Plasticity Response of Culm Form Properties of Phyllostachys heteroclada to Stand Management Measures

In July 2020, 6 sample plots with 20 m×30 m were established in wild Phyllostachys heteroclada forest with different altitude and different slope in Songyang, Zhejiang province. Experiments were carried out on shading, fertilization and irrigation and no treatment (CK). In March 2022, 5 quadrats with 5 m×8 m were set up in every sample plot and 5 Ph. heteroclada culm were random cut in each quadrat for investigation of ground diameter, height, clear bole height and clear bole nodes. The result demonstrated that fertilization significantly reduced the standardized major axis estimation (SMA) slope of allometric relation of ground diameter with clear bole height and clear bole nodes, indicating that the growth rate of clear bole height and clear bole nodes under fertilization was lower than that of no fertilization. Fertilization did not significantly change the allometric growth slope of ground diameter and height (P > 0.05), but the main axis of fertilization SMA moved positively in the y-axis direction and the common slope direction. Shading significantly reduced the SMA slope of ground diameter and height, clear bole height and clear bole nodes,indicating that shading made the growth rate of height, clear bole height and clear bole lower than that of ground diameter, and this effect was stronger without fertilization and irrigation. The comprehensive influence of different management measures on the culm form showed shading >fertilization > irrigation. Shading and fertilization had a strong effect on allometry (P < 0.001), and the slope variation was 227% and 210%, respectively. However, irrigation did not significantly change the SMA slope of ground diameter, height, clear bole height and clear bole nodes (P >0.05). The different performance of allometry of ground diameter with height, clear bole height and clear bole nodes under different management measures reflects the plasticity response of culm form properties to heterogeneous habitats.