Long-term charcoal-induced changes to soil properties in temperate regions of northern Iran

The long-term performance and benefits of charcoal application on the carbon sequestration and properties of forest soils in temperate or non-tropical regions has not been studied in detail in spite of its important role in global warming. This study was conducted to describe the long-term charcoal-induced changes in organic carbon (OC) content and other soil properties of temperate deciduous forests in Mazandaran province, northern Iran. Three sites were sampled to collect composite soil samples from two depths (0–20 and 20–40 cm) inside and outside of a plot of charcoal-enriched soils surrounding a historical charcoal production site (abandoned for more than 120 years). The presence of charcoal in soils for about 120 years elevated significantly the black carbon, total OC, natural soil OC, total nitrogen, dissolved organic matter, soil OC density, exchangeable bases, saturated hydraulic conductivity, available water capacity and available Fe, Mn and Zn compared to the adjacent reference soils. Cation exchange capacity (CEC) and pH were 15.5 cmolc kg^-1 and 0.5 units, respectively, higher than the adjacent reference soils at 0–20 cm soil depth. However, electrical conductivity (EC), bulk density and available Cu were higher in the adjacent reference soil. The aged charcoal had no significant effect on the microbial respiration rate of studied soils. The results of this study provide new insights and strong support for the long-term benefits of biochar application as a management strategy for improving soil productivity as well as sequestering large quantities of durable carbon in soils of the region and mitigating global warming.     

Benzene polycarboxylic acids—A ubiquitous class of compounds in soils

Black carbon (BC) occurs ubiquitously in the environment. Its oxidation in the laboratory yields a suite of benzene polycarboxylic acids (BPCAs), suggesting similar oxidation products in soils. Since only for a few soils the occurrence of BPCAs in the free form has been documented, screening for them in a broad range of contrasting soils was conducted. They were extracted from soil samples with 0.5 M NaOH and quantified using gas chromatography–mass spectrometry. As expected, BPCAs turned out to be as ubiquitous as BC. They were detected not only in every soil sample investigated so far, but also in samples from drill cores up to a depth of 10 m and in recently deposited calcareous tufa. The concentrations covered a range similar to that of some phenolic acids. The range exceeded those reported for low‐molecular‐weight aliphatic acids or simple sugars in soils. The distribution of BPCAs in soil profiles indicated a considerable potential of translocation within, and export from, soil, in particular of benzene hexacarboxylic (mellitic) acid. Mellitic acid may therefore be present in almost any geochemical sample affected by seepage water from soils. Its high water solubility and strong metal‐complexing ability suggest it may be involved in metal‐transport processes, at least on geological timescales.     

简析MODIS(Terra/Aqua)数据在福建省森林火灾监测中的应用

从目前福建省卫星林火监测应用实际出发,通过几种常用气象卫星功能介绍和对比,阐述MODIS(Terra/Aqua)数据在森林火灾监测中的应用优势,并简析MODIS(Terra/Aqua)数据在福建省林火监测中的应用现状。     

基于小型无人机与MODIS数据的草地植被覆盖度研究——以甘南州为例

以甘南州为研究区,采用Canon数码相机和小型无人机搭载相机在不同大小样方上获取草地植被覆盖度数码照片,结合2015年5月-10月的Terra/MODIS植被指数产品MOD13Q1,分析了增强型植被指数(EVI)和归一化植被指数(NDVI)与草地植被覆盖度之间的相关性,建立了研究区草地植被覆盖度的回归模型,并对模型进行了精度评价,筛选出甘南州草地植被覆盖度最优遥感反演模型,并对草地生长季时期覆盖度时空上的动态特征进行分析。结果表明,1)利用小型无人机搭载相机获取草地大样方植被数码照片的方法能用于地面草地覆盖度数据的获取;2)与NDVI相比,用EVI估算草地覆盖度更优,因此确定基于EVI构建的对数模型为甘南州草地植被覆盖度最优反演模型,模型精度可达88.00%;3)研究区2015年生长季草地植被覆盖度除了低平地草甸在8月达到最大值外,其它草地类型均在7月达到最大值;4)甘南州以中高植被覆盖度为主,主要分布在玛曲、碌曲、夏河以及合作四县市。整体而言,中西部和西南部区域草地覆盖度高于东部。通过精确草地植被覆盖度模型的建立,不仅有利于及时准确的了解草地植被覆盖度的时空分布状况和季节性动态变化,也有利于维护甘南州草地生态系统的持续稳定发展。     

