Effects of Stumping on Ecological Stoichiometry and Allometric Growth in Leaf, Absorptive Root, and Rhizosphere Soil of Hippophae rhamnoides

To clarify the effects of stumping on the C, N, and P allocation strategy of <i>Hippophae rhamnoides</i> L. artificial forests at the decaying stage in feldspathic sandstone areas, we tested stumping heights of 0, 10, 15, and 20 cm from the ground (denoted H1, H2, H3, and H4, respectively) with non-stumped trees as a control (CK). The N (LN, RN), P (LP, RP), and N:P (LN:LP, RN:RP) in the leaves and absorptive roots and the C, N, C:N, C:P, and N:P in rhizosphere soils after different treatments all manifested in the order H3 > H2 > H1 > H4 > CK. Among them, the LN and RN of H3 presented the largest amplitudes of increase (31% and 263%, respectively) compared with those of CK. There were very significant allometric relationships between LC and RC (-0.57, trade-off relationship), between LN and RN, and between LP and RP (0.32, 2.01; synergistic relationship) in stumped <i>H. rhamnoides</i>, and the accumulation rates of LC and LN were slower than those of RC and RN. After the stumping, certain correlations were present between the characteristics, except that neither LC nor RC significantly differed across the different treatments. The growth of <i>H. rhamnoides</i> after the different treatments was mainly regulated by P. The stumped <i>H. rhamnoides</i> grew at a faster rate, and the optimal stumping height was 15 cm. These findings are valuable for revegetation and for the prevention and control of soil erosion in feldspathic sandstone areas.