Effect of acetazolamide on cerebral blood flow and tympanic temperature in healthy subjects and patients with subacute subarachnoid haemorrhage

The influence of the increased cerebral blood flow (CBF) induced by acetazolamide on tympanic temperature (T _ty) was examined in three healthy male volunteers and in five patients with subacute subarachnoid haemorrhage (SAH). The CBF was estimated by means of stable xenon-enhanced computed tomography before and after the administration of acetazolamide. The T _ty was recorded continuously in both ears using thermistor thermometers. In all subjects, CBF increased ranging from 11% to 108% after acetazolamide administration. In all the healthy subjects and in two patients with mild SAH, T _ty was higher than the oesophageal temperature (T _oes) and T _ty decreased bilaterally, ranging from 0.07 to 0.35°C as CBF increased. Three patients with severe SAH were febrile, their T _oes exceeding T _ty, and their T _ty rose by 0.30 to 0.53°C with increased CBF. These observations suggest that T _ty follows brain temperature which changes with an increase in CBF in euthermic subjects as well as in febrile subjects. Accepted: 3 September 1996     

Modelling the Effects of Water Stress and Temperature on Seed Germination of Radish and Cantaloupe

Cantaloupe (Cucumis melo L.) and radish (Raphanus sativus L.) are considered as important vegetables with potential for national and international markets due to their sugars, vitamins and minerals. This study arranged, therefore, to simultaneously investigate the effect of temperature (T) and water potential (ψ) on seed germination (SG) of these plants using two hydrothermal time (HTT) models and to determine cardinal Ts and base water potential (ψ_b(50)) for both species. The results indicated that SG of both species was more affected by ψ than T (p ≤ 0.001). At Ts below an optimum temperature (T_o) the ψ_b(50) was constant (− 0.582 and − 0.760 MPa for radish and cantaloupe, respectively) and then increased linearly by 0.0481 and 0.0446 MPa °C⁻¹ as T increased above T_o (as thermoinhibition) until 0 MPa at the ceiling temperature (T_c), respectively. As the first report, however, we observed that the T at which ψ_b(50) begins to change was the same here (that is, T_d = T_o), when determined by either model for both species. This result suggests that the assumption in Rowse and Finch-Savage’s model (T_d is often less and or very close to T_o) may be invalid in some cases. For both species, the base temperature (T_b) and T_o were not affected by ψ and were constant while there was an exception only for T_c for which the value declined with decreasing ψs (more negative). In general, the estimated T_b, T_o and T_c were 9.64, 21.3 and 33.0 °C for radish and 11.8, 28.3 and 45.7 °C for cantaloupe in the control condition (ψ = 0 MPa), respectively. The HTT models used here and their parameters, each with strengths and weaknesses, can be used as a predictive tool in both cantaloupe and radish SG simulation models. However, at first, we need to select an appropriate HTT model based on SG behavior of plant species and then use the best model for quantifying the response of SG across Ts and ψs.

     

Effect of quinones on formation and properties of bacteriochlorophyll c aggregates

Chlorosomes of green photosynthetic bacterium Chlorobium tepidum contain aggregates of bacteriochlorophyll c (BChl c) with carotenoids and isoprenoid quinones. BChl aggregates with very similar optical properties can be prepared also in vitro either in non-polar solvents or in aqueous buffers with addition of lipids and/or carotenoids. In this work, we show that the aggregation of BChl c in aqueous buffer can be induced also by quinones (vitamin K₁ and K₂), provided they are non-polar due to a hydrophobic side-chain. Polar vitamin K_3, which possess the same functional group as K₁ and K₂, does not induce the aggregation. The results confirm a principal role of the hydrophobic interactions as a driving force for the aggregation of chlorosomal BChls. The chlorosomal quinones play an important role in a redox-dependent excitation quenching, which may protect the cells against damage under oxygenic conditions. We found that aggregates of BChl c with vitamin K₁ and K₂ exhibit an excitation quenching as well. The amplitude of the quenching depends on quinone concentration, as determined from fluorescence measurements. No lipid is necessary to induce the quenching, which therefore originates mainly from interactions of BChl c with quinones incorporated in the aggregate structure. In contrast, only a weak quenching was observed for dimers of BChl c in buffer (either with or without vitamin K₃) and also for BChl c aggregates prepared with a lipid (lecithin). Thus, the weak quenching seems to be a property of BChl c itself.     

