scholarly journals Relating Climate, Drought and Radial Growth in Broadleaf Mediterranean Tree and Shrub Species: A New Approach to Quantify Climate-Growth Relationships

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1250
Author(s):  
J. Julio Camarero ◽  
Álvaro Rubio-Cuadrado

The quantification of climate–growth relationships is a fundamental step in tree-ring sciences. This allows the assessment of functional responses to climate warming, particularly in biodiversity and climate-change hotspots including the Mediterranean Basin. In this region, broadleaf tree and shrub species of pre-Mediterranean, subtropical origin, have to withstand increased aridification trends. However, they have not been widely studied to assess their long-term growth responses to climate and drought. Since these species evolved under less seasonal and wetter conditions than strictly Mediterranean species, we hypothesized that their growth would mainly respond to higher precipitation and water availability from spring to early summer. Here, we quantified climate–growth relationships in five of these broadleaf species showing different leaf phenology and wood type (Pistacia terebinthus L., Pistacia lentiscus L., Arbutus unedo L., Celtis australis L., and Laurus nobilis L.) by using dendrochronology. We calculated Pearson correlations between crossdated, indexed, mean ring width series of each species (chronologies) and monthly climate variables (mean temperature, total precipitation). We also calculated correlations between the species’ chronologies and a drought index on 7-day scales. Lastly, we compared the correlation analyses with “climwin” analyses based on an information-theoretic approach and subjected to cross-validation and randomization tests. As expected, the growth of all species was enhanced in response to wet and cool conditions during spring and early summer. In some species (P. lentiscus, A. unedo, C. australis,) high prior-winter precipitation also enhanced growth. Growth of most species strongly responded to 9-month droughts and the correlations peaked from May to July, except in L. nobilis which showed moderate responses. The “climwin” analyses refined the correlation analyses by (i) showing the higher explanatory power of precipitation (30%) vs. temperature (7%) models, (ii) selecting the most influential climate windows with June as the median month, and (iii) providing significant support to the precipitation model in the case of P. terebinthus confirming that the radial growth of this species is a robust proxy of hydroclimate variability. We argue that “climwin” and similar frameworks based on information-theoretic approaches should be applied by dendroecologists to critically assess and quantify climate–growth relationships in woody plants with dendrochronological potential.

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
J. Julio Camarero ◽  
Cristina Valeriano ◽  
Antonio Gazol ◽  
Michele Colangelo ◽  
Raúl Sánchez-Salguero

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions.


Author(s):  
Arjun Adhikari ◽  
Ronald E. Masters ◽  
Henry D. Adams ◽  
Rodney E. Will

We investigated radial growth of post oak (Quercus stellata) growing in a range of stand structures (forest to savanna) created in 1984 by different harvesting and thinning treatments followed by different prescribed fire intervals. We related ring width index (RWI) to monthly and seasonal climate variables and time since fire to assess impacts of climate variability and interactions with management on radial growth. RWI of all treatments was positively correlated to minimum daily temperature the previous September and precipitation late spring/early summer the current-year, and negatively correlated to maximum daily temperatures and drought index late spring/early summer. June weather was most strongly correlated in four of five treatments. While stand structure affected absolute diameter growth, RWI of savanna and forest stands responded similarly to climate variability, and low intensity prescribed fire did not influence RWI. On average, 100 mm reduction in June precipitation decreased RWI by 8%, 1oC increase in previous-year September daily minimum temperature increased RWI by 3.5%, and 1oC increase in June maximum daily temperature decreased RWI by 3.7%. Therefore, negative effects of drought and warmer spring/summer temperatures may be reduced by longer growing seasons under warmer climate scenarios. However, management did not appear to influence RWI.


Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 250
Author(s):  
Kristine Vander Mijnsbrugge ◽  
Arion Turcsán ◽  
Éva Erdélyi ◽  
Hans Beeckman

Background and Objectives: Studying responses in woody plants upon water limitation is gaining importance due to the predicted increase in frequency and intensity of droughts in Europe. We studied the variation in radial growth and in wood anatomical traits caused by water limited growth conditions in offspring from Quercus petraea (Matt.) Liebl., Q. robur L. and their morphological intermediates grown in the same environment. Materials and Methods: Cross sections were prepared from the stems of 210 three-year-old potted seedlings, comprising control plants and seedlings that experienced from late spring until early autumn of the first growing season two sequential periods of water with-holding each followed by plentiful re-watering. Pith radius, ring width of the three growing seasons and latewood vessel diameter in second and third growing season were measured. Presence of intra-annual density fluctuations, dendritic patterns of latewood vessels and the level of ring closure of earlywood vessels were observed. The traits were modelled to examine the explanatory power of the taxon of the mother tree and the drought treatment. Results: Most of the traits displayed significant differences between offspring from Q. petraea and Q. robur and offspring from the morphological intermediates behaved inconsistent among the traits. Most of the traits were significantly affected by the drought stress in the first growing season. Apart from radial growth, also latewood vessel size was reduced in the two growing seasons following the year in which drought was imposed on the seedlings, suggesting an adaptation to improve the tolerance to drought stress. We also found an indication for a compensation growth mechanism, counteracting the lost growing time during the drought stress, as the level of ring closure of the earlywood vessels in the year following the drought treatment was further advanced in the treated seedlings, an effect that disappeared in the subsequent year. Conclusion: Oaks exposed to drought adapt their growth and xylem structure to improve drought resistance. While youth growth of Q. robur is more competition-oriented, with a faster juvenile growth, Q. petraea seems to invest more in a precautious growth, being more prepared for stressful conditions. It is therefore possible that Q. robur seedlings may suffer more from intensified droughts than Q. petraea seedlings.


Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 514 ◽  
Author(s):  
Wuji Zheng ◽  
Xiaohua Gou ◽  
Jiajia Su ◽  
Haowen Fan ◽  
Ailing Yu ◽  
...  

Research Highlights: We compared annually resolved records of tree-ring width and stable isotope of dead and surviving Fokienia hodginsii (Dunn) Henry et Thomas trees. We provide new insights into the relationships and sensitivity of tree growth to past and current climate, and explored the underlying mechanism of drought-induced mortality in F. hodginsii. Background and Objectives: Drought-induced tree decline and mortality are increasing in many regions around the world. Despite the high number of studies that have explored drought-induced decline, species-specific responses to drought still makes it difficult to apply general responses to specific species. The endangered conifer species, Fokienia hodginsii, has experienced multiple drought-induced mortality events in recent years. Our objective was to investigate the historical and current responses to drought of this species. Materials and Methods: We used annually resolved ring-width and δ13C chronologies to investigate tree growth and stand physiological responses to climate change and elevated CO2 concentration (Ca) in both dead and living trees between 1960 and 2015. Leaf intercellular CO2 concentration (Ci), Ci/Ca and intrinsic water-use efficiency (iWUE) were derived from δ13C. Results: δ13C were positively correlated with mean vapor pressure deficit and PDSI from previous October to current May, while ring widths were more sensitive to climatic conditions from previous June to September. Moreover, the relationships between iWUE, basal area increment (BAI), and Ci/Ca changed over time. From 1960s to early 1980s, BAI and iWUE maintained a constant relationship with increasing atmospheric CO2 concentration. After the mid-1980s, we observed a decrease in tree growth, increase in the frequency of missing rings, and an unprecedented increase in sensitivity of 13C and radial growth to drought, likely related to increasingly dry conditions. Conclusions: We show that the recent increase in water stress is likely the main trigger for the unprecedented decline in radial growth and spike in mortality of F. hodginsii, which may have resulted from diminished carbon fixation and water availability. Given that the drought severity and frequency in the region is expected to increase in the future, our results call for effective mitigation strategies to maintain this endangered tree species.


Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 477 ◽  
Author(s):  
Kaelyn Finley ◽  
Jianwei Zhang

With increasing temperatures and projected changes in moisture availability for the Mediterranean climate of northern California, empirical evidence of the long-term responses of forests to climate are important for managing these ecosystems. We can assess forest treatment strategies to improve climate resilience by examining past responses to climate for both managed and unmanaged plantations. Using an experimental, long-term density and shrub removal study of ponderosa pine (Pinus ponderosa Lawson & C. Lawson) on a poor-quality site with low water-holding capacity and high runoff of the North Coastal mountain range in California, we examined the relationships between radial growth and climate for these trees over a common interval of 1977–2011. Resistance indices, defined here as the ratio between current year radial growth and the performance of the four previous years, were correlated to climatic variables during the same years. We found that all treatments’ radial growth benefited from seasonal spring moisture availability during the current growing year. Conversely, high spring and early summer temperatures had detrimental effects on growth. High-density treatments with manzanita understories were sensitive to summer droughts while lower densities and treatments with full shrub removal were not. The explanatory power of the climate regression models was generally more consistent for the same shrub treatments across the four different densities. The resistance indices for the lower density and complete shrub removal treatment groups were less dependent on previous years’ climatic conditions. We conclude that, for ponderosa pine plantations with significant manzanita encroachment, understory removal and heavy thinning treatments increase subsequent growth for remaining trees and decrease sensitivity to climate.


2021 ◽  
Vol 4 ◽  
Author(s):  
Shunsuke Tei ◽  
Ayumi Kotani ◽  
Atsuko Sugimoto ◽  
Nagai Shin

Terrestrial forest ecosystems are crucial to the global carbon cycle and climate system; however, these ecosystems have experienced significant warming rates in recent decades, whose impact remains uncertain. This study investigated radial tree growth using the tree-ring width index (RWI) for forest ecosystems throughout the Northern Hemisphere to determine tree growth responses to autumn climate change, a season which remains considerably understudied compared to spring and summer, using response function and random forest machine learning methods. Results showed that autumn climate conditions significantly impact the RWI throughout the Northern Hemisphere. Spatial variations in the RWI response were influenced by geography (latitude, longitude, and elevation), climatology, and biology (tree genera); however, geographical and/or climatological characteristics explained more of the response compared to biological characteristics. Higher autumn temperatures tended to negatively impact tree radial growth south of 40° N in regions of western Asia, southern Europe, United State of America and Mexico, which was similar to the summer temperature response found in previous studies, which was attributed to temperature-induced water stress.


Forests ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 761 ◽  
Author(s):  
Mizanur Rahman ◽  
Mahmuda Islam ◽  
Jakob Wernicke ◽  
Achim Bräuning

Tree growth in the tropics is strongly influenced by climate. However, reported tree growth responses to climate are largely inconsistent, varying with geographic location, forest type, and tree species. It is thus important to study the growth responses of tropical trees in sites and species that are under-represented so far. Bangladesh, a country influenced by the Asian monsoon climate, is understudied in terms of tree growth response to climate. In the present study, we developed a 121-year-long regional ring-width index chronology of Chukrasia tabularis A. Juss. sampled in two moist forest sites in Bangladesh to investigate tree growth responses to climate in monsoon South Asia. Standard dendrochronological methods were used to produce the ring-width chronologies. The climate sensitivity of C. tabularis was assessed through bootstrap correlation analysis and the stationarity and consistency of climate–growth relationships was evaluated using moving correlation functions and comparing the regression slopes of two sub-periods (1950–1985 and 1986–2015). Tree growth was negatively correlated with the mean, minimum, and maximum temperatures, particularly during the early growing season (March). Likewise, precipitation negatively influenced tree growth in the later growing season (October). Besides, radial growth of Chukrasia sharply ceased in years following strong and moderate El Niño events. In parallel with a significant positive trend in local temperatures, tree growth sensitivity to early growing season (March–April) mean temperatures and July minimum temperatures increased in recent decades. Tree growth sensitivity to October precipitation and April vapor pressure deficit also increased. Overall, climate–growth relationships were stronger during the period 1986–2015 than during 1950–1985. Changes in climate sensitivity might be linked to a warming trend that induced an increase in the dry season length during recent decades. With a further predicted temperature increase at our study sites, our results suggest that radial growth of C. tabularis will further decline in response to climate warming.


