Electronic Supplementary Material
ESM Fig. 1 a) Comparison of the Anemaqin (black curve) and Nianbaoyeze (grey curve) tree-ring chronologies. Smoothed lines indicate long-term growth variations generated by smoothing the original data with an 11-year Fast Fourier Filter (thin black line: Nianbaoyeze, bold black line: Anemaqin); b) expressed population signal (EPS) of the Anemaqin chronology. The threshold of 0.85, above which a chronology is regarded as reliable, is indicated by the horizontal dashed line
ESM Fig. 2 Correlation function between the Anemaqin regional ring-width chronology and regional monthly values of temperature (grey shaded) and precipitation (hatched area). Asterisks indicate correlations significant at p<0.05
ESM Fig. 3 Fallout radionuclides in the Dongerwuka Lake sediment core showing (a) total and supported 210Pb, (b) unsupported 210Pb, (c) 137Cs and 241Am concentrations versus depth
ESM Fig. 4 Pollen diagram of lake surface sediment samples from the Nianbaoyeze Mountains, after Herzschuh et al. (2010)
ESM Fig. 5 Results of Principal Component Analysis (PCA), showing pollen taxa with > 0.5% abundance in at least three samples. To ease visibility, species are displayed as text symbols only (but treated as vectors, as appropriate for linear methods)
ESM Table 1 Statistics of calibration-verification results for the period 1960–1998
ESM Table 2 Summary of radiocarbon dating report
ESM Table 3 Full species list with authorities and synonyms. Asterisk indicates taxa with maximum relative abundance of <1% in at least one sample
ESM Table 1 Statistics of calibration-verification results for the common period 1960–1998
Period / r / R2 / r / RE / CE1960–1979 / -0.628* / 0.394 / - / 0.480 / 0.510
1980–1998 / -0.783** / 0.613 / - / 0.766 / 0.287
1960–1998 / -0.712** / 0.510 / 0.662 / 0.750 / 0.386
* Significant at p 0.01, ** significant at p 0.001.
r is the correlation coefficient between the tree-ring record and the meteorological data; R2 is the variance explained by the calibration model; r is the correlation coefficient between the recorded data and the leave-one-out-derived estimates. RE is the reduction of error and CE is the coefficient of efficiency; any positive value of these statistics indicates confidence in the reconstruction (Fritts 1976)
Fritts HC (1976) Tree Rings and Climate. Academic Press, London, pp 567
ESM Table 2 Summary of radiocarbon dating report
Sample name / Lab. no. / Age 14C / MaterialDongerwuka S13-10 / Poz-50767 / 1,915±35 BP / TOC
Dongerwuka S13-24 / Poz-50768 / 1,740±30 BP / TOC
Dongerwuka S13-36 / Poz-50769 / 1,815±30 BP / TOC
ESM Table 3 Full species list with authorities and synonyms. Asterisk indicates taxa with maximum relative abundance of <1% in at least one sample
Species and Authority / Synonym*Achnanthes acares Hohn & Hellermann, 1963
Achnanthes flexella (Kützing) Mann, 1937 / Eucocconeis flexella
Achnanthes similis McCall, 1933
Achnanthes stolida Krasske, 1949
Achnanthidium biasolettianum (Grunow) Lange-Bertalot, 1999 / Achnanthes biasolettiana
Achnanthidium chlidanos (Hohn & Hellerman) Novelo, Tavera & Ibarra, 2007 / Achnanthes chlidanos
Achnanthidium exiguum (Grunow) Czarnecki, 1994 / Achnanthes exigua
*Achnanthidium macrocephalum (Hustedt) Round & Bukhtiyarova, 1996 / Achnanthes minutissima var. macrocephala
Achnanthidium minutissimum (Kützing) Czarnecki, 1994 / Achnanthes minutissima
Achnanthidium thienemannii (Hustedt) Lange-Bertalot, 2004 / Achnanthes biasolettiana var. thienemannii
Achnanthidium ventralis (Krasske) Haw & Kelly, 1998 / Achnanthes ventralis
Adlafia minuscula (Grunow) Lange-Bertalot, 1999 / Navicula minuscula
Amphora copulata (Kützing) Schoeman & Archibald, 1986 / Amphora libyca
*Amphora inariensis Krammer, 1980
Asterionella species
Aulacoseira species
Brachysira sp.
