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1.
通过对8年生马占相恩人工林生态系统养分积累与分配的研究,结果表明：林地土壤0-50cm土层内全c积累量为69090kg·hm^-2,全N积累量为3725kg·hm^-2,全P积累量为647kg·hm^-2,交换性K积累量为648kg·hm^-2,交换性Ca积累量为987kg·hm^-2,交换性Mg积累量为63kg·hm^-2;凋落物养分积累量N为58．764kg·hm^-2·a^-1,P积累量为1．608kg·hm^-2·a^-1,K积累量为9．021kg·hm^-2·a^-1,Ca积累量为22．898kg·hm-2·a^-1,Mg积累量为4．079kg·hm^-2·a^-1;人工林林分各元素积累量N为277．04kg·hm^-2、P为7．72kg·hm^-2、K为57．21kg·hm^-2、Ca为93．22kg·hm^-2、Mg为10．24kg·hm^-2;林下植被养分积累量N、P、K、Ca、Mg分别为35．40、2．67、29．47、22．38、4．00kg·hm^-2。  相似文献   

2.
The short-term impacts of prescribed burning were determined for the physical and chemical properties of a forest soil on a clear-cut in western Newfoundland, Canada. The experimental site was predominantly covered by black spruce trees (Picea mariana Mill.) that were harvested in 1996. In August 1998, prescribed burning removed most of the logging residues left on the site after harvesting, all above-ground surface vegetation, and parts of the upper humus layer. In October 1998, field samples were taken from four replicated burned plots and four replicated unburned plots. In each study plot, soil samples were taken from the organic layer (F+H) and from the top 10 cm of the mineral soil. In the burned treatments, mass of the humus layer (F+H) was reduced by 24% and, because of the accretion of basic ash materials, acidity of the humus layer was also reduced by up to 1 unit. In the organic layer and the mineral soil, total contents of Mg, Ca, and P, extractable Mg and Ca, available P, sum of NH4Cl-extractable cations, and C/N ratios were increased by burning, while total C and N as well as total and extractable K remained unaffected by burning.  相似文献   

3.
This study reports the effects of shifting cultivation at slashing stage on soil physicochemical properties at Bandarban Sadar Upazila in Chittagong Hill Tracts of Bangladesh. At this initial stage of ...  相似文献   

4.
A green house pot trial was conducted to assess the impact of Prosopis afforestation on the productivity and fertility of degraded sodic soils in Haryana, India. Wheat (Triticum aestivum, L; cultivar HD 2329) plants were grown from seed on top soils collected from a chronosequence of 0, 5, 7, and 30-year-old Prosopis juliflora plantations established on highly sodic soils and a non-sodic reference soil collected from a local farm. The afforestation improved physical and chemical properties of surface soils by decreasing pH, electrical conductivity and exchangeable Na levels, and increasing infiltration capacity, organic C, total N, available P, and exchangeable Ca, Mg, and, K levels. The amelioration effect of the trees on top soil increased with duration of tree occupancy. Soil nutrient status under the 30-year-old plantation was higher than that of the non-sodic farm soil. The reduced soil sodicity and improved fertility contributed to higher germination, survival, growth, and grain yield of wheat plants grown on the Prosopis chronosequence soils, even surpassing the yield attained on the farm soil in the case of 30-year-old plantation soil. Sodium accumulation in the crop declined while N, P, K, Ca, and Mg uptake increased with soil plantation age reflecting the changing nutrient status of the rooting zone due to afforestation. Results confirmed that successful tree plantation may restore the productivity and fertility of highly degraded sodic soils.  相似文献   

5.
In a rubber estate in Kelantan, Malaysia, sheep grazing increased N, P, Ca and Mg levels and soil pH. Foliar N, P, Ca, Mg and Na also increased with grazing, but K decreased. The girth of rubber trees under grazing had a higher increment than in the ungrazed areas.  相似文献   

6.
The objective of this paper is to analyse the degree to which the variation in soil conditions corresponds to the occurrence of specific plant species at micro-scale. The investigation was performed in beech forests with seven plant species growing on three sites with different geological substrates of the Triassic period (Muschelkalk, Oberer and Mittlerer Buntsandstein). At each site three to five plant species of ca. 20 individuals each were selected by stratified random sampling. The growth location of a plant individual was considered to be a potential microsite. At the gowth locations, soil solution was exctracted in situ by low tension lysimetry from the rooted topsoil exactly beneath the selected plant individuals. A soil sample was taken from the same spot and analysed for pH(H2O) and exchangeable cations. In addition, the vegetation was recorded around each target individual and species composition was related to chemical soil properties by multivariate analyses.

