A Preliminary Studies on the Biomass of Bothriochloa isohaemum Community of Loess Plateau in North Shaanxi Province

This paper deals with the seasonal and spacial change of the biomass of aboveground and underground part in Bothriochloa ischaemum community. The results showed obvious biomass seasonal dynamics in B. ischaemum community. The biomass of aboveground achieved peak value (314.66g/m2) in the mid-September. The biomass of underground was minimum during flourishing period and maximum during the withering period. Such change in biomass is relevent to the developmental stages and transport of organic materials.     

Dynamics of Primary Productivity and Soil Organic Matter of Typical Steppe in the Xilin River Basin of Inner Mongolia and Their Response to Climate Change

At the site level, the authors used the Century plant-soil ecosystem model and Landsat remote sensing to estimate the aboveground biomass of Aneurolepidium chinense steppe and Stipa grandis steppe in the Xilin river basin, Inner Mongolia China. The results of century simulation matched well in terms of the seasonal and yearly change of biomass, with those of field moniforing. The results of field monitoring replicated well were about 142.45～144.37 g/m2 and 210. 38~227.44 g/m2 on S. grandis and A. chinense steppe, respectvely, whereas the simulation results were 127. 04～156. 23 g/m2 and 189.25~193.98 g/m2, respectively. Simulated soil organic matter was around ±–25% of the observed data. Normalized differnce vegetation index derived aboveground biomass was around ±25 % of the observed field biomass on the A. chinence and S. grandis steppe, using Landsat TM imagecries on July 31, 1987 and August 11, 1991. The effect of global climate change and elevated CO2 on these steppe was examined, using the climate fields from Global Change Models of Canadian Climate Center and Geophysics Flow Dynamics Laboratory under 1 × CO2 (350 X 10-6) and 2 × CO2 (700 X 10-6) sceneries. Climate change resulted in considerable decrease of primary productivity and soil organic matter of A. chinense and S. grandis steppe, the former being more sensitive to climate change.     

鲁北滨海盐生草甸獐茅群落生长季动态

作者在1982—1984年度对鲁北滨海盐土区的山东省沾化草场改良实验站的獐茅(Aeluropus littoralis var.sinensis)群落生长季内的群落动态及其与环境因子的关系进行了研究(其中1982—1983年配合草场站工作进行月份观测),认为温度的变化与群落生长季内的节律性有明显的相关性。根据生物量的变化,把一个完整的生长季划分为上升期和下降期两个时期,并讨论了这两个时期中生物量、半月平均气温和时间的关系以及生物量和半月平均气温的关系。     

崂山麻栎林种群特征及生物量测定

用点四分法抽测崂山麻栎(Quercus acutissima)林,将获得的150个样点资料建立在通过群落郁闭度系数所反映的光照强度、土壤相对持水量、土壤肥力得分及碱解氮含量的四维空间上,构造了麻栎幼苗,灌木层,草本层及其优势种生物量预测方程;提出度量植物种群对资源选择性系数的新公式,并证明了它的实用性。本文详细探讨了林下优势种的选择性系数、生态位宽度和生态位重叠;指出影响麻栎幼苗生长及栎林群落生产量的限制因子;阐述了种类多样性和均匀度与环境间的关系。     

马尾松林杆材阶段生物产量和经级分化及密度效应初探

马尾松(Pinus massoniana)是我国松树中分布最广、数量最多的主要用材和薪炭材树种。它具有适应性强、生长快、用途广,造林成本低和易于成林等优点,是我国南方荒山造林的重要先锋树种,其经济意义、环境防护效能及美学价值,都是为人们所公认的。马尾松的干材成长阶段,是林木胸径和树高旺盛生长时期,林木与生长空间的矛盾及树木间的竞争较剧烈,天然整枝、林木分化和自然稀疏都很强烈。如何调节和控制这个时期的立木密度,使其形成合理的群体结构,对于保证林木成熟期的材积生长和取得最大生物量将具有十分重要意义。本试验目的就在于探明不同密度松树杆材林的生物量、林木分化与产量结构以及不同密度下的生态效应,为确定合理的造林密度和制定疏伐措施提供科学依据。     

Studies on the Biomass of Robinia pseudoaeacia Plantation

The average height of 31-aged Robinia pseudoacacia plantation in west mountain of Beijing is 7 in and the mean breastheight diameter of tree is 8.3 cm. The number of tree per hectare appears 1750. The canopy coverage of plantation shows 0.5. Using tile diameter square at tree breast height times tree height (D2H), as an independing variable, to estimate the dry weight of various parts of trees, between them the significient correlations occur. According to the modle of Wstem=58.88(D2H)0.88 (WBranch)=e7.77+0.001(D2H) (Wleaf)=e5.71+0.0008(D2H) (Wroot)＝e7.67+0.0009(D2H) 28.45 t/ha of the stem biomass, 11.6 t/ha of the branch biomass. 0.97 t/ha of the leaf biomass, 7.6 t/ha of the root biomass are estimated in arbor layer. The aboveground and belowground biomass of shrub and herb layers axe 13.71 t/ha and 10.72 t/ha respectively in September, the biomass of shrub and herb layer is 24.43 t/ha. 73.05 t/ha of the total biomass in Robinia pseudoacacia plantation is obtained.     

