Carbon isotope ratios of plants and occurrences of C₄ species under different soil moisture regimes in arid region of Northwest China

Abstract

Carbon isotope ratio of leaf dry matter, δ13C, was measured on species occurring within Baiyin desert community, consisting of valley, slope and ridge microhabitats, and within Shandan desert community, consisting of Gobi desert and seasonal flooded creek microhabitats, in Northwest China. δ13C of C3 species increased with a decrease in soil water availability, suggesting that water‐use efficiency (WUE) increased with decreasing soil moisture, whereas for all C4 species, δ13C tended to decrease with decreasing soil water availability, suggesting that WUE also increased with decreasing soil moisture. Above results indicated that water‐use pattern was conservative under drought for C4 and C3 plants. In this present study, C4 species' occurrences within different microhabitats were investigated and C4 plants were observed to be absent and/or scarce within relatively lower soil moisture microhabitats, whereas they occurred and/or even had a high abundance within relatively higher soil moisture microhabitats, suggesting limited moisture available was a key factor of limiting C4 distribution in arid region of Northwest China.

Paleovegetation reconstruction using δ<sup>13</sup>C of Soil Organic Matter

“…Observations of C 3 plant δ 13 C values decreasing along a precipitation gradient reported by this work and others (e.g. Steward et al, 1995;Wang et al, 2005;Liu et al, 2005;Schulze et al, 2006) are consistent with the expectation. For C 4 plants, a decrease in the c i /c a ratio may lead to two opposite isotopic responses; the δ 13 C may increase or decrease depending on the degree of leakiness, φ (Farquhar, 1983), the proportion of carbon dioxide produced within bundle sheath cells from C 4 acids that is not fixed by Rubisco but leaked back to mesophyll cells.…”

“…Relative to C 3 plants, the δ 13 C of C 4 plants is not sensitive to water availability Henderson et al, 1992;Wang et al, 2005Wang et al, , 2006. Studies on C 4 species mostly showed slight increases in δ 13 C with increasing water availability (Buchmann et al, 1996;Schulze et al, 1996;Wang et al, 2005Wang et al, , 2006. A counter example, however, is provided by Liu et al (2005) who observed an opposite pattern in Bothriochloa ischaemum (C 4 ), i.e., δ 13 C decreasing significantly with increasing precipitation (−0.61‰/100 mm).…”

“…This sensitivity is greater than that reported earlier by Steward et al (1995) (−0.34‰/100 mm) and Wang et al (2003) (−0.49‰/100 mm). Relative to C 3 plants, the δ 13 C of C 4 plants is not sensitive to water availability Henderson et al, 1992;Wang et al, 2005Wang et al, , 2006. Studies on C 4 species mostly showed slight increases in δ 13 C with increasing water availability (Buchmann et al, 1996;Schulze et al, 1996;Wang et al, 2005Wang et al, , 2006.…”

“…Many studies have observed that δ 13 C of C 3 plants decreases significantly with increases in precipitation (e.g. Ehleringer and Cooper, 1988;Smedly et al, 1991;Wang et al, 2003Wang et al, , 2005Schulze et al, 2006). Liu et al (2005) measured δ 13 C of three C 3 species occurring in Northwest China, and found that the mean δ 13 C decrease is 1.1‰ with every 100 mm increase in annual precipitation.…”

Stable Isotope Analysis: Outline of Methodology, and a Review of Studies in Siberia and the Eurasian Steppe

“…1). Современный изо-топный фон (анализ растений) региона представлен в ряде работ [Makarewicz, Tuross, 2006;Macarewicz, 2014;Wang, 2004Wang, , 2005Wang et al, 2005;Pyankov et al, 2000;и др.]. Северный Китай.…”