Brachysira styriaca (Grunow) Ross, 1986
*Brachysira vitrea (Grunow) Ross, 1986
Caloneis bacillum (Grunow) Cleve, 1894
Caloneis thermalis (Grunow) Krammer, 1985
Cavinula cocconeiformis (Gregory ex Greville) Mann & Stickle, 1990 / Navicula cocconeiformis
Cavinula pseudoscutiformis (Hustedt) Mann & Stickle, 1990 / Navicula pseudoscutiformis
Clevamphora ovalis var. pediculus (Kützing) Mereschkowsky, 1906 / Amphora pediculus
Cocconeis placentula Ehrenberg, 1838
Craticula halophilioides (Hustedt) Lange-Bertalot, 2001 / Navicula halophiloides
Cyclotella antiqua Smith, 1853
Cyclotella bodanica var. lemanica (Müller) Bachmann, 1903
*Cyclotella comensis Grunow, 1882
*Cyclotella ocellata Pantocsek, 1902
Cyclotella rossii Håkansson, 1990
*Cyclotella wuethrichiana Druart & Straub, 1988
Cymbella affinis Kützing, 1844
Cymbella arctica (Lagerstedt) Schmidt, 1875
Cymbella helvetica Kützing, 1844
Cymbella lanceolata (Ehrenberg) Kirchner, 1878
Cymbella tumidula Grunow, 1875
Cymbella tumidula var. lancettula Krammer, 1985
Cymbellafalsa diluviana (Krasske) Lange-Bertalot & Metzeltin, 2009 / Navicula diluviana
*Denticula kuetzingii Grunow, 1862
Diatoma hyemale var. mesodon (Ehrenberg) Kirchner, 1878 / Diatoma mesodon
Diploneis finnica (Ehrenberg) Cleve, 1891
*Discostella stelligera (Cleve & Grunow) Houk & Klee, 2004 / Cyclotella stelligera
*Encyonema minutum (Hilse) Mann, 1990 / Cymbella minuta
Encyonema neogracile Krammer, 1997 / Cymbella gracilis
Encyonema perpusillum (Cleve) Mann, 1990 / Cymbella perpusilla
Encyonema silesiacum (Bleisch) Mann, 1990 / Cymbella silesiaca
Encyonopsis behrei (Foged) Krammer & Metzeltin, 1997 / Cymbella behrei
Encyonopsis cesatii (Rabenhorst) Krammer, 1997 / Cymbella cesatii
Encyonopsis falaisensis (Grunow) Krammer, 1997 / Cymbella falaisensis
Encyonopsis microcephala (Grunow) Krammer, 1997 / Cymbella microcephala
*Eolimna minima (Grunow) Lange-Bertalot, 1998 / *Navicula minima
*Eolimna subminuscula (Manguin) Moser, Lange-Bertalot & Metzeltin, 1998 / *Navicula subminuscula
Eolimna submuralis (Hustedt) Lange-Bertalot & Kulikovskiy, 2010 / Navicula submuralis
Eolimna utermoehlii (Hustedt) Lange-Bertalot, Kulikovskiy & Witkowski, 2010 / Navicula subrotundata
Epithemia sorex Kützing, 1844
Eucocconeis laevis (Østrup) Lange-Bertalot apud Lange-Bertalot & Genkal, 1999 / Achnanthes laevis
Eunotia argus Ehrenberg, 1843
Eunotia glacialis Meister, 1912
Eunotia incisa Smith, 1854
Eunotia praerupta Ehrenberg, 1843
Eunotia vanheurckii Patrick, 1958 / Eunotia faba
Fragilaria capucina Desmazières, 1925
Fragilariforma constricta (Ehrenberg) Williams & Round, 1988 / Fragilaria constricta
Geissleria kriegeri (Krasske) Lange-Bertalot, 1996 / Navicula kriegerii
Gomphonema affine Kützing, 1844
Gomphonema angustatum (Kützing) Rabenhorst, 1864
Gomphonema hebridense Gregory, 1854
Grunoviella (Grunowiella) pacifica (Grunow) Mills, 1934 / Fragilaria pacifica
Halamphora montana (Krasske) Levkov, 2009 / Amphora montana
Hannaea arcus (Ehrenberg) Patrick, 1961 / Fragilaria arcus
Homoeocladia amphioxys (Ehrenberg) Kuntze, 1898 / Hantzschia amphioxys
