Seasonal variation of water extractable aluminium forms in acidified forest organic soils under different vegetation cover

The Jizera Mountains area is affected by natural and anthropogenic acidification processes. The effect of acidification is reflected by presence of elevated amount of different Al forms in soil horizons. Changes of water extractable forms of Al (total $ {text{Al}}_{{{text{H}}_{2} {text{O}}}} $ , species: Al(X)¹⁺, Al(Y)²⁺ and Al³⁺) and other soil characteristics (e.g. DOC, pH) were investigated in forest soils from April to October 2008. Seasonal changes of Al forms were identified in organic F and H soil horizons. No significant effect of the soil type on Al forms was documented. Nevertheless, influence of vegetation cover (beech and spruce forest, clear-cut area) on Al(X)¹⁺, Al(Y)²⁺ forms was proved. The results show that binding and mobility of Al forms are controlled mostly by pH and dissolved organic carbon (DOC).     

Biological functioning of Brazilian Cerrado soils under different vegetation types

Aims

Over a 2?year period, we compared the soil biological functioning (SBF) of Cerrado physiognomies ranging from grassland-savannic to forest formations, sampling in the middle of the dry and rainy seasons.

Methods

Soil samples were collected at two depths (0 to 5?cm and 5 to 20?cm) under the following physiognomies: Campo Sujo, Cerrado Ralo, Cerrado sensu stricto, Cerrad?o and Mata de Galeria. The SBF was represented by the simultaneous analyses of microbial biomass carbon, soil basal respiration and the activity of enzymes linked to the C, P and S cycles (β-glucosidase, acid phosphatase and arylsulfatase, respectively).

Results

The results demonstrated that Cerrado physiognomies are a major determinant of SBF patterns. The forest-like physiognomies (Mata de Galeria and Cerrad?o) presented the highest biomass and activity compared to the grassland (Campo Sujo) and savanna physiognomies (Cerrado Ralo and Cerrado sensu stricto). These differences were more evident in the topsoil layer (0 to 5?cm), and the seasonal effect on the SBF of the Mata de Galeria and Cerrad?o was more pronounced than on the other physiognomies.

Conclusions

These results provide a benchmark for evaluating changes in SBF and related processes in Cerrado areas due to shifts toward agriculture and cattle production.     

利用PROSPECT+SAIL模型反演植物生化参数的植被指数优化模拟

分析3个植被生化参数(叶绿素含量、叶片含水量和叶面积指数)对冠层光谱反射率变化的敏感程度以及影响波段区间,选择3个植被指数作为代价函数的优化比较对象,然后运用微粒群算法和PROSPECT+SAIL模型分别反演叶绿素含量、叶片含水量和叶面积指数,结果表明:基于植被指数作为优化比较对象的模型反演效率较全波段方法有所提高;叶绿素含量、叶片含水量和叶面积指数反演值与实测值的复相关系数分别为90.8％、95.7％和99.7％,均方根误差分别为4.73μg·cm-2、0.001 g·cm-2和0.08.采用植被指数作为优化比较对象可有效地提高基于PROSPECT+SAIL模型反演植被生化参数的精度和效率.     

Use of biochemical indices in the classification of Sporozoa

The paper presents a survey of literary and author's own data on metabolism of nitric bases, nucleosides and orotic acid in Eimeria, Toxoplasma and Plasmodium. Experimental data on nucleotide content of DNA, fractional content of ribosome RNA, isofermental spectrum of a number of oxidation-reduction enzymes and immunochemical analysis of antigens in various groups of Sporozoa (Eimeria, Toxoplasma and Plasmodium) are given. A possible use of biochemical and immunochemical data for the taxonomy of Sporozoa is suggested.     

