水曲柳落叶松混交林中细根空间分布

采用根钻取样方法对年生水曲柳落叶松混交林中细根空间分布状况进行了研究。结果表明,水曲柳落叶松地下生物量的空间分配差异显著。在林分水平上,水曲柳的根生物量密度高于落叶松(分别为4442.3和2234.9g/m3)。两树种在相邻区域中分配的细根生物量较高,表明种间根系竞争较弱。落叶松行间的水曲柳细根生物量密度和根长密度均高于水曲柳行间的落叶松细根,表明水曲柳地下部分具有较强能力。根系的空间分布有利于混交林中水曲柳的生长。图1表4参19。     

Ecological distribution and seasonal change of soil microorganisms in pure and mixed plantations

lntroductionSoiImicroorganismsareimportantingredientsinsoilandobviouslyaff6ctsoiIf6rtiIity,andtheycanchangethephysicochemicaIpropertiesofthesoilsbythejrmetabolicactivities.The'reproductionofmi-croorganismscanintensiveIyinffuencegrowthanddeveIopmentofpIants.Therootsoffensecretevari-OuskindsofexosmosemateriaIsuchassaccharide,aminoacidandvitamins,whichcanalsostimuIatethereproductionofthesoilmicroorganisms.Thenumberandspeciesofthesoilmicroorgaoismsaredifferentwiththechangeofthesoiltype,environ…     

落叶松水曲柳纯林与混交林根际土壤中养分浓度的变化

在落叶松水曲柳纯林与混交林中,采集林地土和根际土,测定了氮、磷、钾浓度,目的是探讨养分条件变化在混交林增产上的作用。结果表明:混交林林地土全氮浓度和水解氮浓度与水曲柳纯林相近,但要高于落叶松纯林。水曲柳在混交林中根际土全氮和水解氮浓度与纯林中的相近,而落叶松在混交林中根际土水解氮浓度明显高于纯林中的。混交林林地土全磷和全钾浓度与两个树种的纯林相差不大。混交林林地土有效磷、有效钾浓度均高于水曲柳纯林,而且水曲柳在混交林中根际土的有效磷和有效钾浓度与纯林中的相比明显增加,分别高出44.1%~79.6%和13.5%~25.6%。这说明水曲柳在混交林中磷和钾的利用状况得到了改善。表2参15。     

Spatial and temporal patterns of fine root abundance in a mixed oak-beech forest

Spatial distribution and seasonal fluctuation of fine root density (mass per unit soil volume) and abundance (mass or surface area per unit ground surface area) were investigated by the sequential coring technique in a 100–220 year old mixed Fagus sylvatica-Quercus petraea stand on acidic sandy soil in northwest Germany. The fine root systems of the two co-existing species overlapped completely with beech roots being twice as abundant as oak roots. Since Fagus and Quercus occupied equivalent parts of the canopy volume, oak appeared to be under-represented in the below-ground space. There was evidence for some degree of below-ground niche partitioning between the species in both the vertical and the horizontal direction. Oak fine roots were found to be more superficially distributed than beech roots in the organic layers, indicating a vertical stratification of the root systems of the two species. In the forest floor, fine roots were more abundant in the vicinity of aok stems where thicker organic layers occurred. However, this distribution pattern was not a consequence of a greater abundance of oak roots close to their parent stem, but was due to a higher frequency of beech roots here.     

THE SEASONAL DYNAMICS OF NUTRIENT CONTENTS IN MANCHURIA ASH-DAHURIAN LARCH MIXED STAND

StUdiesontheundeopundsboctUfCofmanchurianash-dahurianlarchmixedstandrevealedthatseveralrowsofmanchurianashtreesnearestdahurianlarchbelthaveobviouschangesofrootSindistribution,densityandgrowthtCndenCy.Numerousrootsofmanchu-rianashgrowtowardthelarchbelt,indicatingthattherewerefavorableconditionsfOrtherootstogrowinthelarchbelt.ThedahurianlarchtrCesmusthaveimprovedtheenviron-mentinsomeaspect.STUDYSlTESStUdysitessitUatedinHeilonaiiangProv-ince,mainlyinDongxingForestFarmofKe-dongcounty,wes…     

落叶松水曲柳混交林中根际土壤交换性阳离子含量的比较

通过对落叶松水曲柳混交林中根际土壤交换性阳离子的比较,得到了落叶松水曲柳混交林根际土壤交换性阳离子的变化趋势为:除钠外,落叶松的各项交换性阳离子含量均大于水曲柳,钠与钾、钙、镁存在拮抗作用,营造落叶松混交林有利于促进落叶松的生长。     

Interspecific competition impacts on the morphology and distribution of fine roots in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.)

