Chen J.P.,Southwest University |
Chen J.P.,Guangxi Academy of Agricultural science |
Zeng C.C.,Southwest University |
Wei H.,Southwest University |
And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2017
The water level fluctuation zone of the Three Gorges Reservoir has been affected by a number of ecological problems, most importantly, the loss of previous vegetation. The revegetation of this region is just one example of a potential solution to this issue, and revegetation projects have been carried out in the region over recent years in an attempt to restore the riparian ecosystem within the Three Gorges Reservoir region. The riparian species Hemarthria altissima and Cynodon dactylon have been commonly used in this revegetation effort. Knowledge of the growth responses of plant species to different flood regimes and identifying a suitable planting pattern will lead to improvements in the design of wetland management strategies. Therefore, the aim of this study was to determine the optimal planting pattern for these two species under different flood conditions. Four flooding conditions were designed using an independent-group design and their results were evaluated. These groups were the Control Group (CK), the Flooding-Dry Alternating Group (FD), the Soil-Flooding Group (FL), and the Submergence Group (SM). These groups had four different planting densities, which were 1, 2, 4, or 12 plants per experimental pot. Single cropping strategies were applied to the pot with one plant, while both single and mixed cropping strategies were applied to the pots with, 2, 4, and 12 plants. The ratio of H. altissima to C. dactylon in the mixed intercropping groups was 1:1 in the pots with 2, 4, and 12 plants. The results indicated that the total and aboveground biomasses of H. altissima and C. dactylon were significantly influenced by water treatment, planting density, and planting pattern (P < 0.05). The total and aboveground biomasses of C. dactylon significantly decreased in the mixed intercropping pots with medium and high planting densities under the CK and FD conditions (P < 0.05). In contrast, the total and aboveground biomasses of H. altissima increased in the mixed intercropping pots for all planting densities, and increased significantly at the high planting density under the CK and FD conditions (P < 0.05). The total H. altissima and C. Dactylon biomasses increased in the mixed intercropping pots with low and medium planting density under the FL treatment. The total and aboveground C. dactylon biomasses also significantly increased in the mixed intercropping pots with low and medium planting density under the SM treatment (P < 0.05). However, the mixed intercropping pattern with low and medium planting density did not influence the H. altissima biomass under the SM treatment (P > 0.05). Furthermore, the mixed intercropping pattern with high planting density did not influence the H. altissima and C. Dactylon biomasses under the SM treatment (P > 0.05). The inhibition influence of the mixed intercropping pattern to C. Dactylon declined as flooding stress increased. The results suggested that the long-term coexistence of H. altissima and C. Dactylon would improve if a mixed intercropping pattern with low and medium planting densities was adopted in areas where flooding lasted for a long period. Therefore, in order to strengthen the soil retention functions of H. altissima and C. dactylon, and improve the species diversity and community stability of the vegetation restoration, mixed intercropping with a high H. altissima-to-C. dactylon planting density is the optimal choice in low-altitude areas that are completely flooded. © 2017, Ecological Society of China. All rights reserved.
