Jimmy Yebjeny Yumnam

Soil attributes play a crucial role in determining weed community structure, which affects the overall dynamics of agricultural ecosystems. This study explores the relationships between weed infestation and soil properties in paddy fields of Hojai district, Assam, Northeast India. Soil samples were collected during two crop growing seasons viz. Rabi and Kharif, to analyze important physico-chemical properties between the year 2021 and 2024 from the paddy fields of the study site. The findings of the study showed considerable variations in soil properties across different seasons. Weed species richness exhibited positive correlation with porosity, soil moisture content, soil organic carbon, total nitrogen content, available phosphorus and potassium in both seasons. This study offers valuable insights into how the physico-chemical properties of soil affect weed diversity in agricultural lands, providing a useful basis for developing effective management strategies.

This study was conducted to estimate the Carbon stock potential of roadside trees growing along two important roads of Guwahati, Assam, India viz., Maniram Dewan Road (MDR) and Guwahati Shillong Road (GSR). Total density, total basal cover (TBC), total biomass (TB), total Carbon stock (TCS), and CO₂ equivalent (CO₂ eqv.) of all the tree species growing along the roadsides of MDR and GSR ranged between 32.06 to 32.40 stem ha^–1, 2.14 to 29.02 m² ha^–1, 12.59 to 29.18 Mg ha^–1, 5.04 to 11.67 Mg C ha^–1, and 18.49 to 42.85 Mg ha^–1 respectively. The study revealed that Carbon stock potential of trees from the study sites were comparatively less. Nevertheless, the roadside trees were lessening the effects of CO₂ to some extent, thus mitigating climate change. Therefore, there is a need to increase roadside plantations in both study sites to maximize the amount of Carbon stock potential.

The present study broadly focused on regeneration status, biomass, and carbon stock of Tectona grandis (teak) in three tropical moist deciduous forests, viz. Fatasil Reserve Forest (FRF), Gotanagar Reserve Forest (GRF), and Jalukbari Reserve Forest (JRF) of Kamrup Metropolitan district, Assam, Northeast India. The stratified random quadrat method was employed and individual no. of adult trees, saplings, and seedlings in the quadrats, and girth at breast height (GBH) of adult trees were recorded and used for calculating density and basal area respectively. Regeneration status was checked from the densities of seedlings, saplings, and adult trees. An allometric formula was employed to calculate biomass and carbon stock of the species. Teak exhibited good regeneration status (seedlings>saplings>adult trees) in JRF and GRF, while fair regeneration status (seedlings>saplings<adult trees) has been observed in FRF. Moreover, the study displayed the major contributions of teak in biomass (47.07-163.48 Mg ha-¹), carbon stock (22.12-76.83 Mg C ha-¹), and CO₂ equivalent (81.19-281.98 Mg ha-¹) in the study sites. Therefore, the study is fundamental for intending a conservation strategy for teak and to raise awareness among the local people about its significance in mitigating global warming and climate change.

Uncertainties continue to prevail in the potential of natural forests and plantations in carbon stock assessment. The present study was carried out to assess the carbon stock in natural and plantation forests of Manipur using geo-informatics in Imphal East and West districts. The integrated approach of geospatial technology, along with field inventory based data, was used in spatial modeling of biomass carbon of selected natural and plantation forests. The stand density was similar for both LNG and TRS forests (680 individuals ha⁻¹) and lowest for KHP forest (640 individuals ha⁻¹). Paulownia fortunei (770 individuals ha⁻¹) showed highest density among tree species while Tectona grandis (54.07 m² ha⁻¹) followed by Gmelina arborea (42.18 m² ha⁻¹) had higher basal area compared to other tree species. The soil moisture content (%) in the natural forest ranged from 19.13 ± 0.47 to 26.9 ± 0.26%. The soil moisture content in the plantation forest ranged from 19.16 ± 0.98 to 25.83 ± 0.06%. The bulk density of natural forests ranged from 1.27 g cm⁻³ to 1.37 g cm⁻³ while for plantation forests it ranged from 1.18 g cm⁻³ to 1.34 g cm⁻³. Among the studied sites of natural forest, TRS forest had both the highest AGBC value of 132.74 t ha⁻¹ as well as the BGBC value of 38.49 t ha⁻¹. Similarly, among the plantations, T. grandis plantation showed the highest AGBC (193 t ha⁻¹) and BGBC (55.97 t ha⁻¹). On the other hand, Tharosibi forest and T. grandis plantation had the highest total carbon stock for natural and plantation forest with values of 274.824 t ha⁻¹ and 390.88 t ha⁻¹, respectively. The total above-ground carbon stock estimated for the natural forest of KHP, LNG and TRS were 109.60 t ha⁻¹, 79.49 t ha⁻¹ and 132.74 t ha⁻¹, respectively. On the other hand, the estimated total above-ground carbon stock in plantation of GA, PD, PF and TG were 62.93 t ha⁻¹ 62.81 t ha⁻¹, 45.85 t ha⁻¹ and 193.82 t ha⁻¹. In the present study, the relationship with the biomass was observed to be better in SAVI compared to NDVI and TVI. The linear regression analysis performed to determine the relationship between the estimated and predicted biomass resulted in a correlation coefficient of R² = 0.85 for the present study area, which is an indication of a good relationship between the estimated and predicted biomass.