Response of tropical trees to elevated Ozone: a Free Air Ozone Enrichment study.

Tropospheric ozone (O3) has become one of the main urban air pollutants. In the present study, we assessed impact of ambient and future ground-level O3 on nine commonly growing urban tree species under Free Air Ozone Enrichment (FAOE) condition. During the study period, mean ambient and elevated ozone (EO3) concentrations were 48.59 and 69.62 ppb, respectively. Under EO3 treatment, stomatal density (SD) significantly decreased and guard cell length (GCL) increased in Azadirachta indica, Bougainvillea spectabilis, Plumeria rubra, Saraca asoca and Tabernaemontana divaricata, while SD increased and GCL decreased in Ficus benghalensis and Terminalia arjuna. Proline levels increased in all the nine plant species under EO3 condition. EO3 significantly reduced photosynthetic rate, stomatal conductance (gs), and transpiration rates (E). Only A. indica and N. indicum showed higher gs and E under EO3 treatment. Water use efficiency (WUE) significantly increased in F. benghalensis and decreased in A. indica and T. divaricata. Air Pollution Tolerance Index (APTI) significantly increased in Ficus religiosa and S. asoca whereas it decreased in B. spectabilis and A. indica. Of all the plant species B. spectabilis and A. indica were the most sensitive to EO3 (high gs and less ascorbic acid content) while S. asoca and F. religiosa were the most tolerant (lowgs and more ascorbic acid content). The sensitivity of urban tree species to EO3 is a cause of concern and should be considered for future urban forestry programmes. Our study should guide more such studies to identify tolerant trees for urban air pollution abatement.

Understanding the relationship between soil properties and litter chemistry in three forest communities in tropical forest ecosystem.

In this study, we investigated the relationship between soil properties and litter chemistry in three forest communities, i.e., Sal mixed forest (SMF), dry mixed forest (DMF), and teak plantation forest (TPF), in tropical deciduous forest ecosystem in North India. Fresh leaf litter and soil samples were collected at two soil depths (0-15 and 15-30 cm) from all these three forest communities. Litter bag experiment was also conducted to know differences in litter nutrients after its decomposition. The concentrations (mg kg-1) of different nutrients such as sodium (Na) 2.6, potassium (K) 38.5, calcium (Ca) 425, and carbon (C) 45.54% were highest in fresh litter collected from DMF. Total organic carbon (g kg-1) was significantly higher in SMF (19.23) in comparison to DMF (18.41) and TPF (13.61) at 0-15-cm soil depth. Na, K, Ca, available P, total P, available N, and total N were highest in DMF soil. We observed significantly positive correlation between all nutrients of litter and soil. Although soil bulk density (BD) and particle density (PD) showed their significant negative correlation with litter C, total porosity was positively correlated. Similarly, litter Na has its significant negative correlation with BD and positive correlation with PD. The litter chemistry played a significant role in changing soil pH and TOC. All litter nutrients, except total P, have their significant positive correlation with soil pH. Total P, C, and N of litter have their significant positive correlation with total soil organic carbon. This indicates that litter chemistry and soil properties have specific relation among them despite unique species composition in each forest community.

Investigating the contribution of climate variables to estimates of net primary productivity in a tropical deciduous forest in India.

Investigating the impact of climate variables on net primary productivity is crucial to evaluate the ecosystem health and the status of forest type response to climate change. The objective of this paper is (1) to estimate spatio-temporal patterns of net primary productivity (NPP) during 2001 to 2010 in a tropical deciduous forest based on the input variable dataset (i.e.meteorological and biophysical) derived from the remote sensing and other sources and (2) to investigate the effects of climate variables on NPP during 2001 to 2010. The study was carried out in Katerniaghat Wildlife Sanctuary that forms a part of a tropical forest and is situated in Uttar Pradesh, India, along the Indo-Nepal border. Mean annual NPP was observed to be highest during 2007 with a value of 878 g C m-2 year-1 and 781.25 g C m-2 year-1 for sal and teak respectively. A decline in mean NPP during 2002-2003, 2005 and 2008-2010 could be attributed to drought, increased temperature and vapour pressure deficit (VPD). The time lag correlation analysis revealed precipitation as the major variables affecting NPP, whereas combination of temperature and VPD showed dominant effect on NPP as revealed by generalized linear modelling. The carbon gain in NPP in sal forest was observed to be marginal higher than that of teak plantation throughout the study period. The decrease in NPP was observed during 2010, pertaining to increased VPD. Contribution of different climatic variables through some link process was revealed in statistical analysis and clearly indicated the co-dominance of all the variables in explaining NPP.

