Variations in carbon isotope ratios of C3 plants and distribution of C4 plants along an altitudinal transect on the eastern slope of Mount Gongga

Abstract

Variations in carbon isotopic ratios (δ 13 C) of C 3 plants and distribution of C 4 plants were investigatedalong an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects on them were discussed. It is shown that plants with C 4 photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible for the distributional pattern. In addition, δ 13 C of C 3 plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase rate in δ 13 C for C 3 plants is about 1.3‰ per kilometer. Temperature determines the altitudinal trend of δ 13 C.Mount Gongga, carbon isotopic ratios, C 3 /C 4 plants, C 4 distribution, altitude Carbon isotope ratios (δ 13 C) of plants are influenced by environment factors. Therefore, it is helpful to reveal the relationship between δ 13 C of plants and environment factors in predicting the effects of future global change on plants and in studying the paleoclimate and paleoenvironment [1][2][3] . Mountains have been considered as ideal sites for studying how plant is affected by climatic factors because of marked changes in climatic characteristics with increasing altitude [4] . Although many studies have been done in investigating variations of δ 13 C of C 3 plants along altitude [5 -13] , controversies remain. For example, most of the studies showed that δ 13 C of C 3

Factors influencing altitudinal patterns of C3 plant foliar carbon isotope composition of grasslands on the Qinghai-Tibet Plateau, China

“…3) agrees with the previous findings (Guo and Xie 2006;Körner et al 1988Körner et al , 1991Kogami et al 2001;Li et al 2009;Zhu et al 2010). The rate of d 13 C increase with altitude has differed in different studies.…”

“…0.70% km -1 ) obtained from alpine areas of the world by Körner et al (1988). However, it was lower than rates of 1.37% km -1 on the Qinghai-Tibet Plateau recorded by Guo and Xie (2006), 1.3 % km -1 on the eastern slope of Mount Gongga, China (Li et al 2009), and 1.4 % km -1 for three genera (Saxifraga, Potentilla and Carex) in south-central Europe (Zhu et al 2010).…”

Responses of carbon isotope ratios of C_3 herbs to humidity index in northern China

“…As for plants, temperature can affect their carbon isotope fractionation via the change in biochemical reaction speed during the photosynthesis process (such as the activity of enzymes participating in photosynthesis) and the stomatal conductance of leaves. There are some studies showing that carbon isotope values of C 3 plants were negatively correlated to temperature (Körner et al, 1991;Ning et al, 2002;Li et al, 2009), while there are even more studies indicating that positive correlation existed between carbon isotopes and temperature (Li et al, 1999;Wang et al, 2002;Liu et al, 2007;Lin, 2008). Still, some other studies suggested that there were no links between Abstract: Uncertainties would exist in the relationship between δ 13 C values and environmental factors such as temperature, resulting in unreliable reconstruction of paleoclimates.…”

“…Many factors other than temperature and precipitation, such as altitude, longitude, and latitude, can affect plant δ 13 C (Körner et al, 1991;Sparks and Ehleringer, 1997;Li et al, 2009;Wang et al, 2010). Here, we neglected the effects of these factors when establishing relationships between HIs and δ 13 C because we think that these effects are unlikely to affect our results significantly.…”

“…Therefore, their effects on plant δ 13 C will be embodied in the effects of temperature and precipitation. Although other environmental factors may also vary with altitude, longitude, and latitude, e.g., changes in atmospheric pressure and solar radiation with elevation, it is generally thought that the altitudinal trend of plant δ 13 C can be attributed mainly to the influence of temperature and/or precipitation rather than to changes in air pressure and solar radiation (Sparks and Ehleringer, 1997;Li et al, 2009;Wang et al, 2010Wang et al, , 2013. In addition, the HI calculated by the Holdridge model may have some limitations, but to a certain extent, it considers the combined influence of precipitation and evaporation related to temperature, wind speed, solar radiation, pressure of water vapor, and other meteorological factors (Wang et al, 2004).…”