IAWA Journal ◽  
2019 ◽  
Vol 40 (2) ◽  
pp. 215-S2 ◽  
Author(s):  
J. Julio Camarero

ABSTRACTFunctional traits are considered to influence the performance of woody plants. However, few field studies have tested this idea by using radial-growth data. Here, I test if five major traits of the leafand wood-economics spectra (height, leaf area, specific leaf area – SLA, wood density – WD and hydraulic diameter) explain climate-growth relationships in 14 Mediterranean trees and shrubs. Traits were measured for both gymnosperm (four Juniperus species plus three Pinus species) and angiosperm species (two Quercus species, two Pistacia species, Arbutus unedo, Celtis australis, and one Tamarix species). Climategrowth relationships were calculated relating ring-width indices (RWIs) and local climate data. Leaf area and SLA were high in broadleaf deciduous species (e.g., C. australis), and low in junipers. WD reached minimum and maximum values in pine and oak species, respectively. WD explained 45 % of the variation of the association observed between RWI and April precipitation, one of the main climatic variables driving radial growth. Therefore, WD is a relevant functional trait useful to predict the performance of Mediterranean woody plant species, specifically concerning their growth responses to climate. Functional traits as WD should be further explored to explain growth variability between and within woody species, and to link this variability with responsiveness to climate and ecosystem productivity.


2010 ◽  
Vol 40 (2) ◽  
pp. 273-285 ◽  
Author(s):  
Jiri Doležal ◽  
Hiroaki Ishii ◽  
Tomáš Kyncl ◽  
Koichi Takahashi ◽  
Valentina P. Vetrova ◽  
...  

Radial growth responses to climate were studied in two species of birch broadly distributed across Kamchatka Peninsula. Wood cores were obtained in different locations and environments, from upper to lower treelines, and from wet maritime sites at the Pacific to the subcontinental interior of the peninsula. Response functions were calculated using the four longest meteorological records (1920s–2000) in Kamchatka. In Betula ermanii Cham., the dominant species in mountains and maritime woodlands, ring width in high-elevation (500–600 m) trees increased with warm and less rainy June and July and decreased with rainy/snowy cool weather during the prior September and October. Radial growth in B. ermanii low-elevation trees increased with higher winter precipitation, suggesting that water from melting snow prevents water stress and possibly desiccation in low-elevation trees. In Betula platyphylla Sukaczev, a common taiga species in interior Kamchatka, low summer temperatures limited growth at its upper distributional limit (300–350 m) and in cool, wet sites dominated by Picea ajanensis Lindl. et Gord. On drier sites dominated by Larix cajanderii Mayr., growth was limited by warm April and dry June weather. Variable responses along elevation–continentality gradients reinforce the necessity of a site-dependent differentiation for the assessment of impacts of climate change on species performance and geographic range shifts.


2011 ◽  
Vol 41 (9) ◽  
pp. 1795-1807 ◽  
Author(s):  
Elvin Toromani ◽  
Mitat Sanxhaku ◽  
Edmond Pasho

This paper deals with the response of silver fir ( Abies alba Mill.) growth to climate, mainly drought, presenting data from southern Kosovo, for which only little information is available. Two cores from 55 dominant trees were extracted at two sites representing the limits of the natural distribution of silver fir. We built 80- and 112-year-long chronologies for each site. Comparison of both ring width chronologies showed that they were diverse. Pointer year analysis indicated that high spring temperatures and ample rainfall (1082 mm) influenced positively silver fir growth (wide ring), while low spring temperatures and scarce precipitation had an inverse effect. Bootstrapped response functions confirmed that April and May temperatures of the current growth year influenced positively silver fir growth at the low-elevation site, while the July precipitation of the previous growth year had a negative influence. At the high-elevation site, warm previous December temperatures had a positive influence on silver fir growth. Drought indices indicated two periods (1953–1961 and 1994–2001) with moderate drought. Correlation analysis between silver fir radial growth and drought indices revealed that the impact of drought on radial growth was significant at the time scale of 1.5 months during the summer months.


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