基于光谱特征分析的主要秋季作物类型提取研究

为快速、准确地在遥感图像上提取各种农作物类型信息,满足国家农情遥感监测系统的要求,以2002年北京地区主要秋季作物提取为例,利用Terra/MODIS数据,采用波谱分析的方法,建立一种基于遥感影像全覆盖的秋季作物类型自动提取方法,实现主要秋季作物遥感自动识别。首先根据研究区秋季作物的波谱特性和生物学特性,选取了红波段、蓝波段、近红外波段和中短波红外波段作为秋季作物类型提取的工作波段;同时,还利用由这4个波段构建的陆表水分指数和增强型指标指数作为遥感特征参量。其次根据研究区农作物物候历特征,提取了2002年4月到9月共7个时相的MODIS数据。最后,采用分层决策树方法提取研究区主要秋季作物类型,并进行面积统计。为了验证其精度,与国家农业部农业统计数据进行比较,结果其精度达到86%以上。这表明,仅利用MODIS自身光谱信息,即可较为准确地提取秋季作物类型信息,精度基本能满足了大尺度农情遥感监测的要求,可以为农业决策部门提供信息服务。     

Biogenic calcium phosphate transformation in soils over millennial time scales

Background, aim, and scope  Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Materials and methods  Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Results and discussion  Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600–1,000 years, β-tricalcium phosphate increased to 16% of total P after 900–1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58–65%) across the time scale studied. Conclusions  Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.     

Edaphic interslope and valley bottom differences at “Evolution Canyon”, Lower Nahal Oren, Mount Carmel, Israel

The opposite slopes of lower Nahal Oren, Mount Carmel, Israel, designated “Evolution Canyon”, display physical and biotic contrasts, although both are cut in Upper Cenomanian calcareous limestone. The three-fold greater solar radiation makes the south-facing slope warmer, drier and more variable than the north-facing slope and valley bottom. Consequently, biodiversity is greater. Microclimate (mesic–xeric) is a major force driving adaptive evolution, and causing soil divergence. The soils on both slopes are Terra Rossas in the Israeli classification system (Rhodoxeralfs in US taxonomy). However, selected properties (pH, humus content, NH₄–N content, cation exchange capacity and others) display greater interslope than intraslope differences. The north-facing Terra Rossas have a dark-coloured A1 humic horizon, which is better developed than in south-facing Terra Rossas. Differences in soil morphology, moisture regime and microfabric between the north- and south-facing soils suggest that they belong to different taxonomic classes. These differences probably result in part from the forested ecosystem of the north-facing slope versus the savanna-like ecosystem of the opposite slope.     

High temporal species turnover enhances the complexity of fish assemblages in Amazonian Terra firme streams

Abstract –  The objective of this study was to quantify fish species diversity in Terra firme streams of the Río Amazonas drainage. Fish diversity was quantified as the number of species collected or species richness in two sites of Yahuarcaca stream, a typical, first order tributary of the central Río Amazonas near Leticia (Colombia). The extremely high species richness recorded, 131 and 133 for the two study sites for a total of 171 species, was primarily due to species of low abundance (rare species) mostly with adults <5 cm in total length. The nonasymptotic tendencies of accumulated species richness over time for the 1999 samples at the two study sites and for the combined samples of 1999, 2001 and 2005 at site 2 suggested that the real number of fish species may be still greater. These findings emphasise the importance of long-term sampling designs to quantify species richness in these systems. Terra firme streams actually sustain greater fish richness than previously reported for similar sized streams that in turn, represent a substantial per cent of the total species richness reported for vast areas of the main stem of Río Amazonas including tributaries and lakes. Terra firme streams should be considered critical hotspots for conservation and management efforts which are urgently needed given the rapid development of ornamental fisheries on small streams throughout Río Amazonas drainage.