Sen, A.K., & Kern, Z. (2016). Wavelet analysis of low-frequency variability in oaktree-ring chronologies from east Central Europe. OpenGeosciences,8(1), 478-483.

Thisstudy investigates the low-frequency (interannual and longer period)variability in three hydroclimatic records from east Central Europe. Two ofthese records consist of climate proxies derived from oak-tree rings in Baktaforest, and Balaton Highlands in Hungary, for the time interval 1783-2003. Thethird record consists of homogenized instrumental precipitation data fromBudapest, Hungary, from 1842 to 2003. Using wavelet analysis, the three timeseries are analyzed and compared with one another. It is found that all threetime series exhibit strong interannual variability at the 2-4 years timescales,and these variations occur intermittently throughout the length of each record.Significant variability is also observed in all the records at decadaltimescales, but these variations persist for only two to three cycles. Waveletcoherence among the various time series is used to explore their time-varyingcorrelation. The results reveal significant coherence at the 2-4 years band. Atthese timescales, the climatic variations are correlated to the tree-ringsignal over different time intervals with changing phase. Increased (decreased)contribution of large-scale stratiform precipitation offers a potentialexplanation for enhanced (faded) coherence at the interannual timescale. Strongcoherence was also observed occasionally at decadal timescales, however thesecoherences did not appear uniformly. These results reinforce the earlierassertion that neither the strength nor the rank of the similarity of the localhydroclimate signals is stable throughout the past two centuries.

http://www.degruyter.com/view/j/geo.2016.8.issue-1/geo-2016-0044/geo-2016-0044.xml

Drake, B.L., Hanson, D. T., Lowrey, T. K., & Sharp, Z. D. (2016). The carbonfertilization effect over a century of anthropogenic CO2 emissions: higherintracellular CO2 and more drought resistance among invasive and native grassspecies contrasts with increased water use efficiency for woody plants in theUS Southwest. Global Change Biology.

From 1890to 2015, anthropogenic carbon dioxide emissions have increased atmospheric CO2concentrations from 270 mol mol−1 to 400 mol mol−1. The effect of increasedcarbon emissions on plant growth and reproduction has been the subject of studyof Free Air CO2 Enrichment (FACE) experiments. These experiments have found a)an increase in internal CO2 partial pressure (ci) alongside acclimation ofphotosynthetic capacity, b) variable decreases in stomatal conductance, and c)that increases in yield do not increase commensurate with CO2 concentrations.Our data set, which includes a 115 year long selection of grasses collected inNew Mexico since 1892 is consistent with an increased ci as a response tohistorical CO2 increase in the atmosphere; with invasive species showing thelargest increase. Comparison with Palmer Drought Sensitivity index (PDSI) forNew Mexico indicates a moderate correlation with Δ13C (r2 = 0.32, p < 0.01)before 1950, with no correlation (r2 = 0.00, p = 0.91) after 1950. Theseresults indicate that increased ci may have conferred some drought resistanceto these grasses through increased availability of CO2 in the event of reducedstomatal conductance in response to short term water shortage. Comparison withC3 trees from arid environments (Pinus longaeva and Pinus edulis in the USSouthwest) as well as from wetter environments (Bromus and Poa grasses in NewMexico) suggest differing responses based on environment; arid environments inNew Mexico see increased intrinsic water use efficiency (WUE) in response tohistoric elevated CO2 while wetter environments see increased ci. The presentstudy suggests that a) the observed increases in ci in FACE experiments are consistentwith historical CO2 increases and b) the CO2 increase influences plantsensitivity to water shortage, through either increased WUE or ci in arid andwet environments, respectively.

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13449/full

Germain,d. (2016). A statistical framework for tree‐ring reconstruction of high‐magnitude mass movements: case study of snow avalanches ineastern canada. Geografiska Annaler: Series A, Physical Geography.

Thispaper investigates the application of the peaks-over-threshold method incombination with fitting of the generalized Pareto distribution for estimatingthe frequency of high-magnitude geomorphic events, on the basis of tree-ringdata. In particular, attention is focused on extreme value distribution oftree-ring responses and in the minimum threshold or index number required toassure the past occurrence of high-magnitude events. The objective is to set athreshold, adapted to the sample distribution, which will make the distinctionbetween high-magnitude years and remaining years, where the response of sampledtrees is too weak to be attributed to a high-magnitude geomorphic event. Thestatistical framework proposed is based on the statistics of extremes. Throughthe use of simple, strong and effective mathematics, this model shouldstrengthen the position of dendrogeomorphology in the evaluation and managementof natural hazards.

http://onlinelibrary.wiley.com/doi/10.1111/geoa.12138/full

Landesmann,J. B., Gowda, J. H., & Kitzberger, T. (2016). Temporal shifts in theinteraction between woody resprouters and an obligate seeder tree during a post‐fire succession inPatagonia. Journal of Vegetation Science.

Question

The studyof temporal variation of plant–plant interactions has received little attentiondespite its importance in community dynamics. Successional processes triggeredby disturbances such as fire may be determined by changes in key interactionsbetween dominant woody plants. Taking advantage of a 95-yr-old post-firenatural experiment we assessed temporal shifts in post-fire interactionsbetween woody resprouters and the obligate seeder tree Austrocedrus chilensis.We hypothesized that during the initial post-fire period, resprouters mayfacilitate A. chilensis trees' growth, while at advanced time since fire the interactionbetween A. chilensis trees and resprouters may turn to competition.