Effects of interval training at the ventilatory threshold on clinical and cardiorespiratory responses in elderly humans

This study assessed clinical and cardiorespiratory responses after an interval training programme in sedentary elderly adults using the ventilatory threshold (V _th) as the index of exercise training intensity. A selection of 22 subjects were randomized into two groups: 11 subjects served as the training group (TG) and the others as controls (CG). Maximal exercise tests were performed on a treadmill before (T₀), each month (T₁, T₂) and after the 3-month interval training programme period (T₃). The TG subjects were individually trained at the heart rate corresponding to V _th measured at T₀, T₁ and T₂ as the breakpoint in the oxygen uptake-carbon dioxide production relationship. Their training programme consisted of walking/jogging sessions on a running track twice a week. The sessions consisted of varying durations of exercise alternating with active recovery in such a way that the subjects slowly increased their total exercise time from an initial duration of 30 min to a final duration of 1 h. During training the heart rate was continuously monitored by a cardiofrequency meter. Compared with the daily activities of the controls, no training programme-related injuries were observed in TG. Moreover, programme adherence (73%) and attendance (97.3%) were high. The maximal oxygen uptake and V _th were increased in TG, by 20% (P<0.05) and 26% (P<0.01), respectively. Interval training at V _th also significantly increased maximal O₂ pulse (P<0.05) and maximal ventilation (P<0.01). A significant decrease in submaximal ventilation (P<0.05) and heart rate (P<0.01) was also noted. These results would suggest that for untrained elderly adults, an interval training programme at the intensity of V _th may be well-tolerated clinically and may significantly improve both maximal aerobic power and submaximal exercise tolerance. Accepted: 6 January 1998     

Co-immobilization of manganese peroxidase from Phlebia radiata and glucose oxidase from Aspergillus niger on porous silica beads

Manganese peroxidase (MnP) from Phlebia radiata and glucose oxidase from Aspergillus niger were co-immobilized on porous silica beads. Immobilization of both enzymes on the same carrier provided an integrated system in which H₂O₂ required by MnP was produced by glucose oxidase. The immobilization process resulted in a decrease of both enzymatic activities and substrate affinities. However, immobilization improved the stability of MnP against H₂O₂ or high pH, as well as the storage stability of this enzyme.     

Effects of Epoxiconozale and Pyraclostrobin Fungicides in the Infection Process of Hemileia vastatrix on Coffee Leaves as Determined by Chlorophyll a Fluorescence Imaging

Coffee is the most traded commodity in the world, and Brazil is its largest producer. Coffee leaf rust, caused by the biotrophic fungus Hemileia vastatrix, is the most important coffee disease, reducing coffee yield by 35–50%. This study aimed to use the ratio of variable and maximum fluorescence of dark‐adapted tissue (F_v/F_m) as a parameter to differentiate presymptomatic tissue from healthy tissue during disease development in plants sprayed with pyraclostrobin and epoxiconazole after 4 days postinoculation. Visual severity was considered as an indicative of apparent disease and true severity as an indicative of both apparent and non‐apparent disease. There was a significant linear relationship between the areas of true severity and visual severity, and for each additional unit in the visual severity, there was an increase of 1.53 units on the true severity. For the epoxiconazole and pyraclostrobin treatments, coffee leaf rust symptoms decreased according to both visual and F_v/F_m images. Pustules on the leaves sprayed with epoxiconazole were smaller in size than those on the leaves of non‐sprayed plants but bigger than those sprayed with pyraclostrobin. The reduction in F_v/F_m values at the pustule epicentres present on the leaves of plants sprayed with epoxiconazole, and pyraclostrobin was greater than those of the non‐sprayed plants. This finding was expected and reflects the importance of these fungicides in prohibiting the progress of coffee leaf rust. The photosynthetic capacity of Coffea arabica was affected by H. vastatrix infection, and the F_v/F_m parameter was able to show this effect before the visual symptoms were noticed.     

Calcium effects on electrogenic pump and passive permeability of the plasma membrane ofChara corallina

Summary Removal of Ca²⁺ from the medium results in depolarization of theChara internodal cell and an increase in membrane conductance (G _m). The increase in conductance is associated with an increase in K⁺ conductance, as judged by Ca²⁺ effects on the K⁺ dependence of clamp current. The voltage dependence ofG _m is also affected by Ca²⁺, as is the time course of the response of clamp current to a step change in voltage. Mg²⁺ restores the low conductance and the fast response to a voltage change, but not hyperpolarization at neutral pH, suggesting that there is an additional, independent effect on the electrogenic pump. The membrane does not show the normal ability to increase proton conductance at high pH in the absence of Ca²⁺; this is also restored by Mg²⁺ as well as by Ca²⁺.     