Interaction of abiotic factor on soil CO2 efflux in three forest communities in tropical deciduous forest from India.

Environmental factors along with soil physico-chemical properties play a significant role on the diurnal trend of soil CO2 efflux. Soil CO2 efflux in Indian tropical forests is poorly studied. We studied the soil CO2 efflux in a representative tropical deciduous forest at Katerniaghat Wildlife Sanctuary (KWLS), Uttar Pradesh. The three forest communities namely dry mixed (DMF), Sal mixed (SMF), and Teak plantation (TPF) were selected for measuring soil CO2 efflux in the summer season during April to May 2017 using automated LI-COR 8100 soil CO2 flux system. Soil physico-chemical parameters were also studied in the three abovementioned forest communities. We also measured the different microclimatic variables at forest understorey in all three communities during the summer season. Total day time soil CO2 efflux of 826.70, 1089.24, and 828.94 (µmolCO2 m-2d-1) was observed in TPF, SMF, and DMF respectively. Soil CO2 efflux observed significant differences (P < 0.01) among the three forest communities studied for the summer season in tropical deciduous forest of Terai Himalaya. Average soil CO2 efflux rate (µmol CO2 m-2 s-1) of 4.06 ± 0.36, 5.03 ± 0.45, and 4.37 ± 0.79 was observed in TPF, SMF, and DMF, respectively, which is positively correlated with total organic carbon (TOC) and water holding capacity (WHC) among soil physico-chemical variables. Among microclimatic variables, soil temperature (ST, °C) and air temperature (AT, °C) observed strong positive correlation with day time soil CO2 efflux in all three communities. Significant increase in soil CO2 flux was observed with increasing air and soil temperature (AT and ST) in DMF and SMF. Maximum TOC of 19.23 g Kg-1 was observed in SMF among all communities in the summer season. The result showed that soil CO2 efflux is closely associated with TOC, WHC, AT, and ST for Indian deciduous forest ecosystems.

Response of two rice cultivars differing in their sensitivity towards arsenic, differs in their expression of glutaredoxin and glutathione S transferase genes and antioxidant usage.

Embodied study investigates the role of GRX and associated antioxidant enzymes in the detoxification mechanism between arsenic (As) sensitive (Usar-3) and tolerant cultivar (Pant Dhan 11) of Oryza sativa against As(III) and As(V), under GSH enriched, and GSH deprived conditions. The overall growth and physiological parameters in sensitive cultivar were lower than the tolerant cultivar, against various treatments of As(III) and As(V). The As accumulation in sensitive cv. against both As(III) and As(V) was lower than the corresponding treatments in tolerant cv. However, the As translocation against As(V) was lower (35% and 64%, resp.) than that of As(III), in both the cultivars. In sensitive cv. translocation of Zn and Cu was influenced by both As(V) and As(III) whereas, in tolerant cv. the translocation of Cu, Mn and Zn was influenced only by As(III). Translocation of Fe was negatively influenced by translocation of As in sensitive cv. and positively in tolerant cv. Strong correlation between H2O2, SOD, GRX, GR, GST and GSH/GSSG in sensitive cv. and between DHAR, APX, MDHAR and AsA in tolerant cv. demonstrates the underlying preference of GSH as electron donor for detoxification of H2O2 in sensitive cv. and AsA in tolerant cv. Higher expression of the four GRX and two GST genes in the sensitive cv. than tolerant cv, suggests that under As stress, GRX are synthesized more in the sensitive cv. than tolerant cv. Also, the expression of four GRX genes were higher against As(V) than As(III). The higher As accumulation in the tolerant cv. is due to lower GST expression, is attributed to the absence of thiolation and sequestration of As in roots, the translocation of As to shoots is higher.

Indigenous phytotherapy for genito-urinary diseases used by the Kandha tribe of Orissa, India.

Studies on ethnomedicobotany of Kandha tribe of Orissa, India, are scanty. In view of this the original ethno-botanical information and plant specimens were collected from the Kandhamal district of Orissa by visiting the area several times. The paper reports 27 plant species belonging to 24 families used in the treatment of 17 diseases under the broad heading genito-urinary diseases by the Kandhas of Orissa. The use of these plants does not necessarily imply efficacy, but it does give a list of species that can be studied pharmacologically for its active principles and bioactive effect.