Location

NorthwesternRío Negro province, Patagonia, Argentina.

Methods

Weselected pairs of A. chilensis trees and woody resprouters growing 80 cm apart(growing in association) and both A. chilensis trees and resprouters growing atmore than 3 m apart from any individual (controls). We cored all individuals,measured ring widths and calculated basal area increment (BAI) and the relativeinteraction index (RII).

Results

Duringmid-early stages of post-fire succession, A. chilensis trees' BAI wassuppressed for at least 15 yr when growing in association with resprouters, andaccordingly displayed a negative RII. Strikingly, during the same period,resprouters associated with A. chilensis trees showed higher BAI than controlresprouters, and a positive RII. At advanced time since fire, RII showed aneutral interaction, and according to model estimations, the BAI of A.chilensis trees in association may eventually exceed control BAI whereasresprouters' BAI in association may decline earlier than that of the controls.Interestingly, A. chilensis trees and resprouters' growth was less correlatedwith climate when growing in association than when growing in isolation.

Conclusions

Competitionof resprouters over A. chilensis treess' growth during intermediate post-firestages may be slowing the successional process. However, the associationappears to be at the same time mutually beneficial as it buffers againstadverse climatic conditions. Studying how plant growth varies along thesuccession is essential to understand community functioning and to predictpossible alterations associated with changes in disturbance regimes due toclimate change.

http://onlinelibrary.wiley.com/doi/10.1111/jvs.12430/full

López,L., & Villalba, R. (2016). An assessment of Schinopsis brasiliensis Engler(Anacardiacea) for dendroclimatological applications in the tropical Cerradoand Chaco forests, Bolivia. Dendrochronologia, 40, 85-92.

Given thescarcity of instrumental climatic data in the South American tropics, it isvaluable to explore the dendrochronological potential of the numerous treespecies growing in the region. In this paper, we assessed for the first timethe dendrochronological characteristics of Schinopsis brasiliensis, an arborealspecies from the dry-tropical Cerrado and Chaco forests in Bolivia and adjacentcountries. Similar to most woody species in the Cerrado and Chaco regions,growth rings of S. brasiliensis are delimited by the presence of thin butcontinuous lines of marginal parenchyma. Based on 22 samples from 15 trees, wepresent the first ring-width chronology for this species covering the period1812–2011 (200 years). Additionally, a 106-year floating chronology from S.brasiliensis was developed using cores from four columns from the church of SanMiguel, Santa Cruz, built in the period 1720–1740. Standard dendrochronologicalstatistics indicate an important common signal in the radial growth of S.brasiliensis. The comparison of variations in regional climate and ring widthsshows that tree growth is directly related to spring-summer rainfall andinversely related to temperature. Following the winter dry season, rainfall inlate spring and early summer increases soil water supply, which activates treegrowth. In contrast, above-average temperatures during the same period increaseevapotranspiration, intensify the water deficit and reduce radial growth. Thedependence of S. brasiliensis growth on water supply is evidence of itsdendrochronological potential for reconstructing past precipitation variationsin the extensive tropical Cerrado and Chaco forest formations in South America.Using wood from historical buildings opens the possibility of extending thechronologies of S. brasiliensis over the past 400–500 years.

http://www.sciencedirect.com/science/article/pii/S1125786516300789

Jeong, H.M., Kim, J. Y., Kim, J. Y., & Seo, J. W. (2016). Tree-ring Dating of ThePalsangjeon Wooden Pagoda at The Beopjusa Temple in Boeun, South Korea. J.Korean Wood Sci. Technol, 44(4), 515-525.

ThePalsangjeon Pagoda is a five-story wooden building in the Beopjusa Temple areain the Songnisan national park in Chungcheongbuk-do, Korea. According tohistorical records, it was constructed in either AD 1605 or AD 1626. To specifythe construction year more precisely, we took 41 wood samples for tree-ringanalysis during repair actions in 2013; 28 from red pine (Pinus densiflora S.et Z.), 12 from oak (Quercus spp.), and 1 from fir (Abies spp.). The tree-ringboundaries became clearly visible by smoothing their cross-sectional surface andthe tree-ring widths were measured under a stereo microscope. All tree-ringseries were compared with eachother to establish mean chronologies, which we then compared with local masterchronologies established using tree rings collected from wooden elements of theDaeungjeon Hall which is the main building in the Beopjusa Temple area. As aresult, it was verified that the red pines were felled in AD 1624 and in AD1851. Moreover, it was verified that the oaks were also felled in AD 1624 basedon cross-dating with the red pine chronology. We concluded that the PalsangjeonWooden Pagoda was constructed in AD 1626, as mentioned in the historical record(Daeungdaekwangmyeongjeonbulsangki, 1630) and the letters on a purlin on the4th story, using oak and red pine felled in AD 1624 and repaired later on usingred pine felled in AD 1851.

https://www.researchgate.net/profile/Hyun_Min_Jeong2/publication/305703518_Tree-ring_dating_of_the_Palsangjeon_Wooden_Pagoda_at_the_Beopjusa_Temple_in_Boeun_South_Korea/links/579af92508ae425e491849a3.pdf