scholarly journals Seasonal Divergent Tree Growth Trends and Growth Variability along Drought Gradient over Northeastern China

Forests ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 39 ◽  
Author(s):  
Fangzhong Shi ◽  
Xiuchen Wu ◽  
Xiaoyan Li ◽  
Pei Wang ◽  
Xiaofan Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Large Scale ◽  
Spatial Scales ◽  
Northeastern China ◽  
Spring Temperature ◽  
Growth Trends ◽  
Growth Variability ◽  
Different Seasons ◽  
Semi Arid

With the increasing temperature and intensified drought, global climate change has profound impacts on tree growth in temperate regions, which consequently regulates terrestrial-atmosphere biogeochemical processes and biophysical feedbacks. Thus, increasing numbers of studies have addressed the long-term annual trends in tree growth and their response to climate change at diverse spatial scales. However, the potential divergence in tree growth trends and growth variability (represented by coefficient of variance) in different seasons across large-scale climate gradients remains poorly understood. Here, we investigated the tree growth trends and growth variability in different seasons across diverse drought conditions in forested regions over northeastern China during the period 1982–2015, using both remote sensing observations and in situ tree-ring measurements. We found clear seasonal divergence in tree growth trends during 1982–2015, and the apparent increase was mainly observed in spring and autumn, attributed mainly to the increase in spring temperature and autumn solar radiation, respectively, but not in summer. The magnitudes of increasing trends in tree growth decrease with the increase of the multi-year average dryness index (MAI) in semi-arid areas (1.5 < MAI < 4.0) in all seasons. We further revealed that the interannual variability in tree growth was much larger in the semi-arid regions than in the humid and semi-humid regions in all seasons, and tree growth variability was significantly and negatively correlated with the variations in temperature and water deficit. Our findings improve our understanding of seasonal divergence in tree growth trends and provide new insights into spatial patterns in forest vulnerability in a warmer and drier climate.

scholarly journals Repeated surveying over 6 years reveals that fine-scale habitat variables are key to tropical mountain ant assemblage composition and functional diversity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mulalo M. Muluvhahothe ◽  
Grant S. Joseph ◽  
Colleen L. Seymour ◽  
Thinandavha C. Munyai ◽  
Stefan H. Foord
Keyword(s):  
Climate Change ◽  
Species Composition ◽  
High Altitude ◽  
Functional Diversity ◽  
Large Scale ◽  
Climate Models ◽  
Spatial Scales ◽  
Abiotic Factors ◽  
Composition Analysis ◽  
Fine Scale

AbstractHigh-altitude-adapted ectotherms can escape competition from dominant species by tolerating low temperatures at cooler elevations, but climate change is eroding such advantages. Studies evaluating broad-scale impacts of global change for high-altitude organisms often overlook the mitigating role of biotic factors. Yet, at fine spatial-scales, vegetation-associated microclimates provide refuges from climatic extremes. Using one of the largest standardised data sets collected to date, we tested how ant species composition and functional diversity (i.e., the range and value of species traits found within assemblages) respond to large-scale abiotic factors (altitude, aspect), and fine-scale factors (vegetation, soil structure) along an elevational gradient in tropical Africa. Altitude emerged as the principal factor explaining species composition. Analysis of nestedness and turnover components of beta diversity indicated that ant assemblages are specific to each elevation, so species are not filtered out but replaced with new species as elevation increases. Similarity of assemblages over time (assessed using beta decay) did not change significantly at low and mid elevations but declined at the highest elevations. Assemblages also differed between northern and southern mountain aspects, although at highest elevations, composition was restricted to a set of species found on both aspects. Functional diversity was not explained by large scale variables like elevation, but by factors associated with elevation that operate at fine scales (i.e., temperature and habitat structure). Our findings highlight the significance of fine-scale variables in predicting organisms’ responses to changing temperature, offering management possibilities that might dilute climate change impacts, and caution when predicting assemblage responses using climate models, alone.

scholarly journals No growth stimulation of Canada’s boreal forest under half-century of combined warming and CO2 fertilization

