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This paper analyzes the karst landscape of Southeastern Serbia, Mount Kalafat. The evaluation of five representative caves was performed using M-GAM (modified geosite assessment model) and the perspectives and potentials of karst-based geotourism were presented, through speleology, paleoclimate, and archaeology. Moreover, a unique proposal was presented in the form of a karst protection project through the establishment of a karst theme park. Although there are other attractive karst regions in Serbia, Mount Kalafat has been taken as a study area, due to the willingness of the local management structures and authorities to support projects concerning the protection of geoheritage and the development of karst-based geotourism. The results of the research indicate the evident values of the karst geoheritage and geotourism potentials that can become significant indicators for the development of sustainable geotourism and geoconservation in this area. Thus, precise measures and sustainable strategies that could define the geoethical concept of geotourism development have been presented in this paper. [ABSTRACT FROM AUTHOR]

The past climate in northwestern Thailand remains insufficiently understood because of the limitation of climate proxies. We present a new record of paleoclimate activity during 2050–1551 years BP (before the present), based on the analysis of the oxygen isotope ratios (δ18O) of tree-ring cellulose in ancient teak log coffins excavated from Namjang Cave in Mae Hong Son Province, northwestern Thailand. The ages of the teak log coffin samples were determined using C-14 dating. The average CoffinNJ δ18O value was 23.48 ± 0.77‰, values ranging from 21.23 to 25.42‰. The mean May–October (MO) rainfall reconstructed from the CoffinNJ δ18O data was 274 mm. The mean May–October (MO) rainfall data showed significant negative correlations with stalagmite δ18O data from Laos (r = − 0.254, p < 0.01), highlighting the existence of a weak monsoon from 291 to 294 AD and strong monsoon in 132 AD and 142 AD. Additionally, the MO rainfall data showed a significant positive correlation with reconstructed rainfall in Tibet (r = 0.347, p < 0.01). Spectral analysis of the CoffinNJ δ18O values revealed centennial cycles related to the sunspot number. The CoffinNJ δ18O values have a positive significant correlation with the sunspot number (r = 0.410, p < 0.01) over the entire period. Moreover, we found a highly significant positive correlation (r = 0.644, p < 0.01) between the CoffinNJ δ18O values and stalagmite δ18O values from Wanxiang Cave, China, and this correlation is related variations in the Asian monsoon. We conclude that the CoffinNJ δ18O data reflect the Asian monsoon from 2000 years ago and have the potential to be a paleoclimate proxy in northwestern Thailand. [ABSTRACT FROM AUTHOR]

Thailand is a predominantly agricultural country. An understanding of the dominant driver of decadal-scale changes in Thailand monsoon (TM) rainfall trends is particularly important in terms of agro-meteorological information and monsoon predictions. In this study, a 194-year tree ring chronology of teak trees in northwestern Thailand was developed. Correlations between the tree ring width index (i.e., the Susa index) and climate variables confirmed that this index can be used as a proxy for rainfall in the early monsoon season from May to July. Similar variations with other regional tree ring chronologies confirmed the reliability of the climate signals embedded in the tree ring widths. The possible relationship between the Susa index–based TM rainfall and the Pacific Decadal Oscillation (PDO) was examined. Spectral analysis showed statistically significant PDO periodicities of between 22 and 24 years. The spatial correlations detected across the key regions of the PDO revealed associations with the north Pacific sea surface temperature during recent decades. The long-term relationships between the Susa index and the PDO were nonstationary at the decadal timescale. Positive correlations were found for AD 1824–1875 and AD 1900–1955, whereas negative relationships prevailed for AD 1876–1899 and 1956–2017. The El Niño Southern Oscillation–related anomalous TM was indeed stronger during both the warm and cold phases of the PDO. The PDO is therefore identified as a driving factor of decadal climate variability. This study leads the way to understanding the changes in the TM-PDO relationship over time and demonstrates the utility of teak tree ring width as a potential proxy for PDO teleconnection. [ABSTRACT FROM AUTHOR]

