Water use strategies of natural Pinus sylvestris var. Mongolica trees of different ages in Hulunbuir Sandy Land of Inner Mongolia, China, based on stable isotope analysis
- 191 Downloads
Natural Mongolian pine trees of different ages consistently use shallow water throughout the main growing season; therefore, water stored in the shallow soil layer is vital for maintaining their viability.
Mongolian pine (Pinus sylvestris var. mongolica) plantations in sandy regions often experience dieback after 30–35 years of growth due to water deficiency, whereas natural Mongolian pine forests remain healthy during the same growth stage. However, the water use strategies of natural Mongolian pines remains unclear. Therefore, δ2H and δ18O in twig xylem water, soil water and groundwater were analyzed in 10–20, 20–30 and 30–50-year-old natural Mongolian pine trees to identify their water sources. In addition, needle δ13C was measured simultaneously to assess water use efficiency. Results showed that pine trees of different ages utilized soil water from the same depth. During the growing season (June–August), all pine trees utilized water from 0 to 20 cm soil depth, regardless of the soil water condition. During the end of growing season (September and October), even though soil moisture content in the 0–20 cm depth was higher, pine trees of different ages utilized water from the 0–60 cm soil depth in September and switched to utilize water from the 20–80 cm soil depth in October. There were no significant differences in needle δ13C among the sampling dates for trees in each age group, indicating that pine trees can absorb sufficient water to satisfy their water requirements regardless of age. These findings suggest that water stored in the shallow soil layer (0–20 cm) plays an important role in supporting tree transpiration during the growing season (June–August). Therefore, the stability of shallow soil is vital for maintaining the viability of natural Mongolian pine forests.
KeywordsStable isotopes Deuterium and oxygen isotopic composition Carbon isotopic composition Soil water content Groundwater
This research was supported by Grants from the Key Research Program of Frontier Sciences, CAS (QYZDJ-SSW-DQC027) and the National Nature Science Foundation of China (31770757, 41371511 and 31025007). We thank Dr. Lizhong Yu, Dr. Qiaoling Yan, Dr. Kai Yang, Dr. Xiao Zheng, Dr. Tian Gao and Dr. Yirong Sun in Division of Ecology and Management for Secondary Forest of Institute of Applied Ecology, Chinese Academy of Sciences, China for their helpful discussion on this manuscript. We also thank Yuxiang Ge, Lizhi Zhang and Xiaolin Zhang in Honghuaerji Forestry Administration of Inner Mongolia for providing help and support in the field.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- David TS, Pinto CA, Nadezhdina N, Kurz-Besson C, Henriques MO, Quilhó T, Cermak J, Chaves MM, Pereira JS, David JS (2013) Root functioning, tree water use and hydraulic redistribution in Quercus suber trees: a modeling approach based on root sap flow. For Ecol Manag 307:136–146CrossRefGoogle Scholar
- Farquhar GD, Richards RA (1984) Isotopic composition of plant carbon correlates with water-use efficiency of wheat genotypes. Funct Plant Biol 11:539–552Google Scholar
- Jiang FQ, Cao CY, Zeng DH, Guan WB, Wu XY, Zheng YR (2002) Degradation and restoration of ecosystems on Keerqin sandy land. Chinese Forestry Press, Beijing (in Chinese) Google Scholar
- Jiao SR (2001) Report on the causes of the early decline of Pinus sylvestris var. mongolica shelterbelt and its preventative and control measures in Zhanggutai of Liaoning province. Sci Silvae Sin 37:131–138 (in Chinese with English abstract) Google Scholar
- Kozlowski TT (1987) Soil moisture and absorption of water by roots. J Arboric 13(2):39–46Google Scholar
- Li XM, Zhang XM (2003) Water condition and restoration of natural vegetation in the southern margin of the Taklimakan Desert. Acta Ecol Sin 23:1450–1453 (in Chinese with English abstract) Google Scholar
- Mao L (2009) The stand spatial structure of Pinus sylvestris var. mongolica and its regeneration succession rules in Honghuaerji. MS Dissertation. Beijing Forestry University. ChinaGoogle Scholar
- Zhang PD, Wang X, Chen BR, Xin XP (2014) CO2 release characteristics from Stipa baicalensis meadow steppe in the Hulunbeir region, Inner Mogolia, China. Chin J Appl Ecol 25(2):387–393 (in Chinese with English abstract) Google Scholar
- Zhao XL, Li WY (1963) Mongolian Pine. Agricultural Press, Beijing (in Chinese) Google Scholar