A dynamic model was developed to simulate the variation of spatial species distribution patterns of tile mead-owsteppe grasslands on Songnen Plain in northeast China. Simulation was performed to study the interaction between soil alkalization and vegetation development with special consideration given Io spatial processes such as horizontal species migration and horizontal difusion of soil alkali. The coverage of five species. Calatnagrostis epigeios. Aneurolilliditon chinense. Puccinellia temiforn. Aeluropus littoralis and Suae & l coriculata. and soil alkali were selected as 6 state variables. A positive feedback mechanism embedded hi Ibe model was that when the total planl coverage is large enough, the soil undergoes de-alkalizatinn, which in turn helps improve further the plant growth condition. The de-alkalization is due to the improved soil physicaI properlies indicated by a large amount of soil non-capillary pores coexisting with a large amount of below- ground root bionlass which allows alkaline solutes to leach from surface soil to underground water by means of precipitalion. On tile other hand. when the plant coverage is too small, soil alkalizatinn takes place title to the deterioration of soil pbysical properties indicated by a small amount of plant root biomass and a large anlounl o[ capillary pores which enables evapotranspiration Io bring up alkaline solutes to tile stlrce soil. The alkalizalkm of surlace soil further hinders planl growth. The model was inlplenlented using a software tool. SPAMOD. developed al Institute ol Botany. tile Chi-nese Acadenly of Sciences. The simulation results showed that the model was in very close agreement wilh five year field observalions oll a one hectare fenccd alkaline grassland, implying that the inodeling approach used in this research is very approprlatc for grassland landscape studies: that the spatial processes reflected as horizontal species migratkm and horizontal diffilsion or soil alkali are very importam for the recovery ol A-chineltse, the major grazed species wilh rhizoma as its nlain reproduction mechanisnl: and lhat lhe vanishing rate of S. corniculata, an indicator of serious soil alkalization, is very sensitive to the variation in the soil physical pmperlies.

We use a spatially explicit landscape model to investigate the potential role of rainfall onshrub–grass transitions in the Jornada Basin of southern New Mexico during the pastcentury. In long-term simulations (1915-1998) along a 2700m transect running from a drylake bed to the foothills of a small mountain, we test two hypotheses: (i) that wetterwinters and drier summers may have facilitated shrub encroachment in grasslands, and (ii) that increases in large precipitation events may have increased soil water recharge atdeeper layers, thus favoring shrub establishment and growth. Our model simulationsgenerally support the hypothesis that wetter winters and drier summers may haveplayed a key role, but we are unable to reproduce the major shifts from grass-to shrubdominationthat occurred in this landscape during the early part of the 1900s;furthermore, the positive shrub response to wetter winters and drier summers was onlyrealized subsequent to the drought of 1951-1956, which was a relatively short 'windowof opportunity' for increased shrub establishment and growth. Our simulations alsogenerally support the hypothesis that an increase in the number of large precipitationevents may also have favored shrub establishment and growth, although these resultsare equivocal, depending upon what constitutes a large' event and the timing of suchevents. We found complex interactions among (i) the amount/seasonality of rainfall, (ii)its redistribution in the landscape via run-on and runoff, (iii) the depth of the soil waterrecharge, and (iv) subsequent water availability for the growth and reproduction ofshrubs vs. herbaceous plants at various landscape positions. Our results suggest thatonly a mechanistic understanding of these interactions, plus the role of domestic cattlegrazing, will enable us to elucidate fully the relative importance of biotic vs. abioticfactors in vegetation dynamics in this semiarid landscape.

The behavioral dependence of vegetation simulation models for spatially heterogeneous grasslands on simulationresolutionwas investigated. The dependence can be largely attributed to the non-linearity of themodels.We showedthat increasing scale or decreasing spatial resolution tended to overestimate the changing rate of an ecosystem usingour landscape simulation model for alkaline grasslands in northeast China. A technique for scaling up simulationmodels with diffusive transportation was developed in this study by means of expanding the nonlinear drivingfunctions in the model. The analysis showed that a simulation model for spatially heterogeneous landscapes mightnecessitate modification of both its mathematical structure and parameterization when applied to different scales.The scaling coefficients derived in this study were shown to be proportional to the variances or covariance of thespatially referenced variables, and can be estimated by running the model at a fine resolution for selected samplesof the coarser grid cells. The technique was applied to a grassland landscape in northeast China and the resultswere compared with five-year observations on community succession. The comparison indicated that the proposedtechnique could effectively reduce overall scaling error of the model by as much as 80%, depending on the scalingdifference between the fine and the coarse resolutions as well as the sampling scheme used.