Stalagmites provide one of the few high-quality proxy records of the Thailand monsoon. The Namjang (NJ) cave (19°40′30″N, 98°12′12″E; 923 m a.s.l.), which is situated in the data-scarce region of northwestern Thailand, serves as a unique and important site that offers great potential for multi-proxy climate reconstruction. We present new data on stable oxygen isotopic (δ18O) compositions and growth rates of aragonite stalagmites based on an in situ cave and climate monitoring study performed between August 2012 and October 2013. The dominant factors that control the variations in the δ18O values of rainfall, drip water, and modern aragonite precipitate as well as the variations in the modern speleothem deposition rates and drip water hydrochemical properties were determined to correctly interpret the climatic signals of the parameters that are derived from speleothems. The intraseasonal variations in rainfall δ18O values were faithfully recorded from cave drip water isotopic signals. The monthly mean values of δ18O in cave drip water were lower in the rainy season and higher in the dry seasons and shifted from approximately − 4 in the early rainy months to approximately − 6‰ in the late rainy months. These variations have implications for the use of speleothem δ18O from the NJ cave as a proxy of the seasonal variations in monsoon rainfall δ18O and changes in moisture source trajectories. The deposition rates of modern speleothem deposits are primarily controlled by drip water flow rates, which are linked to the amount of water recharge in the cave during the summer monsoon season. There was a significant correlation between the drip rate and amount of carbonate precipitation for the drip sites NJ-1 (r = 0.54, p < 0.040) and NJ-1202 (r = 0.76, p < 0.004). Combinations of different parameters and proxies from this area could provide the potential for the further development of multi-proxy climate reconstructions over different time scales. [ABSTRACT FROM AUTHOR]

Ancient teak log coffins found in Namjang (NJ) Cave, Pang Ma Pha district of Mae Hong Son province in Northwestern (NW) Thailand, were dated using a combination of C-14 dating and cross-dating techniques. The longest tree-ring width chronology (i.e., the CoffinNJ index) in Thailand covered a 477-year period from 106 BC to AD 371. The ages of the NJ log coffins fell within the log coffin culture epoch in NW Thailand. The NJ coffins are considered to belong to the second component of the log coffin culture period in NW Thailand, which began from approximately 2100 BP to 1200 BP. Spectral analysis of the CoffinNJ index displayed a decadal periodicity of 11.2 years, similar to the well-known 11-year periodic change in the sunspot cycle. A positive relationship (r = 0.31, p < 0.035) was observed between the CoffinNJ index and sunspot number for the entire period from 110 BC to AD 370, particularly during the period of AD 191–370 (r = 0.48, p < 0.045). Comparisons with speleothem proxies sensitive to changes in solar activity showed relationships between the CoffinNJ index and speleothem parameters (layer thickness: r = − 0.50, p < 0.001 and δ18O: r = 0.40, p < 0.001). The results confirmed that the ancient teak trees in this study might have responded, at least partly, to solar variation. The ring widths of the teak log coffins proved to be a promising proxy for studying the evolution of coffin culture and past climate change in this area. [ABSTRACT FROM AUTHOR]

Thailand monsoon is located in the transition zone between the Indian and western North Pacific monsoons. Assuredly, proxy climate data from this area could improve our understanding of the nature of Asian monsoon. Tree rings and stalagmites from this area are two potential materials for high-resolution paleoclimate reconstructions. However, a comprehensive understanding of these multiproxy records is still a challenge. In this study, a 76-year tree ring cellulose oxygen isotope value (δ18O) of a teak tree from northwestern Thailand was developed to test its climatic significance and potential for multiproxy climate reconstruction. The results indicate that the interannual variability of cellulose δ18O can be interpreted as a proxy of rainfall in the early monsoon season (May to July rainfall) as well as a proxy of relative humidity. Comparisons with speleothem proxies from the same locality and tree ring records from wider geographical areas provide a basis for developing a multiproxy approach. The results from a teleconnection analysis reveal that the El Niño-Southern Oscillation (ENSO) is an important climate mode that impacts monsoon rainfall in Thailand. High-quality proxy records covering recent decades are critically important not only to improve proxy data calibrations but also to provide a better understanding of teleconnections within the modern atmosphere. Preliminary findings demonstrated the potential of tree ring stable isotopes from Thai teak to develop multiproxy climate reconstruction. [ABSTRACT FROM AUTHOR]