Aboveground tree carbon stocks of Lowland evergreen mixed vegetation at Gannoruwa

Conservation of global forests is being considered as one of the sustainable ways of mitigating global warming, because forests are widely perceived to act as major sinks for atmospheric carbon. Estimation of carbon stocks of tropical forests are important for management, planning and for REDD initiatives.Therefore, this study was initiated to estimate existing carbon stocks of a Lowland evergreen mixed forest at Gannoruwa and how it has changed overtime.The sampling points were selected using an unsupervised classified Landsat TM satellite image and topograhpic maps, considering the elevation level and the vegetation type. A GPS (Global Position System) was used to detect the correct location of sampling points and sampling plot size was set as 30m×30m. The dbh and height of each individual in the sampling plot which is greater than 5cm dbh was measured.The dbh and height values were applied to a pre-derived regression equation and the above ground biomass was calculated. The equation was Y=exp {-3.3012+0.9439 ln(D2H)},(r2=0.9) where, Y is aboveground biomass, D is dbh and H is height. Assuming the carbon stock as 50% of the biomass, the above ground carbon stock was calculated. It was 146.4 mt/ha of carbon and the total aboveground tree carbon stock was 39.1×103 tons. The estimated basal area of the forest has declined compared to 25 year old recorded data and it reflects the carbon reduction of the forest due to anthropogenic activities.

Aboveground tree carbon stocks of Lowland evergreen mixed vegetation at Gannoruwa

Conservation of global forests is being considered as one of the sustainable ways of mitigating global warming, because forests are widely perceived to act as major sinks for atmospheric carbon. Estimation of carbon stocks of tropical forests are important for management, planning and for REDD initiatives.Therefore, this study was initiated to estimate existing carbon stocks of a Lowland evergreen mixed forest at Gannoruwa and how it has changed overtime.The sampling points were selected using an unsupervised classified Landsat TM satellite image and topograhpic maps, considering the elevation level and the vegetation type. A GPS (Global Position System) was used to detect the correct location of sampling points and sampling plot size was set as 30m×30m. The dbh and height of each individual in the sampling plot which is greater than 5cm dbh was measured.The dbh and height values were applied to a pre-derived regression equation and the above ground biomass was calculated. The equation was Y=exp {-3.3012+0.9439 ln(D2H)},(r2=0.9) where, Y is aboveground biomass, D is dbh and H is height. Assuming the carbon stock as 50% of the biomass, the above ground carbon stock was calculated. It was 146.4 mt/ha of carbon and the total aboveground tree carbon stock was 39.1×103 tons. The estimated basal area of the forest has declined compared to 25year old recorded data and it reflects the carbon reduction of the forest due to anthropogenic activities

Fibroblast senescence in the pathology of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial pneumonia of unknown cause with a median survival of only three years. Little is known about the mechanisms that precede the excessive collagen deposition seen in IPF, but cellular senescence has been strongly implicated in disease pathology. Senescence is a state of irreversible cell-cycle arrest accompanied by an abnormal secretory profile and is thought to play a critical role in both development and wound repair. Normally, once a senescent cell has contributed to wound repair, it is promptly removed from the environment via infiltrating immune cells. However, if immune clearance fails, the persistence of senescent cells is thought to drive disease pathology through their altered secretory profile. One of the major cell types involved in wound healing is fibroblasts, and senescent fibroblasts have been identified in the lungs of patients with IPF and in fibroblast cultures from IPF lungs. The question of what is driving abnormally high numbers of fibroblasts into senescence remains unanswered. The transcription factor signal transducer and activator of transcription 3 (STAT3) plays a role in a myriad of processes, including cell-cycle progression, gene transcription, as well as mitochondrial respiration, all of which are dysregulated during senescence. Activation of STAT3 has previously been shown to correlate with IPF progression and therefore is a potential molecular target to modify early-stage senescence and restore normal fibroblast function. This review summarizes what is presently known about fibroblast senescence in IPF and how STAT3 may contribute to this phenotype

STAT3 Regulates the Onset of Oxidant-induced Senescence in Lung Fibroblasts

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease of unknown cause with a median survival of only 3 years. Other investigators and we have shown that fibroblasts derived from IPF lungs display characteristics of senescent cells, and that dysregulated activation of the transcription factor signal transducer and activator of transcription 3 (STAT3) correlates with IPF progression. The question of whether STAT3 activation is involved in fibroblast senescence remains unanswered. We hypothesized that inhibiting STAT3 activation after oxidant-induced senescence would attenuate characteristics of the senescent phenotype. We aimed to characterize a model of oxidant-induced senescence in human lung fibroblasts and to determine the effect of inhibiting STAT3 activity on the development of senescence. Exposing human lung fibroblasts to 150 μM hydrogen peroxide (H2O2) resulted in increased senescence-associated β-galactosidase content and expression of p21 and IL-6, all of which are features of senescence. The shift into senescence was accompanied by an increase of STAT3 translocation to the nucleus and mitochondria. Additionally, Seahorse analysis provided evidence of increased mitochondrial respiration characterized by increased basal respiration, proton leak, and an associated increase in superoxide (O2−) production in senescent fibroblasts. Targeting STAT3 activity using the small-molecule inhibitor STA-21 attenuated IL-6 production, reduced p21 levels, decreased senescence-associated β-galactosidase accumulation, and restored normal mitochondrial function. The results of this study illustrate that stress-induced senescence in lung fibroblasts involves the activation of STAT3, which can be pharmacologically modulated