Nitrogen cycling in two riparian forest soils under different geomorphic conditions

At the floodplain scale, spatial pattern and successional development of riparian vegetation are under the control of geomorphic processes. The geomorphic and hydraulic characteristics of stream channels affect the sorting of organic material and inorganic sediment through erosion/sedimentation during floods. In turn, the proportion of fine sediments fractions differs by location within a given community of riparian forest succession. In this paper we tested the effect of geomorphic features of floodplains, through soil grain size sorting, on the nitrogen cycling in riparian forest soils. Two typical riparian forests formed by vertical accretion deposits from repeated addition of sediments from overbank flow have been chosen along the River Garonne, southwest France. These riparian forests had equivalent vegetation, flood frequency and duration, differing only in soil grain size composition: one riparian forest had sandy soils and the other had loamy soils. The evolution of the main soil physical and chemical parameters as well as denitrification (DNT), N uptake (N _U ) and mineralization (N _M ) rates were measured monthly over a period of 13 months in the two study sites. The loamy riparian forest presented a better physical retention of suspended matter during floods. Moreover,in situ denitrification rates (DNT) and N uptake by plants (N _U ) measured in the loamy riparian forest soils were significantly greater than in the sandy soils. Although DNT and N _U could be in competition for available nitrogen, the peak rates of these two processes did not occur at the same period of the year, N _U being more important during the dry season when DNT was minimum, while DNT rates were maximum following the spring floods. N retention by uptake (N _U ) and loss by DNT represented together the equivalent of 32% of total organic nitrogen deposited during floods on the sandy riparian forest soils and 70% on the loamy ones. These significant differences between the two sites show that, at the landscape level, one should not estimate the rates of N _U and DNT, in riparian forests soils only on the basis of vegetation, but should take also into account the geomorphic features of the floodplain.     

Effect of simulated forest fire on the availability of N and P in mediterranean soils

The effect of soil burning on N and P availability and on mineralization and nitrification rates of N in the burned mineral soil was studied by combustion of soils in the laboratory. At a fire temperature of 600°C, there was a complete volatilization of NH₄ and a significant increase of pH, from 7.6 in the unburned soil to 11.7 in the burned soil. Under such conditions ammonification and nitrification reactions were inhibited. Less available P was produced immediately after the fire at 600°C, as compared to P amount produced at 250°C. Burning the soils with plants caused a decrease in NH₄-N and (NO₂+NO₃)-N concentrations in the soil as well as a reduction in ammonification and nitrification rates. Combustion of soil with plants contributed additional available P to the burned soil. The existence of a non-burned soil under the burned one played an important role in triggering ammonification and nitrification reactions.     

南亚热带不同植被下丘陵赤红壤结构特征比较研究

比较研究了南亚热带几种植被下丘陵赤红壤结构特征．结果表明,丘陵赤红壤的结构随着植被的演退而退化．表现在表土砂化,即砂粒含量相对增加,粘粒含量相对减少;土壤结构稳定性下降,主要体现在较大粒径水稳性团聚体减少;土壤孔隙性变差,主要体现在容重增加和较大孔径的孔隙减少．自然赤红壤容重增加、较大孔隙减少更为明显;耕型赤红壤结构稳定性下降,表土砂化更为突出．研究结果揭示,由植被演退引起的土壤有机质减少,是丘陵赤红壤结构退化的主要内在因素．     

基于不同光谱指数的植被物候期遥感监测差异

植被物候是陆地生态系统响应气候和环境变化的一项综合性指标.遥感光谱已经被广泛用于提取植被物候期,但遥感提取的物候期与站点观测差别很大,其物理意义尚不明确.本文选取中国东北部的一景MODIS数据(2000—2014年),分析了基于红波段和近红外波段的归一化差值植被指数(NDVI)和简单比植被指数(SR)提取的植被生长季起始期(SOS)和结束期(EOS)的差异.结果表明:两者的物候期存在显著差别,基于NDVI提取的SOS比SR提取的SOS平均早18.9 d,基于NDVI提取的EOS比SR提取的EOS平均晚19.0 d,NDVI得到的生长季长度更长.基于NDVI和SR提取的物候期的年际变化也存在显著差别,超过20%的像元SOS和EOS甚至表现出相反的年际变化趋势.上述差异与两种植被指数自身的季节曲线特征和抗噪性差异有关.NDVI与SR观测数据来源完全一致,仅数学表达形式不同,提取的物候期结果却存在显著差异.说明遥感监测的植被物候期高度依赖于植被指数的数学表达形式,如何建立可靠的植被物候期遥感提取方法仍需进一步研究.     

