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131.
Climate change alters the reproductive phenology and investment of a lacustrine fish,the three‐spine stickleback 下载免费PDF全文
High‐latitude lakes are particularly sensitive to the effects of global climate change, demonstrating earlier ice breakup, longer ice‐free seasons, and increased water temperatures. Such physical changes have implications for diverse life‐history traits in taxa across entire lake food webs. Here, we use a five‐decade time series from an Alaskan lake to explore effects of climate change on growth and reproduction of a widely distributed lacustrine fish, the three‐spine stickleback (Gasterosteus aculeatus). We used multivariate autoregressive state‐space (MARSS) models to describe trends in the mean length for multiple size classes and to explore the influence of physical (date of ice breakup, surface water temperature) and biological (density of con‐ and heterospecifics) factors. As predicted, mean size of age 1 and older fish at the end of the growing season increased across years with earlier ice breakup and warmer temperatures. In contrast, mean size of age 0 fish decreased over time. Overall, lower fish density and warmer water temperatures were associated with larger size for all cohorts. Earlier ice breakup was associated with larger size for age 1 and older fish but, paradoxically, with smaller size of age 0 fish. To explore this latter result, we used mixing models on age 0 size distributions, which revealed an additional cohort in years with early ice breakup, lowering the mean size of age 0 fish. Moreover, early ice breakup was associated with earlier breeding, evidenced by earlier capture of age 0 fish. Our results suggest that early ice breakup altered both timing and frequency of breeding; three‐spine stickleback spawned earlier and more often in response to earlier ice breakup date. While previous studies have shown the influence of changing conditions in northern lakes on breeding timing and growth, this is the first to document increased breeding frequency, highlighting another pathway by which climate change can alter the ecology of northern lakes. 相似文献
132.
Using Satellite Remote Sensing to Estimate the Colored Dissolved Organic Matter Absorption Coefficient in Lakes 总被引:4,自引:0,他引:4
Tiit Kutser Donald C. Pierson Lars Tranvik Anu Reinart Sebastian Sobek Kari Kallio 《Ecosystems》2005,8(6):709-720
Given the importance of colored dissolved organic matter (CDOM) for the structure and function of lake ecosystems, a method
that could estimate the amount of CDOM in lake waters over large geographic areas would be highly desirable. Satellite remote
sensing has the potential to resolve this problem. We carried out model simulations to evaluate the suitability of different
satellite sensors (Landsat, IKONOS, and the Advanced land Imager [ALI]) to map the amount of CDOM in concentration ranges
that occur in boreal lakes of the Nordic countries. The results showed that the 8-bit radiometric resolution of Landsat 7
is not adequate when absorption by CDOM at 420 nm is higher than 3 m−1. On the other hand, the 16-bit radiometric resolution of ALI, a prototype of the next generation of Landsat, is suitable
for mapping CDOM in a wider range of concentrations. An ALI image of southern Finland was acquired on 14, July 2002 and in
situ measurements were carried out in 15 lakes (18 stations). The results showed that there is a high correlation (R2 = 0.84) between the 565 nm/660 nm ALI band ratio and the CDOM absorption coefficient in lakes. Analysis of 245 lakes in the
acquired satellite image showed a normal distribution of CDOM concentration among the lakes. However, the size distribution
of lakes was highly skewed toward small lakes, resulting in the CDOM concentration per unit lake area being skewed toward
high values. We showed that remote sensing enables synoptic monitoring of the CDOM concentration in a large number of lakes
and thus enables scaling up to the level of large ecosystems and biomes. 相似文献
133.