Morphology and vertical distribution patterns of spruce and beech live fine roots (diameter ≤2 mm) were studied using a soil core method in three comparable mature stands in the Solling: (1) pure beech, (2) pure spruce and (3) mixed spruce–beech. This study was aimed at determining the effects of interspecific competition on fine root structure and spatial fine root distribution of both species. A vertical stratification of beech and spruce fine root systems was found in the mixed stand due to a shift in beech fine roots from upper to lower soil layers. Moreover, compared to pure beech, a significantly higher specific root length (SRL, P<0.05) and specific surface area (SSA, P<0.05) were found for beech admixed with spruce (pure beech/mixed beech SRL 16.1–23.4 m g⁻¹, SSA 286–367 cm² g⁻¹). Both indicate a flexible ‘foraging’ strategy of beech tending to increase soil exploitation and space sequestration efficiency in soil layers less occupied by competitors. Spruce, in contrast, followed a more conservative strategy keeping the shallow vertical rooting and the root morphology quite constant in both pure and mixed stands (pure spruce/mixed spruce SRL 9.6/7.7 m g⁻¹, P>0.10; SSA 225/212 cm² g⁻¹, P>0.10). Symmetric competition belowground between mixed beech and spruce was observed since live fine roots of both species were under-represented compared to pure stand. However, the higher space sequestration efficiency suggests a higher competitive ability of beech belowground.     

THE CHARACTERS AND EFFECTS OF AVAILABLE PHOSPHORUS IN DAHURIAN LARCH-MANCHURICA ASH MIXED SEEDLING STAND

Dahurianlarch(Larixgmelinii)isamaintreesPeciesinartificialstandsandManchuriaash(Fnainusma:dehurica)isavaluabIehardwoodsPeciesinti1eforestareaofnortheastChina.SomestUdiesrevealedthatthemixedstandbythetwospecieshadpositivemixedeffectSandnutritionrelationshipwasoneofthemaincausesforthepositiveeffects.lnsomeresearches,itwasfoundthatinline-belttwoflarch-ashmixedstand,theconcentra-tionofavailablephosphorusofsoilinlarchbeltwas2ntimesoftl1atinashbelt.Itisdeducedthatinsuchmixedstandtheashcanabsorbmo…     

In situ measurement of water absorption by fine roots of three temperate trees: species differences and differential activity of superficial and deep roots

The spatial heterogeneity of water uptake by fine roots under field conditions was analyzed in situ with miniature sap flow gauges in a mature beech-oak-spruce mixed stand. Sap flow rate (J), sap flow density (Jd), and root surface-area-specific flow rate (uptake rate, Js) were measured for eight to 10 small-diameter roots (3-4 mm) per species in the organic layer (superficial roots) and in the mineral soil (30-80 cm, deep roots) during four months in summer 1999. We calculated Js by relating J to the surface area of the section of the fine root system distal to the position of the gauge on the root. When measured synchronously, roots of the three species did not differ significantly in mean Js, although oak roots tended to have lower rates. However, Jd decreased in the sequence spruce > beech > oak in most measurement periods. Microscopic investigation revealed differences in fine root anatomy that may partly explain the species differences in Jd and Js. Oak fine roots had a thicker periderm than beech and spruce roots of similar diameter and spruce roots had fewer fine branch rootlets than the other species. Synchronously recorded Jd and Js of nearby roots of the same tree species showed large differences in flow with coefficients of variation from 25 to 150% that could not be explained by patchy distribution of soil water. We hypothesize that the main cause of the large spatial heterogeneity in root water uptake is associated with differences between individual roots in morphology and ultrastructure of the root cortex that affect root radial and root-soil interface conductivities. The high intraspecific variation in Js may mask species differences in root water uptake. Superficial roots of all species typically had about five times higher Jd than deep roots of the same species. However, Js values were similar for superficial and deep roots in beech and spruce because small diameter roots of both species were more branched in the organic layer than in mineral soil. In oak, deep roots had lower Js (maximum of 100 g m(-2) day(-1)) than superficial roots (about 1000 g m(-2) day(-1)). We conclude that temperate tree species in mixed stands have different water uptake capacities. Water flow in the rhizosphere of forests appears to be a highly heterogeneous process that is influenced by both tree species and differences in uptake rates of individual roots within a species.     

