The type, community feature and species diversity of the degraded forest along the reaches of Jinshajiang river in Yunnan province were analyzed. It was found that there were six degraded forest types which were simple on structure and the layer and vertical distribution phenomenon was not obvious. The species diversity index showed deciduous evergreen broadleaf mixed forest evergreen broadleaf forest needle broadleaf mixed forest needle forestshrub in tree and shrub layers, and needle forest needle broadleaf mixed forest deciduous evergreen broadleaf mixed forest evergreen broadleaf forestshrub in herb layer. Within the serious degraded forest, the species diversity index showed herb layershrub layertree layer,and within the slightly degraded one, the species diversity was shrub layertree layerherb layer.
The coexistence of multi-walled carbon nanotubes (MWCNTs) with cadmium (Cd) in soil may cause the combined biological effects, but few study reported about their joint toxic effects on earthworms. Therefore, this study investigated the effects of sub-lethal levels of MWCNTs (10, 50, 100 mg/kg) and Cd (2.0, 10 mg/kg) on earthworms Eisenia fetida for 14 days. The changes in multi-level biomarkers of growth inhibition rate, cytochrome P450 isoenzymes (CYP1A2, 2C9 and 3A4), and small molecular metabolites (metabolomics) were determined. The toxic interaction between MWCNTs and Cd was characterized by the combination of the biomarker integration index (BRI), joint effect index concentration addition index (CAI), and the effect concentration addition index (EAI). The results showed that the single MWCNTs exposure caused insignificant change in most biomarkers, while the combined exposure of MWCNTs (50–100 mg/kg) and 10 mg/kg Cd led to significant changes in ten most important metabolites identified by metabolomics and activities of CYP1A2, 2C9, and 3A4. Compared with the toxicity of Cd alone, the combined toxicity of the mixture was significantly reduced. According to the integration of BRI and CAI/EAI, a clearly antagonistic interaction at relatively low effects was observed between MWCNTs and Cd. The responses of multiple biomarkers suggest the toxic action mode of the mixture on earthworms was related to the oxidative injury, and the disruption of amino acid, purine, and pyrimidine metabolism, and the urea cycle.
Increased production and environmental release of multi-walled carbon nanotubes (MWCNTs) increase soil exposure and potential risk to earthworms. However, MWCNT toxicity to earthworms remains unclear, with some studies identifying negative effects and others negligible effects. In this study, to determine whether exposure to MWCNTs negatively affects earthworms and to elucidate possible mechanisms of toxicity, earthworms were exposed to sublethal soil concentrations of MWCNTs (10, 50, and 100 mg/kg) for 28 days. Earthworm growth and reproduction, activities of cytochrome P450 (CYP) isoforms (1A2, 2C9, and 3A4) and antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and glutathione-s-transferase (GST)), and metabolomics were determined. Effects of MWCNTs on earthworms depended on exposure concentration. Exposure to MWCNTs did not significantly affect growth and reproduction of individual earthworms. Exposure to 50 mg/kg MWCNTs significantly increased activities of CYP2C9, CYP3A4, SOD, CAT, and GST but clearly reduced levels of L-aspartate, L-asparagine, and glutamine. With exposure to 100 mg/kg MWCNTs, toxic effects on earthworms were observed, with significant inhibition in activities of CYP isoenzymes and SOD, significant reductions in L-aspartate, L-asparagine, glutamine, and tryptophan, and simultaneous accumulations of citrate, isocitrate, fumarate, 2-oxoglutarate, pyruvate, D-galactose, carbamoyl phosphate, formyl anthranilate, hypoxanthine, and xanthine. Results suggest that toxicity of MWCNTs to earthworms is associated with reduced detoxification capacity, excessive oxidative stress, and disturbance of multiple metabolic pathways, including amino acids metabolism, the tricarboxylic acid cycle, pyruvate metabolism, D-galactose metabolism, and purine metabolism. The study provides new insights to better understand and predict the toxicity of MWCNTs in soil.
By the analysis of Chongqing water resources and water environment in utilization,the Chongqing water resources and water environment carrying capacity was analyzed and discussed to improve water resources and water environment in Chongqing for utilization of sustainable development,and recommendation was made.
The upper montane evergreen broad-leaved forest in Yunnan occurs mainly in the zone of persistent cloud and has a discontinuous, island-like, distribution. It is diverse, rich in endemic species, and likely to be sensitive to climate change. Six 1-ha sampling plots were established across the main distribution area of the upper montane evergreen broad-leaved forest in Yunnan. All trees with d.b.h. > 1 cm in each plot were identified. Patterns of seed plant distributions were quantified at the specific, generic and family levels. The forests are dominated by the families Fagaceae, Lauraceae, Theaceae and Magnoliaceae, but are very diverse with only a few species shared between sites. Floristic similarities at the family and generic level were high, but they were low at the specific level, with species complementarity between plots. Diversity varied greatly among sites, with greater species richness and more rare species in western Yunnan than central Yunnan. The flora is dominated by tropical biogeographical elements, mainly the pantropic and the tropical Asian distributions at the family and genus levels. In contrast, at the species level, the flora is dominated by the southwest or the southeast China distributions, including Yunnan endemics. This suggests that the flora of the upper montane forest in Yunnan could have a tropical floristic origin, and has adapted to cooler temperatures with the uplift of the Himalayas. Due to great sensitivity to climate, high endemism and species complementarity, as well as the discontinuous, island-like, distribution patterns of the upper montane forest in Yunnan, the regional conservation of the forest is especially needed.
