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Many studies have already addressed the existence of unstable and nonlinear relationships between radial growth of white spruce (Picea glauca) and climate variables in boreal forests along the high latitudes (>60° N). However, along the mid-latitudes, the climate-growth relationship is still poorly understood. In this study, we used a network of ri...
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To better understand the long-term response of boreal forests to increasing environmental changes, we applied the u-w method to detect growth changes triggered by environmental factors. Three species (Picea mariana, Picea glauca, and Populus tremuloides) of various sizes and ages were sampled in a boreal forest in northern Canada. Several stem disk...
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... ch/assessment-report/ar6). Climate change (www.epa.gov/climate-research) is expected to negatively affect the environmental suitability and productivity of spruce trees (Tjoelker et al. 2007). This continued warming, coupled with reduced precipitation, may be unsuitable for growth of spruce trees (Altman et al. 2017;Chen et al. 2017;Kolář et al. 2017;Šijačić-Nikolić et al. 2019). ...
Species in the genus Picea are well-suited for afforestation on high altitudes and latitudes, but are fairly intolerant to high temperatures. In this study, Picea pungens, Picea abies, and Picea omorika were subjected to 45 °C, 40 °C, 35 °C, and ambient temperature (CK) for 6 h, and then allowed to recover for 28 d. Changes in phenotype, relative water content (RWC), and maximal photochemical efficiency (Fv/Fm) of photosystem II (PS II) were observed to ascertain their thermal tolerance. Overall, all three species were negatively affected by exposure to 45 °C, but P. pungens exhibited full recovery, with the highest RWC, while P. omorika exhibited partial recovery, and P. abies showed minimal recovery. The PS II of all three species were damaged after 45 °C treatment, but that of P. pungens exhibited the most dramatic recovery, with Fv/Fm recovering from 0 to 0.26. In conclusion, P. pungens was found to exhibit the greatest thermal tolerance, followed by P. omorika and P. abies. Thus, thermal tolerance should be considered as a tool for species selection for future reforestation endeavor in the face of climate change that is expected to bring high summer temperature events.
... Despite a projected increase in summer precipitation, evaporation and climate moisture deficit will likely increase as air temperatures increase (Foord 2016). Congruently, drought-induced water stress has been identified as one of the main contributors of widespread tree mortality and growth decline in the western boreal forests of Canada (Hogg et al. 2008(Hogg et al. , 2017Ma et al. 2012;Chen et al. 2017aChen et al. , 2017b. ...
... Warm springs were also found to increase white spruce growth at the treeline in Alaska (Wilmking et al. 2004). White spruce radial growth was negatively correlated with summer temperatures of the previous year in white spruce-dominated mixedwood stands in western Canada (Chen et al. 2017b). Our results suggest that the negative growth responses to summer temperatures in the mixedwood stand is related to interactions between air temperature and soil water availability. ...
Variation in annual white spruce growth (Picea glauca (Moench) Voss) has been shown to be dependent on weather conditions such as air temperature and moisture availability. However, questions remain about how intra-annual variation in climate variables influence annual growth, and whether stand composition and structure can influence climate conditions and the trees’ responses to weather stress. We evaluated the importance and influence of seasonal climate on growth (annual ring width increment) of 32-year-old white spruce trees in pure and mixedwood stands in northeastern British Columbia. The importance of climate variables, and their ranked order, differed between pure and mixedwood stands. Soil water potential (SWP) during spring and summer were the main factors influencing spruce growing in both pure and mixedwood stands. However, the relative importance of each variable, their direct effects, and their interactions differed between stand types. Warm springs increased spruce growth in both stands, while warm summers increased spruce growth in the pure spruce stand but decreased growth in the mixedwood stand. Spruce growth in the pure stand was positively correlated with soil water potential during spring and summer, while spruce growth in the mixedwood stand was negatively correlated. In both stand types, there was an interplay between the amount of water available in the soil and air temperature to influence annual growth. Our findings suggest stand composition influences the resilience of spruce to drought.
... For SDI, the exponent of Changbai larch was set to -1.58, and the standard quadratic mean diameter was set to 20 cm (Li & Tang 2010). In terms of climate variable selection, since the lagged or carry-over effects of climate on tree growth have been widely observed in many species, both previous-and current-year climate variables were evaluated (Chhin et al. 2008;Chen et al. 2017;Yu & Liu 2020). A total of 396 climate variables (2 years × (22 annual + 11 × 4 seasonal + 11 × 12 monthly)) were examined for their potential impacts on radial growth using the stepwise selection process. ...
