岩溶区坡面土壤侵蚀特征研究

以重庆南川岩溶区为例,用137C s法研究了岩溶区坡面土壤侵蚀特征。结果表明,坡面上部侵蚀速率较小,平均侵蚀速率为400.8 t/(km2.a),最大侵蚀速率为1 138.4 t/(km2.a);坡面中部侵蚀加剧,平均侵蚀速率2 264.8 t/(km2.a),最大侵蚀速率可达3 760 t/(km2.a);坡面下部侵蚀减弱甚至堆积。土壤表层有机质、表层粘粒及水稳性团聚体含量在坡面上的变化与土壤侵蚀速率具有负相关趋势。     

42年来兴国县土壤侵蚀时空变化规律研究

以江西省兴国县为研究区域,应用遥感和GIS技术,借助6个不同时段的黑白航片、MSS影像和TM数据为信息源,在建立土壤侵蚀解译标志的基础上,对全县3 215 km2范围内的土壤侵蚀进行了监测研究。结果表明,该县从1958—2000年42 a期间,土壤侵蚀的变化分2个阶段。第一阶段是1982年前,全县的侵蚀面积在2 000 km2左右;第二阶段是从80年代初到2000年,该县被列为全国水土流失综合治理重点区,侵蚀面积在18 a间共减少了739 km2,平均每年减少41 km2。将1992与2000年的土壤侵蚀图叠置分析可以看出,该县5个侵蚀等级的面积都有不同程度的降低;在侵蚀等级的转变方面,大约有34%的侵蚀面积,其侵蚀等级发生了改变,其中以改变一个等级的面积为主,大约有66%的侵蚀面积其侵蚀等级未发生变化,说明兴国县的土壤侵蚀已呈现出明显的减弱趋势。     

治理项目公示制,治理质量全达标

2006年1月,复州河流域纳入东北黑土区水土流失综合防治第一期工程。项目区水土流失面积112.04km2,占项目区总土地面积的45.31%。土壤侵蚀模数加权平均值为2 500 t/(km2.a)。水土流失形式主要为水力侵蚀,水力侵蚀主要表现为面蚀、线状侵蚀和沟状侵蚀。5 a规划治理水土流失面积109.8 km2,治理程度达98%。具体实施办法是:项目内容公示,激发出群众的能动作用;用工承诺公示,确保工程如期进行;产权管理公示,确保工程质量效益发挥。     

三峡库区苎麻护坎坡式梯地减蚀效益的~(137)Cs法研究

三峡库区丰都一带,苎麻护坎坡式梯地非常普遍。为了评估苎麻护坎坡式梯地的减蚀效益,在丰都十直镇采用137Cs示踪法测定了苎麻护坎坡式梯地和相邻坡耕地的侵蚀速率。测定结果表明,苎麻护坎坡式梯地的侵蚀模数为802.50 t/(km2.a),相邻坡耕地的侵蚀模数为2 299.70 t/(km2.a),减蚀效率达65.1%。     

植物干根网格在陡坡上的应用

榆树市南大沟属于丘陵漫岗黑土侵蚀区,近年由于降雨等自然因素的破坏,黑土地大量流失,沟蚀严重,土地利用率下降,直接影响到农业生产。针对南大沟流域沟蚀和坡面的现状,在陡坡中采用了植物干根网格作为护坡的方法,得到很好的治理效果。实测结果表明,每年坡面减少流失量5.532万t,同时结合全沟治理工程,整个侵蚀沟的年泥沙流失量由治理前的1 0.3万t降为1 8 0 t,侵蚀模数由1 1.3 3万t/(km2.a)降低为200 t/(km2.a),有效防止了水土流失,提高了土地利用率,林草覆盖率由5.5%增加到67.58%,治理度从32.5%提高到45.7%,土地利用结构和农村产业结构得到合理调整,加快了南大沟流域水土保持生态治理步伐,使生态环境得到明显改善。可在同类型区进行推广。     

三峡地区侵蚀泥沙的137Cs法研究

198 9年以来三峡地区开展的侵蚀泥沙13 7Cs示踪的初步研究表明:三峡地区紫色土陡坡耕地侵蚀强烈,坡度>2 5°的坡耕地,侵蚀速率高达712 6 94 5 2t/(km2 ·a) ;黄壤质地粘重,抗蚀性好,坡度2 9°的陡坡耕地的侵蚀速率仅2 5 0 9t/(km2 ·a)。林草地侵蚀轻微,坡度2 5°林草地的侵蚀速率为30 6 6 88t/(km2 ·a) ,较坡耕地大致低一个数量级。上世纪6 0年代以来,开县小江河床上涨强烈,两岸滩地也有淤积发生,淤积厚度10 70cm不等,低滩地泥沙淤积厚度大于高滩地。开县春秋水库小流域输沙模数为15 6 0t/(km2 ·a) ,由于谷地泥沙淤积极为有限,此值基本可代表该流域的侵蚀模数。全国土壤侵蚀遥感普查公布的川东平行岭谷区侵蚀模数为30 0 0 5 0 0 0t/(km2 ·a)。     

