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1.
本文主要论述了河北低山丘陵区自建国以来封育及被反复砍伐利用的栎林结构及其经营情况。仅山海关林场保存了一些30~50a生的栎林,阳坡为麻栎、栓皮栎及柞栎林,阴坡为蒙古栎林。林内幼树更新良好。萌生栎林早期生长迅速,10a后高生长逐渐减缓,50a生林分平均高才10m.1a生萌生栎林,每亩产枝干干重28.5~425kg不等。在土壤为中层-厚层厚度的条件下,栎林矮林作业轮伐期以3~5a为宜。采伐35~40a生栎林,每年每亩平均产值要略高于短轮伐期的栎林。在较好的立地条件下,还可采用选留木法的矮林作业,形成轮伐期不一致的具有2个林层的栎林。  相似文献   

2.
Standing biomass, net primary production (NPP) and soil carbon (C) pools were studied in a 67-year-old pedunculate oak (Quercus robur L.) stand and a neighboring 74-year- old Scots pine (Pinus sylvestris L.) stand in the Belgian Campine region. Despite a 14% lower tree density and a lower tree height in the oak stand, standing biomass was slightly higher than in the pine stand (177 and 169 Mg ha(-1) in oaks and pines, respectively), indicating that individual oak trees contained more biomass than pine trees of similar diameter. Moreover, NPP in the oak stand was more than double that in the pine stand (17.7 and 8.1 Mg ha(-1) year(-1), respectively). Several observations indicated that soil organic matter accumulated at higher rates under pines than under oaks. We therefore hypothesized that the pines were exhibiting an age-related decline in productivity due to nutrient limitation. The poor decomposability of pine litter resulted in the observed accumulation of organic matter. The subsequent immobilization of nutrients in the organic matter, combined with the already nutrient-poor soil conditions, resulted in a decrease in total NPP over time, as well as in a substantial shift in the allocation of NPP toward fine roots. In the oak stand, litter is less recalcitrant to decay and soil acidity is less severe; hence, organic matter does not accumulate and nutrients are recycled. This probably explains why NPP was much higher in the oaks than in the pines and why only a small proportion of NPP was allocated to oak fine roots.  相似文献   

3.
秦岭松栎林带生物量及其营养元素分布特征   总被引:22,自引:2,他引:22  
秦岭脱齿栎林、油松林和华山林(包括0-60cm土层)营养元素总贮量达29.2500-390.1739t.hm^-2,其大小为锐齿栎林>华山松>油松林,土壤中营养现贮量占系统总量的93.10%-99.39%,植被层和凋落物层仅占0.57%-3.00%和0.10%-1.99%;3林分乔木层生物量、木材蓄积量和营养元素积累量平均值分别为120.483t.hm^-2,129.384m^3.hm^-2和1226.9kg.hm^-2,锐齿栎林>油松林>华山松林。3林分林下植被层生物量现存量和营养元素积累量平均值分别为1.553t.hm^-2和53.1kg.hm^-2,锐齿栎林最大,华山松林最小。林下凋落物现存量和营养元素积量平均值分别为17.475t.hm^-2和502.5kg.hm^-2,3林分凋落物现存量、营养元素含量及其积累量都存在明显的差异。锐齿栎林、油松林和华山松林营养元素年吸收量、归还量、存留量和平均归还率分别为33.4、147.2和264.3,195.6、66.9和84.1,138.8、80.4和180.2kg.hm^-2和0.585、0454和0.318,3林分各营养元素的年吸收量,归还量和存留量也存在一定的差异,锐齿栎林干和皮中Ca和Mg含量远远高于油松林和华山松林的,锐齿栎林多代连作势必导致营养元素的大量流失,特别是Ca和Mg,会破坏土壤原有离子动态平衡,引起林地土壤理化性质改变,林地生产潜力逐渐下降。  相似文献   

