Assessment of carbon density and accumulation in mono- and multi-specific stands in Teak and Sal forests of a tropical dry region in India

We investigated vegetation characteristics, carbon density (CD) and carbon accumulation (CA) of trees in mono- and multi-specific, Tectona grandis (Teak) and Shorea robusta (Sal) forest stands in a tropical dry region of India to address the following questions: (i) How are the mono- and multi-specific stands structured in terms of relative basal area of tree species? (ii) What are the levels of CD and CA in the stem component of tree species in the mono- and multi-specific stands? (iii) Which vegetation characteristics strongly account for the variations in CD and CA in the tree species in the mono- and multi-specific stands? We established 15 stands (six mono- and nine multi-specific stands), each having 4ha area in the forest region. Total number of species across the stands was 46 belonging to 25 families. Average tree density ha−1 and stem basal area (BA, m2ha−1), across the stands were 522 and 11.1, respectively. Margalef’s index of species richness (SR), Whittaker’s index of species evenness (Ew) and Shannon–Wiener index (H′) were greater at multi-specific stands compared to mono-specific stands. Average wood specific gravity (WSG) across species for the mono-specific (Teak) was greatest compared to the other categories. Across the mono- and multi-specific stands, WSG among species ranged between 0.47 and 0.79gcm−3, with 26.2% having WSG⩾0.70gcm−3. Across the plots in mono- and multi-specific stands, stem density showed positive correlation with BA and aboveground stem biomass (AGB). The associations of SR with Ew and H′, and Ew with H′ were significantly positive. The AGB was positively associated with SR, Ew and BA. Repeated measures ANOVA indicated significant effects of year, stand and species for DBH, height and AGB. Average aboveground CD and CA across the stands were 136t-Cha−1 and 5.3t-Cha−1yr−1, respectively. Results of step-wise multiple regression indicated that across the stands, CD was influenced by BA and H′, and CA was affected by SR and BA. Principal component analysis exhibited strong association of CA and CD with multi-specific stands compared to mono-specific stands. Teak and Sal trees showed maximum CA per unit BA at multi-specific stand compared to mono-specific stand. These findings can be used by the forest managers to increase the carbon density and accumulation in Teak and Sal forests of India.