Putrescine metabolism modulates the biphasic effects of brassinosteroids on canola and Arabidopsis salt tolerance

Brassinosteroids (BRs) are known to improve salt tolerance of plants, but not in all situations. Here, we show that a certain concentration of 24-epibrassinolide (EBL), an active BR, can promote the tolerance of canola under high-salt stress, but the same concentration is disadvantageous under low-salt stress. We define this phenomenon as hormonal stress-level-dependent biphasic (SLDB) effects. The SLDB effects of EBL on salt tolerance in canola are closely related to H₂O₂ accumulation, which is regulated by polyamine metabolism, especially putrescine (Put) oxidation. The inhibition of EBL on canola under low-salt stress can be ameliorated by repressing Put biosynthesis or diamine oxidase activity to reduce H₂O₂ production. Genetic and phenotypic results of bri1-9, bak1, bes1-D, and bzr1-1D mutants and overexpression lines of BRI1 and BAK1 in Arabidopsis indicate that a proper enhancement of BR signaling benefits plants in countering salt stress, whereas excessive enhancement is just as harmful as a deficiency. These results highlight the involvement of crosstalk between BR signaling and Put metabolism in H₂O₂ accumulation, which underlies the dual role of BR in plant salt tolerance.     

Effect of CO2, CO2 and Diamox on photosynthesis and photorespiration in Chlamydomonas reinhardtii (green alga) and Anacystis nidulans (Cyanobacterium, blue-green alga)

Photorespiration by Chlamydomonas reinhardtii and Anacystis nidulans was measured as the oxygen inhibition of CO₂ uptake and the CO₂ compensation points. Net photosynthesis was oxygen dependent in Chlamydomonas grown in 5% CO₂, but CO₂ insensitive in cultures bubbled with air. Anacystis, even when cultured in 5% CO₂, exhibited an CO₂ insensitive net photosynthesis. The CO₂ compensation point of Chlamydomonas grown in cultures bubbled with air and Anacystis grown in 5% CO₂ enriched air, were reached shortly after the measurement was begun and the values were very low, less than 10 μl CO₂ 1^?1; while Chlamydomonas grown in 5% CO₂ enriched air for 4 days showed a high, but temporary CO₂ compensation point (60 μl CO₂ 1^?1). After a two hour adaptation in low CO₂, a stable, low CO₂ compensation point was reached. It seems that photorespiration can only be detected by the methods used in this study when the algae are cultured in high CO₂, but a mechanism exists which blocks photorespiration when the green algae are adapted to low CO₂ concentrations. When Chlamydomonas was treated with Diamox, an inhibitor of carbonic anhydrase, after cultivation in low CO₂ (air), the cells behaved as if they had been grown in high CO₂. They showed an oxygen sensitive net photosynthesis and a high CO₂ compensation point. This indicates that carbonic anhydrase plays an important role in the regulation of a measurable photorespiration in Chlamydomonas. The results are discussed in relation to previous observations of photorespiration measured by enzyme assay, metabolic products and gas exchange properties.     

Impact of rainfall manipulations and biotic controls on soil respiration in Mediterranean and desert ecosystems along an aridity gradient

Spatially heterogeneous ecosystems form a majority of land types in the vast drylands of the globe. To evaluate climate‐change effects on CO₂ fluxes in such ecosystems, it is critical to understand the relative responses of each ecosystem component (microsite). We investigated soil respiration (R_s) at four sites along an aridity gradient (90–780 mm mean annual precipitation, MAP) during almost 2 years. In addition, R_s was measured in rainfall manipulations plots at the two central sites where ～30% droughting and ～30% water supplementation treatments were used over 5 years. Annual R_s was higher by 23% under shrub canopies compared with herbaceous gaps between shrubs, but R_s at both microsites responded similarly to rainfall reduction. Decreasing precipitation and soil water content along the aridity gradient and across rainfall manipulations resulted in a progressive decline in R_s at both microsites, i.e. the drier the conditions, the larger was the effect of reduction in water availability on R_s. Annual R_s on the ecosystem scale decreased at a slope of 256/MAP g C m^?2 yr^?1 mm^?1 (r²=0.97). The reduction in R_s amounted to 77% along the aridity gradient and to 16% across rainfall manipulations. Soil organic carbon (SOC) decreased with declining precipitation, and variation in SOC stocks explained 77% of the variation in annual R_s across sites, rainfall manipulations and microsites. This study shows that rainfall manipulations over several years are a useful tool for experimentally predicting climate‐change effects on CO₂ fluxes for time scales (such as approximated by aridity gradients) that are beyond common research periods. Rainfall reduction decreases rates of R_s not only by lowering biological activity, but also by drastically reducing shrub cover. We postulate that future climate change in heterogeneous ecosystems, such as Mediterranean and deserts shrublands will have a major impact on R_s by feedbacks through changes in vegetation structure.     

Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth

Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 μg K₂CrO₄ mL⁻¹, and an inoculum size of 9.6×10⁷ cells mL⁻¹, B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 μg K₂CrO₄ mL⁻¹, Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30°C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings.

     

Effects of ocean warming and acidification on the energy budget of an excavating sponge

Recent research efforts have demonstrated increased bioerosion rates under experimentally elevated partial pressures of seawater carbon dioxide (pCO₂) with or without increased temperatures, which may lead to net erosion on coral reefs in the future. However, this conclusion clearly depends on the ability of the investigated bioeroding organisms to survive and grow in the warmer and more acidic future environments, which remains unexplored. The excavating sponge Cliona orientalis Thiele, 1900 is a widely distributed bioeroding organism and symbiotic with dinoflagellates of the genus Symbiodinium. Using C. orientalis, an energy budget model was developed to calculate amounts of carbon directed into metabolic maintenance and growth. This model was tested under a range of CO₂ emission scenarios (temperature + pCO₂) appropriate to an Austral early summer. Under a pre‐industrial scenario, present day (control) scenario, or B1 future scenario (associated with reducing the rate of CO₂ emissions over the next few decades), C. orientalis maintained a positive energy budget, where metabolic demand was likely satisfied by autotrophic carbon provided by Symbiodinium and heterotrophic carbon via filter‐feeding, suggesting sustainability. Under B1, C. orientalis likely benefited by a greater supply of photosynthetic products from its symbionts, which increased by up to 56% per unit area, and displayed an improved condition with up to 52% increased surplus carbon available for growth. Under an A1FI future scenario (associated with ‘business‐as‐usual’ CO₂ emissions) bleached C. orientalis experienced the highest metabolic demand, but carbon acquired was insufficient to maintain the sponge, as indicated by a negative energy budget. These metabolic considerations suggest that previous observations of increased bioerosion under A1FI by C. orientalis may not last through the height of future A1FI summers, and survival of individual sponges may be dependent on the energy reserves (biomass) they have accumulated through the rest of the year.     

Comparisons of photosynthesis and photoinhibition in the CAM vine Hoya australis and several C3 vines growing on the coast of eastern Australia

Abstract. The CAM vine Hoya australis and three C₃ vines, Smilax australis, Ipomoea pes-caprae and Kennedta rubicunda, were studied at a site on the coast of northeastern New South Wales, Australia. The level of CAM activity (nocturnal acid accumulation) was comparable in H. australis growing in full sunlight and in deep shade. Acclimation to shade by H. australis was indicated by thinner leaves, increased chlorophyll content, decreased chlorophyll a/b ratios, lower dark respiration rates, and lower light compensation points. When growing in full sunlight H. australis exhibited reductions in photochemical efficiency, as indicated by reduced quantum yields and F_v/F_m fluorescence from PS II as well as low rates of photosynthesis at high light. Sun leaves of H. australis experienced a massive quenching of fluorescence from PS II during normal exposure to midday irradiance which was rapidly reversible under low irradiance conditions in the late afternoon. This quenching indicated a reduction in photochemical efficiency, part of which could be accounted for by an increase in non-radiative energy dissipation, while part of it was due to one or more processes not yet identified. Changes in PS II fluorescence from shade H. australis exposed to full sunlight suggest a decrease in the rate constant for photochemistry indicative of damage to the reaction centre, as well as an increase in non-radiative energy dissipation. The C₃ vine S. australis was also shade tolerant, but exhibited little evidence of photoinhibition when growing in full sunlight. Ipomoea pescaprae and K. rubicunda, both of which were apparently shade intolerant (being found only in full sunlight), possessed high quantum yields and much higher photosynthetic capacities than either H. australis or S. australis. From this study, and several others, it appears that plants possessing CAM experience photoinhibition to a greater degree than do C₃ species in full sunlight under natural conditions, which is probably exacerbated by some degree of CAM-idling.     

