亚热带杉木纯林生态系统中营养元素的积累、分配和循环的研究

本文是1980--1983年本所湖南会同森林生态实验站成年杉木纯林中进行定位研究根据所取得的观测资料,分析和论述了营养元素在林内的积累与分配;以及从降雨中的输入量,计算了营养元素的年吸收量和归还量。研究表明,杉木纯林在21--23年生时,即达到主伐年龄期,营养元素年吸收量仍大于归还量,整个林分还处在养分消耗阶段。     

The Element Contents of Platycladus orientalis plantation in Beijing

Carbon is the most abundant element in the organs of the edificator-31 years old Platy- cladus orientalis. High content of Ca occurred in the edificator, there are plenty of N. K. Mg as well with relatively low content of P and high content of Fe. The concentration of elements is greater in leaves than int woody tissues of tree and shrub. The element accumulation in the aboveground part was higher than those in the under ground part of the tree layer, 51 percent of C was accumulated in trunks. The largest percentage of other elements was accumulated by leaves. On the contrary, in tile tree layer the element accumulation in the under ground part was larger than those in the aboveground part of the shrub layer except N accumulation. The element accumulation in the plantation reached 17,000 kg/ha for C, 400 kg/ha for Ca, 104 kg/ha for N, 87 kg/ha for K, 30 kg/ha for Mg, 11–16 kg/ha for Al, P and Fe, 2.5 kg/ha for Na, 1 kg/ha for Mn, Cu and Zn. The retention of C in the plantation was the highest among the elements. The retention in the Tree layer decreased from Ca to N. K. The retention of N in shrub layer is greater than that of Ca. The element retentions in the plantation were 2700 kg/ha, a for C, 70 kg/ ha.a for Ca. 15–20 kg/ha.a for N, K, 2-5 kg/ha, for P, Fe, Al, and Mg, 1 kg/ha.a for the others. The nutrient pool in soil showed C>Ca>N>Fe>Mg>K>P>Na >Al, Mn>Cu>Zn in order. In the same soil condition, the element enrichment factors by various plants were quite different. Usually the enrichment factors of the shrub were greater than those of the tree. The following sequence of the requirment of nutrients by plantation was shown: C> Ca>N >K>Mg >Fe>P>AI>Na>Mn >Cu> Zn.     

Reversal of adverse effects of heavy ammonium sulphate application on growth and nutrient status of a kikuyu pasture

Summary Adverse effects resulting from fertilization with high rates of ammonium sulphate were determined on a kikuyu grass (Pennisetum clandestinum) pasture grown on a krasnozem in a sub-tropical environment. Corrective fertilizer practices using lime and phosphorus were evaluated.Ammonium sulphate application (336 kg N/ha/annum for 4 years followed by 672 kg N/ha/annum for 2 years) decreased soil pH from 5.0 to 4.0. Under these conditions, soluble Al in the soil increased, while exchangeable Ca, Mg, and K decreased. Concentrations of Ca, Mo, and P in the kikuyu tops were lowered, while concentrations of Mn were raised. Liming to pH 5.5 promoted growth more at 672 kg N/ha/annum than at 134 kg N/ha/annum, while generally little further yield response occurred as soil pH was raised to about 6.0. Liming increased the concentrations of P, Ca, N, and Mo but decreased Mn in kikuyu tops.Phosphorus application decreased soluble aluminium in the soil in all nitrogen treatments, but only increased kikuyu yield where 672 kg N/ha/annum was applied. It did not alter plant chemical composition, except for an increase in P concentration.Yield increases to liming and P were attributed to the alleviation of Al toxicity in the high N treatments. Lime responses in low N treatments were due to improved N nutrition resulting from mineralization of organic N.Lime application reduced the amount of N fertilizer required for maximum growth of kikuyu from 672 kg N/ha/annum on the unlimed soil to 134 kg N/ha/annum, while maintaining an adequate level of nutrients in the herbage and avoiding the problems of excess soil acidity. re]19760622     

Leaf-litter and changing nutrient levels in a seasonally dry tropical hardwood forest,Belize, C.A.