4.
蒙古栎林全林整体生长模型及其应用   总被引:2,自引:1,他引:1       下载免费PDF全文
利用汪清林业局1997年、2007年森林经理调查的61块蒙古栎林的固定样地数据建立了蒙古栎林全林整体模型。全林整体模型是一组非线性联立方程组,它由8个非线性模型组成。利用Forstat2.0软件中的"非线性误差变量联立方程组"方法求解模型参数,保证了模型的无偏性。"刀切法"检验结果表明各林分因子的平均相对误差和相对均方误差均在15%以下。应用全林整体模型可以进行不同初始条件林分的生长分析及制定不同立地条件的林分密度控制图,为蒙古栎林的经营提供参考。  相似文献   

5.
MongolianScotspine(Pinussylveslrisvarmongolica)(shortform:MSP)isoneofthemainconiferousspeciesforforestationinNortheastforestregionsofChinasincel958,large-areaplantationofMSPwereplantedinMaoershanExperimentalForestFarmofNortheastForestryUniversity.Alongwiththeincreaseofstandageandseed-bearingrate,andtheimprovementofwithinstandlightcondition,alotofnaturalregeneratedseedling(inshortform:NRS)ofMSPoccurredundercanopyorontheadjacentopenland,andmanyoftheseseedlingsgrowverywell.Thisprovideusa…  相似文献   

6.
Investigations were made in korean pine, mongolian scots pine and dahurian larch plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. Data are tabulated on the amount and seasonal and annual fluctuations of fractional composition of the litter (conifer needles, branches, cones, bark scales, broad leaves) in the three plantations. The accounts of conifer needle branch and bark scale litter are as follows: korean pine: 71.16%, 6.23% and 7.32%; mongolian scots pine: 43.65%, 18.52 % and 32.12%; dahurian larch: 90.30%, 7.83% and 1.85%. There are certain broadleaf litter in dahurian larch and mongolian scots pine plantations (account for 7.61% and 8.92% respectively). The litter wither and fall concent ratively in autumn in dahurian larch plantation and scattered all year long in korean pine and mongolian scots pine plantations. Along with the increase of stand age, the absolute amount of litter tend to increase, the relative amount of main fractional compositions (conifer needle, branch and bark scale) in korean pine and mongolian Scots pine plantations maintain stead, whereas in dahurian larch plantation, the relative amount of conifer needle is decreased gradually and the relative amount of other fractional compositions are increased gradually.  相似文献   

7.
对不同经营方式下蒙古栎次生林林下草本种群特征进行了研究。结果表明:混交模式下草本植物种类要略多于纯林模式下;大多数草本在针阔混交模式下,高度、盖度、数量、频度等指标要大于纯林模式下,即混交模式更适于林下草本的生长繁衍及对资源的占有利用;混交林下草本在保持水分方面与纯林相比更具优势。  相似文献   

8.
Gypsy moth (Lymantria dispar L.) outbreaks affect stand dynamics and successional patterns in pine–oak woodlands of North America's Atlantic coastal plain. Species-poor overstories are dominated by pitch pine (Pinus rigida), black oak (Quercus velutina) and white oak (Quercus alba). Both oaks are preferred food for gypsy moth, and white oak is the dominant late-successional species. We documented, over a 21-year period, the effects of gypsy moth defoliation on forest stand dynamics at Cape Cod National Seashore, Massachusetts. Our goal was to better understand the influence of gypsy moth defoliation on temporal changes in stand composition. Tree species abundance and frequency were measured in 16 stands with varying abundances of pitch pine and oak. Regression of 2-dimesional rates of change calculated from principal components analysis showed that gypsy moth significantly influenced stand dynamics and successional patterns between 1981 and 1992/1993. Defoliation was virtually absent in the 1990s, and analysis of 1992/1993–2002 rates of change showed topographic slope to be the most important factor influencing stand dynamics during this time. For the period 1981–2002 rates of change analysis failed to identify either factor as influencing changes in stand dynamics. We conclude that the 1980s defoliation events had a transitory effect on upland forest composition, but that there exists the potential for significant long-term impact due to recurrent defoliation episodes. Stand composition should be monitored at intervals which roughly correspond to the time it takes for stands to recover to disturbance events, in the case of those we sampled, approximately 10 years.  相似文献   