Influence of the mycotoxins aflatoxin B1, rubratoxin B,patulin and diacetoxyscirpenol on the fermentation activity of baker's yeast

The fermentation activity of baker's yeast (measured by the amount of produced CO₂) is inhibited by 100µg/ml and 10µg/ml aflatoxin B₁, and by 100µg/ml and 10µg/ml diacetoxyscirpenol. Lower concentrations of these mycotoxins as well as of rubratoxin B enhance the fermentation. Only 0.001µg/ml aflatoxin B₁, 0.00001µg/ml diacetoxyscirpenol and 0.01µg/ml rubratoxin B are without effect or slightly inhibitory. Patulin in all concentrations tested does not influence the CO₂ production significantly. Cytochemical studies show that the enzyme alcohol dehydrogenase is inhibited by 100µg/ml and enhanced by 1µg/ml and 0.1µg/ml aflatoxin B₁. It is suggested that the influence of at least aflatoxin B₁ on the fermentation activity of the yeast cells is due to an interaction with alcohol dehydrogenase. It is possible that the activity of other enzymes of yeast is also influenced by mycotoxins.     

Archaeal Community Structure and Pathway of Methane Formation on Rice Roots

The community structure of methanogenic Archaea on anoxically incubated rice roots was investigated by amplification, sequencing, and phylogenetic analysis of 16S rRNA and methyl-coenzyme M reductase (mcrA) genes. Both genes demonstrated the presence of Methanomicrobiaceae, Methanobacteriaceae, Methanosarcinaceae, Methanosaetaceae, and Rice cluster I, an uncultured methanogenic lineage. The pathway of CH₄ formation was determined from the ¹³C-isotopic signatures of the produced CH₄, CO₂ and acetate. Conditions and duration of incubation clearly affected the methanogenic community structure and the pathway of CH₄ formation. Methane was initially produced from reduction of CO₂ exclusively, resulting in accumulation of millimolar concentrations of acetate. Simultaneously, the relative abundance of the acetoclastic methanogens (Methanosarcinaceae, Methanosaetaceae), as determined by T-RFLP analysis of 16S rRNA genes, was low during the initial phase of CH₄ production. Later on, however, acetate was converted to CH₄ so that about 40% of the produced CH₄ originated from acetate. Most striking was the observed relative increase of a population of Methanosarcina spp. (but not of Methanosaeta spp.) briefly before acetate concentrations started to decrease. Both acetoclastic methanogenesis and Methanosarcina populations were suppressed by high phosphate concentrations, as observed under application of different buffer systems. Our results demonstrate the parallel change of microbial community structure and function in a complex environment, i.e., the increase of acetoclastic Methanosarcina spp. when high acetate concentrations become available.     

Studies on the aerobic utilization of synthesis gas (syngas) by wild type and recombinant strains of Ralstonia eutropha H16

The biotechnical platform strain Ralstonia eutropha H16 was genetically engineered to express a cox subcluster of the carboxydotrophic Oligotropha carboxidovoransOM5, including (i) the structural genes coxM, ‐S and ‐L, coding for an aerobic carbon monoxide dehydrogenase (CODH) and (ii) the genes coxD, ‐E, ‐F and ‐G, essential for the maturation of CODH. The cox_Oc genes expressed under control of the CO₂‐inducible promoter P_L enabled R. eutropha to oxidize CO to CO₂ for the use as carbon source, as demonstrated by ¹³CO experiments, but the recombinant strains remained dependent on H₂ as external energy supply. Therefore, a synthetic metabolism, which could be described as ‘carboxyhydrogenotrophic’, was established in R. eutropha. With this extension of the bacterium's substrate range, growth in CO‐, H₂‐ and CO₂‐containing artificial synthesis gas atmosphere was enhanced, and poly(3‐hydroxybutyrate) synthesis was increased by more than 20%.     