Summary Total above ground plant biomass in a 45 year old seasonally dry tropical hardwood forest was estimated to be approximately 56,000 kg/ha oven dry weight. Nutrients immobilized in the standing vegetation were: N, 203 kg/ha; P, 24 kg/ha; K, 234 kg/ha; Ca, 195 kg/ha; Mg, 47 kg/ha; Na, 9 kg/ha; Mn, 1 kg/ha; Cu, 0.5 kg/ha; Zn, 3 kg/ha; Fe, 4 kg/ha. Total nutrients returned each year through the litter were: N, 156 kg/ha; P, 9 kg/ha; K, 59 kg/ha; Ca, 373 kg/ha; Mg, 32 kg/ha; Na, 5 kg/ha; Mn, 1 kg/ha; Al, 21 kg/ha; Zn, 0.3 kg/ha; Fe, 9 kg/ha. Half of the nutrients immobilized in the standing vegetation were found in the leaves and are returned annually to the soil. Although litter fall is interrupted during the year, the mean nutrient content of the litter was high –5.2%.A decomposition rate of 0.48 percent per day was considered high for a seasonally dry tropical hardwood forest. Fluctuations in soil nutrient levels showed a sharp increase at the start of the rainy season. Later during the dry season nutrient levels decreased to concentrations similar to what they were just prior to the rainy season. Soil organic matter levels were very high –20% in the top 12 cm.     

拉萨河流域洪积扇不同植被类型土壤化学计量特征

洪积扇是拉萨河流域珍贵的土地资源,而明悉其土壤养分状况是对其进行科学合理开发利用的基础。为此,在拉萨河流域选取了10个洪积扇,于2020年7-8月调查了其上的植物群落组成并采集对应土壤,测定了土壤有机碳（SOC）、全氮（TN）、全磷（TP）、全钾（TK）、碱解氮（AN）、速效磷（AP）和速效钾（AK）的含量并计算其化学计量比。结果表明：10个洪积扇的60个样方中共发现植物种87种,分属于29科79属,其中禾本科和菊科的物种居多;洪积扇SOC、TN、TP、AN和AK的平均含量分别为34.38 g/kg、2.77 g/kg、0.39 g/kg、130.78 mg/kg和189.79 mg/kg,均表现为草地>灌丛>农田,其中SOC、TN、AN和AP含量在草地和农田下差异显著（P<0.05）;土壤TK的平均含量为19.68 g/kg,表现为农田>草地>灌丛;土壤AP的平均含量为3.36 mg/kg,表现为农田>灌丛>草地;土壤C：N的均值为12.75,表现为农田>灌丛>草地;土壤C：P、N：P和N：K的均值分别为102.50、8.10和0.16,均表现为草地>灌丛>农田,总体来说洪积扇土壤P元素较为稀缺;土壤N：K与SOC、TN、TP、TK、AN、AP、AK均极显著相关（P<0.01）,SOC和TN与植物群落盖度极显著正相关（P<0.01）;典范对应分析（CCA）进一步表明土壤养分及其计量比对洪积扇植物群落组成影响显著（P=0.002）,且TP、K：P和AP是影响洪积扇植物群落组成的主要土壤生态化学计量因子。综上所述,拉萨河流域洪积扇植物种相对丰富,但分布不均匀,组成不稳定。SOC、TN、TK含量相对较高但C：N值低,表现为有机质矿化速率高而土壤肥力低下;土壤TP和AP的含量均较低,洪积扇植物群落在生长发育过程中受到土壤P元素的限制。此外,研究还发现土壤N：K同C：N：P一样可作为评价土壤养分状况的生态化学计量指标。     

Litter production,nutrient recycling and litter accumulation inPinus caribaea Morelet var.hondurensis stands in the northern Guniea savanna of Nigeria

Summary The seasonal pattern and quantity of litterfall were studied during a two-year period in two unthinned stands ofPinus caribaea Morelet var. hondurensis Barr. and Golf. in Nigeria. Although pine needles were cast continuously throughout the year, the peak period of litterfall occurred in the dry months of March and April. Mean values of annual litterfall were 3068 and 3665 kg/ha in the two stands aged 7–9 and 9–11 years respectively. Nutrient returns in litterfall in the stands had mean values of 15.0, 0.6, 17.3, 18.2 and 6.3 kg/ha of N, P, K, Ca and Mg respectively. Comparatively low amounts of N and P returned in litterfall were attributed to soil deficiencies of the two elements.Measurements of ground litter showed considerable dry matter accumulation (11378 kg/ha) in the litter layers. Estimates of litter decomposition rate and recycling time showed that it would take 3 to 4 years for the organic matter in annual litterfall to decompose completely as contrasted to about 2 to 5 months often reported under mixed nautral savanna vegetation in the same climatic environment. Similar estimates of nutrient recycling time also showed that between 2 to 4 years were required to mineralize nutrient elements in the annual litterfall; the relative mobilities of the elements were in the order K>Mg>P>NCa.     