Appropriate vegetation indices for measuring the impacts of deer on forest ecosystems

Increasing deer density can cause serious degradation of forests in the Americas, Europe, and Asia. To manage deer impacts, evaluating their current impacts on forest ecosystems is necessary, usually via vegetation indices. However, the relationship between vegetation indices and absolute deer density, while taking into account tree size, snow depth, light condition, and the type of understory vegetation, has never been investigated. We examined the relationship between various vegetation indices and absolute deer density in 344 study plots in the deciduous broad-leaved forest of Yamanashi Prefecture, central Japan. In each plot, debarking and browsing, along with the coverage and maximum height of understory vegetation, were surveyed. Estimated deer densities for 82 5 × 5-km mesh units ranged from 0.8 deer/km² to 32.7 deer/km². The percentages of debarked trees within a plot ranged from 0 to 84%. Debarking was promoted by high deer density, small tree size, and thick snow. The effect of tree size on debarking was stronger than that of deer density. Occurrence of browsing on understory vegetation was higher at higher deer densities, and where understory vegetation was dominated by evergreen dwarf bamboo. Coverage and maximum height of understory vegetation were unaffected by deer density but increased with canopy openness and the dominance of dwarf bamboo in the understory. Overall, we predict that debarking of small trees living in heavy snow areas should occur even at low deer densities (<10 deer/km²). Browsing on dwarf bamboo should occur at intermediate deer densities (10–30 deer/km²), while debarking of thick trees living in low snow areas should occur only at high deer densities (≥30 deer/km²). Our study shows that debarking and browsing on understory vegetation are appropriate indices for evaluating deer impacts on forest ecosystems, but that tree size, snow depth, and the type of understory vegetation should also be considered.     

Biodegradation of 2,4-dichlorophenol in the presence of volatile organic compounds in soils under different vegetation types

It has been suggested that monoterpenes emitted within the soil profile, either by roots or by decaying biomass, may enhance the biodegradation of organic pollutants. The aim of this study was to evaluate the effect of biogenic volatile organic compounds (VOCs) on the catabolism of 2,4-dichlorophenol in soils. Soils were collected from areas surrounding monoterpene (woodland) and nonmonoterpene (grassland)-emitting vegetation types. Soils were spiked with [UL-¹⁴C] 2,4-dichlorophenol at 10 mg kg⁻¹ and amended with α-pinene, p -cymene or a mix of monoterpenes (α-pinene, limonene and p -cymene in 1 : 1 : 1 ratio). The effects of monoterpene addition on the catabolism of [UL-¹⁴C] 2,4-dichlorophenol to ¹⁴CO₂ by indigenous soil microbial communities were assessed in freshly spiked and 4-week-aged soils. It was found that aged woodland soils exhibited a higher level of [UL-¹⁴C] 2,4-dichlorophenol degradation, which was subsequently enhanced by the addition of monoterpenes ( P <0.001), with the VOC mix and α-pinene amendments showing increased [UL-¹⁴C] 2,4-dichlorophenol catabolism. This study supports claims that the addition of biogenic VOCs to soils enhances the degradation of xenobiotic contaminants.     

Changes in the distribution of South Korean forest vegetation simulated using thermal gradient indices

