黄土丘陵区几种林木茎干径向生长的日变化及其对环境因素的响应

利用树木径向生长仪研究了黄土丘陵区6年生油松(Pinus tabulaef ormis)、山杨(Populus davidiana)和辽东栎(Quercus liaotungensis)及林下灌木胡颓子(Elaegnus umbellata)4种林木整个生长季茎干的径向变化,发现4种林木的径向变化表现为膨胀收缩旋回增长的模式。在整个生长季中,山杨从5月到10月径向持续增长,增长时间最长;而油松和胡颓子的径向生长主要发生在7月份,从8月份开始其增长速率变缓;辽东栎在整个生长季节的径向生长最小。在整个生长季内,山杨径向增长了2.63 mm,胡颓子为0.64 mm,油松和辽东栎则分别为0.40 mm和0.26 mm。辽东栎日收缩量与膨胀量明显大于其他树种。通过对影响林木径向生长的15种环境因子进行主成分分析后,将主要环境因子归结为温度影响因子、湿度影响因子和降水影响因子3个主成分,并提取了影响该区几种林木生长的主要环境因子:日大于0℃的积温、最低6 h相对湿度和日降雨量。采用线性逐步回归方法,建立了日膨胀量与日收缩量与3个主要环境因子之间的关系。发现日收缩量与日大于0℃的积温成正相关,而与最低6 h相对湿度和日降雨...

子午岭森林群落土壤水分与生物量关系研究

通过对黄土丘陵区子午岭北部山杨林、白桦林、油松林和辽东栎林植被群落特征的分析,研究了植被演替过程中土壤水分和生物量的变化及其相互关系。结果表明,在植被正向演替过程中,土壤含水量随植被正向演替而逐渐减少,土壤含水量的大小顺序依次为山杨>白桦>油松>辽东栎;土壤含水量对树枝和树干生物量的影响较大,立地条件致使各林分地上生物量发生明显变化;在林龄差距不大的条件下各林分平均单株生物量的大小关系为辽东栎>白桦>山杨>油松。

黄土高原白羊草、沙棘和辽东栎细根比根长特性

以黄土高原地区典型草本(白羊草)、灌木(沙棘)和乔木(辽东栎)为对象,研究了3种植物细根比根长在不同土层的分布状况以及与其它细根参数和土壤物理因子之间的相关性。结果表明,3种植物细根比根长的变化范围为6~55 mm/mg。在0~80cm土层,白羊草、沙棘和辽东栎细根比根长变化范围分别为18~55 mm/mg,14~40 mm/mg,6~33 mm/mg。3种植物0~80cm土层平均细根比根长从大到小依次为白羊草>沙棘>辽东栎。3种植物0~10cm土层细根比根长依次为沙棘>辽东栎>白羊草,10~80cm依次为白羊草>辽东栎>沙棘,表明3种植物细根比根长不仅在这两土层中的分布不具一致性,而且与0~80cm土层平均比根长也不具有一致性,进一步说明3种植物沿土壤剖面的生物量分配策略不同。相关分析表明,3种植物细根比根长与其它细根参数之间的相互关系各不相同,制约程度存在差异。与土壤物理因子的相关分析表明,3种植物细根比根长均随土壤含水量的增加而减少。土壤各级水稳性团聚体和土壤颗粒对3种植物细根比根长并无一致的影响。

子午岭林区白桦-辽东栎混交林光合生理生态特征研究

对黄土高原子午岭次生林区白桦林、辽东栎林和白桦-辽东栎混交林3种林分的土壤物理特性和叶片光合特性进行了研究。结果表明:(1)白桦-辽东栎混交林地的土壤水分明显改善,其土壤容重最小、土壤孔隙度最大,且均优于纯林,即混交林地有深层次的土壤水分可供利用,并改善了土壤的物理结构;(2)辽东栎林的光合速率和气孔导度最大,其次为白桦-辽东栎混交林,水分利用率(WUE)为混交林白桦>混交林辽东栎>辽东栎林>白桦林;(3)混交林中白桦、辽东栎的Fv/Fm和Fv/Fo值均较大,与纯林差异不显著;白桦林和辽东栎林的qP和NPQ值均大于混交林。