2016 ◽  
Vol 113 (52) ◽  
pp. E8406-E8414 ◽  
Author(s):  
Martin P. Girardin ◽  
Olivier Bouriaud ◽  
Edward H. Hogg ◽  
Werner Kurz ◽  
Niklaus E. Zimmermann ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boreal Forest ◽  
Spatial Patterns ◽  
Tree Growth ◽  
Hydrological Cycle ◽  
Forest Growth ◽  
Spatiotemporal Variability ◽  
Late 20Th Century ◽  
Growth Trends ◽  
Growth Variability

Considerable evidence exists that current global temperatures are higher than at any time during the past millennium. However, the long-term impacts of rising temperatures and associated shifts in the hydrological cycle on the productivity of ecosystems remain poorly understood for mid to high northern latitudes. Here, we quantify species-specific spatiotemporal variability in terrestrial aboveground biomass stem growth across Canada’s boreal forests from 1950 to the present. We use 873 newly developed tree-ring chronologies from Canada’s National Forest Inventory, representing an unprecedented degree of sampling standardization for a large-scale dendrochronological study. We find significant regional- and species-related trends in growth, but the positive and negative trends compensate each other to yield no strong overall trend in forest growth when averaged across the Canadian boreal forest. The spatial patterns of growth trends identified in our analysis were to some extent coherent with trends estimated by remote sensing, but there are wide areas where remote-sensing information did not match the forest growth trends. Quantifications of tree growth variability as a function of climate factors and atmospheric CO2 concentration reveal strong negative temperature and positive moisture controls on spatial patterns of tree growth rates, emphasizing the ecological sensitivity to regime shifts in the hydrological cycle. An enhanced dependence of forest growth on soil moisture during the late-20th century coincides with a rapid rise in summer temperatures and occurs despite potential compensating effects from increased atmospheric CO2 concentration.

scholarly journals Evaluation of a unique approach to high-resolution climate modeling using the Model for Prediction Across Scales – Atmosphere (MPAS-A) version 5.1

2019 ◽  
Vol 12 (8) ◽  
pp. 3725-3743 ◽  
Author(s):  
Allison C. Michaelis ◽  
Gary M. Lackmann ◽  
Walter A. Robinson
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Large Scale ◽  
Southern Oscillation ◽  
Spatial Scales ◽  
Coupled Model ◽  
General Circulation Models

Abstract. We present multi-seasonal simulations representative of present-day and future environments using the global Model for Prediction Across Scales – Atmosphere (MPAS-A) version 5.1 with high resolution (15 km) throughout the Northern Hemisphere. We select 10 simulation years with varying phases of El Niño–Southern Oscillation (ENSO) and integrate each for 14.5 months. We use analyzed sea surface temperature (SST) patterns for present-day simulations. For the future climate simulations, we alter present-day SSTs by applying monthly-averaged temperature changes derived from a 20-member ensemble of Coupled Model Intercomparison Project phase 5 (CMIP5) general circulation models (GCMs) following the Representative Concentration Pathway (RCP) 8.5 emissions scenario. Daily sea ice fields, obtained from the monthly-averaged CMIP5 ensemble mean sea ice, are used for present-day and future simulations. The present-day simulations provide a reasonable reproduction of large-scale atmospheric features in the Northern Hemisphere such as the wintertime midlatitude storm tracks, upper-tropospheric jets, and maritime sea-level pressure features as well as annual precipitation patterns across the tropics. The simulations also adequately represent tropical cyclone (TC) characteristics such as strength, spatial distribution, and seasonal cycles for most Northern Hemisphere basins. These results demonstrate the applicability of these model simulations for future studies examining climate change effects on various Northern Hemisphere phenomena, and, more generally, the utility of MPAS-A for studying climate change at spatial scales generally unachievable in GCMs.

scholarly journals Tree growth is more limited by drought in rear-edge forests most of the times

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
J. Julio Camarero ◽  
Antonio Gazol ◽  
Gabriel Sangüesa-Barreda ◽  
Marta Vergarechea ◽  
Raquel Alfaro-Sánchez ◽  
...  
Keyword(s):  
Tree Growth ◽  
Tree Species ◽  
Large Scale ◽  
Abies Alba ◽  
Growth Patterns ◽  
Widespread Species ◽  
Growth Variability ◽  
Rear Edge ◽  
Species Vulnerability ◽  
The Impact

