Growth, biomass and carbon sequestration of fast-growing tree species under high-density plantation in Prayagraj, Uttar Pradesh, India

We studied the growth performance of fast-growing trees, viz. Eucalyptus spp., Casuarina equisetifolia, Gmelina arborea and Melia dubia in high-density plantation in Prayagraj, Uttar Pradesh, India, with different spacings, viz. 1×1 m, 1.2×1.2 m and 1.5×1.5 m. The experiment was established in July 2019 and data were recorded for the first and second year. In the second year maximum height increment was found in T₁ (Eucalyptus 1×1 m; 3.42 m) followed by T5 (Eucalyptus 1.2×1.2 m; 3.40 m) and minimum in T₂ (Casuarina 1×1 m; 1.39 m), whereas maximum girth increment was found in T₁ (Eucalyptus 1×1 m; 12.43 cm) follo­wed by T₉ (Eucalyptus 1.5×1.5 m; 10.66 cm) and minimum in T₆ (Casuarina 1.2×1.2 m; 6.46 cm). Maximum biomass in the first year was found in T₆ (Casuarina 1.2×1.2 m; 15.51 t ha^–1), followed by T₁ (Eucalyptus 1×1 m; 14.71 t ha^–1) and minimum in T₁₂ (Melia 1.5×1.5 m; 0.66 t ha^–1), whereas in the second year maximum biomass was found in T₁ (Eucalyptus 1×1 m; 202.72 t ha^–1), followed by T5 (Eucalyptus 1.2×1.2 m; 98.81 t ha^–1) and minimum in T₁₂ (Melia 1.5×1.5 m; 17.34 t ha^–1). Carbon stock and carbon sequestration were maximum in the first year in T₆ (Casuarina 1.2×1.2 m) followed by T₁ (Eucalyptus 1×1 m) and minimum in Melia (1.5×1.5 m), with values of 7.75, 7.35, 0.33 t ha^–1, and 28.42, 26.96, 1.21 t ha^–1 respectively. Whereas in the second year maximum was found in T₁ (Eucalyptus 1×1 m) follo­wed by T5 (Eucalyptus 1.2×1.2 m) and minimum in T₁₂ (Melia 1.5×1.5 m), with values of 101.36, 49.41, 8.67 t ha^–1, and 371.59, 181.12 and 31.78 t ha^–1 respectively. Maximum productivity was found in T₁ (Eucalyptus 1×1 m; 188.01 t ha^–1) followed by T₅ (Eucalyptus 1.2×1.2 m; 89.88 t ha^–1) and minimum in T₁₂ (Melia 1.5×1.5 m; 16.68 t ha^–1).