Quantitative assessment of total phenol contents of European oak (Quercus petraea and Quercus robur) by diffuse reflectance NIR spectroscopy on solid wood surfaces

Near infrared spectroscopy (NIRS) combined with multivariate analysis techniques was applied to assess phenol content of European oak. NIRS data were firstly collected directly from solid heartwood surfaces: in doing so, the spectra were recorded separately from the longitudinal radial and the transverse section surfaces by diffuse reflectance. The spectral data were then pretreated by several pre-processing procedures, such as multiplicative scatter correction, first derivative, second derivative and standard normal variate. The tannin contents of sawmill collected from the longitudinal radial and transverse section surfaces were determined by quantitative extraction with water/methanol (1:4, by vol). Then, total phenol contents in tannin extracts were measured by the Folin-Ciocalteu method. The NIR data were correlated against the Folin-Ciocalteu results. Calibration models built with partial least squares regression displayed strong correlation - as expressed by high determination correlation coefficient (r2) and high ratio of performance to deviation (RPD) - between measured and predicted total phenols content, and weak calibration and prediction errors (RMSEC, RMSEP). The best calibration was provided with second derivative spectra (r2 value of 0.93 for the longitudinal radial plane and of 0.91 for the transverse section plane). This study illustrates that the NIRS technique when used in conjunction with multivariate analysis could provide reliable, quick and non-destructive assessment of European oak heartwood extractives.

Sonochemical Acceleration of Conversion of 2-Alkoxytetrahydrofurans to y-Butyrolactones Synthesis of (±)-Quercus Lactone-A

Effect of sonochemical irradiation on the conversion of 2-alkoxytetrahydrofurans to γ-butyro-1actores by Jones reagent, and its extension to the highly stereoselective synthesis of quercus lactone a, is reported.

Spatial ecology of a specialist insect herbivore : the leaf-mining moth Tischeria ekebladella on the pedunculate oak Quercus robur

Herbivorous insects comprise a major part of terrestrial biodiversity, and their interactions with their host plants and natural enemies are of vast ecological importance. A large body of research demonstrates that the ecology and evolution of these insects may be affected by trophic interactions, by abiotic influences, and by intraspecific processes, but so far research on these individual aspects has rarely been combined. This thesis uses the leaf-mining moth Tischeria ekebladella and the pedunculate oak (Quercus robur) as a case study to assess how spatial variation in trophic interactions and the physical distribution of host trees jointly affect the distribution, dynamics and evolution of a host-specific herbivore. With respect to habitat quality, Tischeria ekebladella experiences abundant variation at several spatial scales. Most of this variation occurs at small scales notably among leaves and shoots within individual trees. While hypothetically this could cause moths to evolve an ability to select leaves and shoots of high quality, I did not find any coupling between female preference and offspring performance. Based on my studies on temporal variation in resource quality I therefore propose that unpredictable temporal changes in the relative rankings of individual resource units may render it difficult for females to predict the fate of their developing offspring. With respect to intraspecific processes, my results suggest that limited moth dispersal in relation to the spatial distribution of oak trees plays a key role in determining the regional distribution of Tischeria ekebladella. The distribution of the moth is aggregated at the landscape level, where local leaf miner populations are less likely to be present where oaks are scarce. A modelling exercise based on empirical dispersal estimates revealed that the moth population on Wattkast an island in south-western Finland is spatially structured overall, but that the relative importance of local and regional processes on tree-specific moth dynamics varies drastically across the landscape. To conclude, my work in the oak-Tischeria ekebladella system demonstrates that the local abundance and regional distribution of a herbivore may be more strongly influenced by the spatial location of host trees than by their relative quality. Hence, it reveals the importance of considering spatial context in the study of herbivorous insects, and forms a bridge between the classical fields of plant-insect interactions and spatial ecology.