Abstract Background Equatorward, rear-edge tree populations are natural monitors to estimate species vulnerability to climate change. According to biogeographical theory, exposition to drought events increases with increasing aridity towards the equator and the growth of southern tree populations will be more vulnerable to drought than in central populations. However, the ecological and biogeographical margins can mismatch due to the impact of ecological factors (topography, soils) or tree-species acclimation that can blur large-scale geographical imprints in trees responses to drought making northern populations more drought limited. Methods We tested these ideas in six tree species, three angiosperms (Fagus sylvatica, Quercus robur, Quercus petraea) and three gymnosperms (Abies alba, Pinus sylvestris and Pinus uncinata) by comparing rear-edge tree populations subjected to different degrees of aridity. We used dendrochronology to compare the radial-growth patterns of these species in northern, intermediate, and southern tree populations at the continental rear edge. Results and conclusions We found marked variations in growth variability between species with coherent patterns of stronger drought signals in the tree-ring series of the southern populations of F. sylvatica, P. sylvestris, and A. alba. This was also observed in species from cool-wet sites (P. uncinata and Q. robur), despite their limited responsiveness to drought. However, in the case of Q. petraea the intermediate population showed the strongest relationship to drought. For drought-sensitive species as F. sylvatica and P. sylvestris, southern populations presented more variable growth which was enhanced by cool-wet conditions from late spring to summer. We found a trend of enhanced vulnerability to drought in these two species. The response of tree growth to drought has a marked biogeographical component characterized by increased drought sensitivity in southern populations even within the species distribution rear edge. Nevertheless, the relationship between tree growth and drought varied between species suggesting that biogeographical and ecological limits do not always overlap as in the case of Q. petraea. In widespread species showing enhanced vulnerability to drought, as F. sylvatica and P. sylvestris, increased vulnerability to climate warming in their rear edges is forecasted. Therefore, we encourage the monitoring and conservation of such marginal tree populations.

scholarly journals Uncertainty of Streamflow Forecasting with the Climate Change Scenario in India

2020 ◽  
Vol 1 (3) ◽  
Author(s):  
Ankit Bhatt ◽  
Ajay Pradhan
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Climate Change Scenario ◽  
Climate Models ◽  
Spatial Scales ◽  
Global Climate Models ◽  
Seasonal Effects ◽  
Change Scenario ◽  
Streamflow Forecasting ◽  
Projected Changes

Streamflow and rainfall estimates have utmost importance to compute detailed water availability and hydrology for many sectors such as agriculture, water management, and food security. There are various models developed over the years for runoff estimation but among them only a few models incorporate climate change factors. Snowmelt and rainfall are the main sources of surface as well as groundwater resource and the main inputs in runoff models for estimation of streamflow. There are numerous factors which leads to climate change which intern affects the distribution on rainfall on spatial and temporal scales and the rate of melting of snows in the Himalayan region. Uncertainties in projected changes in the hydrological systems arise from internal variability in the climatic system, uncertainty about future greenhouse gas and aerosol emissions, the translations of these emissions into climate change by global climate models, and hydrological model uncertainty. Projections become less consistent between models as the spatial scale decreases. The uncertainty of climate model projections for freshwater assessments is often taken into account by using multi-model ensembles. The multi-model ensemble approach is, however, not a guarantee of reducing uncertainty in mathematical models. In recent years the floods have occurred due to high intensity rainfall occurred in a very short time, but in several cases the flooding has also occurred because the rainfall has fallen at times when all the storage systems have not been emptied after the previous rainfall. This is what we call coupled rainfall. There is currently no recommendation for how to take coupled rainfall account when applying the climate change scenario. It is estimated that such changes represent at a large scale, and cannot be applied to shorter temporal and smaller spatial scales. In areas where rainfall and runoff are very low (e.g., desert areas), small changes in runoff can lead to large percentage changes. In some regions, the sign of projected changes in runoff differs from recently observed trends. Moreover, in some areas with projected increases in runoff, different seasonal effects are expected, such as increased wet season runoff and decreased dry season runoff. Studies using results from fewer climate models can be considerably different from the other models

