Influence of root temperature on growth of Pinus sylvestris,Fagus sylvatica,Tilia cordata and Quercus robur

One-year-old tree seedlings were incubated in a greenhouse from April to July, under natural daylight conditions, with their root systems at constant temperatures of 5, 10, 15, 20, 25, 30 and 35 °C and with the above ground parts kept at a constant air temperature of 18–20 °C. The course of height growth, total mass increment, root, shoot and leaf weight as well as leaf areas were measured. The results indicate that clear differences exist in the optimal root zone temperatures for various growth parameters in different tree species. Pinus sylvestris had a maximal height increment at about 5–10 °C and maximal total mass increment at 15 °C root temperature. In contrast, the optimum for Quercus robur was at 25 °C. Tilia cordata and Fagus sylvatica had their optima for most growth parameters at 20 °C. The root temperature apparently indirectly influenced photosynthesis (dry weight accumulation) and respiration loss. From the observed symptoms and indications in the literature it seems probable that a change in hormone levels is involved as the main factor in the described effects. Variation of root temperature had only an insignificant effect on bud burst and the time at which the shoots sprouted. Apparently species of northern origin seem to have lower root temperature optima than those of more southern origin. This is to be verified by investigation of other tree species.     

Comparative immunomodulatory effect of scopoletin on tumoral and normal lymphocytes

Some coumarins possess enhancing effects on lymphocyte mitogen responsiveness. In this investigation, the activity of scopoletin, a coumarin that has been isolated from different plants and in this case specifically from T. cordata Mill., was evaluated. For this purpose, normal T lymphocytes and a hyperproliferative T lymphoma cell line were used. Scopoletin was found to exert a dual action on tumoral lymphocytes exhibiting both a cytostatic and a cytotoxic effect. These effects varied with the concentrations analysed and the time of cell incubation (EC(50): 251+/-15 microg/ml) and were associated to the induction of apoptosis. Scopoletin induced cell proliferation on normal T lymphocytes (Proliferation stimulation index: 1 microg/ml scopoletin: 1.26+/-0.1; 10 microg/ml scopoletin: 3+/-0.25; 100 microg/ml scopoletin: 1.86+/-0.08); this stimulatory action was found to be due to the interaction with kinase C (PKC) protein. These results indicate that scopoletin could be a potential antitumoral compound to be used for cancer treatment.     

Complementarity in the use of nitrogen forms in a temperate broad-leaved mixed forest

Background: The complementary use of different forms of soil nitrogen (N) might lead to a higher productivity of mixed forests than monocultures, but convincing evidence for temperate mixed forests is scarce.

Aims: We searched for species differences in N uptake rates and the preference for NH₄⁺, NO₃^? or glycine among five temperate broad?leaved tree species (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia cordata) in a mature mixed stand.

Methods: ¹⁵N tracer was added to the soil and its accumulation in fine root biomass was analysed after 10 min, 1 h and 1 d.

Results: The estimated root uptake rates of the species were in the range of 5–46 µg N g^?1 root h^?1 for NH₄⁺, 6–86 µg N g^?1 h^?1 for NO₃^? and 4–29 µg N g^?1 h^?1 for glycine during the first hour after tracer application. Carpinus, Tilia and Acer tended to prefer NH₄⁺ over NO₃^?, while Fraxinus showed equal preference for both N forms and Fagus seemed to prefer NO₃^?.

Conclusions: The five co-existing tree species differed in uptake rates and partly in their N form preference, but complementarity in the use of different N forms seems to be of minor importance in this forest because tree species appear to be rather flexible in their N form use.     

主要伴生树种叶粉对紫椴幼苗生长的影响

 紫椴(Tilia amurensis)是我国东北东部山地的重要造林树种之一,常常与红松(Pinus koraiensis)、云杉(Picea koraiensis)及水曲柳(Fraxinus mandshurica)等针阔叶树混生,因此,研究这些针阔叶树种对紫椴生长的影响,对于进一步了解这些树种的化感作用和选择适合营造混交林的搭配树种均具有重要意义。本文是通过大量的盆栽实验,以紫椴、水曲柳、红松和云杉等叶粉混拌火山灰进行培育紫椴幼苗,研究这些树种对紫椴生长的影响。实验表明,红松、云杉等针叶树对紫椴幼苗的生长具有明显的抑制作用,并找出紫椴幼苗高生长与针叶含量的相关性。     

Shape of leaf photosynthetic electron transport versus temperature response curve is not constant along canopy light gradients in temperate deciduous trees