Factores asociados a la mortalidad de encinos (Quercus spp.) en la Reserva natural Cerro Tomabú, Estelí, Nicaragua

Con el objetivo de estudiar los factores asociados a la mortalidad de los encinos (Quercus spp), en la Reserva Natural Cerro Tomabú, Estelí; se establecieron seis parcelas de estudio de 0.1 ha, durante los meses de Febrero – Mayo y Junio – Octubre 2014. En cada una se colectaron insectos, suelo y tejido vegetal enfermo; estimación de incidencia y severidad de la marchitez de los encinos; datos dasométricos y antropogénico. Para la identificación de patógenos, se utilizaron medios generales (Papa Dextrosa Agar, Agar Nutritivo y Agar Agua) y selectivos (Caldo V8, agar V8, y Harina de maíz -agar más antibióticos: Piramicina, Ampicillina, Rifampicina, Vancomycina y Benomyl) y caracterización macro morfométrica, con claves taxonómicas. Los datos fueron analizados de manera descriptiva. La población de árboles muestreados fue de 298 Q. segoviensis y Q. sapotifolia son las especies, que predominan en un 58 % y 42 % respectivamente. En el mes de septiembrese registró el mayor porcentaje de incidencia de marchitez en ramas con 88.3 % y 99 % de incidencia por especie en árboles jóvenes de Q. sapotifolia. La severidad con 29.2 %. Phytophthora cinnamomi, se aisló de suelo y tejido vegetal, constituyendo el patógeno que se asocia a la marchitez de ramas, chancros con exudados negros en fuste y muerte en los encinos. Las pocas lluvias y el despale ocasionado por los pobladores participan como factores de estrés en la mortalidad de los encinos. Los insectos colectados se consideran de naturaleza benéfica y constituyen parte de la diversidad de insectos de la reserva.

Adaburuaren eta orbelaren euri interzepzioa haritzean (Quercus robur) eta intsinis pinuan (Pinus radiata)

Zuhaitz adaburuaren interzepzioak oihanpera prezipitazio osoaren frakzio bat soilik pasatzea eragiten du, gainerakoa lurrunketaz galtzen baita. Oihanpera pasatzen den ur horren parte bat ere lurzoruko orbelak interzeptatzen du. Espezie arteko konparaketa bat egiteko asmoz, adaburuaren eta orbelaren euri interzepzioa neurtu zen haritzean (Quercus robur) eta pinuan (Pinus radiata), sei euriteetako datuak aintzat hartuz (hiru neguan eta beste hiru udaberrian, haritzak hostoak zituenean). Horrez gain, laborategian bi orbel moten ur-erretentzio ahalmen maximoa (S) neurtu zen. Adaburuaren interzepzioa % 37koa izan zen haritzean eta % 24koa pinuan. Haritzean interzepzioa handiagoa izan zen udaberrian neguan baino, pinuan berdina izan zen bitartean. Azken honetan Hosto Azalera Indizearen (Leaf Area Index, LAI) balio altuago batek interzepzio altuagoa eragin zuen, haritzean erlazio hori behatu ez zelarik neurturiko LAI balioak homogeneoegiak zirelako seguruenik. Orbelaren interzepzioak prezipitazio osoaren % 2,1 eta % 1,5 suposatu zuen haritzean eta pinuan hurrenez hurren. Orbelaren gain eroritako ur kantitatea (throughfall) handitzean, interzepzioa handitu zen, maximo batera heldu arte (2,5 mm kg-1 m2-koa haritzean eta 1,8 mm kg-1 m2-koa pinuan). Adaburu motak, berriz, ez zuen eragin esangarririk izan, haritz azpian, pinu azpian eta klaroetan orbelak antzeko interzepzioa aurkeztu zuelarik. Ur-erretentzio ahalmen maximoa haritzean handiagoa izan zen, 4,7 eta 5,6 mm kg-1 m2 artekoa pinuaren 2,8 eta 3,1 mm kg-1 m2 arteko balioen aurrean. Pinuaren balio horiek antzekoak izan ziren orbel geruzaren sakonera edozein zela ere, baina haritzean, orbel sakonera handiagoarekin balio baxuagoak lortu ziren. Bi espezieen artean behaturiko ezberdintasunek iradokitzen dute harizti naturalak pinu landaketez ordezkatzeak ziklo hidrologikoa aldaraz dezakeela.

