Fallen logs are essential structural and functional components of the forest ecosystem,but the decomposition of fallen logs is very slow.Until recently,there has been a lack of knowledge about the effect of fallen logs on soil biological properties.The objective of this study was to determine the temporal and spatial distribution patterns of soil enzyme activities under fallen logs and how they were influenced by environmental variables during log decomposition in the Tianbaoyan National Nature Reserve.A multivariate analysis was performed to investigate the connections between environmental variables and soil enzyme activity.This study took place in Tsuga longibracteata forest,which is in the Tianbaoyan National Nature Reserve,Fujian Province,China.In the forest,the coefficient of variance for soil enzyme activity shows a high degree of variation.The cellulase spatial distribution pattern showed the greatest change,whereas changes to protease,urease,and invertase activities were lower.The increase in decay class caused a decreasing trend in protease and urease activities,but cellulase activity increased.Soil enzyme activities were positively associated with soil organic carbon (SOC)and total nitrogen (TN).Among the environmental variables,soil chemical properties had the greatest effect on soil enzyme activities,which suggested that soil chemical properties should be taken into account when assessing the effect of fallen logs on soil enzyme activity.These activities were positively associated with TN,SOC,elevation,and slope.We identified the interactive relationship between fallen logs and soil enzyme activities and showed that the presence of fallen logs plays an important role in forest C recycling.

The rhizosphere, distinct from bulk soil, is defined as the volume of soil around living roots and influenced by root activities. We investigated protease, invertase, cellulase, urease, and acid phosphatase activities in rhizosphere and bulk soils of six Nothotsuga longibracteata forest communities within Tianbaoyan National Nature Reserve, including N. longibracteata + either Phyllostachys pubescens, Schima superba, Rhododendron simiarum, Cunninghamia lanceolata, or Cyclobalanopsis glauca, and N. longibracteata pure forest. Rhizosphere soils possessed higher protease, invertase, cellulase, urease, and acid phosphatase activities than bulk soils. The highest invertase, urease, and acid phosphatase activities were observed in rhizosphere samples of N. longibracteata + S. superba. Protease was highest in the N. longibracteata + R. simiarum rhizosphere, while cellulase was highest in the pure N. longibracteata forest rhizosphere. All samples exhibited obvious rhizosphere effects on enzyme activities with a significant linear correlation between acid phosphatase and cellulase activities (p < 0.05) in rhizosphere soils and between protease and acid phosphatase activities (p < 0.05) in bulk soils. A principal component analysis, correlating 13 soil chemical properties indices relevant to enzyme activities, showed that protease, invertase, acid phosphatase, total N, and cellulase were the most important variables impacting rhizosphere soil quality.

Forest litter plays a central role in water inception, nutrient cycling and soil conservation. To elucidate the regeneration problem of Tsuga longibracteata seedling, a preliminary study on water-holding characteristics of litter in 4 types of T.longibracteata-based mixed forests was carried out in Tianbaoyan National Nature Reserve. Results showed that average litter thickness ranged from 19 to 34 mm, and storage capacity varied between 11.91 and 34.42 t??hm-2 , with the thickest litter and largest storage capacity be-ing in forest that dominated by mix forest of T.longibracteata and Rhododendron simiarum hance. Variations in water-holding capaci-ty, water absorption rate and immersion time of litter were basically similar among 4 forest types, which was that water-holding ca-pacity of litter peaked 6 hours after immersion and after that absorption rate slowed down. Maximum water-holding rate, water-hold-ing capacity, interception capacity and modified interception capacity of litter in 4 forest types approximated at 149.94%~223.47%, 11.91~34.42 t??hm-2 , 15.32~48.84 t??hm-2 and 8.38~18.43 t??hm-2 , respectively. Water-holding capacity of litter had a visible logarithmic correlation with immersion time (R2>0.96), and there existed a significant power function relationship between water absorption rate and immersion time ( R2>0.99) .

