1.        Yu Liu, Xinjia Zhang, HuimingSong, Qiufang Cai, Qiang Li, & Boyang Zhao, et al. (2016).Tree-ring-width-based pdsi reconstruction for central inner mongolia, chinaover the past 333 years. Climate Dynamics.

A tree-ring-width chronology was developedfrom Pinus tabulaeformis aged up to 333 years from central Inner Mongolia,China. The chronology was significantly correlated with the local PalmerDrought Severity Index (PDSI). We therefore reconstructed the first PDSIreconstruction from March to June based on the local tree ring data from 1680to 2012 AD. The reconstruction explained 40.7 % of the variance (39.7 % afteradjusted the degrees of freedom) of the actual PDSI during the calibrationperiod (1951–2012 AD). The reconstructed PDSI series captured the severedrought event of the late 1920s, which occurred extensively in northern China.Running variance analyses indicated that the variability of drought increasedsharply after 1960, indicating more drought years, which may implyanthropogenic related global warming effects in the region. In the entirereconstruction, there were five dry periods: 1730–1814 AD, 1849–1869 AD,1886–1942 AD (including severe drought in late 1920s), 1963–1978 AD and2004–2007 AD; and five wet periods: 1685–1729 AD, 1815–1848 AD, 1870–1885 AD,1943–1962 AD and 1979–2003 AD. Conditions turned dry after 2003 AD, and thePDSI from March to June (PDSI36) captured many interannual extreme droughtevents since then, such as 2005–2008 AD. The reconstruction is comparable toother tree-ring-width-based PDSI series from the neighboring regions, indicatingthat our reconstruction has good regional representativeness. Significantrelationships were found between our PDSI reconstruction and the solarradiation cycle and the sun spot cycle, North Atlantic Oscillation, the ElNiño-Southern Oscillation, as well as the Pacific Decadal Oscillation. Powerspectral analyses detected 147.0-, 128.2-, 46.5-, 6.5-, 6.3-, 2.6-, 2.2- and2.0-year quasi-cycles in the reconstructed series.

http://link.springer.com/article/10.1007/s00382-016-3115-6

2.        Touchan, R., Shishov, V. V.,Tychkov, I. I., Sivrikaya, F., Attieh, J., Ketmen, M., ... & Meko, D. M.(2016). Elevation-layered dendroclimatic signal in eastern Mediterranean treerings. Environmental Research Letters, 11(4), 44020-44027.

Networks of tree-ring data are commonlyapplied in statistical reconstruction of spatial fields of climate variables.The importance of elevation to the climatic interpretation of tree-ringnetworks is addressed using 281 station precipitation records, and a network of79 tree-ring chronologies from different species and a range of elevations inthe eastern Mediterranean. Cluster analysis of

chronologies identifies 6 tree-ring groups,delineated principally by site elevation. Correlation analysis suggests severalof the clusters are linked to homogenous elevational moisture regimes. Resultsimply that climate stations close to the elevations of the tree-ring sites areessential for assessing the seasonal climatic signal in tree-ring chronologiesfrom this region. A broader implication is that the elevations of stationscontributing to gridded climate networks should be considered in the design andinterpretation of field reconstructions of climate from tree rings. Finally,results suggest elevationstratified tree-ring networks as a strategy for seasonalclimate reconstruction.

http://iopscience.iop.org/article/10.1088/1748-9326/11/4/044020/pdf

3.        Watson, E., & Luckman, B.H. (2016). An investigation of the snowpack signal in moisture-sensitive treesfrom the Southern Canadian Cordillera. Dendrochronologia.