An improved understanding of the effects of thinning and climate on tree growth is essential to adopting adaptive forest management strategies under climate change. In this study, we developed a climate-sensitive individual-tree growth model for Changbai larch (Larix olgensis) in northeast China by fusing tree-ring and permanent sample plot data. We assessed the impacts of tree age, competition, site condition, thinning, and climate on radial growth using the mixed-effects modeling approach. Results showed that the radial growth rate of Changbai larch decreased with increasing cambial age and competition intensity. Radial growth was negatively associated with summer water deficit and positively associated with spring growing degree-days. Radial growth also responded positively to mean annual precipitation of the previous year. In addition, a significant positive effect of thinning on radial growth was observed. The magnitude of thinning effects was affected by thinning intensity and time elapsed since the thinning. Hierarchical partitioning analysis showed that cambial age was the most important factor affecting growth (relative contribution 35.96%), followed by competition (31.42%), climate (19.24%), thinning (8.40%), and site condition (4.98%). Compared to unthinned plots, moderate- and high-intensity thinning significantly enhanced the radial growth under unfavorable climates, indicating that thinning has great potential to mitigate the negative effects of future climate. Disentangling different sources of variations in ring width will help advance our understanding of the factors driving radial growth and reduce the uncertainty in forest management decisions.
... Droughts caused by global warming over the past two decades have led to the decline and death of trees in areas such as inland Asia and western Canada [68,[71][72][73][74]. Studies in areas such as high elevations of western North America and central Europe have shown that warming extends the growing season, accelerates tree growth and increases forest biomass in these areas [11][12][13]75,76]. ...
Global warming is causing some regions to experience frequent and severe drought, with important impacts on montane forest vegetation. In this study, the Qilian Mountains is on the northeastern margin of the Tibetan Plateau which was divided into three study areas, the eastern (HaXi), middle (XiShui) and western (QiFeng) parts. This work focused on interannual trend comparison of tree-ring width (TRW) and enhanced vegetation index (EVI), their relationship characterization from 2000 to 2020, and spatial and temporal pattern portrayal of response to climate factors. The results showed that: (1) the overall interannual variation of TRW and EVI showed a stable increasing trend, and the trend of TRW and EVI gradually became consistent with the increase in drought stress (from the eastern region to the western region and from high elevation to low elevation) (p < 0.01); (2) a significant positive relation was observed between TRW and EVI at the same sampling sites, and the synchrony of the positive correlation gradually increased with the increase of drought stress (p < 0.01); and (3) compared to TRW, EVI is significantly more sensitive with climatic variations, and the dominant climate factors affecting both TRW and EVI dynamics are gradually identical with the increase of drought stress.
... White spruce growth decline has been repeatedly associated with high temperatures in excess of the species physiological thresholds (73,74). Among the six species studied here, white spruce also displayed the highest sensitivity to low water availability, in line with recent reports of drought-induced growth decline, and even mortality in Central and Western Canada for that species (71,72,(75)(76)(77). ...
Large projected increases in forest disturbance pose a major threat to future wood fiber supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem. Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics. Here, we apply a machine learning algorithm to an unprecedented network of over 1 million tree growth records (1958 to 2018) from 20,089 permanent sample plots distributed across both Canada and the United States, spanning a 16.5 °C climatic gradient. Fitted models were then used to project the near-term (2050 s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 20.5 to 22.7% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests that warming-induced growth increases should no longer be considered marginal but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.
... Trees may thus respond to drought through changes in wood traits, which can help maintain a favorable water balance in the xylem (Tyree and Ewers 1991). However, Chen et al. (2017) also reported that growth climate relationships vary across populations and environmental gradients. Drought response may also vary with the age of the trees, for instance during the complex and well-described transition from juvenile to mature wood in spruces (e.g. ...
... As expected, the drought-induced stress treatments led to a decrease in biomass index, radial and apical growth of seedlings (Fig. 1). Many studies have shown that tree growth is usually limited by the availability of soil water and that any drought-induced stress affects physiology (Hogg and Schwarz 1997;Escós et al. 2000;Shafer et al. 2001;Shukla et al. 2019;Allen et al. 2010;Pederson et al. 2012;Price et al. 2013;Chen et al. 2017). For instance, stomatal closure is the first reaction to drought stress in most plants, and it . ...