The three sites were found to form a gradient with respect to most analysed soil parameters. Variation coefficients of soil properties increased in the sequence pH, exchangeable Ca, K, Mg, Al, Fe, Mn. Concentrations of cations in the soil solution varied to a higher degree than those of exchangeable cations with the sole exception of Fe that showed a lower variation in the soil solution. Averaged over all sites, the microsite values for pH and exchangeable Ca exhibited a distinct sequence for the investigated species with decreasing values in the root horizon in the sequence Mercurialis perennis, Arum maculatum, Lamiastrum galeobdolon, Galium odoratum, Viola reichenbachiana, Oxalis acetosella and Luzula luzuloides. Within sites, only few significant differences were found between the potential microsites of specific species. The microsites of species on Muschelkalk differed in pH, concentrations of exchangeable Ca and K and of Ca in the soil solution. The microsites on Mittlerer Buntsandstein differed in pH and concentration of exchangeable Fe. No significant differences between species were found on Oberer Buntsandstein. Species composition in a area of 3.14 m2 around the sample locations varied only to a minor degree as was revealed by canonical correspondence analysis (CCA). In addition, the low level of encountered variation could only be explained to a small degree by the soil variables.

It is concluded that the analysed environmental factors are of minor importance for fine-scale species occurrences. At a scale of meters or less, biotic parameters might exert a greater influence than soil parameters.  相似文献   


7.
The long-term nature of forest crop rotations makes it difficult to determine impacts of forestry on soil nutrients that might be depleted by forest growth. We used small scale, highly stocked plots to compress the length of the rotation and rapidly induce nutrient depletion. In the study, two species (Pinus radiata D. Don and Cupressus lusitanica Miller) are compared under two disturbance regimes (soil undisturbed and compacted), and two fertiliser treatments (nil and plus fertiliser), applied in factorial combination at 33 sites, covering the range of climatic and edaphic variation found in plantation forests across New Zealand. To assess our ability to rapidly highlight important soil properties, foliar nutrient concentrations were determined 20 months after planting. It was hypothesised that the densely planted plots, even at a young age, would create sufficient pressure on nutrient resources to allow development of relationships between properties used as indicies of soil nutrient availability and foliar nutrient concentrations. For both species significant relationships between foliar nutrients and 0–10 cm layer soil properties from unfertilised plots were evident for N (total and mineralisable N) and P (total, acid extractable, organic, Bray-2 and Olsen P). With the exception of Ca in C. lusitanica, foliar K, Ca and Mg were correlated with their respective soil exchangeable cation measures. The results thus confirm the utility of the experimental approach and the relevance of the measured soil properties for forest productivity.

In unfertilised plots foliar N and P concentrations in P. radiata exceeded those in C. lusitanica, the differences being eliminated by fertiliser application. Foliar N/P ratios in P. radiata also exceeded those in C. lusitanica. In contrast to N and P, foliar K, Ca and Mg concentrations were all higher in C. lusitanica, the difference being particularly marked for Ca and Mg. P. radiata contained substantially higher concentrations of the metals Zn, Mn and Al than C. lusitanica, whereas the latter contained higher B concentrations. Possible reasons for differences between species in foliar nutrient concentrations are discussed.  相似文献   


8.
Residual effects, after 5 years, of four site preparation treatments: (1) cut and leave; (2) cut, leave and burn; (3) chop and burn; (4) shear, pile, burn and disk; originally applied in regenerating Pinus taeda L. plantations on three soils in eastern Texas; were evaluated by determining soil bulk density, organic matter, total nitrogen and extractable P, K, Mg, Ca and foliar P, K, Ca and Mg concentrations. By the fifth growing season, surface soil (0–8 cm) properties did not vary significantly except for N and Ca concentrations which were lowest for soils on the shear, pile, burn and disk treatments. Increased N and Ca concentrations for the shear, pile, burn and disk treatment below the 0–8 cm depth indicated the lower surface concentrations were a residual effect of disking. Foliar nutrient concentrations did not differ significantly except for foliar N concentrations which were lower for trees on the shear, pile, burn and disk plots.Residual treatment effects on stand development were evaluated by measuring fifth year stand density, stem diameter at breast height (1.4 m) and total height. Although the parameters were not significantly different, stands on the shear, pile, burn and disk treatment tended to have more stems of larger size than the other treatments.  相似文献   