del was built to describe the ecological processes of an alkalinized–salinized meadow steppeecosystem, including the hydrological and alkalization-salinization processes in the soil, as well as the successionand growth dynamics of the grassland communities. A numerical integration model and a water and salt balancemodel were integrated into a physically-based model, describing the dynamics of soil moisture, salt concentration,exchangeable sodium percentage (ESP) and pH. Meteorological variables and soil characteristics were the mainenvironmental factors used to estimate the growth dynamics of three herbaceous communities that were dominatedby Aneurolepidium chinense, Chloris virgata, and Suaeda glauca, respectively. Model validation showed goodagreement between the simulated results and the observed data. Simulation studies were conducted to evaluate thepotential changes in hydrological and alkalization-salinization processes, succession and growth dynamics from1991 to 1998, under five grazing intensities, namely 0%, 25%, 50%, 75% and 90% above-ground biomass removal(AGBR). The simulations show that soil moisture decreased markedly under the 50%, 75% and 90% AGBR, butincreased slightly under the 25% AGBR. The de-alkalization and de-salinization processes would be predominantunder the 0% AGBR, and the processes became a little slower under the 25% AGBR. In contrast, the 50%, 75% and90% AGBR accelerated the degradation of soil properties. The grassland was dominated by A. chinense under the0%AGBR, and by A. chinense and C. virgata under the 25% AGBR. C. virgata could grow on slightly alkalinized-salinized soil and became a dominant species after three years of 50% AGBR. The soil degraded quickly and onlyS. glauca could grow on the severe alkalinized-salinized soil if the grassland received 75% or 90% AGBR. Thegrassland grew well under the 0% AGBR, and the biomass stayed at moderate level under 25% AGBR. The 50%,75% and 90% AGBR decreased the grassland growth greatly. After accumulating the grazed biomass for each year,the 25% AGBR would provide the highest production, and the grassland production would decrease sharply withthe increasing of grazing intensities. The simulation results indicate that 25% AGBR is significant for preservingthe soil from degradation, and maintaining high grassland production.

Aim A regional model of vegetation dynamics was enhancedto include biogeochemical cycling of nitrogen and was thenapplied to a forest transect in east China (FTEC) in order to investigatethe responses of the transect to possible global change. Location Eastern China. Methods Biomass and nitrogen concentration of green andnongreen portions of vegetation, moisture contents of threesoil layers, and total and available soil nitrogen are includedas state variables in the enhanced model. The model wasparameterized and validated against field observations ofbiomass, productivity, plant and soil nitrogen concentration,nitrogen uptake, a vegetation index derived from satelliteremote sensing and digital maps of vegetation and soil distributionsalong a forest transect in eastern China (FTEC). The model was applied to FTEC in order to investigate theresponsive characteristics of the ecosystems to global climaticchange. Scenarios of climate change under doubled CO2produced by seven general circulation models (GCM) wereused to drive the model. Results The simulations indicated that the model is capableof simulating accurately potential vegetation distribution andnet primary productivity under contemporary climatic conditions.The simulations for GCM-projected future climatescenarios with doubled atmospheric CO2 concentrationpredicted that broadleaf forests would increase, but coniferforests, shrubs and grasses would decrease; and that deciduousforests would have the largest relative increase, but evergreenshrubs would have the largest decrease. Conclusions The overall effects of doubling CO2 and climaticchanges on FTEC were to produce an increased net primaryproductivity (NPP) at equilibrium for all seven GCM scenarios.The inclusion of nitrogen dynamics in the model imposesmore constraint on the responses of FTEC to climatic changethan the previous version of the model without nitrogendynamics. Temperature exerts a stronger control on NPPthan precipitation, as indicated by the negative correlationsbetween NPP and temperature. The southern portion of FTEC,at latitudes less than 33