The effect of dynamic light regimes on Chlorella II. Minimum quantum requirement and photosynthesis-irradiance parameters

Comparisons were made of photosynthesis in three light limited cyclostat cultures (LD = 8:16, dilution rate 0.7 d^–1) of Chlorella pyrenoidosa, differing only in the dynamics of irradiance supply: as a constant rate, i.e. a block culture; as a sine function of the light period, i.e. a sinusoidal culture; as an 8 h sine function superimposed by an 1 h sine function, i.e. an oscillating culture. The sinusoidal culture had a constant minimum quantum requirement for oxygen evolution (QR) of 10.8 over the photoperiod. The OR of the oscillating culture increased from 24 to 37 during the photoperiod. From changes in and P _max we suggest that: (1) photosynthetic units (PSU) of the block and sinusoidal sulture increased in number; (2) increasingly fewer chlorophyll molecules participated in oxygenic photosynthesis with a decreasing turnover time of the PSU's during an oscillating photoperiod. Values of I _k decreased slightly in the block culture, increased slightly in the sinusoidal culture and showed a twofold increase in the oscillating culture. From the ratio of in situ oxygen production (qO₂) and P _max we infer a balanced equilibrium between photosystem activity and electron transport capacity for the block and sinusoidal culture. We hypothesize that the qO₂ values of the oscillating culture underestimated true oxygen production rates due to a nonlinear response at peak light intensities. The results show that a dynamical photoperiod provoked significantly different photosynthetic responses, even though the overall growth rate was unaffected.     

Effects of instantaneous and growth CO2 levels and abscisic acid on stomatal and mesophyll conductances

C₃ photosynthesis is often limited by CO₂ diffusivity or stomatal (g_s) and mesophyll (g_m) conductances. To characterize effects of stomatal closure induced by either high CO₂ or abscisic acid (ABA) application on g_m, we examined g_s and g_m in the wild type (Col‐0) and ost1 and slac1‐2 mutants of Arabidopsis thaliana grown at 390 or 780 μmol mol^?1 CO₂. Stomata of these mutants were reported to be insensitive to both high CO₂ and ABA. When the ambient CO₂ increased instantaneously, g_m decreased in all these plants, whereas g_s in ost1 and slac1‐2 was unchanged. Therefore, the decrease in g_m in response to high CO₂ occurred irrespective of the responses of g_s. g_m was mainly determined by the instantaneous CO₂ concentration during the measurement and not markedly by the CO₂ concentration during the growth. Exogenous application of ABA to Col‐0 caused the decrease in the intercellular CO₂ concentration (C_i). With the decrease in C_i, g_m did not increase but decreased, indicating that the response of g_m to CO₂ and that to ABA are differently regulated and that ABA content in the leaves plays an important role in the regulation of g_m.     

乡土植物生活型构成对川渝地区边坡植被水土保持效益的影响

乡土植物灌木化建植是高速公路边坡防护的重要生态模式。为了探讨生态恢复过程中乡土植物的生活型构成对边坡植被水土保持效益的影响,揭示乡土植物生活型-物种多样性-生态系统功能间的偶合关系,借助3个物种配置试验,于2009年4月构建了以草本、灌木或乔木为主体的草本型、灌木型、乔木型绿化配置及草-灌-乔混合型试验区。自建植次年(2010年)起,对试验区进行持续5a生态监测。结果表明:1)边坡植被的物种丰富度与乡土植物的生活型有关,呈现乔木型灌木型草-灌-乔混合型草本型趋势;2)植被的物种多样性(Shannon-Wiener指数、Pielou指数)与乡土植物生活型构成及建植年限有关:建植后第1、第2年,多样性水平呈草本型草-灌-乔混合型灌木型乔木型变化趋势;自建植后第三起(2012—2014年),呈草-灌-乔混合型草本型灌木型乔木型波动;3)植被的水土保持性能(径流系数、侵蚀模数)与群落的物种多样性密切相关:多样性水平越高,水土保持性能越强。可见,乡土植物的生活型构成对提高边坡植被的物种多样性、改善生态性能至关重要。     

Sequential Classification Based on Regression

Let us consider m general populations π₁, …,π_m. Each object belonging to these populations is represented by (p ± 1) characteristics x₁, x₂,…,x_p,y. A certain object, which is an element of one of the m general populations π₁,…,π_m has to be classified into the correct population. It will be assumed that knowledge of the value of the characteristic y would permit its correct classification, but that the observation of this characteristic is expensive, difficult or dangerous, as e.g. in medical applications. y is correlated with a set of p characteristics x₁,x₂,…,x_p, which are observed sequentially. The classification procedure is based on the division of the space of the observed value of characteristics x₁,x₂,…,x_p into nonintersecting areas determined so as to minimize the value of BAYES' risk given by equation (3).