9.
The aqueous extract of the Parinari excelsa barks at doses of 100 and 300 mg/kg/day for 7 days has a significant antihyperglycemic effect on alloxan-induced diabetic rats. At the same dose the acute oral administration of aqueous extract of the P. excelsa barks (100 and 300 mg/kg) induced a significant decrease of blood glucose on glucose-loaded normoglycaemic rats. Our results seem to confirm the rational bases for its use in traditional medicine.  相似文献   

10.
[目的]以浙江省庆元县菇木林为研究对象,探讨菇木林目标树择伐后形成的人工林窗对土壤养分含量和土壤质量的影响.[方法]在对照林分和择伐后林窗内设置调查样地,分层采集0～60 cm土层土壤样品,对比分析土壤养分元素含量和土壤pH值的变化情况.[结果]1)与对照相比,择伐6 a后林窗0～20 cm土层,土壤有机碳、全氮、水解...  相似文献   

11.
The distribution and movement of N, P, K, Na, Mg, and Ca were studied in southeastern Australia in a 37—year-old Pinus radiata plantation and in a nearby Eucalyptus obliqua — Eucalyptus dives forest of the same age and of the same type as that which had been replaced by the P. radiata plantation. The soil beneath the P. radiata plantation contained significantly less total N and exchangeable K, Mg, and Ca than that beneath the eucalypt forest. No large accumulation of nutrients was found in either the litter or the trees in the P. radiata plantation relative to that in the eucalypt forest. However, there was a slightly greater accumulation of N and K in the P. radiata biomass than in the eucalypt biomass. The annual soil nutrient balance obtained by subtracting outputs (mineral soil leachate + biomass incorporation) from inputs (precipitation + mineral weathering) indicated a more favourable balance for each nutrient in the soil beneath the eucalypts than in the soil beneath the pines. Calculations suggested that these balances could only partially account for the differences in soil nutrient quantities between eucalypt and pine ecosystems. It was hypothesized that these differences are also partially explainable in terms of the nutrient losses accompanying two fires which had occurred in the pine plantation area. Nitrogen balances in this study were incomplete because several potentially important fluxes were not measured.  相似文献   

12.
We compared how management approaches affected shade tree diversity, soil properties, and provisioning and carbon sequestration ecosystem services in three shade coffee cooperatives. Collectively managed cooperatives utilized less diverse shade, and pruned coffee and shade trees more intensively, than individual farms. Soil properties showed significant differences among the cooperatives, with the following properties contributing to differentiation: N, pH, P, K, and Ca. Higher tree richness was associated with higher soil pH, CEC, Ca, and Mg, and lower K. Higher tree densities were associated with lower N, K, and organic matter. Although we found differences in the incidence of provisioning services (e.g., fruit), all plantations generated products other than coffee. No differences were observed between C-stocks. The history and institutional arrangements of cooperatives can influence management approaches, which affect ecosystem properties and services. Our study corroborates that interdisciplinary investigations are essential to understand the socio-ecological context of tropical shade coffee landscapes.  相似文献   

13.
The chemical analysis of needles and wood of roots of trees belonging to four stages of disease caused by A. mellea in fertilized (N, P, K, Ca, Mg) and non-fertilized three Scotch Pine plantations were made. The attack caused gradual interruption of absorption and resulted in the exhaustion of some elements (N, P) and concentration of other ones (K, Ca) in needles and in the decrease of P and transitional growth of Mg-level in wood of roots. Considerable growth of concentration of some chemical substances in wood of roots of dead trees was observed. This referred to the fertilized and nonfertilized trees as well. The rate of these changes, however, was different after treatment: fertilization had no effect on the concentration of K in needles of trees in intermediate stages of disease, but it influenced in the lower rate the exhaustion of Mg in wood of roots. The role of K and Mg in defensive reactions is discussed.  相似文献   