Variations in mountain snowpack in thewestern Canadian Cordillera have widespread and important impacts onecosystems, environmental processes and socio-economic activities (e.g. wateravailability downstream). Historical records of snowpack generally span onlythe latter half of the 20th century offering a limited perspective on thecauses and uniqueness of recently observed changes across the region. Thispaper explores the potential utility of a network of low elevation Douglas-fir(Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) tree ring-widthchronologies to reconstruct past snowpack variations. Correlation coefficientsbetween the tree-ring chronologies and a set of snow water equivalent (SWE)records are calculated and mapped. Separate analyses were carried out for totalring- width (TRW) and partial-ring measurements (earlywood and latewood; EW andLW). A set of Adjusted LW chronologies was also developed; in these, therelationship between LW and the preceding EW width has been removed. Thering-width chronologies exhibit moderately strong relationships with SWErecords from the western Canadian Cordillera and these relationships vary insign across the region. Distinctive regional groups are identified wherechronologies exhibit same-sign correlations with SWE, in possible accordancewith the elevation and characteristics of the tree-ring chronology samplesites. The EW chronologies correlate more strongly and consistently with SWErecords in regions where the growth relationship with SWE is negative. The LWchronologies, and particularly the Adjusted LW chronologies, exhibit a greaternumber of positive correlations with the set of SWE records. Collectively theseresults offer valuable insights for developing a targeted sampling and/orreconstruction strategy that can exploit these different relationships with SWEto generate more robust estimates of pre-instrumental snowpack for the region.

http://www.sciencedirect.com/science/article/pii/S1125786516300285

4.        Toohey, M., Krüger, K., Sigl,M., Stordal, F., & Svensen, H. (2016). Climatic and societal impacts of avolcanic double event at the dawn of the Middle Ages. Climatic Change, 1-12.

Volcanic activity in and around the year536 CE led to severe cold and famine, and has been speculatively linked tolarge-scale societal crises around the globe. Using a coupled aerosol-climatemodel, with eruption parameters constrained by recently re-dated ice corerecords and historical observations of the aerosol cloud, we reconstruct theradiative forcing resulting from a sequence of two major volcanic eruptions in536 and 540 CE. We estimate that the decadal-scale Northern Hemisphere (NH)extra-tropical radiative forcing from this volcanic “double event” was largerthan that of any period in existing reconstructions of the last 1200 years.Earth system model simulations including the volcanic forcing show peak NH meantemperature anomalies reaching more than −2 °C, and show agreement with thelimited number of available maximum latewood density temperaturereconstructions. The simulations also produce decadal-scale anomalies of Arcticsea ice. The simulated cooling is interpreted in terms of probable impacts onagricultural production in Europe, and implies a high likelihood of multipleyears of significant decreases in crop production across Scandinavia,supporting the theory of a connection between the 536 and 540 eruptions andevidence of societal crisis dated to the mid-6th century.

http://link.springer.com/article/10.1007/s10584-016-1648-7

5.        Boswijk, G., Brassey, R.,Bader, H. D., Adamson, J., & Jones, M. J. (2016). Dendrochronologicaldating of kauri timbers from Browne's spar station (1832–1836), Mahurangi,Auckland, New Zealand. Journal of Archaeological Science: Reports, 7, 129-137.

In New Zealand, timbers and other woodenobjects have been found preserved in waterlogged prehistoric and historic-eraarchaeological sites, but dendrochronological analysis of such material israre. In 2010 an archaeological investigation was carried out at the site ofBrowne's spar station, Mahurangi, Auckland (CE 1832–1836), documented as theearliest European settlement in the Auckland region. The station supplied sparsto the British Admiralty and sawn timber to the Australian colonies. Timberfeatures, made of kauri (Agathis australis), were present on the foreshore andincluded relics from a possible sawpit structure and a catwalk made fromoffcuts. Tree-ring samples were obtained from these to determine if they wereassociated with the spar station or from a later phase of activity. Afour-timber tree-ring chronology was calendar dated to CE 1756–1831 and fellingdates were obtained from three timbers. These indicated that: (a) the possiblesawpit structure was built from trees felled between May and October 1832; (b)two offcuts used in the catwalk were from trees felled in late 1832 or early1833; and (c) the catwalk was built in or after 1833. The tree-ring datesprovide independent evidence that the timbers were contemporaneous with, andcomplement documentary information related to, the spar station. Analysis ofwood samples also provides some insight into human behaviour regarding treeselection and the use of waste material. The spar station material is only thesecond waterlogged assemblage of kauri timbers to be analysed usingdendrochronology in New Zealand and the first to be recovered from aninter-tidal context. The results demonstrate the potential for tree-ringanalysis of waterlogged wood to provide accurate and precise dates forarchaeological sites in New Zealand.

