What Characteristics of Soil Fertility Can Improve in Mixed Stands of Scots Pine and European Beech Compared with Monospecific Stands?

According to the current trends in forest management, endeavors are made to adjust the species composition to the site conditions and to increase the biodiversity. Changes in the species composition of forest stands lead to modifications of soil properties and nutrients cycle. The objective of the study was to evaluate the effect of monocultures (beech and pine) and mixed-species stands (pine-beech) on soil properties, particularly accumulation of soil organic carbon. We aim to demonstrate how different vegetation types influence soil properties in surface horizons of soil. The study sites are located in Germany and Poland under different tree stands Pinus sylvestris L., Fagus sylvatica L., and mixed-species stand. Contents of organic carbon and nitrogen, pH, and soil texture were analyzed. The studies conducted confirmed the positive effect of beech and mixed-species stands on acidification of surface soil horizons. We ordered the stands tested according to acidification effect on soils: pine stand > mixed stand > beech stand, which is consistent with previous studies. The most beneficial impact on the accumulation of organic carbon was observed in mixed-species stands in which beech and pine were found. Lower carbon-to-nitrogen (C/N) ratios confirm the high rate of organic matter decomposition and lower C/N ratio was reported in soil under beech stand in comparison to pine stands.     

辽东山区天然次生栎林土壤有机碳含量及其与理化性质的关系

通过对设置在辽东山区本溪市草河口镇和庄河市仙人洞镇两个典型天然次生栎林(Quercus spp.)样地内的土样进行分层(0—10,10—20,20—30,30—40cm)采集和室内分析,研究了0—40cm土层土壤有机碳、全氮、全磷等含量的剖面分布特征,探讨了有机碳与理化性质间的关系。结果表明:土壤有机碳及全氮、全磷、全钾、碱解氮、速效磷、速效钾、阳离子交换量的含量均随土层加深而降低,而土壤容重随土层加深而增加,由t检验和方差分析得知,各指标含量在土层间差异均达到5%显著水平;土壤有机碳与粉粒、pH、全氮、全磷、全钾、碱解氮、速效磷、速效钾、阳离子交换量间均呈显著正相关(r=0.430 9~0.919 0,n=44,P0.01),与土壤容重、砂粒间均呈显著负相关(r=0.388 3~0.670 6,n=44,P0.01),而与黏粒间无显著相关性;由逐步回归分析得知土壤碱解氮、碳氮比、全钾、pH、全氮与有机碳间关系最为紧密。土壤有机碳与其他理化性质间关系密切,且以全氮、碱解氮、碳氮比、全钾和pH对其影响最大;同时,各指标均具有明显的剖面分布规律。     

重庆缙云山典型林分土壤结构分形特征

 为了解长江三峡库区森林土壤的物理性质,运用分形原理,研究重庆缙云山4种典型林分林地土壤分形特征,建立土壤结构分维与土壤性质预测模型,运用弹性分析与边际分析,探讨土壤结构分形变化与土壤性质变化的关系。研究表明:土壤机械组成分维、微团聚体组成分维和孔隙组成分维可作为评价土壤结构的指标。不同林分林地土壤颗粒机械组成分维值为2.7～2.9,土壤微团聚体组成分维为2.5～2.8,土壤孔隙组成分维为2.3～2.8。从质地、微团聚体组成和孔隙组成来看,常绿阔叶灌丛土壤结构要明显优于其他林地土壤,而楠竹林最差。不同林分及农地土壤的微团聚体组成、机械颗粒组成和孔隙组成分维与土壤性质存在较明显相关关系,相关系数都在0.5以上。由弹性系数和边际量可以看出,机械分维的影响要大于微团聚体分维和孔隙组分维。这对进一步探讨分形学在土壤结构与土壤性质的应用方面有重要的意义。     

Soil Properties and Selected Aluminium Forms in Acid Forest Soils as Influenced by the Type of Stand Factors

Massive forest damage has been observed in certain mountainous regions affected by acidification. Declining of trees is ascribed to direct effect of SO₂ and also increasing concentration of mobile forms of Al in soils. The aim of this paper is to describe the influence of stand factors to distribution of Al forms in the Jizera Mountains region, Czech Republic. A set of 251 samples from 98 sites was collected. Basic soil characteristics and the content of different Al forms were determined. The amount and relative share of these Al forms under different types of vegetation was evaluated, with emphasis on the surface organic horizons. The results showed that phytotoxic mobile Al forms are the most influenced by altitude and organically bound Al forms by forest type. Non-toxic forms of Al are more abundant in broadleaved forest. Soils under coniferous forest are more affected by acidification.     

A scheme for sampling inorganic nitrogen in forest soils

Abstract

An efficient sampling scheme for evaluating seasonal changes of inorganic nitrogen in a forest soil was designed. It was based on variances of ammonium‐ and nitrate‐nitrogen estimated from core samples from each of three horizons (A1, A2, B1) taken from 8 randomly selected sites in a three‐hectare study area. The scheme adopted was: At each sampling time a single composite sample for each horizon was made using 15 cores from randomly‐selected locations; duplicate subsamples from each composite were analyzed for ammonium‐ and nitrate‐nitrogen.     

