Abstract. We use a chemical transport model to examine the change of sulfate-nitrate-ammonium (SNA) aerosols over China due to anthropogenic emission changes of their precursors (SO2, NOx and NH3) from 2000 to 2015. From 2000 to 2006, annual mean SNA concentrations increased by about 60% over China as a result of the 60% and 80% increases in SO2 and NOx emissions. During this period, sulfate is the dominant component of SNA over South China (SC) and Sichuan Basin (SCB), while nitrate and sulfate contribute equally over North China (NC). Based on emission reduction targets in the 12th (2011–2015) Five-Year Plan (FYP), China's total SO2 and NOx emissions are projected to change by −16% and +16% from 2006 to 2015, respectively. The amount of NH3 emissions in 2015 is uncertain, given the lack of sufficient information on the past and present levels of NH3 emissions in China. With no change in NH3 emissions, SNA mass concentrations in 2015 will decrease over SCB and SC compared to their 2006 levels, but increase over NC where the magnitude of nitrate increase exceeds that of sulfate reduction. This suggests that the SO2 emission reduction target set by the 12th FYP, although effective in reducing SNA over SC and SCB, will not be successful over NC, for which NOx emission control needs to be strengthened. If NH3 emissions are allowed to keep their recent growth rate and increase by +16% from 2006 to 2015, the benefit of SO2 reduction will be completely offset over all of China due to the significant increase of nitrate, demonstrating the critical role of NH3 in regulating nitrate. The effective strategy to control SNA and hence PM2.5 pollution over China should thus be based on improving understanding of current NH3 emissions and putting more emphasis on controlling NH3 emissions in the future.

Abundance of natural regeneration and growth comparisons with planted seedlings 10–13 years after commercial thinning in 50-year-old Douglas-fir, Douglas-fir/western hemlock, Oregon Coast Range

Post-thinning natural regeneration in the Pacific Northwest of USA was evaluated 13years after thinning 50-year-old Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) stands on a drier, interior Coast Range site (McDonald) and 10years after thinning 50- to 55-year-old Douglas-fir/western hemlock (Tsuga heterophylla [Raf.] Sarg.) stands on a moister, coastal site (Blodgett) as part of a long-term study of late-seral habitats following commercial thinning. At each site, thinning varied in residual stand density (ranging from 17 to 34m2/ha) and pattern (uniform thinning or thinning with the incorporation of 0.06- and 0.1-ha gaps). Effects of understory vegetation control were also evaluated. McDonald had minor components of grand fir (Abies grandis [Dougl. ex D. Don.] Lindl.); Blodgett had substantial overstory stocking of western hemlock. Natural seedling densities and heights of natural and underplanted seedlings were recorded where stands had been thinned to four (McDonald) and three (Blodgett) residual densities. Densities of natural Douglas-fir seedlings ranged from 55 to 980/ha at McDonald (13years after thinning) and from 887 to 1566/ha at Blodgett (10years after thinning). Douglas-fir abundance was inversely related to overstory density at McDonald after thinning and was greater at both sites where understory had been chemically controlled. Natural regeneration of grand fir at McDonald was limited by proximity to seed source, but more abundant than Douglas-fir where it occurred. Regeneration of western hemlock 10years after thinning at Blodgett averaged 44,058–56,845/ha and did not vary across overstory densities or with vegetation control. Heights of hemlock and Douglas-fir regeneration were greatest where overstories were least dense. Hemlock was consistently taller than Douglas-fir at the site (Blodgett) where regeneration of both species occurred. However, Douglas-fir was preferentially browsed, which limited height growth. Canopy gaps did not consistently increase density or height of natural regeneration at either site, but many of the tallest seedlings recorded were found within gaps. Heights and recent height growth rates for western hemlock at Blodgett were similar between natural and planted seedlings. Natural Douglas-fir were shorter than planted Douglas-fir at both sites. Reliance on natural Douglas-fir regeneration in thinned stands provided variable stocking, with uncertain futures where post-thinning overstory basal area exceeded 28m2/ha in 50-year-old stands.

Balancing the odds: the relationship between growth and energy storage in juvenile snapper (Chrysophrys auratus : Sparidae)

Larval and early juvenile fish living in temperate environments with limited resources face conflicting metabolic demands. To optimise their survival probability, fish must balance the need to out-grow predators by maximising their growth, while also accumulating sufficient energy reserves to sustain them through winter. We tested the hypothesis that resource allocation in Chrysophrys auratus changed from maximising growth to maximising energy storage over their first summer–autumn by measuring recent growth rates from otolith increments, and lipid, protein and carbohydrate concentrations in fish. Lipid concentrations showed the greatest change over the growing season, increasing three-fold between summer and mid-autumn. Growth rates showed the opposite trend, being significantly lower in mid-autumn than in summer. The relationships between growth rate and lipid or protein concentrations were consistent with a shift in resource allocation from growth to storage. During summer and early autumn, growth rates were independent of protein or lipid concentrations, but during mid-autumn there were significant positive correlations between the variables. Biochemical concentrations were independent of fish size, indicating that the accumulation of sufficient energy reserves for winter is determined by the timing of settlement and subsequent feeding conditions, which are likely to affect interannual recruitment variability of this important species.

Growth trends and temperature responses of treeline Norway spruce in the Czech-Polish Sudetes Mountains

The Earth's climate system has recently experienced substantial warming, and asso- ciated effects are often most pronounced at species-specific distribution limits. Treeline ecotones may therefore be particularly useful to assess the complex interplay of biotic and abiotic factors in relation to environmental change. Here, we present site-dependent growth trends and climate responses of 22 Norway spruce Picea abies (L.) H. Karst. tree-ring chronologies from the treeline ecotone in the Sudetes Mountains (Mts.) along the Czech-Polish border. Annually resolved and absolutely dated ring-width measurements from 2 regions (Giant Mts. and Hrubý Jesenik Mts.), separated by aspect and altitude, resulted in robust chronologies for the 20th century. All sites reveal a close relationship between ring widths and growing season temperatures. The main site- dependent differences in growth trends and temperature responses were attributed to altitude. Trees located at the upper boundary of the treeline ecotone reacted positively to preceding autumn temperatures, and their temperature response was slightly weaker than that of trees from the upper forest limit. Temporal trends in growthclimate responses consisted mainly of a gradual decrease in the influence of preceding October temperatures and an increasing effect of May tem- peratures towards the present. The proportion of younger trees generally increases upwards within the ecotone, and the most recent growth rates appear unprecedented in a century-long context.