Nutrient loading of a forest soil

Summary During July 1988 rooted and non-rooted experimental chambers were established in a Norway spruce (Picea abies. Karst) stand in south Devon U.K. Replicates were supplemented with ammonium and nitrate. The leachates were analysed to monitor the release of mineral-N species and cations over the 17-week experimental period. Ammonium treatments leached 300% more calcium and magnesium than controls. The onset of nitrification resulted in a decrease in sodium losses from ammonium treatments reflecting a decrease in the exchanging capacity of the soil solution. These results are discussed in relation to mineral ion leaching in soils subjected to increesed N-loading, and the ability of soils to buffer these perturbations.     

Changes in forest cover in China during the Holocene

Pollen map data at 2000-year intervals are used to reconstruct changes in Holocene forest cover in China north of the Yangtze River. In almost all regions, the early Holocene from 10 ka b.p. to 6 ka b.p. is characterised by an increase in forest cover although there was a reversal to lower forest cover at 8 ka b.p. in the eastern monsoon regions. A maximum of forest cover was reached at 6 ka b.p. in all regions except for Northeast China where forest cover peaked in the late Holocene. All regions except for Northeast China experienced a marked decline in forest cover after 6 ka b.p. Since 6 ka b.p., forest cover has decreased by about 92% in the middle and lower reaches of the Yellow River, 64% in the easternmost part of the Qinghai-Tibet Plateau and 37% between the Yangtze River and the Huaihe River. In contrast, forest cover in Northeast China increased significantly from 6 ka b.p., but has declined between 2 ka b.p. and the present. Changes in forest cover prior to 6 ka b.p. were probably caused by climate, but the evident drop in forest cover since that time in most regions may have been induced predominantly by human activities.     

Assessment of soil aluminium pools along three mountainous elevation gradients

Anthropogenic soil acidification in mountain forests and consequent Al release still present a significant problem in many regions. The effect of deposition may differ according to stand conditions, including altitude. This contribution is focused on three elevation transects, two in the Jizera Mountains strongly influenced by acid deposition, one in the less affected Novohradske Mountains. Quantification of pools of different Al forms and related soil characteristics (organic carbon, exchangeable hydrogen cations, sorption characteristics, etc.) is evaluated. In the Novohradske Mountains, the pool of both organically bound and water-soluble Al increases with increasing altitudes. In the Jizera Mountains, the distribution is more complicated; it is strongly affected by different forest type (beech vs. spruce), deforestation, and other local differences. Higher amounts of Al are bound in the mineral horizons compared to the surface organic horizons, even in the case of organically bound Al pools. Further differences between different altitudes and between soil horizons in Al distribution were revealed by detailed Al speciation using HPLC/IC method.     

植被覆盖对科尔沁沙地土壤生物结皮及其下层土壤理化特性的影响

为了解不同植被覆盖对沙地土壤生物结皮及其下层土壤的影响,于2006年调查了科尔沁沙地冷蒿、小红柳、杨树和樟子松等植被封育区土壤生物结皮及结皮下0～5 cm土壤的理化特性.结果表明：经过15年的封育保护和植被建设,科尔沁沙地天然植被和人工植被下流动沙地大部分被生物结皮所覆盖,其结皮覆盖度可达60%～80%,厚度1～2 cm;在调查的几种植被中,小红柳植被区的土壤结皮厚度、硬度、粘粉粒、有机质和养分含量最高,其次是樟子松林地,杨树林地和冷蒿植被区相对较差;几种植被区的苔藓结皮的结皮厚度、硬度、粘粉粒、有机质和养分含量均优于地衣结皮;与流动沙地相比,结皮下0～5 cm土壤的理化特性有明显改善,改善程度苔藓结皮强于地衣结皮,小红柳和樟子松植被区强于杨树林地和冷蒿群丛;土壤结皮及结皮下表土理化特性的变化既受植被覆盖类型的影响,也受制于土壤结皮的发育.由于枝叶繁茂的中、高植被有利于降风滞尘和产生较多的凋落物,因而更能促进沙地结皮发育和土壤改良,而苔藓结皮较地衣结皮更有利于其下层土壤理化特性的改善.     

Degradation of humic acid of a forest soil by some fungal isolates

Summary In a laboratory incubation study the humic acid isolated from a forest soil of Palamau (Bihar) was subjected to biodegradation for a period of six weeks by using nine cultures of fungi. These fungi were tested earlier for their cellulose decomposing ability. The humic acid was used as sole source of carbon, nitrogen and carbon plus nitrogen in Czapek-Dox broth. Of the nine culturesAspergillus awamori (IARI),Penicillium sp. (Ranchi),Humicola insolense (Hissar) were found to be very effective in decomposing humic acid. The humic acid used as sole source of carbon was most efficiently degraded followed by that used as carbon+nitrogen source. When it was used as sole source of nitrogen, it could not be degraded so efficiently. This may be due to unavailability of its nitrogen to these microorganisms.     