14.
On a Vertisol under 850 mm rainfall, at an altitude of 1850 m, Faidherbia albida trees that occurred at 6.52 trees ha–1, with a canopy cover that range from 97 m2 ha–1 to 229 m2 ha–1 were recorded. Studies on the lateral and vertical influence of the tree canopy on some physical and chemical properties of the soil, show apparent higher organic matter on the West side of the tree than the East due to accumulated wind blown litter by prevalent wind direction, and organic matter, N, P and K levels were higher under the tree canopy than outside for all directions and depths studied. Soil pH, exchangeable Na, Ca and Mg under the canopy and outside were similar. Available water capacity was 1.5 to 2 times more under than outside the tree. Noticeable increases in the silt fraction under the tree was recorded and discussed in relation to soil condition improvement and plant growth.  相似文献   

15.
木麻黄无性系和实生林的根际土壤养分及酶活性   总被引：1，自引：0，他引：1  
木麻黄无性系林根际土壤有机质、全氮、水解氮、全磷、全钾、速效钾、钙和镁离子含量均大于木麻黄实生林,有效磷含量则相反。与实生林相比,木麻黄无性系林根际和非根际土壤pH值均有所下降,CEC值增加。木麻黄无性系林根际土壤脲酶、磷酸酶、过氧化物酶及多酚氧化酶活性均高于木麻黄实生林。脲酶除外,其余3种酶活性均是根际大于非根际。与木麻黄实生林相比,木麻黄无性系林根际环境得到改善,林地土壤营养贮量和养分供应能力提高,生长效果亦优于本地实生苗造林。  相似文献   

16.
Planted fallow systems under ‘slash and mulch’ management were compared with natural fallow systems at two farms (BM1 and BM2) in the Colombian Andes. The BM1 site was relatively more fertile than the BM2 site. Planted fallow systems evaluated included Calliandra calothyrsus CIAT 20400 (CAL), Indigofera constricta (IND) or Tithonia diversifola (TTH). During each pruning event slashed biomass was weighed, surface-applied to the soil on the same plot and sub-samples taken for chemical analyses. While Indigofera trees consistently showed significantly greater (p < 0.05) plant height and collar diameter than Calliandra trees at both study sites, only collar diameter in Indigofera was significantly affected at all sampling times by differences between BM1 and BM2. After 27 months, TTH presented the greatest cumulative dry weight biomass (37 t ha–1) and nutrient accumulation in biomass (417.5 kg N ha–1, 85.3 kg P ha–1, 928 kg K ha–1, 299 kg Ca ha–1 and 127.6 kg Mg ha–1) among planted fallow systems studied at BM1. Leaf biomass was significantly greater (P < 0.05) for CAL than IND irrespective of site. However, CAL and IND biomass from other plant parts studied and nutrient accumulation were generally similar at BM1 and BM2. At both sites, NAT consistently presented the lowest biomass production and nutrient accumulation among fallow systems. Planted fallows using Calliandra and Indigofera trees had the additional benefit of producing considerable quantities of firewood for household use. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

17.
不同林龄樟子松叶片养分含量及其再吸收效率   总被引：28，自引：0，他引：28  
树木叶片的养分再吸收效率能够反映树木对养分保存、利用以及对养分贫瘠环境的适应能力。以科尔沁沙地东南缘章古台地区樟子松人工林为研究对象,分析了11、20、29、45年生树木叶片的基本特征、养分含量及其再吸收效率。结果表明:叶片衰老后其质量和面积明显减少;叶片凋落前的平均养分含量没有表现出随樟子松年龄增加而出现有规律的变化;凋落叶片中的N、P、K、Mg含量表现出随年龄增加而增加的趋势,而Ca的趋势与之相反;11年生和20年生的樟子松叶片N、P、K的再吸收效率相似,都显著高于29年生和45年生樟子松(P<0.05),而樟子松叶片对Mg的再吸收效率表现出随年龄增大而显著降低,Ca随叶片的衰老而不断累积,再吸收效率表现为负值,20年生的樟子松叶片Ca再吸收效率最大,11年生和45年生最低。樟子松叶片的N、P、K、Mg养分再吸收效率随年龄增加而降低的趋势表明,随年龄增加樟子松对贫瘠养分生境的适应能力逐渐降低,反映了樟子松养分保存方面的衰退特征。  相似文献   