油茶低产林养分需求和时间配置动态变化研究

以常宁油茶低产林为研究对象,分析了油茶低产林树体各器官及土壤养分时间动态变化。结果表明:油茶低产林树体在不同生长期需求的大量元素均为全N、Ca和全K最多,而需求的Mg和全P最少;需求的微量元素均为Mn和Fe最多,Cu和Cd最少;春梢期供应的土壤养分元素是速效N和Mg,夏梢期主要供应的土壤元素是速效K、全N、全P、Fe和有机质,果实成熟期主要供应的土壤养分元素是全K,开花期主要供应的土壤元素是速效P和Ca;不同时间油茶低产林养分需求为春梢期(28.36%)夏梢期(26.17%)果实成熟期(22.75%)开花期(22.73%);土壤养分供应为夏梢期(2999.83±87.04 mg/kg)果实成熟期(2703.93±292.26 mg/kg)开花期(2554.60±508.84 mg/kg)春梢期(2385.88±199.62 mg/kg);油茶低产林在不同生长期需要的养分和土壤供应的养分并不一一对应。研究结果可为油茶低产林的施肥时间配置和养分时间变化提供科学依据,在春梢期多施肥。     

Young secondary vegetation and soil interactions in Izabal,Guatemala

Summary A study of the relationships of soils and vegetation was undertaken in the humid tropical region of Lake Izabal, Guatemala, Central America. Soils and associated 10-month-old secondary growth were analyzed for N, P, K, Ca, and Mg. In addition, organic matter, Al and pH were determined in the soil samples and plant biomass for the secondary growth were calculated. The secondary growth biomass averaged 9,710 kg/ha for the 10-month growth period. Total nutrient content of the vegetation increased linearly with the biomass, except for Mg. The antagonism of Mg on K and Ca nutrition was quite significant when Mg exceeded Ca in the soil under shifting cultivation. Pure stands ofHeliconia sp. andGynerium sp. appeared to be more efficient in accumulating P than stands of mixed vegetation. Chemical composition and dry matter production of native vegetation may provide additional information to evaluate soil fertility in the humid tropics.     

川东红池坝地区红三叶和鸭茅人工草地土壤和植物营养元素含量特征的研究

川东红池坝地区红三叶（Ｔｒｉｆｏｌｉｕｍｐｒａｔｅｎｓｅ）和鸭茅（Ｄａｃｔｙｌｉｓｇｌｏｍｅｒａｔａ）人工草地土壤和植物营养元素的含量特征如下：（１）土壤中的元素含量以铁、钾和镁较高,钠、钙、氮、锰和磷较低,硫、锌、硼、铜和钼微少;（２）从元素的富集特征来看,该区土壤中的钙、硫为重度淋溶元素,钾、磷、镁、锌、钠为中度淋溶元素,铁、铜属轻度淋溶元素,锰属富集元素;（３）根据元素的生物吸收系列,红三叶属氮－钙型植物,鸭茅属氮－钾－磷型植物。（４）两种牧草的生物吸收系数,均以钙、硫、磷较高,钠、铁较低,其余７种元素介于二者之间。     

Distribution and budget of nutrients in a commercial apple orchard

Summary Data on the dry matter distribution and nutrient reserves (N, P, S, Cl, K, Ca, Mg and Na) in the standing biomass of a grassed-down 14 year-old apple orchard are presented together with mean estimates of nutrient inputs, returns and losses over a 2 year period.The major inputs of N P K and S were through fertilizer additions. The major inputs of Na and Cl were in bulk precipitation plus irrigation whilst both sources were important for Mg and Ca. Total inputs by precipitation plus irrigation plus fertilizer in kg/ha/yr were: N, 81; P, 20; S, 42; Cl, 58; K, 64; Ca, 35; Mg, 10 and Na, 33. Nutrient returns to the orchard floor were dominated by those from returns of herbage clippings orginating from the mowing of the orchard pasture. Autumn leaf fall also contributed significant quantities to the total nutrient returns. Total nutrient returns to the orchard floor through petal fall, fruit drop, leaf fall, foliar leaching (includes leaf washing) and pasture clippings in kg/ha/yr were: N, 545; P, 33; S, 41; Cl, 107; K, 442; Ca, 147; Mg, 35 and Na, 16. The major loss of Na, Mg, Ca, Cl and S was through leaching (this may include a certain amount of chemical weathering). In contrast, the major loss of P and K was in the harvested fruit crop, while for N, losses were about equally divided between the fruit crop and leaching. Total nutrient losses from the orchard by removal of the fruit crop and pruning wood plus leaching losses were estimated in kg/ha/yr at: N, 58; P, 5; S, 28; Cl, 81; K, 124; Ca, 55; Mg, 39 and Na, 80. Inputs minus losses in kg/ha/yr were positive for N, P and S(+23, +16 and +14 respectively and negative for Cl, K, Ca, Mg and Na (–24, –60, –19, –30 and –47 respectively).     

