Effects of Cattle Management on Oak Regeneration in Northern Californian Mediterranean Oak Woodlands

Oak woodlands of Mediterranean ecosystems, a major component of biodiversity hotspots in Europe and North America, have undergone significant land-use change in recent centuries, including an increase in grazing intensity due to the widespread presence of cattle. Simultaneously, a decrease in oak regeneration has been observed, suggesting a link between cattle grazing intensity and limited oak regeneration. In this study we examined the effect of cattle grazing on coast live oak (Quercus agrifolia Née) regeneration in San Francisco Bay Area, California. We studied seedling, sapling and adult density of coast live oak as well as vertebrate herbivory at 8 independent sites under two grazing conditions: with cattle and wildlife presence (n = 4) and only with wildlife (n = 4). The specific questions we addressed are: i) to what extent cattle management practices affect oak density, and ii) what is the effect of rangeland management on herbivory and size of young oak plants. In areas with cattle present, we found a 50% reduction in young oak density, and plant size was smaller, suggesting that survival and growth young plants in those areas are significantly limited. In addition, the presence of cattle raised the probability and intensity of herbivory (a 1.5 and 1.8-fold difference, respectively). These results strongly suggest that the presence of cattle significantly reduced the success of young Q. agrifolia through elevated herbivory. Given the potential impact of reduced recruitment on adult populations, modifying rangeland management practices to reduce cattle grazing pressure seems to be an important intervention to maintain Mediterranean oak woodlands.     

Spatial Distribution of Oak Mistletoe as It Relates to Habits of Oak Woodland Frugivores

This study addresses the underlying spatial distribution of oak mistletoe, Phoradendron villosum, a hemi-parasitic plant that provides a continuous supply of berries for frugivorous birds overwintering the oak savanna habitat of California''s outer coast range. As the winter community of birds consuming oak mistletoe varies from group-living territorial species to birds that roam in flocks, we asked if mistletoe volume was spatially autocorrelated at the scale of persistent territories or whether the patterns predicted by long-term territory use by western bluebirds are overcome by seed dispersal by more mobile bird species. The abundance of mistletoe was mapped on trees within a 700 ha study site in Carmel Valley, California. Spatial autocorrelation of mistletoe volume was analyzed using the variogram method and spatial distribution of oak mistletoe trees was analyzed using Ripley''s K and O-ring statistics. On a separate set of 45 trees, mistletoe volume was highly correlated with the volume of female, fruit-bearing plants, indicating that overall mistletoe volume is a good predictor of fruit availability. Variogram analysis showed that mistletoe volume was spatially autocorrelated up to approximately 250 m, a distance consistent with persistent territoriality of western bluebirds and philopatry of sons, which often breed next door to their parents and are more likely to remain home when their parents have abundant mistletoe. Using Ripley''s K and O-ring analyses, we showed that mistletoe trees were aggregated for distances up to 558 m, but for distances between 558 to 724 m the O-ring analysis deviated from Ripley''s K in showing repulsion rather than aggregation. While trees with mistletoe were aggregated at larger distances, mistletoe was spatially correlated at a smaller distance, consistent with what is expected based on persistent group territoriality of western bluebirds in winter and the extreme philopatry of their sons.     