To predict changes in South Korean vegetation distribution, the Warmth Index (WI) and the Minimum Temperature of the Coldest Month Index (MTCI) were used. Historical climate data of the past 30 years, from 1971 to 2000, was obtained from the Korea Meteorological Administration. The Fifth-Generation National Center for Atmospheric Research (NCAR) /Penn State Mesoscale Model (MM5) was used as a source for future climatic data under the A1B scenario from the Special Report on Emission Scenario (SRES) of the Intergovernmental Panel on Climate Change (IPCC). To simulate future vegetation distribution due to climate change, the optimal habitat ranges of Korean tree species were delimited by the thermal gradient indices, such as WI and MTCI. To categorize the Thermal Analogy Groups (TAGs) for the tree species, the WI and MTCI were orthogonally plotted on a two-dimensional grid map. The TAGs were then designated by the analogue composition of tree species belonging to the optimal WI and MTCI ranges. As a result of the clustering process, 22 TAGs were generated to explain the forest vegetation distribution in Korea. The primary change in distribution for these TAGs will likely be in the shrinkage of areas for the TAGs related to Pinus densiflora and P. koraiensis, and in the expansion of the other TAG areas, mainly occupied by evergreen broad-leaved trees, such as Camellia japonica, Cyclobalanopsis glauca, and Schima superba. Using the TAGs to explain the effects of climate change on vegetation distribution on a more regional scale resulted in greater detail than previously used global or continental scale vegetation models.     

Empirical diversity indices applied to forest communities in different successional stages.

In this paper we examine the precision of six diversity indices, four of them empirical when including in their formulae climax adaptation numbers. These numbers define the succession position of the plant species in five forest areas in Sao Paulo State. We simulated hypothetical forests and compared the results with a list of species in the five areas. Low agreement was found among the indices in succession stages. Including the climax adaptation numbers increased precision for only some indices.     

Long-term dynamics of vegetation indices in dark coniferous forest after Siberian moth disturbance

This study considers long-term dynamics of the vegetation indices derived from Landsat imagery of the period from 1989 to 2014. The mass death and damage of forests by Siberian moth occurred in dark coniferous taiga in 1994–1996. The images have covered both altered (disturbed) and background forest conditions. The case study of the forest massive is located in the model area of the Angara Taiga Region of Eastern Siberia (Krasnoyarsk krai). The values of spectral brightness of satellite images are represented by produced index images of NDVI vegetation index and shortwave vegetation index SWVI. The study employed forest-surveying materials from 1992 and data on the degrees of forest damage during the first (in 1995) and second (in 1996) year of Siberian moth outbreak. The latter was obtained by forest-pathology research using production-scale spectrozonal aerophotography. The average background values of indices have gradually decreased with the forest age or remained constant, excluding the young growth stage and 200-year-old light coniferous forests. High seasonal variability of NDVI compared to SWVI is the key to use satellite data for the timeframe of a week in June for every year to analyze long-term dynamics. We have approved the conclusion of other researchers that both the mean and the coefficient of variation of SWVI are the most informative in the evaluation of the degree of Siberian moth damage of forests. We recommend recognizing three degrees of forest damage by Siberian moth—light, moderate, and severe (continuous). Long-term dynamics of vegetation indices in disturbed forests has been marked with demutation and inhomogeneity of stand cover. Taking into account the intensity and frequency of wildfires, it is highly probable that reforestation will not occur in dark coniferous forests. Therefore, the regular satellite monitoring of the sites of Silk moth occurrence would be useful.     

表征亚热带常绿林光合作用季节变化特征的多种植被指数

利用遥感方法可以在区域尺度反演地表植被的光合生理状况和生产力变化,但亚热带常绿林冠层结构季节变化较小,传统的光谱植被指数对植被光合作用难以准确捕捉。利用2014—2015年中国科学院广东省鼎湖山森林生态试验站多角度自动光谱观测系统的光谱反射数据,分别反演传统冠层结构型植被指数(NDVI)、光合生理生化型植被指数(CCI)和叶绿素荧光型植被指数(NDFI_(685)和NDFI_(760)),并利用不同类型植被指数的组合,构建多元线性回归模型。结果表明:亚热带常绿针阔混交林三种类型植被指数均与GPP的动态变化有显著的相关性,其中,NDVI是表征GPP较优的植被指数(R~2=0.60,P0.01),其次为CCI(R~2=0.55,P0.01),而NDFI能够作为辅助指数,有效提高NDVI(R~2=0.68,P0.001)和CCI(R~2=0.67,P0.001)表征GPP的程度。多个植被指数参与构建的多元回归模型能够有效提高亚热带地区常绿林GPP季节动态变化的拟合精度,提升遥感精确评估亚热带森林生产力的能力。     

