Refinar búsqueda
Resultados 1-5 de 5
Effects of nitrogen addition on microbial residues and their contribution to soil organic carbon in China’s forests from tropical to boreal zone
2021
Ma, Suhui | Chen, Guoping | Du, Enzai | Tian, Di | Xing, Aijun | Shen, Haihua | Ji, Chengjun | Zheng, Chengyang | Zhu, Jianxiao | Zhu, Jiangling | Huang, Hanyue | He, Hongbo | Zhu, Biao | Fang, Jingyun
Atmospheric nitrogen (N) deposition has a significant influence on soil organic carbon (SOC) accumulation in forest ecosystems. Microbial residues, as by-products of microbial anabolism, account for a significant fraction of soil C pools. However, how N deposition affects the accumulation of soil microbial residues in different forest biomes remains unclear. Here, we investigated the effects of six/seven-year N additions on microbial residues (amino sugar biomarkers) in eight forests from tropical to boreal zone in eastern China. Our results showed a minor change in the soil microbial residue concentrations but a significant change in the contribution of microbial residue-C to SOC after N addition. The contribution of fungal residue-C to SOC decreased under low N addition (50 kg N ha⁻¹ yr⁻¹) in the tropical secondary forest (−19%), but increased under high N addition (100 kg N ha⁻¹ yr⁻¹) in the temperate Korean pine mixed forest (+21%). The contribution of bacterial residue-C to SOC increased under the high N addition in the subtropical Castanopsis carlesii forest (+26%) and under the low N addition in the temperate birch forest (+38%), respectively. The responses of microbial residue-C in SOC to N addition depended on the changes in soil total N concentration and fungi to bacteria ratio under N addition and climate. Taken together, these findings provide the experimental evidence that N addition diversely regulates the formation and composition of microbial-derived C in SOC in forest ecosystems.
Mostrar más [+] Menos [-]Nitrification-denitrification processes and technologies in new contexts
1998
Verstraete, W. | Philips, S. (Laboratory of Microbial Ecology, University of Gent, Coupure Links 653, B-9000 Gent (Belgium))
Photosynthetic responses to temperature, light flux-density, CO2 concentration and vapour pressure deficit in Eucalyptus tetrodonta grown under CO2 enrichment
1995
Eamus, D. | Duff, G.A. | Berryman, C.A. (School of Biological Sciences, Northern Territory University, PO Box 40146, Casuarina, Darwin, NT 0811 (Australia))
Comparative studies on biomass productivity and lipid content of a novel blue-green algae during autotrophic and heterotrophic growth
2021
Das, Sumona | Nath, Kaustav | Chowdhury, Ranjana
Algae have long been acclaimed as the attractive renewable source for generating third-generation biofuels, particularly biodiesel. Under the present investigation, the trends of production of biomass and lipid during the autotrophic and heterotrophic growth of newly isolated blue-green algae, Leptolyngbya subtilis JUCHE1, were compared and correlated with the variation in C-sources. In the autotrophic and heterotrophic growth studies, CO₂ and glycerol were respectively used as the inorganic and organic C-sources maintaining equivalence in the initial amount of carbon. Light was used as the source of energy in both cases. The concentration of CO₂ in the feed gas stream was varied from 5 to 20% (% v/v). Equivalent quantity of carbon was supplied through glycerol during heterotrophic growth. Small-scale closed algal bioreactors were used for growing the algae at 37 °C and 2.5 kLux light illumination in batch mode for 0–4 days. Primarily, higher biomass production from glycerol compared with CO₂ was observed. In case of photoautotrophic growth, the maximum values of biomass and lipid productivity, obtained at 15% CO₂, were 0.1857 g/L/d and of 0.020 g/L/d respectively. The maximum biomass productivity of 0.2733 g/L/d was obtained for photoheterotrophic growth at a glycerol concentration equivalent to 15% CO₂ (v/v). Under photoheterotrophic growth of Leptolyngbya subtilis JUCHE1, lipid productivity of 0.0702 g/L/d was obtained at glycerol concentration equivalent to 5% (v/v) CO₂, which is 4.66-fold higher than that obtained under corresponding photoautotrophic condition. The “switch-over” from the autotrophy to the photoheterotrophy instigated the oleaginous anabolism and consequent lipid enrichment in L. subtilis JUCHE1, which can be extracted and converted to biodiesel.
Mostrar más [+] Menos [-]Direct Effects of Air Pollution on Physiology of Forest Trees in the Western United States
1993
Bytnerowicz, A. (USDA Forest Service, Riverside, CA (USA). Pacific Southwest Research Station)
Physiological processes of western trees are effected by ozone at concentration over 80 ppb, depending on the duration of the exposures and environmental conditions. At a single fascicle level short-term ozone exposures can cause reduction, no change or increase of stomatal conductance and net assimilation rate. Two seasons of exposures at twice level ozone concentrations caused a significant reduction of stomatal conductance and pigment concentrations in foliage.
Mostrar más [+] Menos [-]