目的：观察黄苓总苷对大鼠急、慢性前列腺炎的影响。方法：分别在大鼠前列腺内注入角叉菜胶、大肠杆菌或消痔灵注射液，造成非菌性和菌性急性前列腺炎及慢性前列腺炎，观察黄芩总苷对前列腺液中白细胞数目、卵磷脂小体密度及腺体组织学改变的影响。结果：黄苓总苷120，240mg/kg灌胃给药，显著减少角叉菜胶或大肠杆菌所致前列腺炎大鼠前列腺液中白细胞数目，升高卵磷脂小体密度。并减轻大鼠前列腺腺腔大小不一、炎细胞浸润和间质水肿的程度。60mg/kg无明显作用。此外，黄芩总苷120，240mg/kg抑制消痔灵所致慢性前列腺炎大鼠腺体的增生和肥大，240mg/kg明显减轻慢性炎细胞浸润，对纤维母细胞增生呈抑制趋势。结论：黄芩总苷对实验性急、慢性前列腺炎均具有改善作用。

目的：观察熟地（黄）和生地（黄）配伍的四物汤对实验性变态反应的影响，比较其作用差异。方法：以compound48/80诱导小鼠过敏性休克、皮肤搔抓反应及大鼠腹腔肥大细胞释放组胺，分别测定1h内的死亡率、10min内的搔抓次数及组胺的释放量和残留量（荧光法）；以氯化钴诱导小鼠耳廓迟发型超敏反应，测定耳廓肿胀度。结果：熟地配伍的四物汤（500mg/kg）显著抑制compound48/80所致小鼠过敏性休克，而生地配伍的四物汤无明显影响；熟地和生地配伍的四物汤（500mg/kg）均明显抑制compound48/80诱导的小鼠搔抓反应及氯化钴所致小鼠迟发型超敏反应，前者的作用强于后者；体外试验中，熟地或生地配伍的四物汤（100～400μg/ml）抑制compound48/80诱导的大鼠肥大细胞释放组胺，前者的作用强于后者，熟地提取物减少组胺释放，而生地提取物无明显作用。结论：熟地配伍的四物汤对肥大细胞依赖性速发型变态反应及T淋巴细胞依赖性迟发型变态反应的抑制作用均强于生地配伍的四物汤，熟地和生地作用的差异可能是其主要原因。

The antiallergic properties of the 70% ethanol extract from Plumbago zeylanica stems (EPZ) were investigatedin the present study. The extract (500, 1000mg/kg, p.o.) dose-dependently inhibited systemic anaphylacticshock induced by compound 48/80 in mice, reduced homologous passive cutaneous anaphylaxis and skin reactionsinduced by histamine or serotonin in rats, significant differences were observed at the dose of 1000 mg/kg.In vitro, EPZ (5, 20, 50mg/ml) concentration-dependently reduced histamine release from rat peritoneal mastcells caused by compound 48/80 and antigen. EPZ (50mg/ml) markedly increased intracellular cAMP content ofrat mast cells. These findings demonstrate that EPZ inhibits mast cell-dependent immediate allergic reactions,which is probably mediated by reducing the release of mediators such as histamine from mast cells via elevatingintracellular cAMP level and weakening the inflammatory action of mediators.

Previous studies have shown that the ethanol extract ofPlumbago zeylanica L. stems (EPZ) suppresses immediateallergic reactions. We extended these studies to examinethe effect of EPZ on delayed-type hypersensitivity reactions. Our results showed that EPZ (500 and 1000mg=kg), orally administered during either sensitizationstage or effector stage, effectively attenuated picryl chloride–induced delayed-type hypersensitivity (PC-DTH) inmice. In vitro, EPZ (100 and 200mg=ml) concentrationdependentlyinhibited Con A-induced splenocyte proliferationand interleukin-2 (IL-2) production but hadlittle effect on nitric oxide (NO) production from murineperitoneal macrophages activated with lipopolysaccharide(LPS). EPZ (500 and 1000mg=kg) also showed asignificant inhibition of ear swelling caused by xylene inmice. These results suggested that EPE alleviateddelayed-type hypersensitivity in mice, which might beattributable to inhibition of proliferation and differentiationof T lymphocytes as well as anti-inflammatoryactivities.