Based on the investigated data of 54 plots of 18 sites in the west coastal area,north plain area,east coastal area and central mountainous area of Hainan Island,the biomass,carbon storage,carbon sequestration and spatial distribution of eucalyptus plantations in Hainan Island,southern China were analyzed.The results indicated that the mean total biomass was 49.72 t·hm-2,and the biomass distribution of the forest system showed such a sequence as:arbor layer(85.10%)>litters(8.08%)>undergrowth layer(6.82%).The mean total organic carbon storage in the eucalyptus plantation ecosystem amounted to 88.84 t·hm-2,of which there was 23.13%(20.55 t·hm-2) stored in the arbor,1.74%(1.55 t·hm-2) in undergrowth vegetations,2.17%(1.93 t·hm-2) in litters,and 72.96%(64.81 t·hm-2) in the soil(0-100 cm).The stem had the biggest organic carbon storage of the total carbon storage in various plant organs,accounted for 52.81% of carbon storage in arbor layer.The mean annual net productivity of eucalyptus plantations was 17.56 t·hm-2a-1,with a mean annual stored carbon up to 8.43 t·hm-2,amounted to 30.91 t CO2·hm-2a-1.The total organic carbon storage and sequestration of the eucalyptus plantations of Hainan Island was 2 958.37×104 t and 280.97×104 t·a-1,respectively.The carbon sequestration of eucalyptus plantations in the central mountain area(11.89 t·hm-2a-1) was largely higher than other three areas,such as the northern plain area(8.97 t·hm-2a-1),the western coastal area(7.18 t·hm-2a-1) and the eastern coastal area(8.26 t·hm-2a-1).The three areas had no significant difference in the carbon sequestration.Except for the western coastal area and the eastern coastal area,the carbon storage among all other areas was significantly different,mainly because of their different carbon storage of soil.

The hydrological function is one of the important ecological functions of forest.To understand the eco-hydrological effects of eucalyptus plantation,we studied the canopy interception,rainfall redistribution and water-retaining capacity of litter and soil based on fixed field observation and measurement of laboratory in Gaoyao,Zhaoqing City,Guangdong Province,China.The results indicate that among the cumulative gross rainfall(2016.7mm)generated during the period from Apr.2006 to Apr.2007,throughfall,stemflow and canopy interception account for 85.70%(1728.4mm),3.62%(72.9mm),and 10.68%(215.4mm),respectively.The stemflow can be produced only when the precipitation is more than 3.93 mm.The throughfall and stemflow are distinctly positive related to the precipitation(P0.01)and the values of the interception ratio to gross rainfall have a distinctly negative relationship to the precipitation(P0.05).The value of interception ratio to gross rainfall keeps generally steady when the precipitation is more than 20 mm.The results also show that the water-capacity of litter is 4.27mm,and among the total 4.27mm,the capacity from the part of leaves(2.54 mm)is the best among all kinds of components of litter.The maximum water-capacity of the soil layer from 0 to 100 cm depth is 470.06 mm,and the non-capillary water-capacity accounts for 20.90%(98.22mm)of the total.Both of the total and non-capillary porosities show a decreasing trend with the increasing of soil depth.The initial and steady infiltration rates in the surface(0-10 cm)are 25.03 mm·min-1 and 8.83 mm·min-1 respectively,and also decrease with the increasing of soil depth.

从桉树林及各种因素(年龄、叶面积、砍伐、造林、火烧等)对蒸发散、流域产水量以及土壤水分和地下水的影响等方面综述国内外桉树人工林水文过程及其效应的研究进展.综合来看,不同区域的桉树人工林对降水的截留量差异较大,桉树人工林的蒸腾量多介于0.5～6.0 mm·d~(-1),叶面积指数、林分密度、土壤水分与灌溉、林分年龄及植被变化等均会影响桉树人工林的蒸发散量;砍伐(皆伐、间伐等)桉树人工林会导致流域产水量增加,营造桉树人工林会导致流域产水量减少,但当林分生长到一定年龄后,随着林分年龄的增加,蒸腾耗水量下降,流域径流量增加,火烧也会导致桉树林流域产水量增加;干旱地区桉树人工林可能会消耗浅层地下水,对深层地下水的影响还未有明显证据.目前中国桉树人工林的水文效应研究还存在诸多问题,急待加强主要研究方向与重点领域的研究.