Spectral vegetation indices as the indicator of canopy photosynthetic productivity in a deciduous broadleaf forest

Aims Understanding of the ecophysiological dynamics of forest canopy photosynthesis and its spatial and temporal scaling is crucial for revealing ecological response to climate change. Combined observations and analyses of plant ecophysiology and optical remote sensing would enable us to achieve these studies. In order to examine the utility of spectral vegetation indices (VIs) for assessing ecosystem-level photosynthesis, we investigated the relationships between canopy-scale photosynthetic productivity and canopy spectral reflectance over seasons for 5 years in a cool, temperate deciduous broadleaf forest at 'Takayama' super site in central Japan.Methods Daily photosynthetic capacity was assessed by in situ canopy leaf area index (LAI), (LAI × V cmax [single-leaf photosynthetic capacity]), and the daily maximum rate of gross primary production (GPP max) was estimated by an ecosystem carbon cycle model. We examined five VIs: normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), green–red vegetation index (GRVI), chlorophyll index (CI) and canopy chlorophyll index (CCI), which were obtained by the in situ measurements of canopy spectral reflectance.Important findings Our in situ observation of leaf and canopy characteristics, which were analyzed by an ecosystem carbon cycling model, revealed that their phenological changes are responsible for seasonal and interannual variations in canopy photosynthesis. Significant correlations were found between the five VIs and canopy photosynthetic capacity over the seasons and years; four of the VIs showed hysteresis-type relationships and only CCI showed rather linear relationship. Among the VIs examined, we applied EVI–GPP max relationship to EVI data obtained by Moderate Resolution Imaging Spectroradiometer to estimate the temporal and spatial variation in GPP max over central Japan. Our findings would improve the accuracy of satellite-based estimate of forest photosynthetic productivity in fine spatial and temporal resolutions, which are necessary for detecting any response of terrestrial ecosystem to meteorological fluctuations.     

Plant biodiversity and vegetation structure in traditional cocoa forest gardens in southern Cameroon under different management

Floristic surveys were performed in 17 traditional cocoa forest gardens under different management regimes in the humid forest area of southern Cameroon, to assess the impact of intensification on plant biodiversity. This impact was evaluated by analyzing species richness, vegetation structure, carbon sequestration and above ground biomass. We hypothesize that: (a) plant (tree and herbs) species richness is negatively correlated to management intensity and (b) vegetational density predictably change with management intensity. Our results show that management as practiced in traditional cocoa forest gardens in southern Cameroon following a gradient of intensification from extensive cocoa forest gardens with high floristic diversity to intensive ones strongly impacts plant diversity, plant biomass and to some extend carbon storage with possible negative consequences on biodiversity. Great differences in species richness, species composition, and, for trees, diameter at breast height and basal area were evident among the five types of traditional cocoa forest garden systems investigated. In terms of plant species richness, we found a decreasing gradient of plant species numbers from extensive forest gardens to intensive ones. This study also highlights the importance of the Management Index for quantifying differences in the management; this index could be used to standardize certification procedures and assess conservation progress and success. Our findings support the idea that traditional cocoa forest gardens can help to protect many forest species, sustains smallholder production and offer more scope for conservation of biodiversity, at both species-level and landscape-level. Moreover, diverse traditional cocoa forest gardens may help in regulating pests and diseases and allow for efficient adaptation to changing socioeconomic conditions.     

