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 Role of Mixed-Species Stands in Attenuating the Vulnerability of Boreal Forests to Climate Change and Insect Epidemics

2021 ◽  
Vol 12 ◽  
Author(s):  
Raphaël D. Chavardès ◽  
Fabio Gennaretti ◽  
Pierre Grondin ◽  
Xavier Cavard ◽  
Hubert Morin ◽  
...  
Keyword(s):  
Climate Change ◽  
Populus Tremuloides ◽  
Tree Growth ◽  
Host Species ◽  
Boreal Forests ◽  
Linear Models ◽  
Black Spruce ◽  
Trembling Aspen ◽  
Mixed Stands ◽  
Species Mixture

We investigated whether stand species mixture can attenuate the vulnerability of eastern Canada’s boreal forests to climate change and insect epidemics. For this, we focused on two dominant boreal species, black spruce [Picea mariana (Mill.) BSP] and trembling aspen (Populus tremuloides Michx.), in stands dominated by black spruce or trembling aspen (“pure stands”), and mixed stands (M) composed of both species within a 36 km2 study area in the Nord-du-Québec region. For each species in each stand composition type, we tested climate-growth relations and assessed the impacts on growth by recorded insect epidemics of a black spruce defoliator, the spruce budworm (SBW) [Choristoneura fumiferana (Clem.)], and a trembling aspen defoliator, the forest tent caterpillar (FTC; Malacosoma disstria Hübn.). We implemented linear models in a Bayesian framework to explain baseline and long-term trends in tree growth for each species according to stand composition type and to differentiate the influences of climate and insect epidemics on tree growth. Overall, we found climate vulnerability was lower for black spruce in mixed stands than in pure stands, while trembling aspen was less sensitive to climate than spruce, and aspen did not present differences in responses based on stand mixture. We did not find any reduction of vulnerability for mixed stands to insect epidemics in the host species, but the non-host species in mixed stands could respond positively to epidemics affecting the host species, thus contributing to stabilize ecosystem-scale growth over time. Our findings partially support boreal forest management strategies including stand species mixture to foster forests that are resilient to climate change and insect epidemics.

scholarly journals Comparison of the Radial Growth Response of Picea crassifolia to Climate Change in Different Regions of the Central and Eastern Qilian Mountains

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1015
Author(s):  
Xuan Wu ◽  
Liang Jiao ◽  
Dashi Du ◽  
Changliang Qi ◽  
Ruhong Xue
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Central Region ◽  
Radial Growth ◽  
Growing Season ◽  
Qilian Mountains ◽  
Growth Patterns ◽  
Total Precipitation ◽  
Picea Crassifolia ◽  
The Qilian Mountains

It is important to explore the responses of radial tree growth in different regions to understand growth patterns and to enhance forest management and protection with climate change. We constructed tree ring width chronologies of Picea crassifolia from different regions of the Qilian Mountains of northwest China. We used Pearson correlation and moving correlation to analyze the main climate factors limiting radial growth of trees and the temporal stability of the growth–climate relationship, while spatial correlation is the result of further testing the first two terms in space. The conclusions were as follows: (1) Radial growth had different trends, showing an increasing followed by a decreasing trend in the central region, a continuously increasing trend in the eastern region, and a gradually decreasing trend in the isolated mountain. (2) Radial tree growth in the central region and isolated mountains was constrained by drought stress, and tree growth in the central region was significantly negatively correlated with growing season temperature. Isolated mountains showed a significant negative correlation with mean minimum of growing season and a significant positive correlation with total precipitation. (3) Temporal dynamic responses of radial growth in the central region to the temperatures and SPEI (the standardized precipitation evapotranspiration index) in the growing season were unstable, the isolated mountains to total precipitation was unstable, and that to SPEI was stable. The results of this study suggest that scientific management and maintenance plans of the forest ecosystem should be developed according to the response and growth patterns of the Qinghai spruce to climate change in different regions of the Qilian Mountains.

Climate Change in Foreign Policy

2017 ◽  
Author(s):  
Amy Below
Keyword(s):  
Climate Change ◽  
Foreign Policy ◽  
Global Climate ◽  
International System ◽  
Policy Issue ◽  
Power Dynamics ◽  
Late 20Th Century ◽  
Environmental Threat ◽  
Academic Scholarship

Climate change emerged in the late 20th century as a topic of global concern and thus a prominent foreign policy issue. Academic scholarship on the international community’s response to the environmental threat was not far behind. Scholars apply a number of theoretical constructs in their search to explain why states behave the way they do in their coordinated approaches to addressing climate-related activities. Of these, systemic theories such as realism, liberalism, and constructivism figure prominently. State-centric theories that consider changing power dynamics in the international system, the importance of evolving coalitions, as well as the role of hegemonic and leadership states, provide contending explanations. Nonstate actors, especially the climate regime itself which has received substantial attention, are similarly considered important variables affecting foreign policy. Constructivist arguments emphasizing the influence of ideas, norms, and identity have become increasingly common, especially as they relate to developmental disparities, “common but differential responsibilities,” and climate justice. While there has been less focus on the role of individual actors, domestic-level variables such as concerns for economic growth, reputation, and capacity to act, as well as multivariable explanations, continue to provide insight. In contrast to the diversity of explanations proposed, the young field is relatively homogeneous in terms of methodological approaches, with qualitative case studies or small-N analyses being most common. If history is a trustworthy guide, however, as on-the-ground, practical approaches to global climate governance evolve, so too will scholarly approaches to its study.