According to the observations of precipitation and runoff in Xiangshuihe Watershed of Liupan Mountains on Jun.-Oct.,2004 and 2005,the effect of slope aspect,altitude and vegetations type on runoff is studied by GIS technique and SPSS software.The results of runoff coefficient for different vegetation types show such an descending order as plantation forest,shrub forest,natural forest,and sub-alpine meadow.The descending order of runoff coefficient for different altitude ranges is lower altitude area(2 060-2 350 m),middle altitude area(2 350-2 640 m),higher altitude area(2 640-2 930 m).With the increasing of altitude,the runoff coefficient in the natural forests decreases at the beginning and then increases,while the runoff coefficients for plantation and shrub forests have the trend of increasing at the beginning and then decreasing.However,the runoff coefficient for subalpine meadow keeps an increasing trend from middle to higher altitude.According to the slope aspects,the runoff coefficient for southern slope is the highest and that for eastern slope is the lowest.

Some indexes,such as the active oxygen protective system and some free radicles,were measured by the controlling the water in container seedlings.The results indicated that the total relative water contents and the protein contents dropped with the increase of stress intensity and the contents of total chlorophyll,chlorophyll a,chlorophyll b and carotinoid had a descending trend.The activities of the SOD,POD and CAT descended firstly,then ascended and descended lastly and the activity of ASP had a descending trend.The free radicles showed different changing trend: the O·-2 producing rates increased firstly,and then decreased and increased lately with the water stress intensity,but the H2O2 contents raised firstly and then decreased.Both MDA content and membrane relative permeability had an ascending trend with the increasing stress.The activity of the enzymes such as SOD, CAT and ASP may evaluate the drought-resistant of the chestnut seedlings as indexes.

Segregation of EST-CAPS markers was investigated by using an interspecific cross of Eucalyptus urophylla×E.tereticornis Smith and seven ESTs derived from E.tereticornis.The results showed that five EST-CAPS markers had a segregation ratio 1∶1,four out of which segregated normally at a Mendelian mode(α=0.05),while the left two EST-CAPSs segregated 1∶1∶1∶1 at a Medelian inheritance mode.The relatively high ratio of normal segregating EST-CAPS markers(6/7=85.7%)implies that the marker type could be reliably used as genetic marker in genetic mapping and the related studies in Eucalyptus species.In addition,the possible causes of EST-CAPS segregation distortion were discussed.

Seven EST-CAPS markers were identified from 54 candidate ESTs for genetic mapping with an F1 population of Eucalyptus urophylla×E.tereticornis,including three specific in female parent(one being aberrant from normal segregation among the sibs),two specific in male parent,and two shared by both parents.Four EST-CAPS markers were integrated to independent linkage groups on the RAPD linkage map of E.urophylla constructed previously,which contributed to some degrees to the extension of linkage group length.Also,four EST-CAPSs were mapped to different linkage groups on the RAPD linkage map of E.tereticornis,which gave rise to the increase of linkage group length.In addition,the aberrant marker was found to be unlinked to any linkage group in E.urophylla.This study demonstrated the usefulness of EST-CAPS markers in genetic mapping in Eucalyptus.

The classification,distribution,characteristics and actuality of genus Nitraria are settled and summarized through systematic studies.Taking Nitraria tangutorum in sand dune as an example,discussed the ecological function from the point of resource heterogeneity,and pointed out that the happening and developing mechanism of Nitraria tangutorum shrub have important meanings to soil degeneration and comeback.The causation of retrogression is analysed and some suggestions of protective measures are proposed according to it.

The niche characteristics of eleven shrub populations in Tetraena mongolica Maxim. community on the North Ordos Plateau were analyzed by using Shannon-Wiener coefficient of niche breadth, similarity of niche breadth and Pianka of niche overlap. The results showed that main species in the community had broad niche breadth, in which niche breadth values of Potaninia mongolica Maxim. and T. mongolica were 1.702 6 and 1.532 8 respectively. Niche similarity of interspecies was lesser. The niche overlap value between P. mongolica and other species was bigger than that of T. mongolica. It indicated that niche breadth of some shrubs which endure arid environment in the community were more and more broad, the hiberarchy of T. mongolica community was single, and the competition between T. mongolica and other species was weaker. It was concluded that the ability to resisted disturbance of whole community was weaker, and the population of T. mongolica inclined to decay.