Lichen respiration in relation to active time, temperature, nitrogen and ergosterol concentrations

1. Respiration in eight lichen species was related to thallus hydration status, external temperature and to total nitrogen, chitin and ergosterol concentrations. Chitin is a nitrogenous and major compound of the fungal cell wall, and ergosterol is a sterol of the plasma membrane in fungi and sometimes in algae.
2. Hydration of previously dry thalli resulted in an initially high rate of respiration. Both the amplitude of this resaturation respiration and the time required to reach steady state varied among species. Generally, peak rates were one to three times higher than steady-state rates, which were reached 3–7 h after hydration.
3. Increases in external temperature also resulted in transient bursts in respiration. Again, both the amplitude of the burst and the time required to reach steady state varied among species. Also depending on species, a temperature increase from 5 to 15 °C resulted in two- to fivefold increases in steady-state respiration.
4. Steady-state respiration, at optimal thallus hydration and a given temperature, varied three- to sixfold among the species, when related to thallus dry mass. This difference correlated best ( r ² = 0·89) with their ergosterol concentration, where a doubling in ergosterol resulted in more than a doubling in respiration. Respiration correlated less well to total nitrogen or chitin.
5. The chitin to ergosterol ratio varied more than one order of magnitude between the species, where species with high nitrogen concentrations had the highest ratio. This implies that species with access to ample amounts of nitrogen can make more fungal cell walls in relation to plasma membrane surface area.     

Deciphering role of technical bioprocess parameters for bioethanol production using microalgae

Microalgae biomass is considered an important feedstock for biofuels and other bioactive compounds due to its faster growth rate, high biomass production and high biomolecules accumulation over first and second-generation feedstock. This research aimed to maximize the specific growth rate of fresh water green microalgae Closteriopsis acicularis, a member of family Chlorellaceae under the effect of pH and phosphate concentration to attain enhanced biomass productivity. This study investigates the individual and cumulative effect of phosphate concentration and pH on specific growth characteristics of Closteriopsis acicularis in autotrophic mode of cultivation for bioethanol production. Central-Composite Design (CCD) strategy and Response Surface Methodology (RSM) was used for the optimization of microalga growth and ethanol production under laboratory conditions. The results showed that high specific growth rate and biomass productivity of 0.342 day⁻¹ and 0.497 g L⁻¹ day⁻¹ respectively, were achieved at high concentration of phosphate (0.115 g L⁻¹) and pH (9) at 21st day of cultivation. The elemental composition of optimized biomass has shown enhanced elemental accumulation of certain macro (C, O, P) and micronutrients (Na, Mg, Al, K, Ca and Fe) except for nitrogen and sulfur. The Fourier transform infrared spectroscopic analysis has revealed spectral peaks and high absorbance in spectral range of carbohydrates, lipids and proteins, in optimized biomass. The carbohydrates content of optimized biomass was observed as 58%, with 29.3 g L⁻¹ of fermentable sugars after acid catalyzed saccharification. The bioethanol yield was estimated as 51 % g ethanol/g glucose with maximum of 14.9 g/L of bioethanol production. In conclusion, it can be inferred that high specific growth rate and biomass productivity can be achieved by varying levels of phosphate concentration and pH during cultivation of Closteriopsis acicularis for improved yield of microbial growth, biomass and bioethanol production.     

不同基质中水鳖对共存的穗花狐尾藻和金鱼藻的影响

研究设置了营养水平不同的3种基质,在有或无浮水植物水鳖共存的情况下,混合种植营养吸收方式不同的两种沉水植物（仅从水中吸收营养的金鱼藻和从水和基质都能吸收营养的穗花狐尾藻）,探讨在不同的基质中浮水植物对沉水植物的影响。结果显示:实验中水鳖的存在均未对共存的两种沉水植物的生长产生抑制作用。当水鳖覆盖水面时,与无根的金鱼藻竞争光照和水体营养,促使其增加分枝数和茎长,并增加叶生物量的分配,最终导致水鳖的共存促进了金鱼藻的生物量积累。但与金鱼藻不同,有根的穗花狐尾藻可通过基质吸收营养,与共存的水鳖之间只存在光照竞争,使穗花狐尾藻仅以改变植株形态来适应浮水植物的表层覆盖,生物量积累并未发生显著变化。与沙处理相比,水鳖在营养水平较高的泥处理和泥沙混合处理中生长更旺盛,基质没有显著影响沉水植物的生物量和分株数。因此,在退化湿地生态系统中恢复水生植物时,为了提高群落的物种多样性,可以将沉水植物与少量的浮水植物组合配置,少量的浮水植物不会对沉水植物的生长带来负面影响。