Impacts of forest cover change on ecosystem services in high Andean mountains

Land conversion affects the delivery of ecosystem goods and services. In this study, we used a 50 years time series of land cover maps to assess the potential impacts of forest cover changes on ecosystem services. A multi-source data integration strategy was followed to reduce inconsistencies in land cover change detection that result from the comparison of historical aerial photographs and satellite images. Our forest cover change analysis highlighted a shift from net deforestation to net reforestation in the early 1990s, consistent with the forest transition theory. When taking the nature of forest cover changes into account, our data show that the areal increase of the forested area was not associated with an improvement in ecological conditions. The overall capacity of the landscape to deliver ecosystem services dropped steadily by 16% over the 50 years’ study period. Conversion of native forests to agricultural land was associated with the strongest decline in ecosystem services. Conversion of natural grasslands into pine plantations mostly led to negative and probably irreversible impacts on the delivery of ecosystem services. Conversion of degraded agricultural lands into pine plantations led to an improvement in ecological conditions. An effective spatial targeting of forestation programs has the potential to maximize the environmental benefits that forest plantations may offer while minimizing their environmental harm.     

城市不同地表覆盖类型下土壤有机碳矿化的差异

土壤有机碳(SOC)矿化是陆地生态系统碳循环的重要过程。因受到强烈的人为干扰,城市土壤生态服务功能严重退化,进而对城市土壤地球化学循环尤其是碳循环产生深刻的影响。以北京市奥林匹克森林公园的5种典型地表覆盖类型(草坪、灌木、行道树、植草砖、硬化地表)下土壤为研究对象,研究了城市不同地表覆盖类型下土壤有机碳矿化过程及固碳能力的差异。结果表明,城市5种地表覆盖类型下的土壤有机碳矿化趋势与自然生态系统中的土壤基本一致,都表现为前期矿化较为快速,后期明显减慢并且趋于平稳;不同地表覆盖类型下土壤的有机碳矿化作用有显著差异,灌木、行道树、植草砖覆盖下土壤有机碳矿化能力较强,硬化地表和草坪较弱,与土壤有机碳含量特征类似;一级动力学方程对各土样有机碳矿化过程的模拟结果较好,结果显示草坪覆盖下土壤固碳能力较强,灌木覆盖下次之,行道树、植草砖和硬化地表覆盖下较弱;土壤固碳能力的高低并不对应着土壤有机碳含量的高低,城市人为干扰和外源有机碳的输入对土壤有机碳储量影响较大;硬化地表下不同土层有机碳矿化作用无明显差异,而其他地表覆盖类型下的土壤有机碳矿化作用随土层加深显著减弱,特别是植草砖和行道树特征最为明显;各地表覆盖类型下土壤固碳能力随土层深度变化的规律不显著。城市土壤有机碳矿化的最主要限制因子是土壤有机碳的含量,土壤p H值、养分含量、粘粒含量等性质也通过影响土壤有机碳含量及微生物活动等对土壤有机碳矿化过程产生影响。     

Bare soil cover and arbuscular mycorrhizal community in the first montane forest restoration in Central Argentina

Soil erosion affects extensive areas worldwide and must be urgently reduced promoting plant cover and beneficial microorganisms associated with plants, including arbuscular mycorrhizal fungi (AMF). In mountain environments, plant cover is difficult to enhance due to harsh conditions during the dry season and steep slopes. Our objective was to evaluate the percentage of the soil surface covered by plants and the AMF community associated with trees 12.5 years after planting during forest restoration efforts in microsites at different levels of soil degradation. The study was performed in the first montane forest restoration initiative of Central Argentina, where one of the trials consisted of planting Polylepis australis saplings at microsites with different levels of soil degradation: high, intermediate, and low. After 12.5 years, percentage of bare soil cover was significantly reduced by 36 and 37% in the high and intermediate degradation microsites, respectively. Low degradation microsites were initially very low in bare soil and did not significantly change. Mycorrhizal colonization, hyphae, vesicles, arbuscules, AMF diversity, and community structure were similar among microsite types. Percentage of hyphal entry points was higher at microsites with low degradation, number of spores was higher in high and intermediate degradation, and species richness was higher in high degradation. Acaulospora and Glomus were the most abundant genera in all microsites. We conclude that even in the most degraded microsites around 2.8% of the bare soil is covered by vegetation each year and that the arbuscular mycorrhizal community is highly tolerant and adapted to soils with different disturbance types.     