scholarly journals Intra-Annual Wood Formation of Cryptomeria fortunei and Cunninghamia lanceolata in Humid Subtropical China

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhuangpeng Zheng ◽  
Feifei Zhou ◽  
Patrick Fonti ◽  
Ping Ren ◽  
Xiaoxia Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Boreal Forests ◽  
Cambial Activity ◽  
Cunninghamia Lanceolata ◽  
Growth Monitoring ◽  
Specific Information ◽  
Summer Drought ◽  
Growth Responses ◽  
Xylem Growth

Monitoring cambial activity is important for a better understanding of the mechanisms governing xylem growth responses to climate change, providing a scientific basis for tree-ring-based climate reconstructions and projections about tree growth under future climate scenarios. It plays an even more important role in investigating evergreen tree growth in regions with less distinct seasonal cycles. Subtropical evergreen forests have been studied in recent years for their sensitivity to climate change, but it remains unclear how xylem growth is driven by subtropical climates. To further understand the climate-growth response strategies of subtropical conifers, we micro-cored Cryptomeria fortunei and Cunninghamia lanceolata weekly in 2016 and 2017 at the humid subtropical Gushan Mountain in southeastern China. Our weekly growth monitoring showed that the vegetation periods of these two species were both approximately 2–3 months longer than trees in temperate and boreal forests. The growth of C. fortunei in 2016 and 2017 and C. lanceolata in 2017 showed a bimodal pattern of xylogenesis, which was induced by summer drought. The results also indicated that the earlier end of the xylem formation was related to the yearly drought stress. These findings provide more specific information about tree growth and evidence of how climate influences wood production at the cellular level in subtropical regions.

Snowmelt and early to mid‐growing season water availability augment tree growth during rapid warming in southern Asian boreal forests

2019 ◽  
Vol 25 (10) ◽  
pp. 3462-3471 ◽  
Author(s):  
Xianliang Zhang ◽  
Rubén D. Manzanedo ◽  
Loïc D'Orangeville ◽  
Tim T. Rademacher ◽  
Junxia Li ◽  
...  
Keyword(s):  
Tree Growth ◽  
Water Availability ◽  
Boreal Forests ◽  
Growing Season

Terrestrial Processes and Their Roles in Climate Change

2021 ◽  
Author(s):  
Nathalie de Noblet-Ducoudré ◽  
Andrew J. Pitman
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Land Surface ◽  
Seasonal Cycle ◽  
Spatial Scales ◽  
Climatic Conditions ◽  
Surface Processes ◽  
Climate Modelling ◽  
Climate Simulations

The land surface is where humans live and where they source their water and food. The land surface plays an important role in climate and anthropogenic climate change both as a driver of change and as a system that responds to change. Soils and vegetation influence the exchanges of water, energy and carbon between the land and the overlying atmosphere and thus contribute to the variability and the evolution of climate. But the role of the land in climate is scale dependent which means different processes matter on different timescales and over different spatial scales. Climate change alters the functioning of the land with changes in the seasonal cycle of ecosystem growth, in the extent of forests, the melt of permafrost, the magnitude and frequency of disturbances such as fire, drought, … Those changes feedback into climate at both the global and the regional scales. In addition, humans perturb the land conditions via deforestation, irrigation, urbanization, … and this directly affects climatic conditions at the local to regional scales with also sometimes global consequences via the release of greenhouse gases. Not accounting for land surface processes in climate modelling, whatever the spatial scale, will result in biases in the climate simulations.

Disentangling the relative role of climate change on tree growth in an extreme Mediterranean environment

2018 ◽  
Vol 642 ◽  
pp. 619-628 ◽  
Author(s):  
Jaime Madrigal-González ◽  
Enrique Andivia ◽  
Miguel A. Zavala ◽  
Markus Stoffel ◽  
Joaquín Calatayud ◽  
...  
Keyword(s):  
Climate Change ◽  
Tree Growth ◽  
Relative Role ◽  
Mediterranean Environment

Moving towards carbon neutrality: CO2 exchange of a black spruce forest ecosystem during the first 10 years of recovery after harvest

2012 ◽  
Vol 42 (11) ◽  
pp. 1908-1918 ◽  
Author(s):  
Carole Coursolle ◽  
Marc-André Giasson ◽  
Hank A. Margolis ◽  
Pierre Y. Bernier
Keyword(s):  
Boreal Forests ◽  
Black Spruce ◽  
Ecosystem Respiration ◽  
Co2 Exchange ◽  
Relative Role ◽  
Ecosystem Productivity ◽  
Eastern Canada ◽  
Post Harvest ◽  
C Dynamics ◽  
Rate Of Increase