落叶松与水曲柳混交林的营造

通过对落叶松与水曲柳生物生态学特性 ,以及选择混交树种的条件和依据的论述 ,说明了营造落叶松与水曲柳混交林的可行性     

马尾松苦竹混交林根系分布格局

对马尾松苦竹混交林根系分布格局进行研究.结果表明:混交林根系垂直分布比较合理.水平上有重叠,但根系多相互交错,穿插延伸.低密度混交经营的马尾松细根在40～60 cm土层占细根总量的83.8%,而苦竹竹鞭及其构成的竹林地下吸收、输导、贮存系统主要分布在0～40 cm土层占96.0%,较合理地利用了不同土层的营养物质.混交林分中马尾松水平根幅8.9 m,但在0～40 cm土层主要为水平骨骼根,呈疏散框架扩展延伸,给苦竹鞭根的运行、穿插腾出了空间.而苦竹的竹根水平占据空间较小,一般在30 cm左右,鞭根稀少.马尾松利用疏林结构模式兼营苦竹的混交林分不仅形成合理的地上结构,而且地下结构也较合理.     

Effects of intercropping systems of trees with soybean on soil physicochemical properties in juvenile plantations

The intercropping system of tree with soybean in juvenile plantations, as a short-term practice, was applied at Lao Shan Experimental Station in Mao’er Shan Forest of Northeast Forestry University, Harbin, China. The larch (Larix gmelinii)/soybean (Glycine max.) and ash (Fraxinus mandshurica) intercropping systems were studied in the field to assess the effects of the intercropping on soil physicochemical properties. The results showed that soil physical properties were improved after soybean intercropping with larch and ash in one growing season. The soil bulk density in larch/soybean and ash/soybean systems was 1.112 g·cm⁻³ and 1.058 g·cm⁻³, respectively, which was lower than that in the pure larch or ash plantation without intercropping. The total soil porosity also increased after intercropping. The organic matter amount in larch/soybean system was 1.77 times higher than that in the pure larch plantation, and it was 1.09 times higher in ash/soybean system than that in the pure ash plantation. Contents of total nitrogen and hydrolyzable nitrogen in larch/soybean system were 4.2% and 53.0% higher than those in the pure larch stand. Total nitrogen and hydrolyzable nitrogen contents in ash/soybean system were 75.5% and 3.3% higher than those in the pure ash plantation. Total phosphorus content decreased after intercropping, while change of available phosphorus showed an increasing trend. Total potassium and available potassium contents in the larch/soybean system were 0.6% and 17.5% higher than those in the pure larch stand. Total potassium and available potassium contents in the ash/soybean system were 56.4% and 21.8% higher than those in the pure ash plantation. Biography: FAN A-nan (1972–), female, Ph. Doctor in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China.     

A model for vertical distribution of fine roots in Robinia pseudoacacia plantations on the Loess Plateau

Based on a detailed investigation of vertical distributions of fine roots in Robinia pseudoacacia plantations at the Ansai Soil and Water Conservation Station, Shaanxi Province, a model was developed for the deep distribution of fine roots of R. pseudoacacia, which reflects the growth of fine roots affected by the mixed process of infiltration water and deep soil water. The maximum depth of the distribution h _max and the depth of the highest fine root density (FRD) h _p were determined and the maximum depth of infiltration water supplied for fine root growth h _q could also be calculated, h _q was considered as the approximate boundary between infiltration water and deep soil water in support of the growth of fine roots. According to the model, the soil water of R. pseudoacacia woodland in the profile could be classified into three layers: the first layer from the soil surface to h _p was the active water exchange layer, very much affected by precipitation; the second was the soil water attenuation layer, between h _p and h _q and largely affected by the vertical distribution of fine roots; the third was the relatively stable soil water layer below h _q, below which soil water did not change much. The percentage of infiltration water supplied for the growth of fine roots reached a level of 88.32% on the shaded slopes and 85.21% on sunny slopes. This indicated infiltration of precipitation played a crucial role in the growth of R. pseudoacacia in the gully region of the Loess Plateau. The research of interaction between the distribution of fine roots and soil water in the profile will help to explain the reasons for the complete drying out of soils and provide a theoretical basis for continuing the policy of matching tree species with sites on the Loess Plateau. Translated from Scientia Silvae Sinicae, 2006, 42(6): 40–48 [译自: 林业科学]     

Ectomycorrhizal colonisation of roots and ash granules in a spruce forest treated with granulated wood ash

Granulated wood ash has been proposed as a slow release fertiliser suitable for forest soils. In this study ectomycorrhizal colonisation of roots and ash granules was studied in a 40-year-old spruce forest treated with 0, 3 or 6 t ha⁻¹ granulated wood ash. We used PCR-RFLP methods for ITS-typing and identification of ectomycorrhizal fungi. In total 20 different ITS-types were recognised on roots in the organic soil horizon. Five of these were identified to species and two to genus. Six species, Tylospora fibrillosa Donk, Cortinarius sp. 3, Piloderma sp. 1, and three unidentified ITS-types (Ve-95-1, Tö-95-3 and Ve-95-9) each occurred on over 5% of the total root tips analysed. Together these comprised 55% of the ectomycorrhizal community on the screened roots.

