天水小陇山锐齿栎群落土壤全N分布特征及与生物多样性关系研究

对天水小陇山锐齿栎群落不同演替阶段土壤全N含量进行了分析 ,探讨了土壤全N与群落生物多样性之间的关系 ,结果表明 :随发育阶段土壤全N含量呈稳定的变化趋势。发育中期 ,随多样性指数、均匀度指数、优势度指数的增加 ,全N含量呈“V”型变化趋势 ,随丰富度指数增加 ,全N含量呈逐渐减小趋势 ;发育后期 ,随着多样性指数、丰富度指数、优势度指数的增加 ,全N呈逐渐增加趋势 ,随着均匀度的增加 ,全N变化不明显 ;发育末期 ,多样性指数、均匀度指数、优势度指数趋于稳定 ,土壤全N含量不稳定 ,随丰富度指数的升高 ,全N有先升高后降低的趋势。     

Effect of oak (Quercus persica) acorn level on apparent digestibility,ruminal fermentation,nitrogen balance and urinary purine derivatives in pregnant goats

The aim of this experiment was to investigate the effect of dietary oak (Quercus persica) acorn (OA) level on dry matter intake (DMI), apparent nutrient digestibility, nitrogen (N) utilization, ruminal fermentation, protozoa population and urinary purine derivatives (PD) during the last 60 days of goat pregnancy. Twenty‐four multiparous pregnant goats (41.7 ± 2.3 kg BW) were assigned to one of three experimental diets consisted of control diet (C, without OA) and diets containing 20 (OA₂₀) or 40 g/100 g of OA (OA₄₀) on a DM basis in a completely randomized block design. Goats fed OA₄₀ had lower DMI (p < .01), DM (p < .01), OM (p < .01) and NDF (p < .05) digestibility, ruminal NH₃‐N concentration (p < .01), N intake (p < .01) and N retention (p < .01). Crude protein digestibility and ruminal acetate and total volatile fatty acid (VFA) concentration were lower in animals fed OA‐contained diets (p < .01), whereas ruminal propionate concentration was higher in goats fed the C diet (p < .01). Animals fed OA₄₀ had higher faecal N excretion and lower urinary N excretion (p < .01). Urinary PD was lower in goats fed diets containing OA in relation to those fed the C diet (p < .01). Total protozoa population decreased linearly with increasing OA level in the diet (p < .05). These results suggest that feeding OA, especially high level, has negative impacts on DMI, nutrient digestibility, VFA concentration, N retention and urinary PD excretion that may have adverse effects on metabolism and performance of pregnant goats.     

地表火对宝天曼栎类森林生态系统服务功能的影响研究

2008年4月至2010年6月采用时间序列代替空间序列的方法,对宝天曼栎类森林生态系统服务功能受地表火影响在不同时间的涵养水源、保育土壤、固碳释氧、生物保育、积累营养物质、负离子提供和森林病虫害防治等7个方面进行了初步评估。结果表明,地表火干扰造成宝天曼栎类森林生态系统服务功能损失的价值在时间序列上依次为1年是24.95万元.hm-2,5年是11.68万元.hm-2,10年是4.91万元.hm-2,15年是0.68万元.hm-2;各项服务功能价值量损失排序为保育土壤>涵养水源>病虫害防治>固碳释氧>积累营养物质>净化大气>生物保育,其中保育土壤和涵养水源两项的损失占总损失量的70%左右,这表明地表火主要影响宝天曼栎类森林生态系统中的保育土壤和涵养水源功能。     