9.
The relationship between competition and tree growth was studied in four stands of Pinus sylvestris L. occurring in a continental Mediterranean mountain area (in the Guadarrama range, Spain), i.e., an uneven-aged stand, a stand with oak (Quercus pyrenaica Willd.) understorey, a plantation, and a mature even-aged stand. Competition was measured by a simple size-ratio distance-independent index and was negatively associated with tree diameter. This negative association was stronger in the uneven-aged, plantation and mature even-aged stands than in the stand with oak understorey. Competition was also negatively associated with current diameter increment. This relationship was moderately strong in the mature even-aged stand and weak in the uneven-aged stand and the plantation. In the uneven-aged and the mature even-aged stands, a weakly significant relationship was found between diameter growth and tree size, whereas these parameters were not associated in the stand with oak understorey. The competition index provided a better prediction of growth rate than the alternative use of diameter. Both diameter and basal area growth were greater in the uneven-aged than in the even-aged stands.  相似文献   

10.
Sudden oak death (SOD), caused by the recently discovered non-native invasive pathogen, Phytophthora ramorum, has already killed tens of thousands of native coast live oak and tanoak trees in California. Little is known of potential short and long term impacts of this novel plant–pathogen interaction on forest structure and composition. Coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica) form mixed-evergreen forests along the northern California coast. This study measured tree mortality over a gradient of disease in three time periods. Direct measurements of current mortality were taken during 2004, representing a point-in-time estimate of present and ongoing mortality. Past stand conditions, c. 1994, were estimated using a stand reconstruction technique. Future stand conditions, c. 2014, were calculated by assuming that, given a lack of host resistance, live trees showing signs of the disease in 2004 would die. Results indicate that coast live oaks died at a rate of 4.4–5.5% year−1 between 1994 and 2004 in highly impacted sites, compared with a background rate of 0.49% year−1, a ten-fold increase in mortality. From 2004 to 2014, mortality rates in the same sites were 0.8–2.6% year−1. Over the entire period, in highly impacted sites, a 59–70% loss of coast live oak basal area was predicted, and coast live oak decreased from 60% to 40% of total stand basal area, while bay laurel increased from 22% to 37%. Future stand structures will likely have greater proportions of bay laurel relative to coast live oak.  相似文献   

11.
Koreanpine(Pinuskoraiensis)(KP),mongolianscotspine(Pinussylvestrisvarmongolica)(MSP)anddahurianlarch(LarisgmeIinii)(DL)arethemainconiferousspeciesforforestationinnortheastregionofChina-LargeareplantationsofKP,MSPandDLhavebeenplantedintheregionsincel95o's.Whetherthestandstabilityandecolo-gicalequilibriumcanbemaintainedandtheforestfloorproductivitycanincreaseintheplantati0nsismainlydeterminedbytheamount,fracti0nalandchemicalcomp0sitionanddecomp0sitionrateof1itters,exceptforinfluenceofl0ca…  相似文献   

12.
This paper established an integrated stand growth model of Mongolian oak(ISGM_oak) using the data from 61 permanent sample plots measured in 1997 and 2007.ISGM_ oak is a group of nonlinear simultaneous equations.The method of nonlinear error-in-variable simultaneous equations is used to estimate the parameters of ISGMoak with the statistical software Forstat 2.0,so the parameter estimation of the group of correlated equations in ISGMoak is unbiased and the equations are compatible.Model validation using bootstrap method showed that both the average relative error and square error are less than 15 percent.The ISGM_ oak model can be used to simulate the stand growth with different values of site index,stand density and to draw stand density management diagram for decision-making.  相似文献   