http://www.sciencedirect.com/science/article/pii/S2352409X16301031

6.        Fardusi, M. J., Ferrio, J. P.,Comas, C., Voltas, J., de Dios, V. R., & Serrano, L. (2016). Intra-specificassociation between carbon isotope composition and productivity in woodyplants: a meta-analysis. Plant Science.

The study of intra-specific variations ingrowth and plant physiological response to drought is crucial to understand thepotential for plant adaptation to global change. Carbon isotope composition(δ13C) in plant tissues offers an integrated measure of intrinsic water-useefficiency (WUEi). The intra-specific association between δ13C and productivityhas been extensively studied in herbaceous crops, but species-specificinformation on woody plants is still limited and has so far providedcontradictory results. In this work we explored the general patterns of therelationship between δ13C and growth traits (height, diameter and biomass)using a meta-analysis. We compiled information from 49 articles, including 176studies performed on 34 species from 16 genera. We found a positive globalintra-specific correlation between δ13C and growth (Gr = 0.28, P < 0.0001),stronger for biomass than for height, and non-significant for diameter. Theextent of this intra-specific association increased from Mediterranean tosubtropical, temperate and boreal biomes, i.e. from water-limited toenergy-limited environments. Conifers and shrubs, but not broadleaves, showedconsistent positive intra-specific correlations. The meta-analysis alsorevealed that the relationship between δ13C and growth is better characterizedat juvenile stages, under near-optimal and controlled conditions, and byanalyzing δ13C in leaves rather than in wood.

http://www.sciencedirect.com/science/article/pii/S0168945216300589

7.        Rossi, S., Anfodillo, T.,Čufar, K., Cuny, H. E., Deslauriers, A., Fonti, P., ... & Jyske, T. (2016).Pattern of xylem phenology in conifers of cold ecosystems at the northernhemisphere. Global Change Biology.

The interaction between xylem phenology andclimate assesses forest growth and productivity and carbon storage acrossbiomes under changing environmental conditions. We tested the hypothesis thatpatterns of wood formation are maintained unaltered despite the temperaturechanges across cold ecosystems. Wood microcores were collected weekly orbiweekly throughout the growing season for periods varying between 1-13 yearsduring 1998-2014 and cut in transverse sections for assessing the onset andending of the phases of xylem differentiation. The dataset represented 1321trees belonging to 10 conifer species from 39 sites in the Northern hemisphereand covering an interval of mean annual temperature exceeding 14 K. The phenologicalevents and mean annual temperature of the sites were related linearly, withspring and autumnal events being separated by constant intervals across therange of temperature analysed. At increasing temperature, first enlarging,wall-thickening and mature tracheids appeared earlier, and last enlarging andwall-thickening tracheids occurred later. Overall, the period of wood formationlengthened linearly with the mean annual temperature, from 83.7 days at -2 °Cto 178.1 days at 12 °C, at a rate of 6.5 days °C-1. April-May temperaturesproduced the best models predicting the dates of wood formation. Our findingsdemonstrated the uniformity of the process of wood formation and the importanceof the environmental conditions occurring at the time of growth resumption.Under warming scenarios, the period of wood formation might lengthensynchronously in the cold biomes of the Northern hemisphere.

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13317/full

8.        Tape, K. D., Gustine, D. D.,Ruess, R. W., Adams, L. G., & Clark, J. A. (2016). Range Expansion of Moosein Arctic Alaska Linked to Warming and Increased Shrub Habitat. PLoS One,11(4), e0152636.