Ash granules collected from the fertilised plots were normally colonised by fungal mycelia. PCR-RFLP analysis of these mycelia revealed the presence of four ITS-types. Three of these (Piloderma sp. 1, Ha-96-3 and Tor-97-1) were also present on the mycorrhizal roots. Piloderma sp. 1 was the most abundant species colonising roots. A possible role of ectomycorrhizal mycelia in the direct mobilisation of nutrients from ash granules is discussed.     

Effect of nitrogen fertilizer, root branch order and temperature on respiration and tissue N concentration of fine roots in Larix gmelinii and Fraxinus mandshurica

Root respiration is closely related to root morphology, yet it is unclear precisely how to distinguish respiration-related root physiological functions within the branching fine root system. Root respiration and tissue N concentration were examined for different N fertilization treatments, sampling dates, branch orders and temperatures of larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) using the excised roots method. The results showed that N fertilization enhanced both root respiration and tissue N concentration for all five branch orders. The greatest increases in average root respiration for N fertilization treatment were 13.30% in larch and 18.25% in ash at 6°C. However, N fertilization did not change the seasonal dynamics of root respiration. Both root respiration and root tissue N concentration decreased with increase in root branch order. First-order (finest) roots exhibited the highest respiration rates and tissue N concentrations out of the five root branch orders examined. There was a highly significant linear relationship between fine root N concentration and root respiration rate. Root N concentration explained >60% of the variation in respiration rate at any given combination of root order and temperature. Root respiration showed a classical exponential relationship with temperature, with the Q(10) for root respiration in roots of different branching orders ranging from 1.62 to 2.20. The variation in root respiration by order illustrates that first-order roots are more metabolically active, suggesting that roots at different branch order positions have different physiological functions. The highly significant relationship between root respiration at different branch orders and root tissue N concentration suggests that root tissue N concentration may be used as a surrogate for root respiration, simplifying future research into the C dynamics of rooting systems.     

Responses of fine root mass,length, production and turnover to soil nitrogen fertilization in <Emphasis Type="Italic">Larix gmelinii</Emphasis> and <Emphasis Type="Italic">Fraxinus mandshurica</Emphasis> forests in Northeastern China

The responses of fine root mass, length, production and turnover to the increase in soil N availability are not well understood in forest ecosystems. In this study, sequential soil core and ingrowth core methods were employed to examine the responses of fine root (≤1 mm) standing biomass, root length density (RLD), specific root length (SRL), biomass production and turnover rate to soil N fertilization (10 g N m⁻² year⁻¹) in Larix gmelinii (larch) and Fraxinus mandshurica (ash) plantations. N fertilization significantly reduced fine root standing biomass from 130.7 to 103.4 g m⁻² in ash, but had no significant influence in larch (81.5 g m⁻² in the control and 81.9 g m⁻² in the fertilized plots). Similarly, N fertilization reduced mean RLD from 6,857 to 5,822 m m⁻² in ash, but did not influence RLD in larch (1,875 m m⁻² in the control and 1,858 m m⁻² in the fertilized plots). In both species, N fertilization did not alter SRL. Additionally, N fertilization did not significantly alter root production and turnover rate estimated from sequential soil cores, but did reduce root production and turnover rate estimated from the ingrowth core method. These results suggested that N fertilization had a substantial influence on fine root standing biomass, RLD, biomass production and turnover rate, but the direction and magnitude of the influence depended on species and methods.     