By the experiments of water retention capability for the red-brown purple soils,grey-brown purple soils,and brown purple soils that were disturbed or undisturbed,the effects of gravel on water retention capabilities of purple gravelly soils in a hilly area were studied.Results showed that by considering gravel of undisturbed soils,the saturated water contents were reduced by 0.70%~10.70% and the field capacities,by 2.07%~4.33%.When the gravel content was less than 10%,it did not have an obvious relationship with the saturated water contents and field capacities of undisturbed soils.When the gravel content was more than 10%,the saturated water contents and field capacities increased with the decreased gravel content.At 0~30 kPa,the water-holding capacities and the a values of power functions for undisturbed and disturbed soils,the clay contents of undisturbed soils,and the specific water capacities of disturbed soils were all increased with the decreased gravel content.The specific water capacities of undisturbed soils decreased with the decreased gravel content.
The effect of rock fragment content on soil water movement of water source around reservoir in Chongqing was studied.The results showed that:the values of simulating formula of power functions for water retention characteristic curves of disturbed soils were opposite to rock fragment contents and the values were in accordance with rock fragment contents.In vertical infiltration and horizontal diffusion,with rock fragment increasing,the accumulative infiltration(diffusion) quantities dropped,the total infiltration(diffusion) times first decreased then increased,the total infiltration(diffusion) rates were opposite.In vertical infiltration,the saturated water weight,the draining weight,the beginning leaky time and the stable leaky time dropped.The Kostiakov infiltration model was used to simulate infiltration(diffusion) in any time,and the coefficient increased with rock fragment increasing,but the exponents were opposite.In the soil evaporations,the initial water contents and accumulate evaporations in the soils recovered with rock fragments were the least.Sixty one hours before,the average water contents decreased with rock fragments increasing.Sixty one hours later,the
Sequential soil coring and in situ exposure of largely undisturbed soil columns technique was used to study the nitrogen mineralization of five forest types soils in the east side of Gaoligongshan mountains, which were Dry-Hot Vally (D), Montane Rain Forest (MR), Monsoon Evergreen Broad-leaved Forest (M), the Mid-Montane Humid Evergreen Broad-leaved Forest (H), Tsuga Forest (Ts). The results indicated that NH 4 + -N content decreased for all the forest types soil after four months training, the order of decrease proportion is monsoon evergreen broad-leaved forest (84.1%)> montane rain forest (69.3%)> the mid-montane humid evergreen broad-leaved forest (34.7%)> dry-hot vally (8.7%)> tsuga forest (7.3%). And NO 3 - -N content increased for the soils, the increasing multiples is tsuga forest (39.0 times)> dry-hot vally (18.8 times)> the mid-montane humid evergreen broad-leaved forest (4.7 times)> monsoon evergreen broadleaf forest (4.0 times) > montane rainforest (2.8 times). We conclude that NH 4 + -N is the main form of inorganic nitrogen in forest soil, which is the main reason of changing the soil nitrogen mineralization and mineralization rate.
According to the study of Zhanmadi small watershed,6 modes for vegetation improvement and reconstruction head of Pearl River were proposed.These modes were applied in Fuyuan county's conversion of arable land back to forest project and pearl river shelter forest project.Through the vegetation improvement and reconstruction,the income from the forest was obvi- ously increased,the soil erosion modulus decreased from 1 767 t/(km~2·a) to 1 087 t/(km~2·a),the reduction rate was 38.48%.
With the experiments of soil water for red-brown purple soils,grey-brown purple soils,brown purple soils and coarse dark purple soils,the article studied water retention capability of purple rock fragment soils in hills.The results showed that: Considered rock fragments,the saturated water content reduced 0.70%～10.70% and the field capacity reduced 2.07%～4.33%.the saturated water content and the field capacity hadn't obvious relationship when rock fragment contents less than 10%,the saturated water content and the field capacity had reverse trend when rock fragment contents more than 10%.In 0～30 kPa,the water-holding capacity and the specific water capacity of 0～20 cm soil layer in different slope positions were in accordance with rock fragment contents and opposite to physical clay content.The a values of simulating formula of power functions for water retention characteristic curves were opposite to rock fragment contents and the b values were in accordance with rock fragment contents.
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