Karayevia amoena(Hustedt) Bukhtiyarova, 1999 / Achnanthes amoena
*Karayevia carissima (Lange-Bertalot) Bukhtiyarova, 1999 / Achnanthes carissima
Karayevia laterostrata (Hustedt) Round & Bukhtiyarova, 1996 / Achnanthes laterostrata
*Karayevia suchlandtii (Hustedt) Bukhtiyarova, 1999 / Achnanthes suchlandtii
Microcostatus kuelbsii (Lange-Bertalot) Lange-Bertalot, 1999 / Navicula kuelbsii
Navicula absoluta Hustedt, 1950
Navicula arvensis Hustedt, 1937
Navicula cryptotenella Lange-Bertalot, 1985
Navicula difficillima Hustedt, 1950
Navicula difficillimoides Hustedt, 1957
Navicula modica Hustedt, 1945
Navicula pseudoventralis Hustedt, 1934
*Navicula schmassmannii Hustedt, 1943
Navicula ventralis Krasske, 1923
Nitzschia fonticola Grunow, 1881
Nitzschia liebetruthii Rabenhorst, 1864
*Nitzschia perminuta (Grunow) Peragallo, 1903
Parlibellus protractoides (Hustedt) Witkowski, Lange-Bertalot & Metzeltin, 2000 / Navicula protractoides
Pinnularia borealis Ehrenberg, 1843
Pinnularia species
Placoneis elginensis (Gregory) Cox, 1987 / Navicula elginensis
Placoneis signata (Hustedt) Mayama, 1998 / Navicula gastrum var. signata
Planothidium calcar (Cleve) Round & Bukhtiyarova, 1996 / Achnanthes calcar
Planothidium granum (Hohn & Hellerman) Lange-Bertalot, 1999 / Achnanthes grana
*Planothidium lanceolatum (Brébisson ex Kützing) Bukhtiyarova, 1999 / Achnanthes lanceolata
Platessa montana (Krasske) Lange-Bertalot, 2004 / Achnanthes montana
Platessa ziegleri (Lange-Bertalot) Lange-Bertalot, 2004 / Achnanthes ziegleri
Psammothidium curtissimum (Carter) Aboal, 2003 / Achnanthes curtissima
Psammothidium didymum (Hustedt) Bukhtiyarova & Round, 1996 / Achnanthes didyma
Psammothidium grischunum (Wuthrich) Bukhtiyarova & Round, 1996 / Achnanthes grischuna
Psammothidium grishunum f. daonensis (Lange-Bertalot) Bukhtiyarova & Round, 1996 / Achnanthes daonensis
Psammothidium lacus-vulcani (Lange-Bertalot) Bukhtiyarova, 1996 / Achnanthes lacus-vulcani
*Psammothidium levanderi (Hustedt) Bukhtiyarova & Round, 1996 / Achnanthes levanderi
Psammothidium marginulatum (Grunow) Bukhtiyarova & Round, 1996 / Achnanthes marginulata
*Psammothidium rosenstockii (Lange-Bertalot) Lange-Bertalot, 1999 / Achnanthes rosenstockii
Psammothidium rossii (Hustedt) Bukhtiyarova & Round, 1996 / Achnanthes rossii
Psammothidium sacculum (Carter) Bukhtiyarova, 1996 / Achnanthes saccula
Psammothidium scoticum (Flower & Jones) Bukhtiyarova & Round, 1996 / Achnanthes scotica
Psammothidium semiapertum (Hustedt) Aboal, 2003 / Achnanthes semiaperta
Psammothidium subatomoides (Hustedt) Bukhtiyarova & Round, 1996 / Achnanthes subatomoides
*Pseudostaurosira brevistriata (Grunow 1885) Williams & Round, 1987 / Fragilaria brevistriata
*Pseudostaurosira brevistriata var. papillosa (Grunow) Williams & Round, 1987 / Fragilaria brevistriata var. papillosa
Pseudostaurosira parasitica (W. Smith) Morales, 2003 / Fragilara parasitica
*Pseudostaurosira pseudoconstruens (Marciniak) Williams & Round, 1987 / Fragilara pseudoconstruens
Reimeria sinuata (Gregory) Kociolek & Stoermer, 1987 / Cymbella sinuata
Rossithidium linearis (Smith) Round & Bukhtiyarova, 1996 / Achnanthes linearis
