Pre-monsoon precipitation signal in tree rings of timberline Betula utilis in the Central Himalayas 1,2Binod Dawadi, 2Eryuan Liang 1Central Department of Hydrology and Meteorology, Tribhuvan University, Kathmandu, Nepal 2Institute of Tibetan Plateu Research, Chinese Academy of Sciences, Beijing e-mail: firstname.lastname@example.org 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. 2008 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. • .
Dendrochronological studies in Nepal Sano et al 2005 Thapa et al 2014 Cook et al 2003 [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
Reconstructed temperature in Nepal Cooling AD1790-1810 1950- 2000 Sano et al., 2005 Tambora in 1815–1816 Cooling from 1960s to 1991 late-20th century warming, Cook et al.,(2003) Multi-decadal to century-scale warming and cooling trends are matching.
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 1830-3630m 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 Kyangjing Langtang National Park
Landscape of the sampling site Kyanjing
Clear Ring-width of Himalayan birch When moisten rings are clearly visible and easy to cross date
Result and discussion 41 trees, 49 cores, 458 Year Chronology (1552-2009) 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 * for the common interval from 1900-2000.
Correlation between Climate and RI Ring index of Himalayan birch showed Positive correlation with Pre-monsoon precipitation and inverse relation with temperature
Results and discussion • 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 contd Occurrence of Missing rings in the extreme dry Year • 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). • 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 elevationNamche 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.. (1998-2011)
Results and discussioncontd WMO, 2011 (Cook et al 2010) IPCC, 2007 East Indian drought (1796-1798) Islam & Das 2009 Late Victorian great drought (1876-1878) Shakya &Yamaguchi 2007 Other Megha drought 1560s Strange Parallels drought (1756-1768) Attri and Tyagi 2010 Regional historical drought Sigdel & Ikeda 2010 2.4 Singh et al. 2009;Yadav 2011 2.0 Tree-ring based precipitation Instrumental/ Satellite
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