Responses of foliar light-saturated net assimilation rate (A_max), capacity for photosynthetic electron transport (J_max) and mitochondrial respiration rate (R_d) to long-term canopy light and temperature environment were investigated in a temperate deciduous canopy composed of Populus tremula L. in the upper (17–28 m) and of Tilia cordata Mill. in the lower canopy layer (4–17 m). Climatic measurements indicated that seasonal average daily maximum air temperature (T_max) was 5·5 °C (range 0·7–10·5 °C) higher in the top than in the bottom of the canopy, and strong positive correlations were observed between T_max and seasonal average integrated quantum flux density (Q_int), as well as between seasonal average daily mean temperature and Q_int. Because of changes in leaf dry mass and nitrogen per unit area, A_max, J_max, and R_d scaled positively with Q_int in both species at a common leaf temperature (T). According to J_max versus T response curves and dark chlorophyll fluorescence transients, photosynthetic electron transport was less heat resistant in P. tremula with optimum temperature of J_max, T_opt, of 33·5 ± 0·6 °C than in T. cordata with T_opt of 40·7 ± 0·6 °C. This difference was suggested to manifest evolutionary adaptation of photosynthetic electron transport to cooler environments in P. tremula, the range of which extends farther north than that in T. cordata. Possibly because of acclimation to long-term canopy temperature environment, T_opt was positively related to Q_int in P. tremula, foliage of which was also exposed to higher irradiances and temperatures, but not in T. cordata, in the canopy of which quantum flux densities and temperatures were lower, and gradients in the environmental factors less pronounced. Parallel to changes in T_opt, the activation energy for photosynthetic electron transport decreased with increasing Q_int in P. tremula, indicating that J_max of leaves acclimated to colder environment was more responsive to T in lower temperatures than that of high T acclimated leaves. Similar alterations in the activation energy for mitochondrial respiration rate were also observed, indicating that acclimation to temperature of mitochondrial and chloroplastic electron transport proceeds in a co-ordinated manner, and possibly involves long-term changes in membrane fluidity properties. We conclude that, because of correlations between temperature and light, the shapes of J_max versus T, and R_d versus T response curves vary within tree canopies, and this needs to be taken account in modelling whole canopy photosynthesis.     

紫椴根际土壤肥力与外生菌根侵染关系

调查帽儿山老山生态站紫椴(Tilia amurensis Rupr.)外生菌根的侵染情况与根际土壤肥力指标,结合Pearson相关性分析与逐步回归分析的统计方法,分析紫椴外生菌根侵染率与根际土壤肥力指标的相关性。结果表明:紫椴外生菌根侵染率与碱性磷酸酶、碱解氮、有效磷、土壤水分含量呈极显著负相关,与脲酶呈极显著正相关,与速效钾呈显著正相关。逐步回归分析发现,影响紫椴外生菌根侵染率的主要土壤肥力因子是碱性磷酸酶和土壤水分含量。     

椴树属的地理分布

椴树属Tilia是椴树科一个形态特殊且唯一的北温带分布属,分布于亚洲、欧洲和北美,构成典型的北温带分布格局,三个分离的分布区之间缺乏共有种。本文对各分布区的种类进行重新评价,确认全属25种。其中东亚17种,占68％,包含了现存种类各个演化阶段的类群,是现代分布中心;欧洲-西西伯利亚6种,属于木果组及壳果组;北美2种,均为木果组成员。化石分布与现代地理分布格局基本相似,但分布纬度较现代分布偏北,达到北纬80°附近,且还出现于现今无椴树分布的亚洲大陆腹地,北美西部椴树至第三纪末完全绝迹,而东部到第四纪才有化石记录。根据现代地理分布,结合化石证据、地质历史、气候变迁及形态演化推测,椴树属可能在白垩纪晚期起源于中国东部亚热带山地,至少到始新世之前已散布至欧洲和北美西部。渐新世之后的全球降温和更新世大冰期对椴树属现代地理分布格局的形成起着至关重要的作用。     

Variability of Mercury Concentrations in Soil and Leaves of Acer plantanoides and Tilia platyphyllos in Poznań City,Poland

The paper presents the results of research on mercury in the soil and leaves of maple (Acer plantanoides) and linden (Tilia platyphyllos) collected in the four districts of the city of Poznań (Poland), which differ in terms of anthropogenic pressure. The average concentration of mercury in soil was 132 μg kg^?1. The highest concentration of mercury was determined in Tilia platyphyllos (233 μg kg^?1), whereas in Acer plantanoides it amounted to 207 μg kg^?1. Based on the study, it was found that the highest concentration of mercury in the investigated leaf species was observed in the samples collected in the districts of Grunwald, Je?yce, and Old Town. The lowest concentration was observed in the samples collected in the district of New Town. The comparison of the obtained results of mercury concentration in soil and leaf samples was made in terms of anthropogenic pressure in the investigated areas and depending on the studied leaf species. Based on the statistical analysis, it was found that there is no statistically significant relationship between mercury concentration in both studied species of trees. There was, however, a relationship between the mercury concentration in leaves and soil.