Rossithidium nodosum (Cleve) Aboal, 2003 / Achnanthes nodosa
Rossithidium petersenii (Hustedt) Aboal, 2003 / Achnanthes petersenii
*Sellaphora pupula (Kützing) Mereschkowsky, 1902 / Navicula pupula
Sellaphora pupula var. mutata (Krasske) Bukhtiyarova, 1995 / Navicula pupula var. mutata
*Sellaphora seminulum (Grunow) Mann, 1989 / Navicula seminulum
Sellaphora stroemii (Hustedt) Kobayasi, 2002 / Navicula stroemii
Sellaphora vitabunda (Hustedt, 1930) Mann, 1989 / Navicula vitabunda
Stauroforma exiguiformis (Lange-Bertalot) Flower, Jones & Round,1996 / Fragilaria virescens var. exigua
Stauroneis smithii Grunow, 1860 / Stauroneis smithii
*Staurosira construens Ehrenberg, 1843 / Fragilaria construens
*Staurosira construens f. venter (Ehrenberg) Bukhtiyarova, 1995 / Fragilaria construens var. venter
Staurosira construens var. pumila (Grunow) J.C. Kingston 2000 / Fragilaria construens var. pumila
*Staurosirella lapponica (Grunow) Williams & Round, 1987 / Fragilaria lapponica
*Staurosirella pinnata (Ehrenberg) Williams & Round, 1987 / Fragilaria pinnata
*Staurosirella pinnata var. intercedens (Grunow) Hamilton, 1994 / Fragilaria pinnata var. intercedens
Surrirella species
Tabellaria quadriseptata Knudson, 1952
*Tabularia investiens (Smith) Williams & Round, 1986 / Fragilaria investiens
Ulnaria ulna (Nitzsch) Compère, 2001 / Fragilaria ulna
ESM Text 1
In the laboratory, wood surfaces were smoothed with razor blades and ring widths were measured on a LINTAB II measuring table (RINNTECH, Germany) with a precision of 0.01 mm. Cross-dating between the samples was accomplished with the software TSAP (RINNTECH, Germany), skeleton plotting and by visual comparison of tree-ring patterns (Stokes and Smiley 1968; Rinn 2003). Biological age trends in the raw ring-width data were eliminated after a power transformation was applied to reduce the influence of outliers and to stabilize variance over time (Cook and Peters 1997). Trend curves for the individual trees were modeled as cubic smoothing splines with a frequency loss of 50% at 2/3 rds of the individual series length (Cook and Peters 1981). Because the mean tree age (so called ‘segment length’) is almost 470 years in the Anemaqin chronology, multi-centennial climate variations are still preserved in the tree-ring index chronology after removing the biological age trend. All calculations were performed with the so-called ‘standard’ chronologies, which include a considerable amount of low-frequency variation.
Cook E, Peters K (1997) Calculating unbiased tree ring indices for the study of climatic and environmental change. The Holocene 7: 361-370
Cook ER, Peters K (1981) The smoothing spline: a new approach to standardizing forest interior tree ring width series for dendroclimatic studies. Tree Ring Bull 41: 45-53
Rinn F (2003) TSAPWin: Time series analysis and presentation for dendrochronology and related applications. Heidelberg, pp 76
Stokes MA, Smiley TL (1968) An Introduction to Tree-Ring Dating. The University of Chicago Press, Chicago, London, pp 73
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