Correlation structure of economic losses due to floods across Europe

2020 ◽  
Author(s):  
Stefano Zanardo ◽  
Rebecca Smith ◽  
Ludovico Nicotina ◽  
Anongnart Assteerawatt ◽  
Arno Hilberts
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Correlation Structure ◽  
Mitigation Measures ◽  
Economic Losses ◽  
River Flooding ◽  
The North ◽  
Negative State ◽  
Different Seasons ◽  
Flood Losses

&lt;p&gt;Large scale climatic patterns and river network topology have an important impact on the space-time structure of floods. For example, in a recent study we showed that the effect of the North Atlantic Oscillation (NAO) is visible in the structure of economic losses at the European scale. The analysis revealed that in Northern Europe the majority of historic winter floods occurred during a positive NAO state, whereas the majority of summer floods occurred during a negative state. Through the application of a state-of-the-art flood catastrophe model, we also observed that there exists a statistically significant relationship between economic flood losses and the NAO. In this study we further advance the analysis by exploring the correlation structure of flood losses in Europe during different seasons and for different NAO states.&amp;#160; Flood loss correlation is measured in terms of &amp;#8220;loss synchrony scale&amp;#8221; (LSC), a metric formalized for this study following the definition of &amp;#8220;flood synchrony scale&amp;#8221; in Berghuijs et al. (2019). For an individual event and an individual CRESTA region, the LSC is defined as the maximum radius around the CRESTA, within which at least half of the other CRESTA regions experience a loss due to the same event. We analyse the LSC across Europe, as produced by the loss model, and check &amp;#160; for consistency with the data-based flood synchrony scale in Berghujs et al. (2019). We further explore how the LSC changes between different seasons, and between NAO states. This analysis can help improve financial preparedness to catastrophic floods as a better understanding of the correlation structure of the flood events allows for a better distribution of resources as well as a more efficient application of mitigation measures.&lt;/p&gt;&lt;p&gt;Berghuijs W R, Allen S T, Harrigan S and Kirchner J W 2019 Growing spatial scales of synchronous river flooding in Europe&amp;#160;Geophys. Res. Lett.&amp;#160;46&amp;#160;1423&amp;#8211;8&lt;/p&gt;

scholarly journals Previous growing season climate controls the occurrence of black spruce growth anomalies in boreal forests of Eastern Canada

2016 ◽  
Vol 46 (5) ◽  
pp. 696-705 ◽  
Author(s):  
Clémentine Ols ◽  
Annika Hofgaard ◽  
Yves Bergeron ◽  
Igor Drobyshev
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Boreal Forests ◽  
Black Spruce ◽  
Spatial Scales ◽  
Growing Season ◽  
Eastern Canada ◽  
Late 20Th Century ◽  
Growth Anomalies

To better understand climatic origins of annual tree-growth anomalies in boreal forests, we analysed 895 black spruce (Picea mariana (Mill.) B.S.P.) tree-growth series from 46 xeric sites situated along three latitudinal transects in Eastern Canada. We identified interannual (based on comparison with previous year growth) and multidecadal (based on the entire tree-ring width distribution) growth anomalies between 1901 and 2001 at site and transect levels. Growth anomalies occurred mainly at site level and seldom at larger spatial scales. Both positive interannual and multidecadal growth anomalies were strongly associated with below-average temperatures and above-average precipitation during the previous growing season (Junet–1 – Augustt–1). The climatic signature of negative interannual and multidecadal growth anomalies was more complex and mainly associated with current-year climatic anomalies. Between the early and late 20th century, only negative multidecadal anomalies became more frequent. Our results highlight the role of previous growing season climate in controlling tree growth processes and suggest a positive association between climate warming and increases in the frequency of negative multidecadal growth anomalies. Projected climate change may further favour the occurrence of tree-growth anomalies and enhance the role of site conditions as modifiers of tree response to regional climate change.