Effects of regeneration burning on the properties of forest soils in southern Tasmania: Comments on recent study by Elliset al. (1982)

Summary Important methodological factors which should be considered when attempting to measure and interpret the effects of hot slash fires on the properties of forest surface soils are briefly discussed. Soil properties cannot be assumed to be similar, prior to cutting and burning of forest, on coupes located several kilometres apart in dissected terrain. In order to study the effects of forest treatment on soil properties, sites should either be closely adjacent or preferably measurements should be taken before and after treatment on the same experimental area.It is argued that the conclusions reached by Elliset al. regarding the effects of regeneration burning on soil properties in southern Tasmania are unjustified because of the use of inappropriate experimental methods.     

Influence of radiata pine seedlings on chemical properties of some New Zealand montane grassland soils

Interaction between soil acidity and vegetation phenolic concentration was investigated to identify mechanisms by which forests sustain productivity on extremely acidic, infertile soils. Contrasting soils on well-preserved marine terraces of the “Ecological Staircase’ near Mendocino, CA comprise an extreme edaphic gradient. Pygmy forests of dwarf (< 5m) Mendocino cypress (Cupressus pygmaea), Bolander pine (Pinus contorta var. bolanderi), and Bishop pine (Pinus muricata) are found on the oldest, most acidic soils, and along a gradient that includes three distinct levels of soil acidity, with pH(CaCl₂) ranging from 5.0 to 3.0 in the upper mineral soil and from 4.0 to 2.0 in the litter layer where fine roots are concentrated. Mature foliage was collected from five sites on this edaphic gradient. Aqueous methanol extracts of the samples were analyzed for concentrations of total phenols and condensed tannin by the Prussian blue and acidified vanillin assays, respectively. There were significant differences (p<0.05) in foliar condensed tannin and phenolic concentrations within each species and concentrations were inversely related to soil pH, approximately doubling along the gradient. Natural selection for soil-regulated variation in polyphenol concentration is interpreted in the context of plant-litter-soil interactions as an adaptation that permits these conifers to survive in extremely acidic soils. H Lambers Section editor     

填埋覆土甲烷氧化微生物及甲烷氧化作用机理研究进展

甲烷是一种长期存在于大气中的温室气体,它对温室效应的贡献率是二氧化碳的26倍.生活垃圾填埋场是大气甲烷的主要产生源之一,由其产生的甲烷约占全球甲烷排放总量的1.5%～15%.甲烷氧化微生物在调节全球甲烷平衡中起着重要作用.垃圾填埋场覆土具有相当强的甲烷氧化能力.填埋覆土甲烷氧化菌及其氧化作用机理的研究,已成为环境微生物学研究领域的热点之一.本文对生活垃圾填埋场填埋覆土中甲烷氧化微生物、甲烷氧化机理及动力学机制、甲烷与微量填埋气体的共氧化机制以及影响甲烷氧化的环境因子研究的最新进展进行综述,并对生活垃圾填埋场甲烷氧化微生物的研究进行展望.     

The physical and chemical responses of a degraded sandy clay loam soil to cover crops in southern Nigeria

The physical and chemical responses of a degraded sandy clay loam Ultisol to two leguminous and four grass cover crops in southern Nigeria were studied after five years to assess the rejuvenative effects of the covers. There were relative increases of 26% and 112% in soil organic carbon and phosphorus levels and also appreciable improvements in the CEC and Ca levels under vegetative covers compared with the initial conditions. The improvements were more pronounced with legume covers than with grass covers. Furthermore, the vegetative covers improved mean organic carbon level by 28% and appreciably improved mean CEC, Ca, and Mg levels over the values for the bare soils. The percentage of water-stable aggregates >1.0 mm was significantly reduced under bare fallow ( = 27.7%) compared with soils under vegetative cover = 79.3%). The correlation between water-stable aggregates > 1.0 mm and exchangeable aluminum was negative and significant (r = −0.705°) at p = 0.05. There were highly significant treatment effects (P = 0.01) for penetrometer resistance, pore size distribution, water infiltration, water retention and saturated hydraulic conductivity. Grass and legume fallows which protect the soil and guarantee regular additions of organic materials are ecologically sound and socially acceptable components of sustainable agricultural production. Indications, however, are that this degraded tropical Ultisol would require a period exceeding five years under vegetative covers for restoration of its fertility to acceptable productive status. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of effects of sustained decadal precipitation manipulations on soil carbon stocks