大熊猫栖息环境的森林凋落物动态研究

本文以王朗自然保护区冷杉、云杉暗针叶林为对象,在定位测定森林凋落量及其动态和枯枝落叶贮量的基础上,研究了凋落物分解速率及其主要营养元素含量的变化,结果表明：(1)地表枯枝落叶总贮量变化在30.0—91.8t／ha,其中未分解层4.9—17.8,半分解层11.5—19.7,腐殖质层13.6—57.3t／ha。(2)森林凋落的枯枝落叶量因林型不同而略有差异,平均为2.8 t／ha·yr,其凋落高峰期分别在生长季开始的5月和生长季末的10月。(3)每年以凋落物形式返回林地的养分,氮为35.5kg／ha、磷为5.7kg／ha、钾为7.0kg／ha、镁为6.8kg／ha、钙为62.9kg／ha。(4)森林各种凋落物的混合物年分解率为0.3041g／g。95%的凋落物被分解需时约10年,在分解一段时间后,凋落物中的氮、钙、镁含量略有上升,钾明显减少,而磷含量变化不大。(5)森林凋落物的混合物腐解过程中,养分释放速率大小的顺序为：K>P>Mg>Ca>N,大熊猫主食竹的凋落叶则为：K>N>Ca>Mg>P。     

The response ofPinus caribaea mor. var. Hondurensis seedlings to nitrogen,phosphorous and potassium fertilizers

Summary A soil pot culture experiment was conducted to study the response ofPinus caribaea var. hondurensis seedlings to the N, P, K fertilizers in a 3³ factorial combination of nutrients in four replicates. For this purpose, seedlings were grown in plastic pots in soils collected from Bahau pine experimental area. These soils belong to Durian series and are generally poor in nutrients.The seedlings were supplied with 112 kg/ha, 336 kg/ha and 560 kg/ha (100 lb/ac, 300 lb/ac and 500 lb/ac) of N, P, K in solution form in all possible combinations. Periodic growth measurements were taken and dry matter production was estimated at the conclusion of the experiment.The results indicate that phosphorous is the most important nutrient for the height growth of seedlings. The absolute height increment under the best treatment combination (N₁P₃K₁) was about threefolds (25.7cm) compared to 8.8 cm in the control. It was also found that higher levels of N and K, though not beneficial to height growth, resulted in better radial growth and more dry matter production compared to control plants. However, highest levels of N and K in the present experiment produced inhibitory influence as regards height growth even in the presence of low level of phosphorous.The study indicates that application of phosphorous at least at the rate of 560 kg/ha per plant is necessary on this type of soil to boost the initial height growth ofPinus caribaea var. hondurensis. Nitrogen at the rate of 336 kg/ha and potassium at the rate of 112 kg/ha will induce better radial growth.     

Study of the Effect of Phosphorus on Mineral Nutrition of Faba Bean « Vicia fabae L.»

Our study focuses on the study of the phosphorus efficiency on the mineral nutrition of a leguminous plant; to study this efficiency, we tested the effect of increasing doses of phosphorus on the mineral nutrition of faba bean and on the concentration of Nt (total nitrogen), Pi (available phosphorus), KE (exchangeable potassium), C (organic carbon), and the organic matter (OM) rate in the rhizospheric soil after harvest, as well as the concentration of N, P, K, Na, and Ca in the roots, stems, leaves, and seeds of faba bean. The faba bean crop was subjected to four phosphorus doses (P0?=?0 kg/ha; P1?=?70 kg/ha; P2?=?140 kg/ha; P3?=?210 kg/ha). The main results obtained showed that the concentration of the mineral elements in the different faba bean parts reacted differently to the phosphorus treatments. Regarding the dosage of nutrients in the different parts of the faba bean, the results obtained highlight that Pi deficiency in the soil does not only affect phosphate nutrition but can also affect the absorption of other mineral elements, a synergy is recorded between the K concentration in the roots and in the stems with the organic carbon in the soil, and an antagonism between K and Na in the different parts of the plant. All the results obtained in this work show that a phosphate fertilization for doses between 70 kg/ha and 140 kg/ha of P2O5 improves the microbial life of soil microorganisms.

