广西沙生红树植物—土壤相互作用及群落演替的研究

1992年于广西北海大冠抄测定了开阔海岸沙生白骨壤群落土壤的机械组成、有机碳和腐殖质的含量,及红树群落的结构和生物量等。由向陆林带到向海林带,土壤的粉粒粘粒含量和有机质含量随着群落树高和生物量的下降而降低,植物在相当程度上决定了土壤的特征。木榄、红海榄只偶见于向陆林带,桐花树和秋茄可生长到中间林带。这种分带现象部分地取决于土壤的质地和有机质含量。在土壤的垂直剖面上,植物跟土壤间也存在与上述相似的关系。这些表明,先锋红树植物白骨壤与土壤的共同进化为后来种创造了适宜的生境。在此基础上,提出了广西沙生红树林演替的模式。

Interaction of Pb and Cd in Soil－Water－Plant System and its Mechanism： I．Pb－Cd Interaction in Red Soil－Plant System

A study on the effect of Pb-Cd interaction on plant growth and on the chemistry of elements in plants was conducted under greenhouse condition with red soil-wetland rice system in different growth stage. The results showed that Pb-Cd interactions on growth and metal uptake varied with different growth stageS and chemical compounds added. The plant height and the root weight were markedly affected by Pb-Cd interiction in the young stage but not in the ripening stage of rice at the treatments of PbCl_2 and CdCl_2 added. However, the weight of rice straw in the ripening stage was significantly effected by Pb-Cd interaction with the treatments of Pb(OAc)_2 and CdCl_2. The chemistry of elements in plants also depended on Pb-Cd interaction in varying degrees on account of different plant parts and growth stage. It seems that Pb-Cd interaction occurred not only in roots but also in other parts of wetland rice.

Interactions between Soil Characteristics, Environmental Factors, and Plant Species Abundance: A Case Study in the Karst Mountains of Longhushan Nature Reserve, Southwest China

The ability to manage and restore plant communities in the face of human-induced landscape change may rely on our ability to predict how species respond to environmental variables.Understanding this response requires examining factors or their interactions that have influence on plant and resource availability.Our objective was to analyze the relationships between changes in plant abundance and the interaction among environmental habitat factors including soil, geological(rock type), and other environmental variables in the Longhushan karst mountains ecosystem.Species density and dominance were examined using ANOVA, ANCOVA,and Generalized Linear Models to establish the single or combined effects of these groups of factors.The results showed that trends in abundance were mainly affected by rock type(related to the percentage content of dolomite and calcite), soil characteristics in association with topography.Both plant indices were higher in dolomite dominated areas and varied positively with moisture, and elevation, but negatively with organic matter, while density also increased with slope degree.The results demonstrate that significant variations in species abundance was produced with the combination of variables from soil, geological, andenvironmental factors, suggesting their interaction influence on plants.We postulate that spatial variations in plant abundance in karst ecosystem depends on the carbonate rock type in addition to water and nutrient availability which are mainly controlled by topography and other factors such as soil texture and temperature.The study suggests that in karst areas carbonate rock type, in addition to local environmental variables, should be taken into account when analyzing the factors that have impact on plant communities.

Interaction between Cross-Linked Polyacrylamide and Water and Solute Flow in a Sand and Loam

Superabsorbents such as cross-linked PAM （polyacrylamides） are frequently used to increase water availability to plants. Commercial PAM providers suggest that besides its increasing water availability, PAMs also increase nutrient availability to plants. To test this premise, four application rates （0.0 g·kg^-1, 0.33 g·kg^-1, 1.66 g·kg^-1, 3.33 g·kg^-1 and 6.66 g·kg^-1） ofa PAM were mixed with sandy and loamy soils to evaluate its effect on nutrient leaching and retention in these soils. Miscible displacements of chloride were conducted on columns of PAM-soil mixtures and results were evaluated by an equilibrium CDE （convection dispersion equation） model. Increasing the PAM rates up to 1.66 g·kg^-1 resulted in increased early appearance and dispersive transport of chloride in sand. In addition, increasing the PAM rates gradually caused increased tailing of the breakthrough curves of chloride in both soils. These suggested that PAM increased preferential transport of chloride while it increased retention of chloride in soils. Effect of PAM on preferential transport and retardation of CI was greater in sand than loam.

The negative effects of soil microorganisms on plant growth only extend to the first weeks

Soil biotic communities can strongly impact plant performance.In this paper,we ask the question:how longlasting the effect of the soil microbial community on plant growth is.We examined the plant growth rates at three stages:early,mid and late growth.We performed two growth experiments with Jacobaea vulgaris,which lasted 49 and 63 days in sterilized soil or live soil.In a third experiment,we examined the effect of the timing of soil inoculation prior to planting on the relative growth rate of J.vulgaris with four different timing treatments.In all experiments,differences in biomass of plants grown in sterilized soil and live soil increased throughout the experiment.Also,the relative growth rate of plants in the sterilized soil was only significantly higher than that of plants in the live soil in the first two to three weeks.In the third experiment,plant biomass decreased with increasing time between inoculation and planting.Overall,our results showed that plants of J.vulgaris grew less well in live soil than in sterilized soil.The negative effects of soil inoculation on plant mass appeared to extend over the whole growth period but arise from the negative effects on relative growth rates that occurred in the first weeks.

Effects of arbuscular mycorrhizal fungi on Solidago canadensis growth are independent of nitrogen form

Aims Invasive plants may alter soil fungal communities in a way that improves their growth.Nitrogen(N)content of soil affects the symbiosis between plants and arbuscular mycorrhizal fungi(AMF),further determining plant growth.Yet,it is unclear whether altered AMF communities change the dependence of invasive and native species on N-form,and whether N forms alter the invasive plant–AMF interaction(PSIM).Methods Two synthetic plant communities,including four Solidago canadensis individuals and four native plant species,were inoculated with AMF spores from S.canadensis-invaded soils and adjacent non-invaded soils,and were provided with nitrate,ammonia or glutamate.After their growth,the performance of the two plant communities in treatments of AMF origin and N forms,and the pathways of the N forms affecting S.canadensis growth and PSIM were evaluated.Important Findings Solidago canadensis had no obvious N-form dependence in any of the AMF inoculations.Native plant species showed weak N-form dependence,but invasive AMF could remove their N-form dependence.In the absence of N,AMF did not affect growth of S.canadensis and the native plants.In contrast,with N addition,invasive AMF significantly increased belowground and total biomass of the invasive plants but not those of the native plants.Positive PSIM of S.canadensis was also evidently greater than that of native plant species and was realized through directly or indirectly regulating phenotypic traits including plant height,leaf number and number of rhizomes.Our findings emphasize the importance of plant–AMF interactions and a unique N-acquisition strategy during plant invasions.