Throughout a 13 year period, the Throughfall Displacement Experiment sustained both increased (+33; wet) and decreased (−33%; dry) throughfall into an upland oak forest in Tennessee. Organic (O) horizon carbon (C) stocks were measured at several occasions before, during and after the experiment and mineral soil C stocks before and after the experiment. In the O horizon, higher C stocks were observed in the dry treatment compared to the ambient and wet, attributable to a combination of enhanced litter inputs and reduced decomposition. No precipitation treatment effects on mineral soil C stocks were found to a depth of 60 cm. Conversely, long-term reductions in surface mineral soil C stocks were surprisingly high for all treatments (3.5–2.7% C in the 0–15 cm layer and from 0.6 to 0.5% in the 15–30 cm layer) over the duration of the experiment. A clear explanation for this temporal trend in C storage was not readily apparent.     

缙云山森林群落次生演替中土壤理化性质的动态变化

选择典型、有代表性的不同演替阶段群落,进行了植被调查和土壤分析.结果表明,土壤理化性质在演替方向和土壤剖面上表现出较强的规律.土壤有机质随植被从低级向高级演进逐渐积累,分别是19.5(X₁)、37.0(X²)、50.1(X₃)和71.6 g·kg^-1(X₄);土壤全N、碱解氮和速效钾等也呈上升趋势;土壤pH和盐基饱和度降低,阳离子交换量增加.在土壤剖面上,有机质、全N等指标表现出A＞B＞C层的趋势.灰色关联度分析表明,随着演替的进行,土壤肥力提高,物种丰富度和郁闭度也相应增加.不同群落土壤理化性质在不同季节有显著差异,但这种差异并不影响植物与土壤在大时间尺度下的演变方向.土壤理化性质的动态变化与植物演替相适应.     

Influence of vegetation cover on evapotranspiration patterns in mountainous areas

The study presents results of calculation of potential evapotranspiration based on vegetation cover and actual solar energy income modeling obtained in the Jalovecky creek experimental hydrological basin in the Western Tatra mountains. Vegetation cover in the basin is represented by Bare rock, Grass, Natural grassland, Coniferous forest and Dwarf pine. Spatial evapotranspiration patterns for vegetation cover were calculated with three different methods build in the SOLEI model. They are Simple regression model, Radiation model by FAO and Penman-Monteith model. Vegetation cover is represented in all mentioned methods by albedo maps derived from the land use grid map. Together with Digital elevation model (DEM) it is the main input value to the SOLEI model. Albedo coefficients influence mainly solar energy income to the slopes. Because the Simple regression model and Radiation model by FAO are mainly based on solar energy income, the shapes of calculated spatial evapotranspiration patterns are similar to solar energy spatial maps. Results obtained from PenmanMonteith model are more closed to vegetation maps.     

Responses of soil bacterial and fungal communities to reciprocal transfers of soil between adjacent coniferous forest and meadow vegetation in the Cascade Mountains of Oregon

Little information exists on the responses of soil fungal and bacterial communities in high elevation coniferous forest/open meadow ecosystems of the northwest United States of America to treatments that impact vegetation and soil conditions. An experiment was conducted in which soil cores were reciprocally transplanted between immediately adjacent forests and meadows at two high elevation (∼1,600 m) sites (Carpenter and Lookout) in the H.J. Andrews Experimental Forest located in the Cascade Mountains of Oregon. Half of the cores were placed in PVC pipe (closed) to prevent new root colonization, whereas the other cores were placed in mesh bags (open) to allow recolonization by fine roots. A duplicate set of open and closed soil cores was not transferred between sites and was incubated in place. After 2 year, soil cores were removed and changes in fungal and bacterial biomasses determined using light microscopy, and changes in microbial community composition determined by PLFA analysis, and by length heterogeneity PCR of the internal transcribed spacer region of fungal ribosomal DNA. At both sites soil microbial community structures had responded to treatments after 2 year of incubation. At Carpenter, both fungal and bacterial community structures of forest soil changed significantly in response to transfer from forest to meadow, with the shift in fungal community structure being accompanied by a significant decrease in the PLFA biomarker of fungal biomass,18:2ω6,9. At Lookout, both fungal and bacterial community structures of forest soil changed significantly in response to open versus closed core treatments, with the shift in the fungal community being accompanied by a significant decrease in the 18:2ω6,9 content of closed cores, and the shift in the bacterial community structure being accompanied by a significant increase in bacterial biomass of closed cores. At both sites, fungal community structures of meadow soils changed differently between open and closed cores in response to transfer to forest, and were accompanied by increases in the18:2ω6,9 content of open cores. Although there were no significant treatment effects on the bacterial community structure of meadow soil at either site, bacterial biomass was significantly higher in closed versus open cores regardless of transfer.     