13.
水基聚氨酯胶粘剂在集成材生产中的应用   总被引:4,自引:1,他引:3  
讨论了水基聚氨酯木材胶粘剂的反应机理和影响其胶接性能的主要因素,进行了SR-100木材结构胶制备集成材的应用试验。结果表明:该胶用于针叶材云杉和阔叶材水曲柳、榆木、柞木,所制得集成材的粘接性能达到结构用集成材的指标要求,为生产结构集成材提供技术依据。  相似文献   

14.
Oak regeneration failure in the hardwood forests of eastern North America has been well documented. Silvicultural treatments of prescribed burning and canopy thinning (fire surrogate) are being studied as possible management tools to promote oak regeneration in oak dominated forests. We examined oak seed production and predation by acorn weevils (Coleoptera: Curculionidae) from two experimental forests in southeastern Ohio, under four different silvicultural treatments. Treatments consisted of replicate stands that received a prescribed burning, thinning, and thinning followed by a prescribed burn, in addition to an untreated control. Initial thinning and prescribed burning treatments were conducted in winter/spring of 2000–2001, with a second prescribed burn in spring 2005. Within each treatment unit, nine black oak and nine chestnut oak trees were selected for study and two 0.25 m2 seed fall traps were placed beneath each tree. Seed collections were completed for five seasons from 2001 to 2005. Data were analyzed using a randomized complete block design, utilizing a mixed-model repeated measures analysis. Overall, stand level treatments resulted in only a slight increase in acorn production (in the burn and thin + burn stands) relative to the control; however, this response was species specific. Masting, the intermittent production of large seed crops, was evident in our study though occurrence of a mast event was not influenced by the treatments. Chestnut oak displayed greater yearly, as well as individual variation in seed production than did black oak. Treatments had no effect on predation by acorn weevils. Predation percentages were lowest during mast years for chestnut oak; however, percentages were mostly stable for black oak across all 5 years. Our data suggest that variation due to climate and genotype are more influential in affecting seed production and masting cycles than are stand level disturbances. Thus, stand level management activities are not likely to have a large influence on oak seed production and oak regeneration must be more strongly influenced at other stages of its life history.  相似文献   

15.
The dynamics of three major mineral nutrients (K, Ca, Mg) and six heavy metals (Fe, Mn, Zn, Cu, Pb and Cd) were studied in decomposing natural, unpolluted litter in two forest types: Scots pine needle litter in a pure Scots pine forest and oak‐hornbeam leaf litter in a mixed oak‐hornbeam stand. Of the mineral nutrients, only K in the oak‐hornbeam system showed a significant decrease in concentration during the course of litter decomposition. For Ca and Mg in both systems and for K in the Scots pine system no clear relation between concentration and accumulated litter‐mass loss was observed. On the other hand, for Fe, Zn, Pb and Cd at both sites, as well as for Mn in the oak‐hornbeam stand and Cu in the Scots pine stand highly significant positive relations were found between heavy metal concentrations and accumulated mass loss. A decrease in concentration was noted only in the case of Mn in the Scots pine system. No clear pattern was found for Cu in the oak‐hornbeam stand. Concentrations of heavy metals in the decomposing litter reached levels at or above those reported to retard decomposition in other studies. At the oak‐hornbeam stand increased also the absolute amounts of Fe, Zn, Pb and Cd.  相似文献   

16.
对福建省浦城县36a生栓皮栎人工造林效果进行了调查研究。结果表明,栓皮栎人工林具有较高的林分生产量,林分总生物量达266.560t/hm~2,乔木层为257.149t/hm~2;林分平均树高20.4m,平均胸径19.5cm,蓄积量达201.87m~3/hm~2。与杉木人工林相比,栓皮栎人工林具有良好的土壤结构和较强的养分供应能力。其表层土壤>0.25mm水稳性团聚体含量比杉木人工林高9.99%,土壤有机质含量比杉木人工林高0.695%。栓皮栎人工林还具有良好的水源涵养能力,林分总持水量比杉木人工林高10%。  相似文献   