     

Is primary production in holm oak forests nutrient limited?

Correlations between primary production and patterns of nutrient use and nutrient availability were investigated in 18 plots in closed holm oak (Quercus ilex L.) stands in the Montseny mountains (NE Spain), searching for evidence of nutrient limitation on primary production. The plots spanned a range of altitudes and slope aspects within a catchment. Nutrients considered were nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg) in plant samples, and the above plus calcium (Ca) and sodium (Na) in the soil. Primary production was found by summing the annual aboveground biomass increment to the annual litterfall. Across plots, primary production was correlated with the annual return of nutrients in litterfall, but this relationship probably arose from the common effects of the amount of litterfall on both primary production and nutrient return, and not from any nutrient limitation. Primary production was not significantly correlated with nutrient concentrations in mature leaves nor leaf litterfall, nor with absolute or relative foliar retranslocation of nutrients before leaf abscission, nor with the concentration and content (kg/ha) of total N, extractable P, and exchangeable K, Mg, Ca and Na in the upper mineral soil. We conclude that there is no correlational evidence that primary production is nutrient limited in this holm oak forest.     

The effects of pruning,fertilizers, and organic amendments on lowbush blueberry production

A four-year field study was conducted on a Hebert gravelly sandy loam (pH 4.5) in Nova Scotia to assess the effects of pruning management and seven fertility amendments on lowbush blueberry (Vaccinium augustifolium Ait) production (yield, above ground and root tissue composition) and soil fertility. Pruning by oil burning produced higher fruit yields than flail mowing but burning had the opposite effect on the plant N content (with a lesser influence on above ground Mn and Zn). None of the fertility treatments (chicken manure, dairy manure, swine manure, urea, sawdust, NPK, NPK+S+Lime+Micronutrients) produced fruit yields significantly greater than the control. Treatments provided the equivalent of 50kg total N/ha/2-yr cycle. Treatments influenced tissue N, P, K, Ca, Mg, B, Mn, Cu, Zn and Mo levels. In general, the three manure treatments produced the highest levels of plant macronutrients; the urea treatment produced the lowest levels of plant nutrients. In most cases, extractable levels of soil P, K, Ca and Mg were highly correlated with the plant tissue content of these elements. Overall, the dairy manure treated soils were the highest in soil fertility.     

无牧草原生态系统营养元素的生物地球化学特征

以内蒙古锡林河流域的两种优势草原群落羊草草原和大针茅草原为研究对象,探讨了中纬度地区未放牧情况下的草原生态系统植物营养元素的生物地球化学特征．结果表明,两类草原群落土壤-植物系统中土壤分室N、P、K、S、Ca、Mg、Si的贮量远大于植物亚系统的贮量,地上活体和枯草分室的各元素贮量小于根分室．在两类草原群落中,N、P、K、S从枯草分室中消失的速率要大于Ca、Mg和Si．羊草草原的枯草分室元素流失量大于大针茅草原．研究区草原生态系统中,羊革草原物质的生物地球化学循环近于平衡状态,大针茅草原处于失衡状态．物质循环量羊草草原远大于大针茅草原．     

The biogeochemistry of a north-temperate grassland with native ungulates: Nitrogen dynamics in Yellowstone National Park

Nutrient dynamics of large grassland ecosystems possessing abundant migratory grazers are poorly understood. We examined N cycling on the northern winter range of Yellowstone National Park, home for large herds of free-roaming elk (Cervus elaphus) and bison (Bison bison). Plant and soil N, net N mineralization, and the deposition of ungulate fecal-N were measured at five sites, a ridgetop, mid-slope bench, steep slope, valley-bottom bench, and riparian area, within a watershed from May, 1991 to April, 1992.Results indicated similarities between biogeochemical properties of Yellowstone grassland and other grassland ecosystems: (1) landscape position and soil water affected nutrient dynamics, (2) annual mineralization was positively related to soil N content, and (3) the proportion of soil N mineralized during the year was negatively related to soil C/N.Grazers were a particularly important component of the N budget of this grassland. Estimated rates of N flow from ungulates to the soil ranged from 8.1 to 45.6 kg/ha/yr at the sites (average = 27.0 kg/ha/yr), approximately 4.5 times the amount of N in senescent plants. Rates of nitrogen mineralization for Yellowstone northern range grassland were higher than those measured in other temperate grassland ecosystems, possibly due to grazers promoting N cycling in Yellowstone.     