Estimating plant abundance using inflated beta distributions: Applied learnings from a lichen–caribou ecosystem 下载免费PDF全文
Jonah L. Keim Philip D. DeWitt J. Jeremy Fitzpatrick Noemie S. Jenni 《Ecology and evolution》2017,7(2):486-493
Quantifying abundance and distribution of plant species can be difficult because data are often inflated with zero values due to rarity or absence from many ecosystems. Terrestrial fruticose lichens (Cladonia and Cetraria spp.) occupy a narrow ecological niche and have been linked to the diets of declining caribou and reindeer populations (Rangifer tarandus) across their global distribution, and conditions related to their abundance and distribution are not well understood. We attempted to measure effects related to the occupancy and abundance of terrestrial fruticose lichens by sampling and simultaneously modeling two discrete conditions: absence and abundance. We sampled the proportion cover of terrestrial lichens at 438 vegetation plots, including 98 plots having zero lichens. A zero‐inflated beta regression model was employed to simultaneously estimate both the absence and the proportion cover of terrestrial fruticose lichens using fine resolution satellite imagery and light detection and ranging (LiDAR) derived covariates. The probability of lichen absence significantly increased with shallower groundwater, taller vegetation, and increased Sphagnum moss cover. Vegetation productivity, Sphagnum moss cover, and seasonal changes in photosynthetic capacity were negatively related to the abundances of terrestrial lichens. Inflated beta regression reliably estimated the abundance of terrestrial lichens (R2 = .74) which was interpolated on a map at fine resolution across a caribou range to support ecological conservation and reclamation. Results demonstrate that sampling for and simultaneously estimating both occupancy and abundance offer a powerful approach to improve statistical estimation and expand ecological inference in an applied setting. Learnings are broadly applicable to studying species that are rare, occupy narrow niches, or where the response variable is a proportion value containing zero or one, which is typical of vegetation cover data. 相似文献
134.
135.
Examination of temperature variations over the past centuryfor Europe and the Arctic from northern Norway to Siberia suggeststhat variations in the North Atlantic Oscillation are associatedwith an increase in oceanicity in certain maritime regions.A southward depression of the treeline in favour of wet heaths,bogs and wetland tundra communities is also observed in northernoceanic environments. The physiological basis for this changein ecological succession from forest to bog is discussed inrelation to the long-term effects of flooding on tree survival.The heightened values currently detected in the North AtlanticOscillation Index, together with rising winter temperatures,and increased rainfall in many areas in northern Europe, presentsan increasing risk of paludification with adverse consequencesfor forest regeneration, particularly in areas with oceanicclimates. Climatic warming in oceanic areas may increase thearea covered by bogs and, contrary to general expectations,lead to a retreat rather than an advance in the northern limitof the boreal forest. High water-table levels are not automaticallydetrimental to forest survival as can be seen in swamp, bottomlandand mangrove forests. Consequently, the inhibitory effects offlooding on tree survival and regeneration in northern regionsshould not be uncritically accepted as merely due to high waterlevels. Evidence is discussed which suggests that physiologicaland ecological factors may interact to inhibit forest regenerationin habitats where there is a risk of prolonged winter-floodingcombined with warmer winters and cool moist summers. 相似文献
136.
INA FRANZN BERNARD SLIPPERS RIMVYDAS VASILIAUSKAS JAN STENLID 《Molecular ecology resources》2006,6(3):870-872
Seven polymorphic microsatellite markers were developed for the wood‐decay basidiomycete Phlebia centrifuga. The primers were identified using two techniques, based on intersimple sequence repeats (ISSR) and amplified fragment length polymorphism (AFLP), respectively. The markers were screened on 27 isolates from Europe and North America. Two markers varied only on a worldwide scale, but not within Europe. The other five showed variation on both scales. These markers will now be used to characterize populations of P. centrifuga, which is red‐listed as near‐threatened in its natural habitat due to human disturbance. 相似文献
137.
S. E. Bayley D. W. Schindler B. R. Parker M. P. Stainton K. G. Beaty 《Biogeochemistry》1992,17(3):191-204
In a boreal forest catchment in the Experimental Lakes Area in northwestern Ontario, wildfire caused an increase in the concentrations
of strong acid anions and base cations of the stream. In the naturally base-poor Northwest (NW) Subbasin, a 1980 wildfire
caused exports of strong acid anions to increase more than export of base cations, causing a 2.5 fold increase in the acidity
of the stream. Mean annual stream pH declined from 5.15 prior to fire to 4.76 two years after fire. Acid-neutralizing capacity
(ANC), calculated as the difference between total base cations and strong acid anions, decreased to 20% of pre-fire values.