Twentieth century warming has increasedvegetation productivity and shrub cover across northern tundra and treelineregions, but effects on terrestrial wildlife have not been demonstrated on acomparable scale. During this period, Alaskan moose (Alces alces gigas)extended their range from the boreal forest into tundra riparian shrub habitat;similar extensions have been observed in Canada (A. a. andersoni) and Eurasia(A. a. alces). Northern moose distribution is thought to be limited by forageavailability above the snow in late winter, so the observed increase in shrubhabitat could be causing the northward moose establishment, but a previoushypothesis suggested that hunting cessation triggered moose establishment.Here, we use recent changes in shrub cover and empirical relationships betweenshrub height and growing season temperature to estimate available moose habitatin Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1m tall c. 1860, greatly reducing the available forage above the snowpack,compared to 2 m tall in 2009. We believe that increases in riparian shrubhabitat after 1860 allowed moose to colonize tundra regions of Alaska hundredsof kilometers north and west of previous distribution limits. The northernshift in the distribution of moose, like that of snowshoe hares, has been inresponse to the spread of their shrub habitat in the Arctic, but at the sametime, herbivores have likely had pronounced impacts on the structure andfunction of these shrub communities. These northward range shifts are abellwether for other boreal species and their associated predators.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152636

9.        Zhang, R., Yuan, Y., Gou, X.,Yang, Q., Wei, W., Yu, S., ... & Qin, L. (2016). Streamflow variability forthe Aksu River on the southern slopes of the Tien Shan inferred from tree ringrecords. Quaternary Research.

Gauged river flow records from Chinagenerally span only a few decades, which hampers the detection of long-term,decadal- to centennial-scale cycles and trends in streamflow variability. Newand updated tree-ring chronologies help reconstructed the water-year(October–September) streamflow for the Aksu River, which is an important riverat the edge of the Taklimakan Desert that drains into the Tarim Basin. Thereconstruction dates back to 1692 and has an adjusted r2 of 0.61 (1957–2006).Based on frequency, intensity and duration of droughts and pluvial events, thelowest streamflows occurred in the 1920s. Since then streamflow hascontinuously increased, and was exceptionally rapidly after the 1960s, untiltoday. The start and end of the 20th century to the present were the higheststreamflow periods. The mid-20th century was the longest and driest period overthe past 300 yr. The reconstructed streamflow series has a strong positivecorrelation with the North Atlantic Oscillation Index. Changes in mid-latitudecirculation patterns influencing precipitation may have indirectly resulted instreamflow variations along the Aksu River over the past 300 yr. The rapidincrease and the exceptional streamflows of the 1960s are likely linked withglobal warming and mid-latitude atmospheric circulation changes.

http://www.sciencedirect.com/science/article/pii/S0033589416000247

10.    Vasileva, P., & Panayotov,M. (2016). Dating fire events in Pinus heldreichii forests by analysis of treering cores. Dendrochronologia.

Bosnian pine (Pinus heldreichii Christ,also known as Pinus leucodermis Antoine) is a relict species found in isolatedlocations in the mountains of the Balkan Peninsula and Southern Italy. Theforests are of high conservational value because they are extremely rich inrare and endemic species of plants and fungi. Yet, the natural history anddisturbance regime of Pinus heldreichii ecosystems is not well understood. Firetraces show that fires played a major role, but there is very limitedhistorical data. Therefore proxy methods to reconstruct past events have to beused. The analysis of tree rings provides such an opportunity. To ourknowledge, there have been no attempts to use tree ring cores from Pinusheldreichii trees to date fire events. Our aim was therefore to test if treering cores collected with an increment borer could successfully be used to datefires and verify other tree ring indicators caused by the fire events. Wetested an approach that was based on extracting multiple cores fromfire-scarred trees and nearby standing trees without injuries. A total of 136cores from 99 trees were collected from which we dated all 34 cores with firescars. We found the exact fire years for 29 of the samples, and the remaining 5samples were approximately dated. Up to 83% of all sampled trees had additionalgrowth reactions, mostly suppressions lasting 5 to 10 years after the fireyears.

http://www.sciencedirect.com/science/article/pii/S1125786516300340

11.    O'Donnell, A. J., Allen, K. J.,Evans, R. M., Cook, E. R., Trouet, V., & Baker, P. J. (2016). Wood densityprovides new opportunities for reconstructing past temperature variability fromsoutheastern Australian trees. Global and Planetary Change.