制造橡木桶用木材的微观结构研究

为比较制造橡木桶用木材的微观结构特征,选用10种橡木(Quercus L.)为试验材料,通过显微镜观察橡木的导管、木射线和轴向薄壁组织,分析常见橡木的共性与个性。结果表明,栓皮栎(Q.variabilis Bl.)导管内侵填体较少,液体流透性比较高;美国红橡(Q.rubra L.)管孔较大,与外界的空气接触过多,二者均不适合制造橡木桶。夏橡(Q.robur L.)、卢浮橡(Q.sessiliflora Salisb)、孚日橡(Q.pendunculata L.)、无梗花橡[Q.petraea(Matt.)Liebl.]、星毛橡(Q.stellata Wangenh)、美洲白橡(Q.alba L.)、沼生白橡(Q.bicolor Willd.)、蒙古栎(Q.mongolica Fisch.ex Ledeb)这8种橡木适合制造橡木桶,其共同特征是有合适的管孔大小,具有一定的透气性,可以与外界空气发生微氧反应;有丰富的侵填体,可以堵塞橡木桶内壁管孔,降低气体和液体在木材中的渗透性,从而保证陈酿过程中酒的口感。10种橡木的木射线和轴向薄壁组织无明显区别。为此,橡木的导管大小和侵填体多少是判定是否适合制造橡木桶的关键要素。     

Behavior of phenolic substances in the decaying process of plants

The behavior of phenolic substances in the decaying process of rice straw, ladino clover, and fanen leaves of red oak under moist conditions, and also of rice straw under various conditions were compared in the laboratory. The amounts of phenolic substances, divided into either humic acid and fulvic acid fractions, or ether-extractable, butanol-extractable and organic solvent-unextractable fractions, and the amounts of individual phenolic acids were periodically determined during incubation for 150 days. The following results were obtained.

1) The amounts and behavior of phenolic substances in various fractions differed considerably among the plant materials. The total amount of phenolic substances was remarkably larger in red oak leaves than in the others during the whole period of incubation. The amounts of phenolics in the fulvic acid fraction changed to a larger extent than those in the humic acid fraction during the decaying process of plant materials. The changes in total amount of phenolics in decaying red oak leaves and ladino clover were mainly due to changes in the level of relatively hydrophilic phenolics in the fulvic acid fraction, but the changes in decaying rice straw were mainly due to changes in the level of relatively lipophilic phenolics.

2) Rice straw and ladino clover, especially the former, contained large amounts of p-coumaric and ferulic acids, but these decreased rapidly in the early stage of the decaying process. The amounts in red oak leaves were small, but did not decrease markedly during incubation.

3) The changes in amounts of phenolics in both humic acid and fulvic acid fractions in the decaying process of rice straw were largely influenced by temperature, moisture, and pH, but not to a large extent by C/N ratio and the presence of soil. At higher temperatures under moist conditions, phenolic substances disappeared rapidly. Also, acidification of the system inhibited the degradation process.     

Interaction between climate and management on beta diversity components of vegetation in relation to soil properties in arid and semi-arid oak forests,Iran

This study aimed to investigate the interaction between regions with different climatic conditions(arid vs. semi-arid) and management(protected vs. unprotected) on the turnover and nestedness of vegetation in relation to physical, chemical and biological properties of soils in the Ilam Province of Iran. In each of the two regions, we sampled 8 sites(4 managed and 4 unmanaged sites) within each of which we established 4 circular plots(1000 m~2) that were used to investigate woody species, while two micro-plots(1 m×1 m) were established in each 1000-m~2 plot to analyze herbaceous species. In each sample unit, we also extracted three soil samples(0–20 cm depth) for measuring soil properties. The results indicated that the interaction between region and conservational management significantly affected the percent of canopy cover of Persian oak(Quercus brantii Linddl), soil respiration, substrate-induced respiration, as well as beta and gamma diversities and turnover of plant species. The percent of oak canopy cover was positively correlated with soil silt, electrical conductivity, available potassium, and alpha diversity, whereas it was negatively correlated with plant turnover. In addition, plant turnover was positively related to available phosphorus, while nestedness of species was positively related to organic carbon and total nitrogen. According to these results, we concluded that physical, chemical, and biological characteristics of limited ecological niche generally influenced plant diversity. Also, this study demonstrated the major contribution of the beta diversity on gamma diversity, especially in semi-arid region, because of the higher heterogeneity of vegetation in this area.     

