Pre-monsoon precipitation signal in tree rings of timberline Betula utilis in the Central Himalayas 1,2 Binod Dawadi, 2 Eryuan Liang 1 Central Department of Hydrology and Meteorology, Tribhuvan University, Kathmandu, Nepal 2 Institute of Tibetan Plateu Research, Chinese Academy of Sciences, Beijing 19 March, 2015

Tree-ring studies in Himalayan and surrounding region Indian Himalaya (Western and Eastern Himalaya) Temperature reconstruction: Yadav et al. (1997); Borgaonkar et al. (1996); Pant et al. (1998); Yadav et al. (1999); Yadav and Singh (2002); Bhattachryya and Chaudhary (2003),Yadav et al (2011) etc. Precipitation reconstruction: Yadav and Park (2000); Singh and Yadav (2005); Singh et al. (2006); Singh et al. (2009); Yadav (2011a); Yadav (2011b) etc. Studies from Karakoroum/Tien Shan Mt range of Pakistan Ahmed,M (1989); Ahmed,M (1991); Ahmed, et al (2009) Ahmed et al (2011); Esper et al.(1995); Esper J.(1995); Esper et al.(2001); Esper et al.(2002); Esper et al.(2003); Esper et al.(2007); Khan et al.(2008) etc.

Dendroclimatological studies from Tibetan Plateau Precipitation reconstruction Zhang and Wu 1997; Gou et al. 2001; Kang et al. 2002; Qin et al. 2003; Zhang et al. 2003; Sheppard et al. 2004; Shao et al. 2005; Huang and Zhang 2007; Liu et al. 2006; Yin et al etc. Temperature reconstruction: Shao and Fan 1999; Bräuning and Mantwill 2004; Liu et al. 2005; Gou et al. 2007; Fan et al. 2008; Liang et al. 2008; 2009, 2008; Zhu et al. 2008, 2011 etc..

[ Suzuki(1990); Bhattachryya et al.(1992); Cook et al.(2003);Sano et al.(2005); Sano et al. (2009): Sano et al. (2011), Gaire et al (2012), Dawadi et al 2013, 2013, Liang et al 2014, Gaire et al 2014, Thapa et al 2014]. Studied species: Abies spectabilis,Pinus roxburgii,Pinus wallichiana,Tsuga dumosa, Picea smithiana,Juniperus recurva,Ulmus wallichiana,Larix potanini, Cupressus torulosa Dendrochronological studies in Nepal Cook et al 2003 Sano et al 2005 Thapa et al 2014

Reconstructed temperature in Nepal Tambora in 1815–1816 Multi-decadal to century-scale warming and cooling trends are matching. Cooling AD late-20th century warming, Cooling from 1960s to 1991 Cook et al.,(2003) Sano et al., 2005

Reconstructed temperature in Nepal Thapa et al 2014 Different than Cook et al 2003 and Sano et al 2005, may be due to the Reconstructed month/ season

Some gaps Dendrochroclimatological study in Central Himalaya Suzuki E (1990) and Bhhatachrrya et al. (1992)  Did not find tree-ring climate correlation, why? Cook et al (2003)  They covered wide area from elevation m but most of the samples were not from treeline/Timberline.  In spite of wide distribution of Himalayan birch in the high Asia from Afghanistan, Pakistan, India, Nepal, Bhutan, Southern China, Myanmar, why there is very a few dendrochronological studies on this species ?  Not only in Asia why there is a few studies on Himalayan birch worldwide?

Objectives  To investigate the dendroclimatic potentiality of Himalayan birch (betula Utilis)  To develop long tree-ring chronology from Nepal  To study the tree-ring based climate change from the tree ring of central Nepal

Sampling Area Where: Central Himalaya, Nepal, Around 4000 m sal. How many sites: 4 sites but only 2 sites are used Sampling Place: Kaynjing ( LT1) & Langtang Village ( LT4) How many samples: 19 (23) LT1 & 23 (26) from LT4 Langtang National Park Kyangjing

Landscape of the sampling site Kyanjing

Birch trees near by Kaynjing

When moisten rings are clearly visible and easy to cross date Clear Ring-width of Himalayan birch

41 trees, 49 cores, 458 Year Chronology ( ) Result and discussion Fig (a) Tree-ring width chronology with its 9 year moving average curve (thick solid line) and sample depth (dashed line) (b) Variation of RBAR and EPS over time.

Results and discussion ParametersDuration/value Chronology time span (year) (458) Mean sensitivity0.19 Standard deviation0.23 First-order autocorrelation0.45 Expressed population signal*0.93 Signal-to-noise ratio*12.87 Variance in first eigenvector*30% Correlation among all radii*0.26 * for the common interval from

Correlation between Climate and RI Ring index of Himalayan birch showed Positive correlation with Pre-monsoon precipitation and inverse relation with temperature

 Elevation-dependent precipitation: Pre-monsoon precipitation at Kyangjing (3,950 meter)- 94 mm.  Under very strong solar radiation at high elevation, temperature could increase drought stress by enhancing evapo- transpiration, resulting in a negative correlation between tree growth and the mean March-May temperature, as reported by Liang et al. (2012).  The similar response of most of the conifers from the Himalayan region: (Sano et al., 2005; Singh et al., 2009; Borgaonkar et al., 2011; Yadav, 2011) and inverse with temperature (Borgaonkar et al., 1996; Yadav et al., 2004) Results and discussion

Results and discussion contd Missing rings were dated well  1954 (5.8%)  1995 (7.8%)  1999 (13.5%)  2003 (23.6%)  2004 (22.0%)  The 2003,2004 and 1999 are the years with extreme pre monsoonal drought condition in South Asia including Nepal (Sigdel and Ikeda 2009; WMO 2011). Occurrence of Missing rings in the extreme dry Year  LT4- South west facing slope produced higher frequency of missing rings than LT1. High percentage of missing rings in the extreme drought year confirmed the growth of Himalayan birch was drought sensitive

Decrease in precipitation beyond certain elevation Namche bazar (3400m)- 1000mm (Miehe et al. 2007), Pyramid (5050m)- 465mm (Bollasina et al. 2002), Khumbu glacier (5300m)- 450mm( Dhara and Nandargi, 2000 ) ( ) Results and discussions contd..

Sigdel & Ikeda 2010 WMO, 2011 IPCC, 2007 Islam & Das 2009 Shakya &Yamaguchi 2007 Attri and Tyagi 2010 Late Victorian great drought ( ) Strange Parallels drought ( ) Other Megha drought 1560s (Cook et al 2010) Singh et al. 2009;Yadav 2011 Results and discussion contd Regional historical drought Tree-ring based precipitation Instrumental/ Satellite East Indian drought ( )

Conclusion  Developed a 458-year chronology of Himalayan birch, the longest chronology of this species till date.  The chronology statistics showed its potentiality for dendroclimatic studies.  The climate and tree growth relationships demonstrated that the growth of Himalayan birch was an excellent proxy of March-May precipitation. .Tree-ring captured most of the local and regional drought events.  Himalayan birch from the central Himalayas can be use for the reconstruction of pre-monsoon precipitation