The Chemical Elements of Planted Forest of Pinus tabnlaeformis

The concentration of chemical elements in the edifieator Pinus tabulaeformis of 28- aged pine plantation from leaves, small branches(< 1.5 cm diameter), branches (> 1.5 cm diameter) to trunk graduately declined. C was the most abundant element in pine plantation. The N content was more abundant in leaves, Ca, K, Mg. P were plentiful as well. The mineral content in small root (<2 cm diameter) was richer than that in root (>2 cm diameter). There were plenty of C, N, P. and Ca in the shrub layer, especially in the leaves of shrubs. The concentration of mineral elements in aboveground part of grasses was obviously lower than those in the leaves of shrubs. Comparing chemical elements of litter with those in living leaves and branches, the contents of Fe and A1 in the litter increased, the other elements more or less decreased. The accumulation of C in different layer of plantation except litter reached 22.43 t/ha, the accumulation amounts of Ca and N ranged 157–161 kg/ha. The retention of C in pine plantation was the highest among the elements, Ca retained in tree layer and N, K in shrub layer showed very plentiful also. Ca returned by litter was more than the others except C. The efficiency of P and K uptaked by plant from soil was high. To use the P and K fertilizers will accelerate the growth of Pine plantation.     

Land use intensity,rather than plant species richness,affects the leaching risk of multiple nutrients from permanent grasslands

The intensification of land use constitutes one of the main drivers of global change and alters nutrient fluxes on all spatial scales, causing landscape‐level eutrophication and contamination of natural resources. Changes in soil nutrient concentrations are thus indicative for crucial environmental issues associated with intensive land use. We measured concentrations of NO₃–N, NH₄–N, P, K, Mg, and Ca using 1,326 ion‐exchange resin bags buried in 20 cm depth beneath the main root zone in 150 temperate grasslands. Nutrient concentrations were related to land use intensity, that is, fertilization, mowing, grazing intensities, and plant diversity by structural equation modeling. Furthermore, we assessed the response of soil nutrients to mechanical sward disturbance and subsequent reseeding, a common practice for grassland renewal. Land use intensity, especially fertilization, significantly increased the concentrations of NO₃–N, NH₄–N, K, P, and also Mg. Besides fertilization (and tightly correlated mowing) intensity, grazing strongly increased NO₃–N and K concentrations. Plant species richness decreased P and NO₃–N concentrations in soil when grassland productivity of the actual year was statistically taken into account, but not when long‐term averages of productivity were used. Thus, we assume that, in the actual study year, a distinct drought period might have caused the observed decoupling of productivity from fertilization and soil nutrients. Breaking up the grassland sward drastically increased NO₃–N concentrations (+146%) but reduced NH₄–N, P, and K concentrations, unbalancing soil nutrient stoichiometry and boosting the risk of N leaching. Reseeding the sward after disturbance did not have a short‐term effect on nutrient concentrations. We conclude that renewal of permanent grassland should be avoided as far as possible and future grassland management has to strongly rise the effectiveness of fertilization. Additionally, grassland management might have to increasingly taking care of periods of drought, in which nutrient additions might not increase plant growth but potentially only facilitate leaching.     

锥栗人工林结果初期养分动态特征及其模拟

应用系统分析和动态模拟的方法 ,对结果初期锥栗人工林的养分动态变化进行了分析和模拟 ,构建了林分树体地上部分、地下部分、土壤和凋落物 4个分室 ,测定了各分室的N、P、K、Ca、Mg各养分元素的现存库量 .土壤分室中N、P、K、Ca的现存量最高 ,分别达 311.4 7、11.4 36、2 18.9kg·hm-2 和 87 5 6kg·hm-2 ,Mg含量水平以凋落物分室最高 ,达 7.2 6 9kg·hm-2 .根据分室模型 ,计算了 5种元素各分室的流通量和流通率 ,并在不同营养元素补偿水平下 ,对系统各分室在未来 5年内的养分变化进行了模拟 ,结果表明 ,各元素每年最适宜的补充量为N 2 0kg·hm-2 、P 8kg·hm-2 、K 5kg·hm-2 、Ca 10kg·hm-2 、Mg 5kg·hm-2 .在这种补偿条件下 ,系统各分室间养分流动通畅 ,树体生长代谢正常 .研究结果可为锥栗人工林该期栽培营养管理提供依据