麻栎叶片含水率与水分指数关系分析

选择江苏省连云港市花果山优势树种麻栎树为研究对象,采集其位于不同海拔位置的树木叶片,测量鲜重及经不同程度阴干处于不同水分状态下叶片的水分指数(W I)和含水率(FMC),在叶片水平上,研究水分指数与含水率之间的关系。研究表明,水分指数对麻栎叶片含水率的变化敏感,二者之间统计关系明显;叶片含水率可以通过水分指数进行曲线拟合,拟合曲线为y=19.022x2-32.707x+14.064,其稳定性较好。     

暖温带-亚热带过渡区鸡公山落叶栎林和松栎混交林 土壤有机碳空间分布特征

河南省鸡公山位于暖温带-亚热带过渡区,落叶栎类栓皮栎(Quercus variabilis Blume.)和麻栎(Q.acu-tissima Carr.)混交林和马尾松(Pinus massoniana Lamb)栎类混交林是该区域的2种典型林分类型。分别在海拔200、400和600 m的落叶栎林和松栎混交林中设置样地,比较土壤有机碳(SOC)含量和碳密度的变化。结果表明,随着海拔升高,2种类型林分的土壤有机碳含量和密度显著增加(P0.05);在200和400 m海拔高度上,松栎混交林分土壤有机碳密度高于落叶栎林。在600 m海拔高度上,落叶栎林土壤有机碳密度高于松栎混交林。对于各个海拔高度林分来说,土壤有机碳含量和密度随着土壤深度增加而降低,0～20 cm土层有机碳密度对剖面总有机碳贡献率为77%～93%。这些结果揭示该地区森林土壤有机碳分布特点,也为当地碳汇林业的经营提供了依据。     

Recreational preferences depending on thinning practice in young even-aged stands of pedunculate oak (Quercus robur L.): comparing the opinions of forest and landscape experts and the general population of Denmark

The aim of this study was to investigate to which extent forestry professionals, other “green” professionals (mainly landscape architects) and natural resource students in Denmark agree with the general population regarding their recreational preferences for contrasting stem densities in young, even-aged stands of pedunculate oak (Quercus robur L.). The study was based on five pairs of colour photographs from each of the five recently thinned experimental plots in a 13-year-old stand. The plots represented five different residual stem densities: 7000 (unthinned), 5300 (traditional thinning), 1000, 300 and 100 stems ha^?1. All cut trees were left on the ground. The analysis was carried out as a survey of forest and landscape experts (n=158) and the general public (n=243) based on questionnaires. Interviewees ranked the photographs according to the criterion: “Which forest environment do you prefer as a visitor?” Principal component factor analysis showed that the general public tended to perceptually group photos according to similar overall pattern of openness, presence of row structure and stand accessibility (including presence/absence of slash). As long as a stand appeared accessible, stand density had little influence on their preferences for a wide range of stand densities (5300?300 stems ha^?1). In contrast, foresters, other “green” professionals and students seemed to perceptually group photos according to treatment type, and the presence of slash had little influence on their preferences. This suggests an influence of professional background, making experts visually analyse and evaluate stands according to contemporary management standards and paradigms within their own profession.     

Testing variability in pathogenicity of Phytophthora cinnamomi

Forty eight isolates of Phytophthora cinnamomi from various host plants in France (35 isolates) and in other countries were tested for pathogenicity. Seedlings of chestnut, northern red oak, pine and eucalyptus were infected by soil contamination. Taproots, stems and bark strips of plants of chestnut and different oak species were inoculated with mycelium agar disks. Results of the different experiments were in good agreement. All isolates appeared pathogenic to all the different test species but with variable levels of virulence. Isolates with consistent low or high level of virulence, which could be used as standards in further studies, were identified. Interaction between P. cinnamomi isolates and host plant species was significant in terms of lesion lengths. These interactions could not be related to host from which P. cinnamomi was isolated. Consistent with this, in Quercus rubra, the isolate-provenance interaction was not significant. This feature is encouraging for provenance screening for resistance to P. cinnamomi in this species. The variation in virulence was not related to other isolate characteristics (mating type, electrophoretic type, age).