中国卧龙自然保护区不同海拔川滇高山栎(Quercus aquifolioides)群体的遗传变异

海拔梯度造成的环境异质性，如崎岖的地形、复杂的植被结构以及花期延迟等可能会极大地影响到物种的形态和遗传变异格局。理解物种形态和遗传变异的海拔格局对于物种多样性的管理和保护是非常重要的。尽管植物群体遗传学是一个飞速发展的研究领域，然而与海拔相关的形态变异、遗传变异及群体间遗传差异的研究却很少。到目前为止，还不清楚遗传变异与海拔之间是否必然的相关性。 川滇高山栎是一种重要的生态和经济型树种，广泛分布于中国西南的四川、西藏、贵州和云南省的高海拔地区，在保持水土、调节气候方面起着十分重要的作用。尽管主要受阳光限制而仅分布于阳坡，但其海拔梯度范围较大，表明川滇高山栎对不同的环境具有很强的适应性。本文通过叶型及生理响应、微卫星分子标记和扩增性片段长度多态性方法，试图探索川滇高山栎叶沿海拔梯度的形态和生理响应及其沿海拔梯度的遗传变异格局，为川滇高山栎的保护和利用提供进一步的遗传学理论依据和技术指导。 对叶形、含氮量及碳同位素的试验结果表明，平均比叶面积、气孔密度、气孔长度和气孔指数等气孔参数随海拔的升高呈非线性变化。在海拔大于2800 m时，川滇高山栎的比叶面积、气孔长度和气孔指数都随海拔升高而降低，但是在海拔小于2800 m时，这些指标都随海拔的升高而增大。相对而言，单位叶面积的含氮量和碳同位素则表现出相反的变化模式。另外，比叶面积是决定碳同位素沿海拔梯度变化的最重要参数。本研究结果表明，海拔2800 m附近是川滇高山栎生长和发育的最适地带，在这里生长的植物叶片厚度更薄、气孔更大、叶碳同位素值更小。 利用六对微卫星引物对五个不同海拔川滇高山栎群体遗传多样性进行研究，结果表明，群体内表现出较高的遗传多样性，平均每位点等位基因数11.33个，平均期望杂合度达0.820。群体间差异较小，分化仅为6.6％。聚类分析也并没有显示出明显的海拔格局。然而低频率等位基因却与海拔呈显著性正相关(R2=0.97, P < 0.01)，表明在高海拔处，川滇高山栎以更多的稀有基因来适应恶劣的环境条件。本试验结果表明由海拔梯度形成的选择性压力对川滇高山栎群体的遗传变异影响并不明显。 为了进一步探讨川滇高山栎群体遗传变异与海拔之间的相互关系，我们还对其进行了扩增性片段长度多态性分析。结果表明：(1)随海拔的升高(从群体WL2到群体WL5)，群体内遗传变异降低，而群体间遗传差异增加；(2)低海拔群体WL1表现出最低的遗传变异性(HE = 0.181)，同时与其余四个群体间呈现出最大的遗传差异性(平均FST = 0.0596)；(3)在除去低海拔群体WL1后，Mantel检测表明群体间遗传距离与海拔距离之间表现出正相关性。另外，研究结果还表明，遗传变异受生境条件(过度的湿热环境)及人为干扰(火烧、砍伐和放牧)的影响，这一点至少在低海拔群体WL1上发生了作用。 通过叶形态、生理及DNA分子水平的研究，结果表明叶形态特征和碳同位素与海拔紧密相关，与海拔之间呈非线性变化，海拔2,800 m附近是川滇高山栎生长和发育的最适地带。海拔梯度在一定程度上会影响到川滇高山栎群体的遗传变异结构，但在这样一个狭窄的地理分布区域里，这种影响并不足以导致群体间较大的遗传分化。同时生境条件及人为干扰也是影响遗传变异的限制性因子，不容忽视。 Altitudinal gradients impose heterogeneous environmental conditions, such as rugged topography, a complex pattern of vegetation and flowering delay, and they likely furthermore markedly affect the morphological and genetic variation pattern of a species. Understanding altitudinal pattern of morphological and genetic variation at a species is important for the management and conservation of species diversity. Although plant population genetics is a fast growing field of research, there are only few recent investigations, which analyzed the genetic differentiation and changes of intra-population variation along altitudinal gradients. At present, it is still unclear whether there are some common patterns of morphological and genetic variation with altitude. Quercus aquifolioides Rehder & E.H. Wilson, which is an important ecological and economical endemic woody plant species, is widely distributed in the Yunnan and Sichuan provinces, Southwest China. Its large range of habitat across different altitudes implies strong adaptation to different environments, although it is mainly restricted to sunny, south facing slopes. It plays a very important role in preventing soil erosion, soil water loss and regulating climate, as well as in retaining ecological stability. In this paper, we tried to understand the altitudinal pattern of morphological and genetic variation along altitudinal gradients through the experiments of leaf morphological and physiological responses, microsatellite analysis and AFLP markers. In leaf morphological and physiological responses experiment, we measured leaf morphology, nitrogen content and carbon isotope composition (as an indicator of water use efficiency) of Q. aquifolioides along an altitudinal gradient. We found that these leaf morphological and physiological responses to altitudinal gradients were non-linear with increasing altitude. Specific leaf area, stomatal length and index increased with increasing altitude below 2,800 m, but