The collection,conservation,evaluation and utilization of Orchidaceae germplasm in Guangdong were introduced in this paper.At the same time,some advice for developing Orchidaceae germplasm were brought forward,including enhancing the conmunication and cooperation of domestic and foreign Orchidaceae germplasm,strengthening the conservation and appraisal system,as well as extending the utilization of Orchidaceae germplasm.

Abstrcat The paper studies the effects of storage temperature, vacuum and normal pressure, thaw ways on viability of storage pollen in Daemonorops margaritae (Hance) Becc. The results show that viability of storage pollen lessens while storage days increase; On the other hand, the lower the temperature is, the slower the viability decreases; Viability is higher in vacuum at normal temperature, 0, -5 or -20℃ than that in normal pressure, but there are no notable differences between those in -30℃ and 40℃, and it is the same with the viability of storage pollen between thawing in 40℃ water quickly and resuscitating in room slowly.

文章对黄藤开花习性、花粉采集时间及萌发条件进行了初步研究,结果表明:在黄藤开花盛期,日开花高峰期集中在9:00～13:00,上午8:30～12:30收集的花粉萌发力最强;在150 g/L蔗糖液体培养基中,常温(31.0～32.5℃)条件下培养6 h或9 h,或35℃的条件下培养6 h,花粉萌发与生长效果极佳.

The result,which studies POD kinetic characteristic of chestnut leaves,indicates that the POD optimum temperature is 38 ℃,the optimum pH is 46,optimum H2O2 concentration is 01%,Km value is 12817 mmol/L and Vmax value is 28168 U/(s·gFW) (H2N)2CS and NaHSO3 can inhibit POD activity and CaCl2 and KNO3 can motivate the POD activity

Trials on applying NPK-mixed fertilizer at different compounding ratios on 5-yr-old Castanea henryi showed that all the trees tried had no visible difference in chlorophyll content, cone number per branch and per tree,cone weight,nut weight,ratio of cone and nut,cone and nut yield of individual plants,but had significant difference in leaf protein content and number of fruit shoots. Soil fertilizing urea 0.2kg+autunite magnesium phosphorus 0.1kg+potassium chloride 0.15kg per tree was most economic and efficient.

The imposition of water stress leads to increase production of active oxygen in plant cell, but active oxygen species can't be scavenged in time by enzymatic and no enzymatic protecting system in plant and the producing capacity of active oxygen is better than scavenging capacity. So active oxygen metabolism doesn't balance and damages the plant. It discusses active oxygen metabolism in the water stress:(1) active oxygen species is produced by someways in the water stress and it may damage the plant; (2) the scavenging system of active oxygen species has a very important pole in the scavenging active oxygen species and the change of all kinds of protective enzyme in the water stress is very differerent.; (3) active oxygen metabolism has very intimate relation to the drought resistance of the plant, they may serve as the reference indexes to evaluate the drought resistant capacity and drought resistant Breeding.Suggestion has been proposed for further study on active oeygen.

The effects of Pb?Zn on the changes of photosynthetic pigments, active oxygen metabolism and cell membrane permeability were studied. The results showed that, with the increase of Pb?Zn stress concentration, the malondialdehyde (MDA) content and membrane relative permeability of leaves of Ipomoea Aquatic Forsk increased distinctly; the contents of chlorophyll and carotenoid and chlorophyll a/b ratio all first increased and then decreased; the activities of superoxide dismutase(SOD) and peroxide(POD) had the same trend as chlorophyll and carotenoid(CAR), their response concentrations with Pb? Zn toxicity differed and their maximum value were located in concentration of 10 mg/L(Pb) and 25 mg/L(Zn). The medanism of Pb?Zn toxicity was and discussed that active oxygen species was among the important causes of toxicity and SOD? POD and carotenoid had some roles in preventing toxicity of active oxygen species.