Fine root dynamics along an elevational gradient in the southern Appalachian Mountains,USA

Attributes of fine roots (<2.0 mm diameter) were quantified in five southern Appalachian plant communities along an elevational gradient. These attributes include the seasonal dynamics of fine root mass and length, the depth distribution of fine roots, fine root width and, most importantly, the annual appearance and disappearance of fine roots. The principal objectives of this study were two-fold: (1) to compare these attributes of fine roots between plant communities and (2) to compare the results of the two methods used to quantify the attributes: (1) harvesting roots from forest soil with soil cores and (2) photographing roots growing against the windows of minirhizotron boxes. The plant communities that were sampled are characteristic of the region and are designated as follows from lowest elevation (782 m) to highest elevation (1347 m): (1) xeric ridge, (2) cove hardwoods, (3) low elevation mixed oak, (4) high elevation mixed oak, and (5) northern hardwoods. Fine root mass varies seasonally in this temperate region with lowest and highest mass in the spring and autumn, respectively. Fine root mass and fine root mass appearance were lowest in the cove hardwood community and highest in the low elevation mixed oak community. The total length of fine roots was highest in the xeric ridge community and lowest in the low elevation mixed oak community. The high total root length in the xeric ridge community was due to the presence of an exceptionally dense mat of very fine roots found there. The width of these roots was significantly less than that of roots on all other plots. Subsequent regression illustrates two strong patterns in the data. First, fine root mass, fine root mass appearance and leaf production were positively correlated. Second, fine root length and soil moisture were negatively correlated. The accumulation of root mass in these communities was linked to overall site productivity and the development of root length in response to moisture stress. Only the timing of root growth initiation was related to elevation and the associated parameter of soil temperature. The best estimates of fine root appearance and disappearance were generated by harvesting roots rather than photographing them. Some methodological problems with root photography implemented in this study are addressed.     

Vertical distribution of fine root density, length density, area index and mean diameter in a Quercus ilex forest

We used minirhizotrons to determine the vertical distribution of fine roots in a holm oak (Quercus ilex L.) forest in a typical Mediterranean area over a 3-year period (June 1994-March 1997). We measured fine root density (number of roots per unit area), fine root length density (length of roots per unit area), fine root area index (area of roots per unit area) and fine root mean diameter. Variables were pooled for each 10-cm depth interval to a depth of 60 cm. Fine roots tended to decrease with increasing depth except between 0 and 10 cm, where the values of all fine root variables were less than in the 10-cm stratum below. Fine root vertical distribution was compared with soil water content and soil temperature at different depths in the soil profile.     

杨树刺槐混交林细根养分动态研究

对两树种细根在北京市潮白河沿河沙地加拿大杨 (2 7a生 )刺槐 (2 2a生 )混交林中的分解情况进行了研究 ,从细根养分循环角度探索了两树种混交协调生长的机理。结果表明 :(1)加拿大杨和刺槐林木细根的分解特点不同 ,杨树细根在分解前期的N、Ca、Mg元素浓度逐渐升高 ,P、K元素浓度则逐渐降低。刺槐细根分解过程中N、P、K元素浓度逐渐降低 ,杨树刺槐混交林细根混合分解中各元素含量变化介于两树种细根单独分解之间 ;(2 )细根的N、K、Mg年归还量以刺槐纯根最大 ,两树种混根次之 ,杨树纯根最小 ;(3)混交林中N素归还量的增加有利于改善杨树的N素状况 ,杨树细根的P素归还量大于刺槐细根 ,有利于改善刺槐的P素营养 ,混交林杨树与刺槐在细根N、P养分方面形成协调互补的关系     

Above- and belowground biomass and primary productivity of a Larix gmelinii stand near Tura, central Siberia

We assessed above- and belowground biomass and net primary production (NPP) of a mature Larix gmelinii (Rupr.) Rupr. forest (240-280 years old) established on permafrost soils in central Siberia. Specifically, we investigated annual carbon budgets in roots in relation to root system development and availability of soil resources. Total stand biomass estimated by allometry was about 39 Mg per ha. Root biomass (17 Mg per ha) comprised about 43% of total biomass. Coarse root (>/= 5 mm in diameter) biomass was about twice that of fine roots (< 5 mm). The aboveground biomass/root biomass ratio (T/R) of the larch stand was about unity, which is much less than that of other boreal and subalpine conifer forests. The proportion of fine roots in total root biomass (35%) was relatively high compared with other cold-climate evergreen conifer forests. Total NPP, defined as the sum of annual biomass increment of woody parts and needle biomass, was estimated to be 1.8 Mg per ha per year. Allocation of total NPP to needle production was 56%. The proportion of total NPP in belowground production (27%) was less than for evergreen taiga forests. However, belowground NPP was probably under-estimated because root mortality was excluded. We conclude that L. gmelinii trees invested annual carbon gains largely into needle production or roots, or both, at the expense of growth of aboveground woody parts. This carbon allocation pattern, which resulted in the construction of exploitative root networks, appeared to be a positive growth response to the nutrient-poor permafrost soil of central Siberia.