Dry matter dynamics and CO2 mitigation in the herb layer of Central Himalayan agroecosystems along an altitudinal gradient, India

Herbaceous entity plays a significant role in the structural dynamics of natural ecosystems and its responsibility increased by many times in case of agricultural systems. The present study has been performed to assess the ecological performance, biomass, carbon stock, and CO2 mitigation potential of the herbaceous layer in Central Himalayan agroecosystems of India. Four different altitudes have been selected viz. very low altitude (< 450 m; VLA), low altitude (450-900 m, LA), mid altitude (900-1500 m; MA) and high altitude (1500-2200 m, HA) and samples studied in a stratified manner (4 altitudes x 3 agroecosystems x 3 replicates x 3 seasons = 108 samples). A total of 41 herbs (21 cultivated + 20 wild) species belonging to 16 families were recorded within agroecosystems and results depicted that maximum species encountered during the rainy season (30) followed by summer (18) and winter season (12). The regression analysis between herb density and diversity depicted that the diversity (MA > HA > VLA > LA) showed just inverse pattern of herb density (LA > VLA > HA > MA), which indicates that increasing density may results in the dominance of one or two species thus downgrading the diversity. Brassica oleracea spp., Eleusine coracana, Solanum tuberosum, Solanum lycopersicum, Pisum sativum, etc. were common and proliferated cash crops towards higher altitudes, while low altitude agroecosystems were dominated by grain and pulse crops (Oryza sativa, Triticum aestivum, Zea mays, Glycine max, Vigna mungo, etc.). These crops are responsible for the higher biomass and higher C stock in agroecosystems, together with they are fulfilling the multifarious needs of adjacent communities.

Automated summary

This study assessed the ecological performance, biomass, carbon stock, and CO2 mitigation potential of the herbaceous layer in Central Himalayan agroecosystems of India. The results showed an inverse relationship between herb diversity and density, and different crop species dominated at different altitudes.