Oak Flat Restoration on Phosphate-Mine Spoils

Phosphate mining in Beaufort County, North Carolina, impacts a rare plant community type, oak flats (nonriverine wet hardwood forests [NRWHF]). Reclamation of land after mining utilizes three by‐products of mining and manufacturing: clay tailings containing dolomite, low‐pH phosphogypsum, and bucket‐wheel spoil from the surface 10 m. The open mine is backfilled with a blend of phosphogypsum and clay tailings, which may be left as the surface or capped with bucket‐wheel spoil. The objective of this study was to determine the feasibility of using these by‐products as substrates for restoring NRWHF. A field study measured survival of 11 tree and four shrub species planted in replicated plots of blend or bucket‐wheel spoil. Survival at the end of the second growing season was 59% on the blend and 52% on the bucket‐wheel spoil. A greenhouse experiment compared growth of four species of NRWHF oaks on bucket‐wheel spoil, blend, local topsoil (sterilized and unsterilized), and a commercial potting mix. Germination rates of acorns of all four species planted in topsoil were almost double those in bucket‐wheel spoil and 1.5 times greater than those in the blend. Height and stem volume of trees were significantly greater when grown in topsoil than in bucket‐wheel spoil and blend. There was no difference in tree growth on bucket‐wheel spoil and blend. In field and greenhouse soil tests, the blend had cadmium levels over 100 times that of local topsoil and the bucket‐wheel spoil had levels 40 times greater. Leaf chemical analysis in the field and greenhouse found higher cadmium levels in plants grown on the blend than on the bucket‐wheel spoil. These results indicate that the use of topsoil from the advancing mine front may lead to successful restoration of NRWHF.     

北京山区的栎林

 本文叙述了北京山区的主要栎林——辽东栎林、槲栎林、槲树林和栓皮栎林的群落学特征。栎林是由温带植物区系所组成的落叶阔叶林。组成栎林的植物以菊科、蔷薇科、禾本科和豆科植物种类为最丰富。在群落结构中有重要作用的植物,乔木层以壳斗科的栎属为主,灌木层以蔷薇科的绣线菊属、李属、豆科的胡枝子属,马鞭草科的荆条属和虎耳草科的溲疏属占有重要地位。草本层常以莎草科的苔草属,禾本科的隐子草属、大油芒属、野古草属和白草属植物为优势种或常见种。栎林的植物生活型谱,从种类成分分析是以地面芽植物为主,高位芽植物次之,地下芽植物亦占一定比例,但从各类生活型植物的优势度分析,显然以高位芽植物占有优势。组成栎林植物的叶级,是以小型叶植物为主,中型叶植物次之,大型叶植物为罕见。就各类栎林种类成分的相似性分析,以槲树林与槲栎林最为相似,辽东栎林与栓皮栎林差异较大。     

Oak seedlings grown in different light qualities

Oak seedlings (Quercus robur L.) were germinated in darkness for 3 weeks and then given continuous long wavelength far-red light (LFR; wavelengths longer than 700 nm). A control group of seedlings was kept in darkness. After 2 additional weeks the chlorophyll formation ability in red light was examined in the different seedlings. The stability of the protochlorophyll(ide) and chlorophyll(ide) forms to high intensity red irradiation was also measured. Oak seedlings grown in darkness accumulated protochlorophyll(ide) (6 μg per g fresh matter). Absorption spectra and fluorescence spectra indicated the presence of more protochlorophyll(ide)_628–632 than protochlorophyllide_650–657. The level of protochlorophyll(ide) was higher in leaves of plants cultivated in LFR light (13 μg per g fresh matter) than in leaves of dark grown plants. 12% of the protochlorophyll(ide) was esterified in both cases. The level of protochlorophyll(ide)_628–632 in LFR grown oaks varied with the age of the leaves, being higher in the older (basal) leaves, but also in the very youngest (top-most) leaves. The ability of the leaves to form photostable chlorophyll in red light showed a similar age dependence, being low in rather young and in older leaves. A low ability to form photostable chlorophyll thus appears to be correlated with a high content of protochlorophyll(ide)_628–632. Upon irradiation only the protochlorophyllide_650–657 was transformed to chlorophyllide. After this phototransformation the chlorophyllide peak at 684 nm shifted to 671 nm within about 30 min in darkness. This shift took place without any accompanying change in photostability of the chlorophyll(ide). Upon irradiation with strong red light a similar shift took place within one minute. This indicates that the chlorophyllide after phototransformation was rather loosely bound to the photoreducing enzyme. The development towards photostable chlorophyll forms consists of three phases and is discussed.     