八达岭山地次生林土壤养分与磷酸酶活性研究

 为探讨北京八达岭山地土壤肥力状况,以黑桦、糠椴、核桃楸3种次生林为对象,对其土壤养分和磷酸酶活性进行研究。结果表明:土壤养分有明显的表聚效应;土壤全磷含量仅为0.39～0.66g.kg-1之间,有可能出现缺磷现象;土壤磷酸酶的活性以酸性磷酸酶为主,呈垂直递减分布规律;各种土壤养分和磷酸酶活性均有明显的根际效应,根系/本土比值在1.02～5.25之间。用SPSS软件进行分析表明,土壤磷酸酶活性与土壤pH、有机质、全氮、有效氮、有效磷和速效钾显著正相关,可以作为土壤肥力评价的一个指标。     

Chemical response of soil leachate to alternative approaches to experimental acidification

Abstract

One approach to evaluating computer models which predict terrestrial‐aquatic ecosystem response to acid deposition is the experimental acidification of soils with subsequent comparisons among predicted and measured soil solution response. Using a soil microcosm experimental approach, comparisions between simulated acid rain (i.e. dilute H₂SO₄), dry NH₄NO₃, and prilled reduced S were made for suitability for large‐scale field experiments. Soil microcosms consisting of reconstructed soil profiles received a background simulated throughfall dosing over the six month treatment period. Results indicated that simulated throughfall, applied at twice the ambient rate, acidified soil leachates approximately 0.5 pH units over the treatment period. Along with the decline in leachate pH was an apparent release of base cations as well as Fe and Al. Over the length of the treatment period, very little of the prilled S dissolved and the simulated acid rain treatment did not have significant effects on leachate chemistry.     

Acidification of soils in five catchments in Norway

Soil plots were established in catchments within the frame of the Norwegian Monitoring Programme for Long-Range Transported Air Pollutants. Four soil plots of about 10 m by 20 m were established within each catchment in areas with relatively homogeneous soil and vegetation. Multiple soil cores were taken at 50 points in a grid from each plot (repeated 4 times) and the samples were pooled by depths. Each soil core was divided by soil horizon, by predefined depths or by a combination of these, usually giving one soil sample for each 2-cm-depth down to about 15 cm. The soil pH measured in water suspension varied for all soils between 3.5 and 4.9. Base saturation measured at pH 7 varied between 2% and 22% with the highest values in the upper, more humus rich layers. All of the monitored catchments include acid soils poor in base cations. After 8 years the plots were resampled using the same procedure as for the first sampling. In most of the plots a decreasing pH trend from the first to the second sampling was measured. However, the base saturation was generally higher in all plots at the second sampling compared with the first. There are no clear effects of the different pollution regimes in the various catchments. It must be emphasized, however, that 8 years is a short period for measuring long-term soil changes.     

Humic Substance Fractions and Attributes of Histosols and Related High‐Organic‐Matter Soils from Brazil

Abstract

Knowledge of the distribution of soil organic matter (SOM) fractions is important in managing soils toward a sustainable agricultural system in a tropical environment. However, data on Histosols is limited. This study developed 19 profiles of Histosols and soils with high organic-matter content from different regions of Brazil. Soil organic matter was fractionated into fulvic acids (FAF), humic acids (HAF), and humin (HUM). The ratios HAF/FAF and AE (alkaline extract)/HUM were calculated. The objectives were to evaluate the method for SOM fractionating in Histosols and related soils and to correlate the distribution of organic fractions with other soil attributes. The humic fractions presented significant correlations with other soil attributes, the best being the correlation between FAF and nutrient level. The HAF and HUM presented high correlation with cationic exchange capacity, active acidity (H⁺) and pH. Humin and the alkaline extract absorbance measured at 380 nm and 465 nm and presented good correlation with total organic carbon.     

A soil quality index based on the equilibrium between soil organic matter and biochemical properties of undisturbed coniferous forest soils of the Pacific Northwest

Recent studies have suggested that the organic matter contents of undisturbed soils (under natural vegetation) are in equilibrium with biological and biochemical properties. Accordingly, we hypothesised that such equilibria should be disrupted when soils are subjected to disturbance or stress, and that measurement of this disruption can be expressed mathematically and used as a soil quality index. In this study, we evaluated these hypotheses in soils from the H.J. Andrews Experimental Forest in Oregon. Both O and A horizons were sampled from nine sites in Spring 2005 and Fall 2006. Soil samples were analyzed for enzyme activities (phosphatase, β-glucosidase, laccase, N-acetyl-glucosaminidase, protease and urease), and other biological and chemical properties including N-mineralization, respiration, microbial biomass C (MBC), soil organic carbon (SOC) and total nitrogen content. In addition, soil samples from one old-growth site were manipulated in the laboratory to either simulate chemical stresses (Cu addition or pH alteration) or physical disturbances (wet-dry or freeze-thaw cycles). The results showed variation in biological and biochemical soil properties that were closely correlated with SOC. Multiple regression analysis of SOC levels against all soil properties showed that a model containing only MBC and phosphatase activity could account for 97% of the SOC variation among the sites. The model fit was independent of spatial and temporal variations because covariates such as site, stand age, sampling date, and soil horizon were found to be not statistically significant. Although the application of stress/disturbance treatments inconsistently affected most of the individual biochemical properties, in contrast, the ratio of soil C predicted by the model (C_p), and soil C measured (C_m) was consistently reduced in soils submitted to at least one level of stress and disturbance treatments. In addition, C_p/C_m was more affected in soils submitted to wet-dry cycles and Cu contamination than to freeze-thaw cycles or shifts in soil pH. Our results confirm previous evidence of a biochemical balance in high quality undisturbed soils, and that this balance is disrupted when the soil is submitted to disturbances or placed under stress conditions. The C_p/C_m ratio provides a simple reference value against which the degrading effects of pollutants or management practices on soil quality can be assessed.