Jia Z.,Southwest University |
Jia Z.,Southeast Sichuan Geological Group |
Wei H.,Southwest University |
Sun X.,Southwest University |
And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011
Cadmium (Cd) is the most popular heavy metal element in the contaminated soil of Three Gorges Reservoir Region. Cadmium has significant negative effects on the health of soil-plant system in the research area due to its high concentration and biological activity. Thus, it is essential to study the tolerance and accumulative ability of plant species in cadmium contaminated soils in order to protect the ecological environment and plan the reasonable land use. Salix variegate and Pterocarya stenoptera are two native riparian plants which can be used widely in the vegetation restoration of the hydrofluctuation zone in Three Gorges Reservoir Region. In order to reveal the response of these two species to cadmium, five different kinds of cadmium treatment were applied to determine the growth, biomass and cadmium concentration in various parts of S. variegate and P. stenoptera seedlings. The cadmium treatments were 0(control), 10, 20, 50, and 100 mg/kg. The results showed that: (1) The root biomass, aerial biomass, changes of stem length and stem diameter of S. variegate and P. stenoptera seedlings decreased with Cd content raised. Tolerance index (Ti) based on the dry biomass and growth parameters of two species showed no significant difference in 10 mg/kg in contrast with a significant decrease in 20, 50, and 100 mg/kg (P < 0. 05), when compared to the control respectively. (2) The cadmium concentration reached up to 61.73, 163. 04, and 91. 05 mg/kg in stems, leaves, and roots of S. variegate in turn when treated with cadmium less than 20 mg/kg. However, in the same treated condition, the highest cadmium concentration was 7. 9,5. 25, and 190. 68 mg/kg in stems, leaves, and roots of P. stenoptera, respectively. (3) Cd accumulation in S. variegate was highest in leaves and lowest in stems except in the control, with the translocation factor (Tf) between 0. 789-1. 513. Very differently, Cd accumulation in P. stenoptera was highest in roots and lowest in stems also except in the control, with the translocation factor (Tf) between 0. 037- 0. 044. Thus, the translocation factor (Tf) o f P. stenoptera was far less than that of S. variegate. These characteristics indicated strategies of cadmium uptake and translocation by two plant species growing in Cdcontaminated soil were not totally different: Cd tended to be immobilised and held primarily in the roots of P. stenoptera, whereas it was more easily translocated to the aerial tissues of S. variegate. The tolerance of species to cadmium was demonstrated by these two strategies so that the plants were able to survive and had a high productivity. (4) The results indicated that S. variegate and P. stenoptera seedlings had a high capacity of growth adaptation and tolerance under 10 mg/ kg Cd stress, and also, the capacities of translocation and cadmium accumulation in aerial parts of S. variegate seedlings were higher than that of P. stenoptera seedlings, which verified that the differences in accumulation of cadmiumwere not correlated with tolerance ability of plants. Such a behavior in the seedlings of two species was further confirmed by the calculation of the bio-concentration factor (BCF). The study suggested that S. variegate had considerable potential application to those cadmium contaminated areas in the hydro-fluctuation zone of the Three Gorges Reservoir Region.
Yan M.-S.,Southeast Sichuan Geological Group |
Yan M.-S.,Chengdu University of Technology |
Li W.-B.,Southeast Sichuan Geological Group |
Yang L.-C.,Southeast Sichuan Geological Group |
And 2 more authors.
Research of Environmental Sciences | Year: 2014
Speciation characteristics, influencing factors and effectiveness of As, Cd, Cr and Pb in four main types of soils (purplish soil, limestone soil, yellow soil and paddy soil) were investigated through analyzing total contents and fractions of heavy metals in soils in Yubei District, Chongqing. The results showed that fractions of heavy metals significantly varied among different types of soils. Cr and Pb were the main components of the residual in all kinds of soils. Cd was mainly ion-exchangeable and residual speciated in yellow soils and purplish soils, which counted for 37.44% and 29.97% of the total Cd contents, respectively. The contents of available speciation of heavy metals in soils was as follows: w (available As) and w (available Cr) were 0.04 and 0.96 mg/kg in purplish soil respectively, w (available Cd) 0.13 and 0.09 mg/kg in paddy and purplish soil respectively, w (available Pb) was 1.94 mg/kg in yellow soil, which perhaps indicated a strong bio-effectiveness, when the bio-effectiveness of heavy metals in limestone-soil was lower. Available As and Cd significantly positively were correlated with total contents in main factors influencing on the chemical speciation and transformation process of heavy metals. However, there were significant negative correlations between available contents of Cd and Pb with pH, and between available Cr with soil organic matters. Available Cd, Cr, and Pb have a multivariate nonlinear logarithmic regressive relationship with total contents, pH and SOM in purplish soil. In conclusion, the equation can be used to effectively predict available contents of the heavy metals in the study area.