Integrating selected ecological effects of mixed European beech–Norway spruce stands in bioeconomic modelling

The simplicity of many bioeconomic models has been criticised several times, due to their lack of realism resulting from a deterministic nature and a single-species focus. In this context it was interesting to test the financial sensitivity of bioeconomic modelling against fairly well documented ecological effects in mixed forests. For this purpose our study linked existing results of ecological research with bioeconomic modelling. The presented methodological approach could not only show the importance of considering ecological effects in bioeconomic models; it in fact enabled prioritising ecological research from a financial point of view.In a first step, the possible influence of the tree species mixture on forest stand resistance, productivity and timber quality was derived from existing studies. In a second step, the available Monte Carlo simulations for Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.), simulated under site conditions and risks typical of southern Germany, were extended by the mentioned ecological effects and then evaluated from a financial perspective.The results showed a clear influence of all tested ecological effects on the financial indicators, financial risk and return. While testing each ecological effect separately, an increased resistance against wind, snow and insect attacks had the greatest influence on financial risk and return. It over-proportionally enhanced the financial return while simultaneously the financial risk was reduced. In contrast, a degraded timber quality could eliminate the positive effect of risk compensation in mixed forests almost completely. The least influence on the financial indicators finally showed a changed volume growth in mixed forests.A combination of the separately tested ecological effects (increased resistance, changed volume growth and decreased timber quality), between both tree species, underlined the dominating importance of the stand resistance. The integration of ecological effects, induced by interdependent tree species, in our bioeconomic model resulted in significantly lower financial risk than ignoring these effects. Moreover, the financial return of mixed stand variants with a proportion of Norway spruce greater than 60% even exceeded that of the most profitable pure stand.In conclusion this paper clearly confirmed that ignoring ecological effects in bioeconomic models could lead to seriously biased financial results. While a changed volume growth proved rather to be of minor importance for European beech/Norway spruce stands, tree resistance and timber quality may change the financial results significantly.     

酸雨胁迫下黑壳楠Lindera megaphylla Hemsl.幼苗在夏季和秋季的生理生态特性

浙江为酸雨危害严重地区之一,而植物在酸雨胁迫下的生长和生理变化情况可以衡量其对酸雨的耐受能力,亦可作为植被引种、经营和管理的参考依据.采用盆栽法,研究了在不同季节不同强度酸雨胁迫下黑壳楠Lindera megaphylla Hemsl.的生理生态特性,设置了3个酸雨处理:重度酸雨处理(pH2.5)、中度酸雨处理(pH4.0)和酸雨对照处理(pH5.6).研究结果表明:①酸雨、季节以及酸雨和季节的交互效应对黑壳楠的株高、地径和叶绿素相对含量没有显著影响.②黑壳楠的最大净光合速率(Amax)、表观量子效率(AQE)、光补偿点(LCP)和暗呼吸速率(Rd)对酸雨胁迫敏感,而季节并未显著影响到植物的光合特性.③酸雨胁迫显著影响黑壳楠的气孔导度(Gs)、蒸腾速率(Tr)和水分利用效率(WUE).季节对黑壳楠的蒸腾速率(Tr)和水分利用效率(WUE)影响显著.酸雨和季节的交互效应极显著影响到植物的胞间CO2(Ci)浓度和蒸腾速率(Tr).研究表明夏季黑石楠受酸雨胁迫的影响比秋季严重.重度酸雨胁迫严重影响到黑壳楠的生理生长,在酸雨危害严重地区如浙江不适宜大量种植黑壳楠.     

培养基种类和培养条件对白腐真菌生长和产酶特性的影响

以白腐真菌(Phanerochaete chrysosporium)为研究对象,比较了该菌种在人工合成培养基和天然培养基中的生长和产酶特性,考察了竹子浸出液,pH,载体和抗生素等对白腐真菌在天然培养基中生长和产酶特性的影响.结果表明,天然培养基中白腐真菌的生物量、菌丝小球直径和木质素过氧化物酶(LiP)活性均大于人工培养基.以天然培养基为基础培养基,加入竹子浸出液可以促进白腐真菌的生长和提高木质素过氧化物酶活性;较低pH(4.5)条件下菌丝小球直径较小;载体的加入使得菌体以附着形式生长;抗生素两性霉素B对白腐真菌的生长和产酶的影响存在阈值,当ρ(两性霉素B)超过50　mg/L时,白腐真菌的生长和产酶受到明显的抑制.      

鞑靼荞麦离体再生体系的建立

研究了苗龄、外植体、激素配比对鞑靼荞麦(Fagopyrum tataricum Gaertn.)离体培养的影响,初步建立了鞑靼荞麦离体再生体系.结果表明,鞑靼荞麦离体再生的最佳取材时间为苗龄6～8 d;诱导愈伤组织的最适培养基为Ms+2.0 mg/L 2,4.D+1.5 mg/L 6-BA,子叶诱愈率达75%左右,下胚轴诱愈率可高达86.62%;愈伤组织分化的最适培养基为MS+0.1 mg/L IAA+2.0 mg/L 6-BA+1.0 mg/L K1.+0.5 mg/L TDZ,来自下胚轴愈伤组织的分化率可达9.52%.下胚轴的诱愈率与分化率均高于子叶,更适于离体再生培养.培养基巾加入AgNO_3后,能有效降低褐化率.生根最适培养基为含有0.5 mg/L NAA的1/2MS培养基,生根率在50%左右.TDZ在诱导鞑靼荞麦的愈伤组织分化出芽的过程中起到明显的促进作用,可提高分化率约20%.表3图2参23     