Oxidation of methane in boreal forest soils: a comparison of seven measures

Methane oxidation rates were measured in boreal forest soils using seven techniques that provide a range of information on soil CH₄ oxidation. These include: (a) short-term static chamber experiments with a free-air (1.7 ppm CH₄) headspace, (b) estimating CH₄ oxidation rates from soil CH₄ distributions and (c)²²²Rn-calibrated flux measurements, (d) day-long static chamber experiments with free-air and amended (+20 to 2000 PPM CH₄) headspaces, (e) jar experiments on soil core sections using free-air and (f) amended (+500 ppm CH₄) headspaces, and (g) jar experiments on core sections involving tracer additions of¹⁴CH₄. Short-term unamended chamber measurements,²²²Rn-calibrated flux measurements, and soil CH₄ distributions show independently that the soils are capable of oxidizing atmospheric CH₄ at rates ranging to < 2 mg m^–2 d^–1. Jar experiments with free-air headspaces and soil CH₄ profiles show that CH₄ oxidation occurs to a soil depth of 60 cm and is maximum in the 10 to 20 cm zone. Jar experiments and chamber measurements with free-air headspaces show that CH₄ oxidation occurs at low (< 0.9 ppm) thresholds. The¹⁴CH₄-amended jar experiments show the distribution of end products of CH₄ oxidation; 60% is transformed to CO₂ and the remainder is incorporated in biomass. Chamber and jar experiments under amended atmospheres show that these soils have a high capacity for CH₄ oxidation and indicate potential CH₄ oxidation rates as high as 867 mg m^–2 d^–1. Methane oxidation in moist soils modulates CH₄ emission and can serve as a negative feedback on atmospheric CH₄ increases.     

A comparison of the vegetation in semi-natural grasslands under different agricultural practices in Finnish and Russian Karelia

The vegetation of semi-natural grasslands under modern, cereal/forage cropping in Finnish Karelia (n = 11) and old fashioned animal husbandry in adjacent Russian Karelia (n = 11) was compared in terms of their species composition. Each grassland site was paired with one in the other country which was as similar as possible in respect to its natural conditions. The species composition indicated differences in management between the two countries. The mean number of species was 4S.S in the Finnish sites and 52.6 in the Russian sites. A total of 12 species exhibited a statistical difference in their indicator values between the two countries. Traditional grassland species (e.g. Leontodon hispidus, Dianthus deltoides ), indicating grazing, hay making and old settlement, occurred more oñen in Russian sites, while species related to nutrient enrichment and cultivation (e.g. Urtica dioica, Elymus repens ) were more characteristic of Finnish sites.     

Repression of nitrification in soils under a climax grassland vegetation

Abstract Two hypotheses on repression of nitrification in climax vegetations (i.e. nitrogen immobilization and allelopathy) were investigated. In this study the potential nitrification activities and numbers of ammonium-oxidizing bacteria were established in a nature reserve with a series of natural grasslands with vegetational different stages of succession of plants species. The pastures had not been fertilized for 3, 7, 20 and 46 years, respectively, and the gradual decrease in availability of nutrients had led to pastures dominated by different grass species. In each field soil parameters, potential nitrification activities (PNA) and numbers of ammonium-oxidizing bacteria were determined in the root zone of Holcus lanatus as well as in that of a grass species characteristic of the stage of succession. In the rhizosphere of H. lanatus decreasing PNA and numbers of ammonium-oxidizing bacteria were observed as the period of non fertilization increased. Within each field no significant differences in PNA were observed between the root zones of H. lanatus and those of the dominant grass species. From these results it is concluded that, in these fields, decreasing nitrification was related only to decreasing ammonium availability and not to species composition. No indications were obtained that allelochemicals were involved in the flow nitrification potentials of late stages of succession. The optimum pH of the ammonium-oxidizing community, measured as PNA, decreased as the period of non fertilization increased. It is suggested that impoverishment of the grassland soil with respect to nitrogen availability selects against ammonium-oxidizing bacteria with a relatively high pH optimum.     

旅游开发对芜湖市森林公园植被与环境质量的影响

以芜湖市各森林公园为例,采用游览频率、植被景观重要值、物种丰富度指数、旅游影响系数、环境质量重要值、伴人植物比例以及管理力度系数7项指标,对该市植被环境质量与旅游的关系进行了分析。结果表明：游览频率与植被景观重要值和丰富度指数成负相关;旅游影响系数、伴人植物比例与环境质量重要值及管理力度系数成负相关。同时探讨了旅游对环境质量及植被影响的规律性。