Disturbances control the landscape-level C dynamics of boreal forests, but post-disturbance C dynamics are usually poorly quantified. In the current study, we use 10 years of CO2 flux measurements at a boreal black spruce ( Picea mariana (Mill.) B.S.P.) cutover in eastern Canada to estimate time to C neutrality, quantify the relative role of respiration versus photosynthesis during recovery, and determine the agreement between cumulated CO2 fluxes and plot-level changes in C content. The site was a net source of 139 g C·m–2·year–1 2 years post-harvest, dropped further to a source of 173 g C·m–2·year–1 4 years post-harvest, following a scarification treatment, and was nearly C neutral 10 years post-harvest. Gross ecosystem productivity (GEP) increased by 50 g C·m–2·year–1 post-scarification, while ecosystem respiration (ER) increased by only 23 g C·m–2·year–1. The resulting net rate of increase of 27 g C·m–2·year–1 in net ecosystem productivity was driven by changes in increasing leaf area. In fact, vegetation regrowth had a much greater impact on annual fluxes than did interannual variability in climate. Biometric-based measurements of total C losses after harvest were in relatively good agreement with eddy-covariance-based estimates 8 years after the harvest.

scholarly journals Wood density and wood shrinkage in relation to initial spacing and tree growth in black spruce (Picea mariana)

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Shu Yin Zhang ◽  
Haiqing Ren ◽  
Zehui Jiang
Keyword(s):  
Path Analysis ◽  
Wood Density ◽  
Tree Growth ◽  
Picea Mariana ◽  
Black Spruce ◽  
Planting Density ◽  
Longitudinal Shrinkage ◽  
Eastern Canada ◽  
Initial Spacing ◽  
Transverse Shrinkage

AbstractThis study has quantified basic wood density and various types of wood shrinkage in relation to initial spacing (or initial planting density) and tree growth based on a 48-year-old black spruce (Picea mariana) spacing trial in eastern Canada. A total of 139 sample trees were collected from four initial spacings (3086, 2500, 2066, 1372 trees/ha) for this study. Analyses of variance (ANOVA) show that initial spacing is the most important parameter affecting wood density significantly, followed by tree diameter at breast height (DBH) class. With increasing spacing, wood density, radial and volumetric shrinkage tend to decrease, whereas longitudinal shrinkage tends to increase gradually. The largest spacing has the lowest wood density, the smallest transverse shrinkage and the largest longitudinal shrinkage. Path analysis indicates that wood density is the most important parameter affecting transverse shrinkage, followed by the distance from the pith. Furthermore, much of the variation of the transverse shrinkage with wood density may be due to the initial spacing and tree DBH class. Path analysis also reveals that longitudinal shrinkage is mainly related to log height and tree DBH class. With increasing log height, longitudinal shrinkage tends to increase, and transverse shrinkage tends to decrease. With increasing DBH class, the trees tend to have an increasing longitudinal shrinkage and a decreasing transverse shrinkage. Overall, this study suggests that a large increase in the initial spacing (e.g., 1372 trees/ha) might lead to a significant reduction in both wood density and transverse shrinkage, and a significant increase in longitudinal shrinkage in black spruce.

CO2 stimulation and response mechanisms vary with light supply in boreal conifers

2020 ◽  
Author(s):  
Qing-Lai Dang ◽  
Jacob Marfo ◽  
Fengguo Du ◽  
Rongzhou Man ◽  
Sahari Inoue
Keyword(s):  
Elevated Co2 ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Black Spruce ◽  
Net Photosynthesis ◽  
Growing Season ◽  
White Spruce ◽  
Light Supply ◽  
Ecophysiological Responses ◽  
Light Effects

Abstract Aims Black spruce (Picea mariana [Mill.] B.S.P.) and white spruce (Picea glauca [Moench] Voss.) are congeneric species. Both are moderately shade tolerant and widely distributed across North American boreal forests. Methods To understand light effects on their ecophysiological responses to elevated [CO2], 1-year old seedlings were exposed to 360 and 720 µmol mol -1 [CO2] at three light conditions (100, 50 and 30% of full light in the greenhouse). Foliar gas exchanges were measured in the mid- and late-growing season. Important Findings Elevated [CO2] increased net photosynthesis (Pn) and photosynthetic water use efficiency, but it reduced stomatal conductance and transpiration. The stimulation of photosynthesis by CO2 was greatest at 50% light and smallest at 100%. Photosynthesis, maximum carboxylation rate (Vcmax) and light saturated rate of electron transport (Jmax) all decreased with decreasing light. Elevated [CO2] significantly reduced Vcmax across all light treatments and both species in mid-growing season. However, the effect of elevated [CO2] became insignificant at 30% light later in the growing season, with the response being greater in black spruce than in white spruce. Elevated [CO2] also reduced Jmax in white spruce in both measurements while the effect became insignificant at 30% light later in the growing season. However, the effect on black spruce varied with time. Elevated [CO2] reduced Jmax in black spruce in mid-growing season in all light treatments and the effect became insignificant at 30% light later in the growing season, while it increased Jmax later in the season at 100% and 50% light. These results suggest that both species benefited from elevated CO2, and that the responses varied with light supply, such that the response was primarily physiological at 100% and 50% light, while it was primarily morphological at 30% light.

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