Controls on leaching from coniferous forest floor microcosms

Summary Studies were conducted with coniferous forest floor microcosms to examine the potential influence of acid precipitation, temperature changes, and plant uptake upon the chemistry of soil leachate solutions. The experimental design included two temperatures and three different simulated throughfall chemistry treatments. When the acidity of throughfall inputs to the microscosms increased, the forest floors exhibited increased leaching losses of calcium, magensium, potassium, and ammonium. The fact that aluminum losses did not incrase correspondingly suggested that there may be a kinetic lag in the mobilization and leaching of aluminum. When microcosms were exposed to warmer temperatures, percolates showed increased leaching losses of calcium, potassium, ammonium, sulfate, nitrate, and organic anions. Forest floor microcosms exposed to simulated average field conditions behaved very much like field plots under the same environmental conditions; however, there were predictable differences in leaching losses between laboratory and field systems for those ions which are strongly controlled by plant uptake. In general, the exclusion of plant uptake from microcosms resulted in increased leaching of potassium, nitrate, ammonium. and sulfate relative to field plots.     

Effect of reclamation of sandy soil on some chemical and microbiological properties

The physico-chemical properties of the soil were gradually improved; a progressive increase in silt and clay, moisture equivalent, organic matter, total nitrogen, C : N ratio and cation exchange capacity was observed during reclamation. Microbiological analysis showed that bacteria, actinomycetes and fungi had increased progressively as a result of cultivation. The increase in the microbial counts showed a positive relation with the increase in the organic matter content of the soil. This indicates that one of the limiting factors for microbial proliferation is organic matter. It was also found that the aerobic cellulose-decomposers, nitrifiers, Azotobacter and Clostridia had increased gradually with the cultivation of these soils. The increase of Clostridia was more remarkable than that of Azotobacter.     

The effect of some soil amendments on chemical and microbiological properties of an alkali soil

Summary A representative alkali soil sample from Tal-El-Kebir was treated in pots with different rates of gypsum or sulphur. These amounts were calculated according to the exchangeable sodium present in the soil. Chemical and microbiological properties were studied during reclamation process.Addition of gypsum in appropriate amounts to replace exchangeable sodium on the clay complex is much faster and more superior to the addition of the corresponding amounts of sulphur.Counts of total microbial flora, Azotobacter, nitrifiers, and aerobic cellulose-decomposers increased as the reclamation proceeded, on the other hand, counts of spores of aerobic sporeformers, streptomyces, and clostridia decreased.Cultivation of such reclaimed soils exerted beneficial effect on its microbial flora. Plant vigor which was taken as a resultant of the improvement of the physico-chemical and biological properties of the soil due to reclamation was found to be superior in case of addition of an amount of gypsum equivalent to the amount of adsorbed sodium.     

Effectiveness of natural protected areas to prevent land use and land cover change in Mexico

This study evaluated the extent to which natural protected areas (NPAs) in Mexico have been effective for preventing land use/land cover change, considered as a major cause of other degradation processes. We developed an effectiveness index including NPA percentage of transformed areas (agriculture, induced vegetation, forestry plantations, and human settlements) in 2002, the rate and absolute extent of change in these areas (1993–2002), the comparison between rates of change observed inside the NPA and in an equivalent surrounding area, and between the NPA and the state(s) in which it is located. We chose 69 terrestrial federal NPAs, decreed before 1997, that were larger than 1,000 ha, not urban/reforested with non-native vegetation, not islands and not coastal strips, and estimated the extent of transformed areas using 1993 and 2002 land use/land cover maps. Over 54% of NPAs were effective, and were heterogeneously distributed by management categories: 65% of Biosphere Reserves, 53% of Flora and Fauna Protection Areas, and 45% of National Parks. 23% of NPAs were regarded as weakly effective, and the remaining 23% as non-effective. We recognize the importance of NPAs as a relevant conservation instrument, as half of NPAs analyzed (particularly biosphere reserves) prevented natural vegetation loss compared with their geographic context. Our results suggest that conservation based on NPAs in Mexico still faces significant challenges. Our approach can be expanded for evaluating the effectiveness of NPA in other regions, as land use/land cover maps are now available almost worldwide.