With a pace of about twice the observed rate of global warming, the temperature on the Qinghai-Tibetan Plateau (Earth's 'third pole') has increased by 0.2°C per decade over the past 50 years, which results in significant permafrost thawing and glacier retreat. Our review suggested that warming enhanced net primary production and soil respiration, decreased methane (CH 4 ) emissions from wetlands and increased CH 4 consumption of meadows, but might increase CH 4 emissions from lakes. Warming-induced permafrost thawing and glaciers melting would also result in substantial emission of old carbon dioxide (CO 2 ) and CH 4 . Nitrous oxide (N 2 O) emission was not stimulated by warming itself, but might be slightly enhanced by wetting. However, there are many uncertainties in such biogeochemical cycles under climate change. Human activities (e.g. grazing, land cover changes) further modified the biogeochemical cycles and amplified such uncertainties on the plateau. If the projected warming and wetting continues, the future biogeochemical cycles will be more complicated. So facing research in this field is an ongoing challenge of integrating field observations with process-based ecosystem models to predict the impacts of future climate change and human activities at various temporal and spatial scales. To reduce the uncertainties and to improve the precision of the predictions of the impacts of climate change and human activities on biogeochemical cycles, efforts should focus on conducting more field observation studies, integrating data within improved models, and developing new knowledge about coupling among carbon, nitrogen, and phosphorus biogeochemical cycles as well as about the role of microbes in these cycles.

Collecting and storing solar energy to hydrogen fuel through a photo-electrochemical (PEC) cell provides a clean and renewable pathway for future energy demands. Having earth-abundance, low biotoxicity, robustness, and an ideal n-type band position, hematite (α-Fe O ), the most common natural form of iron oxide, has occupied the research hotspot for decades. Here, a close look into recent progress of hematite photoanodes for PEC water splitting is provided. Effective approaches are introduced, such as cocatalysts loading and surface passivation layer deposition, to improve the hematite surface reaction in thermodynamics and kinetics. Second, typical methods for enhancing light absorption and accelerating charge transport in hematite bulk are reviewed, concentrating upon doping and nanostructuring. Third, the back contact between hematite and substrate, which affects interface states and electron transfer, is deliberated. In addition, perspectives on the key challenges and future prospects for the development of hematite photoelectrodes for PEC water splitting are given.

Ectomycorrhizas (EMs) alleviate stress tolerance of host plants, but the underlying molecular mechanisms are unknown. To elucidate the basis of EM-induced physiological changes and their involvement in stress adaptation, we investigated metabolic and transcriptional profiles in EM and non-EM roots of gray poplar (Populus 3 canescens) in the presence and absence of osmotic stress imposed by excess salinity. Colonization with the ectomycorrhizal fungus Paxillus involutus increased root cell volumes, a response associated with carbohydrate accumulation. The stress-related hormones abscisic acid and salicylic acid were increased, whereas jasmonic acid and auxin were decreased in EM compared with non-EM roots. Auxin-responsive reporter plants showed that auxin decreased in the vascular system. The phytohormone changes in EMs are in contrast to those in arbuscular mycorrhizas, suggesting that EMs and arbuscular mycorrhizas recruit different signaling pathways to influence plant stress responses. Transcriptome analyses on a whole genome poplar microarray revealed activation of genes related to abiotic and biotic stress responses as well as of genes involved in vesicle trafficking and suppression of auxin-related pathways. Comparative transcriptome analysis indicated EM-related genes whose transcript abundances were independent of salt stress and a set of salt stress-related genes that were common to EM non-salt-stressed and non-EM salt-stressed plants. Salt-exposed EM roots showed stronger accumulation of myoinositol, abscisic acid, and salicylic acid and higher K + -to-Na + ratio than stressed non-EM roots. In conclusion, EMs activated stress-related genes and signaling pathways, apparently leading to priming of pathways conferring abiotic stress tolerance.Under natural conditions, many economically important tree species including fast-growing poplars (Populus spp.) form ectomycorrhizas (EMs) between roots and EM fungi. Colonization with EM fungi leads to profound changes in root architecture and morphology. Usually, EM roots are strongly ramnified and EM root tips show a bulb-like appearance (Smith and Read, 2008). In EMs, plants and fungi interact mutualistically: while the plant receives mineral nutrients and water through the fungus, the fungus is supplied with carbohydrates by its host (Smith and Read, 2008). To fulfill these functions, specific anatomical structures are established, which involve the formation of a hyphal mantle ensheathing the root tip with hyphae emanating into soil for nutrient uptake. Inside the mantle, hyphae grow between, but not inside, the cortex cells within the cell wall, forming an interface called the Hartig net for bidirectional nutrient exchange.The establishment of EMs requires a coordinated developmental program in both partners of the symbiosis. Transcriptional changes during initial stages of host recognition and colonization have been the focus of several recent studies (Johansson et al., 2004;Duplessis et al., 2005;Le Queré et al., 2005;Morel et

This review describes recent developments of single-crystal silicon (Si) as the photoelectrode material for solar water splitting, including the promising strategies to obtain highly efficient and stable single-crystal Si-based photoelectrodes for hydrogen evolution and water oxidation, as well as the future development of spontaneous solar water splitting with single-crystal Si-based tandem cells.