Forest plantations play an important role in maintaining a supply of high-quality timber from managed forest. With an expected increase in the prevalence of drought in some forested areas, climate change increases concerns about future seedling growth. A promising approach to promote the suitability of plantation seedlings to current and future climate would be to use variation in growth and wood traits of trees under drought as selection criteria in tree breeding programs, especially at a young stage when they are most vulnerable to drought. We evaluated the genetic control of the growth and wood density response of white spruce clonal seedlings submitted to various drought conditions in a greenhouse experiment. By varying the watering treatment of 600 two year-old seedlings from 25 clones, we simulated three levels of drought-induced stress during two growing seasons. Apical and radial growth decreased markedly as the intensity of drought increased, whereas wood density tended to increase. We also developed a woody biomass index composed of wood density and ring area, which was observed to decrease slightly with increasing drought. There was important variation in all traits among clones and heritability tended to decrease with the intensity and duration of drought-induced stress, mainly for wood density and radial growth. However, the heritability of apical growth tended to increase under drought conditions. Our results show that the response of young white spruce clones to drought is highly variable, and together with the significant levels of heritability noted, the results indicate that multi-trait genetic selection for drought stress response at a young age could represent a promising approach to increase resilience to drought.
... Within a certain threshold, vegetation structure and function are changed and growth is inhibited; when crossing an ecological response threshold, vegetation will die and be replaced by other species, resulting in a secondary succession of vegetation [6,7]. Additionally, in the context of global warming, evapotranspiration increases [8], vegetation transpiration is accelerated, and the negative effects of regional drought on vegetation may be amplified [9,10]. ...
Under the background of climate warming, the increase in the frequency and severity of drought leads to vegetation facing severe challenges. A comprehensive and systematic assessment of the stability of vegetation under drought stress in the middle reaches of Yellow River basin (MRYRB) will help to grasp the characteristics of vegetation response to drought. In this study, the normalized difference vegetation index (NDVI) was used to achieve quantitative and qualitative assessments of vegetation stability to drought, and the smoothed monthly standardized precipitation evapotranspiration index (SPEI) was used to describe the characteristics of drought events in 2005/2006 and identified vegetation stability parameters using a standardized anomaly of NDVI across space, which included the resistance duration, resilience duration, drought threshold, and lag time. Vegetation was dominated by less resistance and less resilience. The 2005/2006 drought event affected most of the study area, and vegetation growth was inhibited.The duration of vegetation resistance over 100 days accounted for 65.7%, and vegetation in 89.4% of the regions could return to normal within 100 days. The drought threshold of vegetation gradually decreased from northwest to southeast, and the lag time was mainly concentrated from 1 to 3 months. These findings contribute to a better understanding of the effects of drought on the environment, as well as scientific references for reducing ecological, economic, and social losses in future droughts, and promoting ecological environmental governance and high-quality development in the MRYRB.
... Feng et al.: Lengthening of the growth season, but no increased water availability ies have shown that a warming climate will extend the growing season of vegetation, increase the rate of photosynthesis, and make forest growth faster (Lindner et al., 2010;Pretzsch et al., 2014;Mcmahon et al., 2010). However, climate warming increases evapotranspiration, leading to drought stress on tree growth (Worrall et al., 2013;Hogg et al., 2017;Chen et al., 2017). Therefore, observing and studying forest growth dynamics and understanding their relationship with climate change are essential for forest management and sustainable development (Anderegg et al., 2012;Wang et al., 2021). ...
On the eastern Tibetan Plateau, the growth of trees is
strongly affected by climate change. Previous researchers have found that
climate warming changes thermal and hydraulic conditions, lengthening the
growing season and promoting tree growth. Some studies have analyzed the
effects of drought, precipitation, and temperature on tree growth. However,
previous studies have mainly focused on natural forests, with few studies on
the response of plantations to climate change. Therefore, we studied the
relationship between dendrochronology (basal area increment, BAI),
normalized difference vegetation index (NDVI), and climate factors to
explore the response of Picea likiangensis var. rubescens plantations to climate change. The results
showed that from 1990 to 2018, the temperature in the study area increased
significantly; the rate of increase was 0.39∘ per decade. Among the
climate factors, self-calibrated Palmer drought severity index (scPDSI) had
the most significant impact on BAI. From P_May (P_ represents the month of
the previous year) to December, BAI was always negatively correlated with
the scPDSI, with 9 months being significantly negatively correlated. BAI
was significantly positively correlated with the minimum 2 m temperature
(TMN) in P_July, P_September, July, and September. BAI was significantly
positively correlated with the maximum 2 m temperature (TMX) in P_October,
P_December, and July. BAI was significantly positively correlated with the
mean 2 m temperature (TMP) in P_July, P_December, and July. There is a
significant positive correlation between BAI and annual NDVI (NDVIa), which
means that NDVI can be used to study the response of plantations to climate
change. Our study contributes to a better understanding of the response of
plantation growth in high-altitude areas to climate change, which is needed
by forest managers.