湿害处理对不同生育时期芝麻叶片保护酶活性和种子产量的影响

对蕾期、盛花期和终花期的芝麻品种进行了24～60 h的湿害处理.测定了叶片保护酶(POD、SOD、CAT)、植株萎蔫率、死株率等14个性状.结果表明,蕾期和盛花期芝麻叶片中保护酶SOD、POD和CAT活性随着湿害处理时间的延长均呈先升后降的趋势,品种间存在差异.蕾期和盛仡期湿害处理对芝麻生长速率、植株萎蔫率和死株牢影响较大,尤以盛花期最为严重.3个生育时期的芝麻品种受湿害处理后均蒴果数减少、种子产量降低、根系早衰甚至烂根.芝麻叶片保护酶活性与植株萎蔫率、死株率旱显著或极显著负相关,与生长速率、有效蒴果数等9个考察性状呈正相关,且大部分相关系数达到显著或极显著水平.综合各项考察指标,湿害处理对芝麻盛花期影响最为严重,K36 h是多项指标发生急剧变化或转折的敏感时间,湿害后的表现型性状变化趋势与叶片保护酶活性变化趋势在品种间基本一致.图4表1参23     

温度两阶段控制策略发酵生产重组角质酶

为进一步提高重组Bacillus subtilis WSHB06-07发酵生产角质酶的产量和生产强度,在pH两阶段控制策略的基础上,考察了温度(27～40℃)对菌体生长和产酶的影响.研究发现,37℃适于菌体生长而30℃适于菌体产酶.通过分析发酵过程中菌体比生长速率及产物比合成速率的变化,确定了温度两阶段控制策略,即0～4 h时控制温度37℃,4 h后将温度调至30℃.通过采用这一优化策略,角质酶酶活和生产强度分别可达312.5 U/mL和13.02 kU L-1 h-1,相比恒定温度37℃控制模式下分别提高了83.4%和10.9%.图6表2参13     

A derivation of the statistical characteristics of forest fires

The analysis of large data sets concerning fires in various forested areas of the world has pointed out that burned areas can often be described by different power-law distributions for small, medium and large fires and that a scaling law for the time intervals separating successive fires is fulfilled. The attempts of deriving such statistical laws from purely theoretical arguments have not been fully successful so far, most likely because important physical and/or biological factors controlling forest fires were not taken into account. By contrast, the two-layer spatially extended forest model we propose in this paper encapsulates the main characteristics of vegetational growth and fire ignition and propagation, and supports the empirically discovered statistical laws. Since the model is fully deterministic and spatially homogeneous, the emergence of the power and scaling laws does not seem to necessarily require meteorological randomness and geophysical heterogeneity, although these factors certainly amplify the chaoticity of the fires. Moreover, the analysis suggests that the existence of different power-laws for fires of various scale might be due to the two-layer structure of the forest which allows the formation of different kinds of fires, i.e. surface, crown, and mixed fires.     

A comparison of four process-based models and a statistical regression model to predict growth of Eucalyptus globulus plantations

In forest management and ecological research, consideration of the impacts and risks of climate change or management optimisation is complex. Computer models have long been applied as tools for these tasks. Process-based forest growth models claim to overcome the limitations of empirical statistical models, but the capacity of different process-based models and modelling approaches have rarely been compared directly. This study evaluates stepwise multiple regression models in comparison to four process-based modelling approaches (3-PG, 3-PG+, CABALA and Forest-DNDC) for greenfield predictions of Eucalyptus globulus plantation growth from 2 to 8 years after planting throughout southern Australia.     

Consideration of translocation into a growth model of a plant organ

Taking account of the Bertalanffy's differential equation on animal growth, plant growth is also considered as the net result of anabolism and catabolism. When we, however, consider the growth of a plant organ, it is necessary to add a term of translocation because it plays an important role in the growth of plant organs, such as leaf and fruit. Considering translocation, therefore, a growth model of a plant organ was proposed on the basis of the compartment model for estimating the carbon balance in the organ by using the experimental data on translocation, photosynthesis and respiration of a tropical fruit of durian (Durio zibethinus Murray). The present growth model of a plant organ belongs to an extended Bertalanffy's growth equation, and was possible to be transformed into the simple Bertalanffy's growth equation on the basis of the proportionality between the growth and translocation rates. The Bertalanffy's growth equation of a plant organ was also possible to apply to that of the whole plant on the assumption of the allomeric relationship between a plant organ and the whole plant.     

南湖富营养化主要控制因子分析

全面分析了南湖湖泊系统中营养物之间、营养物与藻类生长之间的相互关系,探讨了各种环境因子对南湖富营养化的影响,结合藻类增长潜力试验结果确定南湖富营养化的主要控制因子。结果表明,光、温度、碳、氮不能成为南湖富营养化的主要控制因子,控制南湖富营养化的关键在于控制磷。