Tree-ring based climate reconstructionshave been critical for understanding past variability and recent trends inclimate worldwide, but they are scarce in Australia. This is particularly thecase for temperature: only one tree-ring width based temperature reconstruction– based on Huon Pine trees from Mt Read, Tasmania – exists for Australia. Here,we investigate whether additional tree-ring parameters derived from Athrotaxiscupressoides trees growing in the same region have potential to provide robustproxy records of past temperature variability.

We measured wood properties, includingtree-ring width (TRW), mean density, mean cell wall thickness (CWT), andtracheid radial diameter (TRD) of annual growth rings in Athrotaxiscupressoides, a long-lived, high-elevation conifer in central Tasmania,Australia. Mean density and CWT were strongly and negatively correlated withsummer temperatures. In contrast, the summer temperature signal in TRW wasweakly positive. The strongest climate signal in any of the tree-ring parameterswas maximum temperature in January (mid-summer; JanTmax) and we chose this asthe target climate variable for reconstruction. The model that explained mostof the variance in JanTmax was based on TRW and mean density as predictors. TRWand mean density provided complementary proxies with mean density showinggreater high-frequency (inter-annual to multi-year) variability and TRW showingmore low-frequency (decadal to centennial-scale) variability. The finalreconstruction model is robust, explaining 55% of the variance in JanTmax, andwas used to reconstruct JanTmax for the last five centuries (1530–2010 C.E.).The reconstruction suggests that the most recent 60 years have been warmer thanaverage in the context of the last ca. 500 years. This unusually warm period islikely linked to a coincident increase in the intensity of the subtropicalridge and dominance of the positive phase of the Southern Annular Mode insummer, which weaken the influence of the band of prevailing westerly winds andstorms on Tasmanian climate. Our findings indicate that wood properties, suchas mean density, are likely to provide significant contributions toward thedevelopment of robust climate reconstructions in the Southern Hemisphere andthus toward an improved understanding of past climate in Australasia.

http://www.sciencedirect.com/science/article/pii/S0921818115301211

12.    Ashiq, M. W., & Anand, M.(2016). Spatial and temporal variability in dendroclimatic growth response ofred pine (Pinus resinosa Ait.) to climate in northern Ontario, Canada. ForestEcology and Management, 372, 109-119.

Growth–climate relationships of trees arespecies-specific and can vary over space and time. Here, we study red pine(Pinus resinosa Ait.) by analyzing tree-ring width data from 37 sites acrossnorthern Ontario, Canada for the period 1901–2010. We performed responsefunction and moving response function analyses using seasonal data of threeclimatic variables: precipitation, minimum temperature and maximum temperature.Our analyses show considerable spatial and temporal variability in red pinegrowth response to climate during the 20th century. In general, red pine growthresponses to climate were more significant in northwestern Ontario than innortheastern Ontario. Overall, precipitation was the most significant predictorof red pine growth, with seasonal variations across sites. Unlike many otherstudies, we did not find any significant growth response to current year summertemperature. Instead, at many sites in northwestern Ontario, red pine had asignificant negative growth response to prior summer temperatures. The resultsof canonical correspondence analysis show that red pine growth response toclimate follows a longitudinal gradient. Temporal stability analyses revealedthat growth–climate response of red pine at any site was not stable during the20th century. We observed a general shift from significant growth response toseasonal temperature during the first half of the 20th century to significantgrowth response to seasonal (except for spring) precipitation during recentdecades. The spatial and temporal variability of red pine growth response toclimate detected in our study should be considered in future plans for forestmanagement of this species and can also be used for better understanding forestecological dynamics at the regional scale for conservation purposes.

http://www.sciencedirect.com/science/article/pii/S0378112716301645

13.    Vezzola, L. C., Diolaiuti, G.A., D’Agata, C., Smiraglia, C., & Pelfini, M. (2016). Assessing glacierfeatures supporting supraglacial trees: A case study of the Miagedebris-covered Glacier (Italian Alps). The Holocene, 1, 11.