... (Seidl et al. 2017). Warming has exacerbated drought stress on trees in forests, causing tree death and forest reduction at many high elevations and high latitudes and in dry areas (Hogg et al. 2017;Huang et al. 2021;Jiao et al. 2016;Zhou et al. 2020;Chen et al. 2017). Conversely, a warmer climate could also lengthen growing seasons in cold humid areas, thereby increasing the photosynthetic rate of trees and producing more carbohydrates for growth (Liu 2019;Pretzsch et al. 2014;Bosela et al. 2018;Gao et al. 2022;Guo et al. 2019). ...
Key message
Qinghai spruce at different elevations showed inconsistent growth trends and responses to climate change.
Abstract
Under global warming, mountains in arid and semi-arid regions have become the main ecologically vulnerable areas affected by climate change. Northwest China has experienced intermittent climate change in recent decades that can be divided into three periods: steady change (T1), a rapid temperature increase (T2) and a warming hiatus (T3). How this unsteady change in climate has affected the growth and response of trees at different elevations in the region remains unclear. Therefore, we established three standard chronologies of Qinghai spruce (Picea crassifolia) at high, middle and low elevations in the central Qilian Mountains to investigate its responses during different periods. We drew three primary conclusions. First, trees at high elevations are primarily impacted by higher temperatures, while trees at middle and low elevations are mainly impacted by water stress due to drought. Second, trees at the three elevations showed unstable responses to all temperature factors, while those at the middle and low elevations showed relatively stable responses to total precipitation in the late growing season of the previous year. Third, different interannual growth variations were observed at the three elevations, indicating a nonsignificant change at high elevations and significant declines at middle and low elevations. At the same time, growth patterns were different for the three climatic periods. Therefore, the dominant conifers at different elevations of the Qilian Mountains showed inconsistent responses during different periods. It is necessary to take effective measures to manage forest ecosystems according to spatial and temporal adaptation strategies for climate change.
... p < .001; Figure 1 and Figure S1). If precipitation cannot compensate for increased evaporation caused by warming, then the water deficit will increase, which may limit photosynthesis, and reduce carbohydrate assimilation and storage (Chen et al., 2017;Lu et al., 2021). ...
Under climate change circumstances, increasing studies have reported the temporal instability of tree growth responses to climate, which poses a major challenge to linearly extrapolating past climate and future growth dynamics using tree‐ring data. Space‐for‐time substitution (SFTS) is a potential solution to this problem that is widely used in the dendrochronology field to project past or future temporal growth response trajectories from contemporary spatial patterns. However, the projected accuracy of the SFTS in the climate effects on tree growth remains uncertain. Here, we empirically test the SFTS method by comparing the effect of spatial and temporal climate variations on climate responses of white spruce (Picea glauca), which has a transcontinental range in North America. We first applied a response surface regression model to capture the variations in growth responses along the spatial climate gradients. The results showed that the relationships between growth and June temperature varied along spatial climate gradients in a predictable way. And their relationships varied mainly along with local temperate condition. Then, the projected correlation coefficients between growth and climate using SFTS were compared against the observed. We found that the growth response changes caused by spatial versus temporal climate variations showed opposite trends. Moreover, the projected correlation coefficients using the SFTS were significantly lower than the observed. This finding suggests that applying the SFTS to project the growth response of white spruce might lead to an overestimation of the degree of tree maladaptation in future climate scenarios. And the overestimation is likely to get weaker from Alaska and Yukon Territory in the west to Quebec in the east. Although this is only a case study of the SFTS method for projecting tree growth response, our findings suggest that direct application of the SFTS method may not be applicable to all regions and all tree species.
