太行山低山丘陵区植被退化与恢复的生态学思考

太行山低山丘陵区天然植被的退化较为严重,植被恢复构建直接影响到该地区植被的生态、经济和社会效益的持续发挥。本文在分析太行山低山丘陵区现代生境基本特点的基础上,总结了太行山低山丘陵区植被退化的生态学原因、恢复构建的基本原则和途径,并提出了同质种植和异质种植的概念。

A comparative assessment on regeneration status of indigenous woody plants in Eucalyptus grandis plantation and adjacent natural forest

Diversity, density and species composition of naturally regenerated woody plants under Eucalyptus grandis plantation and the adjacent natural forest were investigated and compared. Twenty plots, with an area of 20 m × 20 m for each, were established in both of E. grand＆ plantation and adjacent natural forest, independently. In each plot, species name, abundance, diameter and height were recorded. Numbers of seedling were collected in five sub-plots （4 m2） within each major plot. A total of 46 species in the plantation, and 52 species in the natural forest, which belongs to 36 families were recorded. The diversity of species （H＇） is 2.19 in the plantation and 2.74 in the natural forest. The density of understory woody plant was 3842 stems/ha in the plantation and 4122 stems/ha in the natural forest. The densities of seedlings in the natural forest and the plantation were 8101 stems/ha and 4151 stems/ha, respectively. High similarity of woody species composition was found between the natural forest and the plantation. The E. grand＆ plantation was found favoring the regeneration and growth of Millitiaferruginia and Coffea arabica in a much better way than other underneath woody species.

Evaluation of Spatial Variability of Soil Properties in a Long-Term Experimental Tobacco Station in Southwest China

Analysis of the spatial variability of soil properties is important to arrange the experimental treatments in the experimental station. This paper aims to study the spatial structure of soil variables and their distribution in the Pengshui tobacco experiment station in Chongqing, China. Soil samples were taken from 289 soil points on 20 m grid in March 2012. Twenty-two soil chemical and physical properties were analyzed by classical statistical and geo-statistical methods. Soil pH, cation exchange capacity （CEC）, total phosphorus （TP）, available phosphorus （AP）, zinc （Zn）, magnesium （Mg） and sulphur （S） have the strong spatial dependence, with nugget/sill ratios of less than 25%. The others have the moderate dependence with nugget/sill ratios of 26.17% to 71.04%. Ranges of the spatial correlation varied from 51.30 m for chlorine （C1） to 594.90 m for TP. The clearly patchy maps of the nutrients showed the spatial distributions of the soil variables, which can be used for better management of experimental treatments, achieving reliable exoerimental results in the tobacco exnerimental station.Highlight： Scientific experimentation assumes the existence of random variability for soil attributes. This research was to evaluate the spatial variability of soil chemical and physical attributes and to interpolate the spatial distribution of soil properties in the tobacco experimental station in Chongqing. The result of this work can be used for the agricultural management of tobacco cultivation.

The Synergistic Effect of HT and Complement Regulatory Proteins in Resisting the Immunological Rejection of Heterogenic Transplantation

Objective：To establish the polytransgenic mice expressing the human HT and complement regulatory proteins （CRPs） and discuss their ability to resist the hyperacute rejection （HAR） and delayed xenograft rejection （DXR） of heterogenic transplantation. Methods ：Transgenic mice were produced by microinjection to construct gene for human HT, delay acceleration factor （DAF） and/or CD59 into the male pronucleus of zygote. PCR and Southern blot were used to screen the positive trarisgenic mice. Flow cytometry （FCM） was used to detect the expression of HT, ct-Gal and DAF or CD59 on the PBMCs of transgenic mice. The survival time and function of the heart of transgenic mice were determined by a modified Langendorff cardiac perfusion apparatus： The change of proteinosis on IgM,IgG, C3c and C9 from different cardiac vascular iendothelial cells of transgenic mice were detected by immunohistochemistry. Results：HT, DAF or CD59 were highly expressed on the positive transgenic mice by FCM. The deposition of IgM,IgG,C3c or C9 in the cardiac vascular endothelial cells of the positive transgenic mice were de- creased. The survival time and function of the heart of the co-transgenic mice with AB serum perfusion were significantly longer and higher than that of the single HT positive transgenic mice（P 〈0.05）. Conclusion ：The mice co-expressing HT/DAF or HT/CD59 could resist the HAR,which was better than those expressing HT alone. It is feasible to use HT and CRPs co-transgenic methods to resist the HAR and DXR.

Effects of three-dimensional soil heterogeneity on seed germination in controlled experiments

Aims Seed germinations react to their local growing conditions,but the impacts of soil heterogeneity on seed germinations are not well known.Methods Effects of three-dimensional soil heterogeneity on seed germinations of grasses species were explored,where two levels of such soil heterogeneity were created via alternatively filling nutrient-poor and nutrientrich substrate in pot in all directions.Patch sizes of the two heterogeneity levels are around 7.5 and 15 cm,respectively.Fifty seeds of each of the grasses species(Lolium perenne and Elymus nutans)were set either in these heterogeneous soils or in petri dishes with distilled water.Seed germinations of these species were daily recorded.Important Findings We found that pots with smaller patches had relatively lower germination rate,which is con sistent with our expectati on that shorter distance between nutrient-rich and nu trient-poor patches in pots with smaller patches allows plants to reduce their germination rates and delay their germination,in order to reduce the negative impacts of the strong variation of soil resources in these pots.Our results also revealed that pots with smaller patches yielded more heterogeneous seed germination,i.e.seed germinations highly diverged among these pots.These findings highlight that the realistic three-dimensional design can improve our understanding of seed germination as driven by soil spatial heterogeneity.

Differences in seed dormancy and germination in amphicarpic legumes:manifold bet-hedging in space and time

Aims Dispersal through space or time via dormancy is one of the primary processes whereby organisms can influence the environment they experience.In plants,strong evolutionary correlations are expected between the two kinds of dispersal because both are performed by the seeds and play comparable adaptive roles.In this paper,we investigated these evolutionary correlations using amphicarpic plants,which simultaneously produce aerial seeds with high spatial dispersal propensity and subterranean seeds that do not disperse.Methods We investigated the variation in dormancy and germination in aerial and subterranean seeds of two amphicarpic legumes(Vicia amphicarpa L.and Lathyrus amphicarpos L.)and two closely related homocarpic taxa(Vicia sativa L.and Lathyrus cicera L.)by estimating germination percentages following different combinations of dormancy breaking treatments(i.e.dry after-ripening,cold stratification and physical scarification).Important Findings Our results showed complex interactions between spatial and temporal dispersal.Right after dispersal,aerial seeds were more dormant than their subterranean counterparts,but this trend reversed with after-ripening,as seeds developed physical dormancy.Seeds of homocarpic plants germinated at higher percentages than those of their amphicarpic congeners and lost dormancy homogeneously with after-ripening.Conversely,amphicarpic seeds exhibited varied dormancy strategies modulated by both physiological and physical dormancy.These are expected to increase variation in emergence timing,providing multiple levels of diversifying bet-hedging.This strategy might be adaptive under highly unpredictable conditions by enabling plants to rely on historically favorable sites in good seasons without preventing spatial and temporal migration.