Oak Seedlings Grown in Different Light Qualities

Seedlings of oak (Quercus robur) were germinated in darkness for 3 weeks and then given continuous light or short pulses of light (5–8 min every day). The morphological development was followed during 25 days. In continuous white, blue, and red light the stem growth terminated after about 10 days by formation of a resting bud. At that time the seedlings were about 100 mm high. In con tinuous long wavelength farred light (wavelength longer than 700 nm) the stem growth including leaf formation was continuous without the formation of resting buds, and the stem length was about 270 mm after 25 days. The number of nodes developed became twice that of the seedlings grown in while light. The leaves became well developed in all light colours, but leaf areas were largest in plants cultivated in white light. Compared to dark grown seedlings the mean area per leaf was increased about five times in continuous long wavelength far red light. A supplement with short (5 min) pulses of red light each day increased the leaf area up to 20 times. The stem elongation showed a high energy reaction response, i.e. the stem length increased only in continuous long wavelength far-red light but was not influenced by short pulses of red light or far-red light. The leaf expansion, however, was increased by short pulses of red light with a partial reversion of the effect by a subsequent pulse of far-red light. The fraction of the plant covered with periderm was higher in plants given continuous light. In respect to periderm inhibition continuous long wavelength far red light was the most effective. The transfer of seedlings from darkness to continuous white light gave anthocyanin formation in the stem 10–20 mm below the apex. This formation took place in the cortex and was evident in plants grown in darkness or under short pulses of light. Plants grown in continuous red, blue or long wavelength Far red light showed only traces of anthocyanin.     

Oak wood hemicelluloses extracted with aqueous-alcoholic media

Hemicellulose fractions were isolated from oak wood ethanol extracts (40–90%). To determine the composition of these fractions, they were hydrolyzed and the hydrolysis products in the form of trimethylsilyl derivatives were analyzed by GLC/MS. Depending on the content of the ethanol, hemicelluloses of a different composition were extracted from wood. In alcohols that were kept in oak wood, intended for manufacturing brandy and whisky, the content of the hemicelluloses increased depending on the duration of storage. It is assumed that this makes drinks more full-bodied and makes them softer.     

Studies of Phenological Forms of Pedunculate Oak

We review the specificity of early and late phenological types of pedunculate oak differing in the spring flushing of leaves, namely, its occurrence in topographical elements, soil conditions and hydrology, responses to weather, and vulnerability to unfavorable factors. We show that phenological forms differ in a set of morphological and physiological indicators, growth energy, and peculiarities of the wood. We focus on the importance of the phenological specificity of planting materials when organizing oak plantations with regard to ongoing climatic changes and the ubiquitous decline of oak forests. The late form of oak is more preferable in most cases, because it is more resistant to spring frosts and insect damage, as well as the fact that it has higher quality wood in solid-volume trunks.     

栎树繁殖生物技术进展

栎树是重要的森林树种.由于常规营养繁殖困难、种子繁育开花结实迟等原因,栎树的繁育问题一直未得到很好的解决.综述栎树繁殖生物技术的历史与进展;分析栎树的体细胞胚胎从诱导到萌发的过程及机理;阐述欧洲栓皮栎等树种的小孢子胚胎发生技术、双单倍体培养技术、体胚遗传转化技术、人工种子技术以及相关的遗传稳定性与变异性检测技术.     

蒙古栎苗期种源分析

对带岭试验地25个蒙古栎种源的树高、地径进行调查分析,得到如下结论：（1）蒙古栎1年生苗高、地径及6年生树高、地径间呈正相关且达到了极显著水平。蒙古栎种源各生长性状存在着显著性差异,这表明蒙古栎种源选择是十分必要的。苇河、集安种源可初步作为带岭试验地的优良种源应用于林业生产。（2）蒙古栎地理变异总趋势受经纬度影响,其中经度影响略大。（3）不同蒙古栎种源生长性状、地理、气象因子之间具有一定的相关性。（4）将参试的25个种源划分为3个种源区,Ⅰ区种源多数分布在长白山南部、龙岗山一带,Ⅱ区种源多数分布在长白山及老爷岭,Ⅲ区种源位于小兴安岭和张广才岭。