decreased with increasing altitude above 2,800 m. In contrast, leaf nitrogen content per unit area and carbon isotope composition showed opposite change patterns. Specific leaf area seemed to be the most important parameter that determined the carbon isotope composition along the altitudinal gradient. Our results suggest that near 2,800 m in altitude could be the optimum zone for growth and development of Q. aquifolioides, and highlight the importance of the influence of altitude in research on plant physiological ecology. Genetic variation and differentiation were investigated among five natural populations of Q. aquifolioides occurring along an altitudinal gradient that varied from 2,000 to 3,600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (HE) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R2=0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (FIS=0.136) and a low level of differentiation among populations (FST=0.066). The result of the cluster analysis demonstrates that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation. To further elucidate genetic variation pattern of Q. aquifolioides populations under sub-alpine environments, genetic variation and differentiation were investigated along altitudinal gradients using AFLP markers. The altitudinal populations with an average altitude interval of 400 m, i.e. WL1, WL2, WL3, WL4 and WL5, correspond to the altitudes 2,000, 2,400, 2,800, 3,200 and 3,600 m, respectively. Our results were as follows: (i) decreasing genetic variation (ranging from 0.253 to 0.210) and increasing genetic differentiation with altitude were obtained from the WL2 to the WL5 population; (ii) the WL1 population showed the lowest genetic variation (HE = 0.181) and the highest genetic differentiation (average FST = 0.0596) with the other four populations; (iii) the positive correlation was obtained using Mantel tests between genetic and altitude distances except for the WL1 population. Our results suggest that altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides populations to some extent. In addition, habitat environments (unfavorable wet and hot conditions) and human disturbances (burning, grazing and felling) were possible influencing factors, especially to the low-altitude WL1 population. The present study shows that there were close correlations between morphological features and carbon isotope composition in our data. This indicates that a coordinated plant response modified these parameters simultaneously across different altitudes. Around 2,800 m altitude there seems to be an optimum zone for growth and development of Q. aquifolioides, as indicated by thinner leaves, larger stomata and more negative d13C values. All available evidence indicates altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides to some extent. Decreasing genetic variation and increasing genetic differentiation with altitude was obtained except for the WL1 population. And the environment of habitats and human disturbances were also contributing factors, which impact genetic variation pattern, especially to the low-altitude WL1 population.

Envolvimento de Phytophthora cinnamomi no declínio de Quercus suber e Q. rotundifolia: estudo da influência de factores bióticos e abióticos na progressão da doença. Possibilidades de controlo químico do declínio

Tese dout., Ciências Agrárias, Universidade do Algarve, 2007