scholarly journals Forest wildflowers bloom earlier as Europe warms – but not everywhere equally

2021 ◽  
Author(s):  
Franziska M. Willems ◽  
J. F. Scheepens ◽  
Oliver Bossdorf
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Spatial Scales ◽  
Flowering Phenology ◽  
Spatial Modelling ◽  
Forest Understory ◽  
Herbarium Specimens ◽  
Ecological Communities ◽  
Improved Model

AbstractSome of the most striking biological responses to climate change are the observed shifts in the timing of life-history events of many organisms. Plants, in particular, often flower earlier in response to climate warming, and herbarium specimens are excellent witnesses of such long-term changes. However, in large-scale analyses the magnitude of phenological shifts may vary geographically, and the data are often clustered, and it is thus necessary to account for spatial correlation to avoid geographical biases and pseudoreplication. Here, we analysed herbarium specimens of 20 spring-flowering forest understory herbs to estimate how their flowering phenology shifted across Europe during the last century. Our analyses show that on average these forest wildflowers now bloom over six days earlier than at the beginning of the last century. These changes were strongly associated with warmer spring temperatures. Plants flowered on average of 3.6 days earlier per 1°C warming. However, in some parts of Europe plants flowered earlier or later than expected. This means, there was significant residual spatial variation in flowering time across Europe, even after accounting for the effects of temperature, precipitation, elevation and year. Including this spatial autocorrelation into our statistical models significantly improved model fit and reduced bias in coefficient estimates. Our study indicates that forest wildflowers in Europe strongly advanced their phenology in response to climate change during the last century, with potential severe consequences for their associated ecological communities. It also demonstrates the power of combining herbarium data with spatial modelling when testing for long-term phenology trends across large spatial scales.

scholarly journals Divergent Last Century Tree Growth along An Altitudinal Gradient in A Pinus sylvestris Dry-edge Population

Forests ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 532
Author(s):  
Laura Fernández-Pérez ◽  
Miguel Ángel Zavala ◽  
Pedro Villar -Salvador ◽  
Jaime Madrigal-González
Keyword(s):  
Climate Change ◽  
Global Change ◽  
Pinus Sylvestris ◽  
Tree Growth ◽  
Altitudinal Gradient ◽  
Tree Age ◽  
Growth Responses ◽  
Growth Trends ◽  
Local Factors ◽  
The Impact

Research Highlights: This research highlights the importance of environmental gradients in shaping tree growth responses to global change drivers and the difficulty of attributing impacts to a single directional driver. Background and Objectives: Temperature increases associated with climate change might strongly influence tree growth and forest productivity in temperate forest species. However, the direction and intensity of these effects at the dry edge of species range are still unclear, particularly given the interaction between local factors and other global change drivers such as land use change, atmospheric CO2 increase and nitrogen deposition. While recent studies suggest that tree growth in cool temperate forests has accelerated during the last decades of the 20th century, other studies suggest a prevalence of declining growth, especially in dry-edge populations. Materials and Methods: Using historical forest inventories, we analyzed last century tree growth trends (1930–2010) along an elevation gradient (1350–1900 meters above sea level (m a.s.l.)) in a dry edge scots pine (Pinus sylvestris L.) forest in Central Iberian Peninsula. Growth was estimated as decadal volume increments in harvested trees of different size classes from 1930 to 2010 (1930–1940, 1939–1949, 1949–1959, 1959–1968, 1989–1999, 2000–2010). Results: Our results showed opposite growth trends over time depending on elevation. While tree growth has accelerated in the low end of the altitudinal gradient, tree growth slowed down at higher elevations (1624–1895 m a.s.l.). Moreover, the magnitude of growth reduction along the altitudinal gradient increased with tree age. Conclusions: Throughout the last 80 years, growth trends in a rear-edge Pinus. sylvestris forest has shown divergent patterns along an altitudinal gradient. Specifically, environmental conditions have become more adverse for growth at high altitudes and have improved at low altitudes. This suggests that local factors such as topography can modulate the impact of climate change on forest ecosystems.

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