17.
Absence of, or poor, oak (Quercus spp.) regeneration is a problem in uneven-aged, mixed closed-canopy broadleaved forests. Browsing by ungulates on small trees may contribute to poor oak regeneration in such forests. This possibility was investigated in 25 Swedish stands, and browsing damage was analysed in relation to landscape and stand factors. The proportion of browsed small (<20 cm tall) oak seedlings and other seedlings was low, and apparently a minor mortality factor. For saplings (20–130 cm tall), accumulated browsing damage was generally higher on oak than on five major competing tree species: Fraxinus excelsior, Corylus avellana, Tilia cordata, Acer platanoides and Sorbus aucuparia. Leaf removal was rare in late summer, except for rowan. The amount of cover (shelter) for ungulates near plots was positively correlated with oak browsing intensity; within plots, a high density of ash saplings may reduce browsing on oak saplings. In these forests, browsing probably retards growth of oak saplings relative to competing trees. Oak may persist as a minor stand component, but monitoring is needed to study future changes.  相似文献   

18.
Our objective was to investigate the differences in the spectral trajectory of the LANDSAT Thematic Mapper with stand volume development between Japanese larch (Larix kaempferi) and Japanese oak (Quercus mongolica var. crispula) in the experimental forest of Kyushu University, Hokkaido, Japan. We used nonlinear regression and a categorical variable to investigate the relationship between spectral reflectance factor and stand volume for each forest type. This research showed that the reflectance factor of Japanese larch and Japanese oak reached saturation and that both forest types had different spectral trajectories with stand development. In addition, we found that middle of development stage (stand volume was between 100 and 200 m3/ha) of each forest type had similarity in reflectance factor.  相似文献   

19.
山西太岳山典型森林群落土壤有机质及氮素研究   总被引:2,自引:0,他引:2  
分析了太岳山7种典型森林群落土壤有机质和氮素的基本状况,结果表明:不同林型,土壤腐殖质层和淀积层有机质含量均是油松辽东栎混交林最高,分别为4.908g/kg和3.528g/kg;土壤腐殖质层有机质含量油松林最低,为3.959g/kg,淀积层有机质含量山杨林最低,为1.779g/kg;土壤腐殖质层全氮含量,白桦林最高,为0.368%,辽东栎林最低,为0.176%。;土壤腐殖质层速效氮含量华北落叶松林最高,为292.191mg/kg,油松林最低,为167.725mg/kg;土壤淀积层全氮含量油松林最高,为0.277%,油松辽东栎混交林最低,为0.094%;土壤淀积层速效氮含量山杨林最高为200.183mg/kg,油松辽东栎混交林最低,为49.151mg/kg;土壤有机质、全氮及速效氮含量均是上层土壤高于下层。腐殖质层和淀积层土壤有机质含量在各林型间差异均不显著(P>0.05),而全氮和速效氮含量在各林型间的差异均达到极显著水平(P<0.01)。  相似文献   

20.
This study focuses on two rarely studied aspects of oak decline: relations with site characteristics and effects on tree growth. The study was carried out in a 5.5 ha stand in Hungary which is strongly affected by oak decline. The nearly pure sessile oak (Quercus petraea) stand of mostly coppice origin was 90 years old at the beginning of the study. Within-stand site heterogeneity was described by the herbaceous vegetation. Four ecological site types were distinguished by the species composition of herbs, and characterized by the ecological indicator values of the species. Tree growth between 1987 and 1993 was measured, and tree vigour was estimated from visual characteristics five times between 1987 and 1993. Potential volume increment of declining trees was estimated with the growth rates of healthy trees of the same size. Volume increment loss caused by oak decline was also assessed. Significant positive relationships were found between tree vigour and tree size and between tree vigour and tree growth. The growth of seriously declining trees dropped to almost one-half of that of healthy ones. Growth reduction of living trees at the stand level amounted to 5.4%, whereas growth reduction of all trees, including those that died during the observation period, amounted to 19.9% of the potential growth. Tree size and growth were greater on better sites. A strong relationship was also found between tree vigour and site type, but sessile oak was more susceptible to decline at better sites.  相似文献   

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