Sulfate and chloride were the strong acid anions responsible for the decline in ANC, increasing four-fold. While nitrate increased
eleven-fold, concentrations were too low to significantly affect ANC. There was a significant correlation between weekly sulfate
concentration and base cation concentration (r
2 = 0.83) in the two years after fire. Recovery of ANC was caused by the more rapid decline in concentration of sulfate than
by changes in base cations. Drought produced a similar but weaker response than fire, with increased sulfate concentrations
and decreased stream pH. Climatic warming that increases drought and fire frequency would have effects that mimic the impacts
of acidic precipitation (i.e. higher sulfate concentrations and acidic stream waters). Areas which have higher concentrations
of stored S from past acid precipitation or have large areas of peatlands in the watershed may have aggravated losses of S
and H+ after drought and fire. 相似文献
138.
Although boreal forests are currently sinks for atmospheric C, there is some concern that they may not remain so under hypothesized warming of the boreal climate. The ecosystem model ecosys was used to evaluate possible changes in ecosystem C exchange and accumulation under changes in atmospheric CO2 concentration (Ca) proposed in emissions scenario IS92a, and accompanying changes in air temperature and precipitation proposed by general circulation models running under IS92a. Ecosys was first tested under current climate by comparing modelled rates of C exchange and accumulation with those measured in a mixed aspen–hazelnut stand in central Saskatchewan. The model was then run with daily increments of Ca, temperature and precipitation, and differences in C exchange and accumulation between current and changing climates were evaluated. Model results indicated that over a 120‐y period, a mixed aspen–hazelnut stand currently accumulates about 14 kg C m?2. Under the hypothesized changes in climate this stand would accumulate an additional 8.5 kg C m?2, largely through higher rates of CO2 fixation and longer growing seasons under higher Ca and temperature. This additional accumulation would be entirely as aspen wood, while soil organic matter would change little. This accumulation would therefore be vulnerable to losses from fire and insects. 相似文献
139.
The role of fire in the boreal carbon budget 总被引:12,自引:0,他引:12
J. W. Harden S. E. Trumbore † B. J. Stocks ‡ A. Hirsch † S. T. Gower § K. P. O'neill¶ E. S. Kasischke 《Global Change Biology》2000,6(S1):174-184
140.
Stefan G. Schreiber Uwe G. Hacke Sabrina Chamberland Christopher W. Lowe David Kamelchuk Katharina Bräutigam Malcolm M. Campbell Barb R. Thomas 《Plant, cell & environment》2016,39(2):272-281
Hybrid poplars are an important renewable forest resource known for their high productivity. At the same time, they are highly vulnerable to water stress. Identifying traits that can serve as indicators for growth performance remains an important task, particularly under field conditions. Understanding which trait combinations translate to improved productivity is key in order to satisfy the demand for poplar wood in an uncertain future climate. In this study, we compared hydraulic and leaf traits among five hybrid poplar clones at 10 plantations in central Alberta. We also assessed the variation of these traits between 2‐ to 3‐year‐old branches from the lower to mid‐crown and current‐year long shoots from the mid to upper crown. Our results showed that (1) hybrid poplars differed in key hydraulic parameters between branch type, (2) variation of hydraulic traits among clones was relatively large for some clones and less for others, and (3) strong relationships between measured hydraulic traits, such as vessel diameter, cavitation resistance, xylem‐specific and leaf‐specific conductivity and leaf area, were observed. Our results suggest that leaf size could serve as an additional screening tool when selecting for drought‐tolerant genotypes in forest management and tree improvement programmes. 相似文献