The number of debris-covered glaciersfeaturing supraglacial trees is increasing worldwide as a response of highmountain environments to climate warming. Generally, their distribution on theglacier surface is not homogeneous, thus suggesting that some glacierparameters influence germination and growth of trees. In this study, we focusedour attention on the widest Italian debris-covered glacier, the Miage Glacier(Mont Blanc massif). We analyzed the ablation area in the range from 1730 to2400 m a.s.l. where continuous debris coverage is present and trees are found.Using data obtained by remote sensing investigations and field surveys, wedefined a record of glacier parameters to be analyzed with respect to thepresence and abundance of trees. We found that supraglacial trees are presentat the Miage Glacier (1) whenever exceeding a debris thickness threshold (⩾475px), (2) with a gentle slope (⩽10°), (3) with a low glacier surface velocity (⩽7.0m/yr), and (4) where the vertical changes due to glacier dynamicsare positive (i.e. prevalent increase ranging between +7 and +28 m over 28years due to both slow debris accumulation and preservation of ice flowinputs). The statistical analysis supports our findings. The analysis of thesame parameters might be conducted on other debris-covered glaciers featuringsupraglacial trees, in order to evaluate whether such conditions are local onesor whether they are general factors driving germination and growth of trees. Byidentifying the features supporting the presence and growth of trees in theseenvironments, and their thresholds, a contribution is given for a betterunderstanding of the importance of debris-covered glaciers and, in general, ofdebris-covered ice, as a refuge for trees during glacial and warm intervals ofthe Holocene.

http://hol.sagepub.com/content/early/2016/03/09/0959683616632883.full.pdf

14.    Mäkelä, A., Pulkkinen, M.,& Mäkinen, H. (2016). Bridging empirical and carbon-balance based forestsite productivity–Significance of below-ground allocation. Forest Ecology andManagement, 372, 64-77.

In forestry, site productivity is commonlydescribed using the concept of site index (SI) and its effect on the potentialmean annual increment. Although a unified causal explanation between SI andproductivity is still missing, operational methods have been developed todetermine SI on the basis of the existing tree crop or other indirectindicators of environmental drivers. In ecology, progress has been made inderiving productivity from the carbon balance, including photosynthesis,respiration and tissue longevity, but considerable gaps remain in quantifyingthe impact of soil processes on below-ground carbon allocation which would becrucial for closure of the total carbon balance. Recent empirical studies inFinland have found significant and consistent differences in the foliage tofine-root ratio and fine-root lifetime between the conventional SI based onfield layer vegetation in geographical vegetation zones. In this study, weutilised this information to bridge the gap between the large body of empiricalinformation on SI and productivity, and productivity as derived from the carbonbalance. We incorporated assumptions concerning the climate and soil responseof the carbon balance components in a process-based model, PipeQual, andapplied the approach to Norway spruce stands in Fenno–Scandian conditions. Theresults agreed well with an empirical growth and yield model and providedfairly accurate projections for two contrasting test sites. The study providedinsights into the role of the component processes of productivity. Importantly,the north-south gradient of productivity was equally attributed to a northwarddecrease in temperature and an increase in carbon allocation to fine roots.This cautions against climate change projections on the basis of current growthvariation with temperature and calls for improved mechanistic modelsincorporating plant, soil and microbial interactions in regulating thesoil-forest carbon and nitrogen fluxes.