18.
In order to understand nutrient dynamics in tropical farming systems with fallows, it is necessary to assess changes in nutrient stocks in plants, litter and soils. Nutrient stocks (soil, above ground biomass, litter) were assessed of one-year old fallows with Piper aduncum, Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea. The experiment was conducted on a high base status soil (Typic Eutropepts), and in Papua New Guinea such soils are intensively used for agriculture. Soil samples were taken prior to fallow establisment and after one year when the fallows were slashed and above ground biomass and nutrients measured. The above ground and litter biomass of piper was 13.7 Mg dry matter ha-1, compared to 23.3 Mg ha-1 of gliricidia and 14.9 Mg ha-1 of imperata. Gliricidia produced almost 7 Mg ha-1 wood. Total above ground biomass returned to the soil when the fallows were slashed was the same for piper and gliricidia (8 Mg ha-1). Gliricidia accumulated the largest amounts of all major nutrients except for K, which was highest in the above ground piper biomass. Imperata biomass contained the lowest amount of nutrients. The largest stocks of C, N, Ca and Mg were found in the soil, whereas the majority of P was found in the above ground biomass and litter. Almost half of the total K stock of piper and gliricidia was in the biomass. During the fallow period, soil organic C significantly increased under gliricidia fallow whereas no net changes occurred in piper and imperata fallows. The study has shown large differences in biomass and nutrient stocks between the two woody fallows (piper, gliricidia) and between the woody fallows and the non-woody fallow (imperata). Short-term woody fallows are to be preferred above grass (imperata) fallows in the humid lowlands of Papua New Guinea because of higher nutrient stocks.  相似文献   

19.
油茶人工林土壤肥力及对树体生长的影响   总被引：1，自引：1，他引：0  
对不同立地条件下油茶人工林的树高、地径及其土壤化学性质进行测定,并运用灰色关联分析方法探讨土壤化学性质对油茶高生长和地径生长的影响,综合评价油茶人工林土壤肥力状况。结果表明:9个样地中土壤肥力属于Ⅲ级(一般)的有5个,属于Ⅳ级(差)的有2个,属于Ⅴ级(极差)的有2个,说明9个油茶林地的土壤肥力普遍较低;而对油茶高生长影响最大的是土壤全K、全N和有效Zn,影响相对较小的是土壤有效P和交换性Ca;对油茶地径生长影响最大的是土壤有效Zn、全K和全N,影响相对较小的是土壤交换性Ca和pH值。  相似文献   

20.
Soil fertility decline caused by deforestation, soil degradation and low input use has become a primary factor limiting sustainable utilization of soil resources in cocoa agroforestry systems on acid soils in lowland humid Ghana. Changes in and responses of soil physico-chemical properties and soil quality to land-use change was investigated along a chronosequence of farm fields on a Ferric Lixisol in the Ashanti region of Ghana. Soil bulk density increased significantly only in the top 0–10 cm soil layer. Concentrations and stocks of soil organic carbon (SOC) and total N decreased significantly in the top 0–10 and 10–20 cm soil depths. By 30 years after forest conversion, cocoa system had re-accumulated up to 38.8 Mg C ha?1 or 85 % of initial forest carbon stock values. Total porosity (%) decreased significantly in shaded-cocoa fields in comparison with the natural semi-deciduous forest. An assessment of soil deterioration using degradation indices (DIs) revealed that total soil quality (0–20 cm) deteriorated significantly (DI = –60.6) in 3-year-old of cocoa system but improved in 15 and 30-year-old systems. Available P stocks declined consistently while soil exchangeable Ca, K and Mg stocks as well as cation exchange capacity (CEC) and base saturation remained more or less stable with a tendency to improve. The inclusion of leguminous shade trees during early plantation development, development of mechanisms for the integration of cover crops and enhancement of farmer capability in improved farm management are required to maintain high C and nutrient base, minimize soil quality degradation during plantation development phase and sustain long-term productivity.  相似文献   

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