等高草灌带在长汀水土流失治理中的应用与成效

长汀县在2000年以来的水土流失综合治理过程中,根据坡面径流调控理论,创新采用坡面工程与生物措施相结合的等高草灌带造林技术,并作为关键技术运用在强度侵蚀区的治理实践中。与对照坡地相比,等高草灌带治理区植被盖度由28%上升为91%,侵蚀模数由4836t/km2.a下降为438t/km2.a,径流系数由0.52减少为0.27,有效地削减了坡面径流泥沙,控制了水土流失,促进植被快速生长覆盖地表,从而使退化生态系统得到较好的恢复。     

基于GIS的呼伦贝尔地区土壤侵蚀动态变化研究

基于1995年、2000年和2005年3个时期TM影像数据.运用ArcGIS 9.2软件和通用水土流失方程(RU-SLE),定量研究呼伦贝尔地区不同时期土壤侵蚀动态,运用马尔科夫模型对2010年和2015年呼伦贝尔地区水土流失状况进行了预测.结果表明.在过去10 a中,呼伦贝尔地区土壤侵蚀程度以微度侵蚀为主,轻度以上侵蚀面积仅占总面积的10%左右.其中,1995-2000年呼伦贝尔地区微度侵蚀面积净减少534.33 km~2,轻度以上侵蚀面积增加了580.02 km~2,说明1995-2000年的5 a中呼伦贝尔地区土壤侵蚀强度呈增大趋势;2000-2005年微度侵蚀面积净增8 326.69 km~2,轻度以上侵蚀面积净减少了8 360.54 km~2,土壤侵蚀强度呈减小趋势,说明2000年以来,呼伦贝尔地区水土流失现状较以前有明显改观.这与同期当地实施生态保育措施有较大关系.预测到2010年和2015年,呼伦贝尔地区土壤侵蚀强度将得到缓解,其中,轻度以上侵蚀面积分别比2005年减少24.8%和38%.     

汉江中下游土壤侵蚀及颗粒态非点源磷负荷研究

以汉江中下游为研究区,考虑流域内部地理要素和时空过程的异质性,划分子流域作为基本的响应单元,利用2007年Landsat TM影像、DEM、土壤、气象和社会经济数据等,建立了流域基础数据库.在此基础上运用ArcGIS 9.2和Erdas 9.2计算得到流域降雨侵蚀力因子R,土壤可蚀性因子K,坡度坡长因子LS,经营管理因子C,水土保持因子P等.采用USLE和颗粒态非点源负荷经验方程,分别探讨了汉江中下游土壤侵蚀及非点源磷负荷的空间分布特征.结果表明:汉江中下游土壤的侵蚀模数为867.55 t/(km2·a),属于轻度侵蚀,但依然有5.69%的区域侵蚀模数大于2 500 t/(km2·a).流域内由于土壤侵蚀导致的颗粒态非点源磷负荷流失量达8 496.79 t/a,其中南河、唐白河、蛮河等支流的非点源流失状况最为严重,最高单位负荷量可达8.42 kg/(hm2·a).非点源负荷产生的关键源区主要分布在神农架林区、房县、保康等山地丘陵以及南阳盆地等农业生产区,因此增加植被郁闭度,控制坡地耕作,科学施肥,防止水土流失对于控制非点源污染有着重要意义.     

长江上游水蚀区降雨侵蚀力的时空分布特征

降雨侵蚀力的时空分布特征对于分析和认识土壤侵蚀规律十分重要.根据长江上游7个省市的704个站点1981-2010年30 a的逐日降雨量资料计算了多年平均降雨侵蚀力R值,多年平均半月降雨侵蚀力及其占年降雨侵蚀力的比例,并分析了长江上游水蚀区降雨侵蚀力的空间分布规律.结果表明,长江上游水蚀区的降雨侵蚀力R值范围为273～11 394MJ·mm/(hm2·h· a);受地形的影响R值的空间分布有3个高值区,位于四川省峨眉山市、贵州省毕节地区和湖北省宜昌市附近;建立了多年平均降雨量和降雨侵蚀力R值的关系,相关系数R2达到0.80;研究区降雨侵蚀力的年内分布集中度较大,均值为69％,主要集中在5-10月.     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.