2009—2019年山东省耕地生态安全评价及障碍因子诊断

耕地生态安全是国家和区域生态安全的重要组成部分。为了明确认识耕地生态安全及其障碍因子、促进耕地生态与农业发展,利用PSR模型构建耕地生态安全的指标体系,基于第三次国土调查和第二次土地调查数据,评估了山东省2009—2019年的耕地生态安全变化,同时利用障碍度模型,诊断了影响耕地生态安全的障碍因子。结果表明:(1)山东省2009—2019年耕地生态安全整体上呈现下降的态势,生态安全指数由0.27下降至0.14;(2)2009—2019年不同地级市耕地生态安全状况变化不同,5个地级市呈现上升的趋势,4个地级市耕地安全基本稳定,7个地级市出现不同程度的下降;(3)二三产业从业人员比重、二三产业产值比重、农村居民人均可支配收入、耕地平均海拔和复种指数在2009—2019年是影响耕地生态安全的主要障碍因子。综上,2009—2019年山东省耕地生态安全出现下降的趋势,存在多个影响耕地生态安全的障碍因子。研究认为加强耕地污染治理、发展生态农业、缓解产业结构不平衡是改善耕地生态安全的关键措施。     

土地生态安全预警系统设计与实现

土地生态安全问题是区域生态安全的核心问题之一。定量化、可视化、自动化的评价和预测土地生态安全状况并进行实时预警,对土地资源的可持续利用具有重要意义。本文以河北省为研究实例,基于PSR(压力、状态、响应)模型构建了土地生态安全评价指标体系,采用投影寻踪模型对土地生态安全状况进行评价,采用主成分相关分析法诊断土地生态安全的主要影响因子,采用空间差异系数模型分析了土地生态安全的时空格局,采用马尔科夫预测模型对土地生态安全水平进行预测,通过划分土地生态安全预警等级建立了预警机制,并利用MATLAB的图形用户界面(GUI)开发了土地生态安全预警系统。结果表明:1)2010—2018年,河北省土地生态安全指数呈不断增长态势,由0.300上升到0.611,年均增长率为12.92%,土地生态安全状态由"恶化级"转变为"敏感级",预警等级由"巨警"转变为"中警",土地生态安全总体水平仍然较低。2)土地生态安全主要限制因子是人口密度、工业化率、单位播种面积农药负荷、单位土地工业三废负荷、城市建设用地比重、工业用地比重和GDP能耗等。3)河北省各地级市土地生态安全区域差异性不断缩小,近年趋于平稳,至2018年,空间差异系数为32.54%,各市之间的差异性仍然不容忽视,大部分地级市土地生态安全状态处于"敏感级",预警等级为"中警",土地生态安全水平有待进一步提高。4)2019—2025年,河北省土地生态安全指数呈稳步上升趋势,到2025年为0.834,达到"较安全级",预警等级为"轻警",土地生态朝着良性方向发展的潜力较大。     

西安市耕地生态安全测度及影响因素分析

耕地生态安全评价对改善耕地生态系统安全状况、促进耕地可持续利用具有重要的现实意义。以西安市为研究区域,采用压力—状态—响应模型,构建了基于能值理论的耕地生态安全指标评价体系,采用组合赋权法来确定指标权重,测度了2001—2012年西安市耕地生态安全水平值及变动趋势,并采用多元线性回归模型分析了耕地生态安全的影响因素。结果表明:西安市耕地生态安全值总体波动趋势为:2001—2007年耕地资源由较安全区下降至安全临界区,在2004年出现一次波动;2007—2010年耕地资源安全评价值呈上升趋势,且达到最高值,耕地生态状况由安全临界区跨越到较安全区;2010—2011年耕地资源安全状态下降至安全临界区,幅度较大,2012年虽有升高,但仍然处于安全临界区。提高人均能值产出、增加农业财政支出比例和严格管控建设用地占用耕地是改善西安市耕地生态安全的重要措施。     

基于RBF模型的广东省土地生态安全时空演变预警研究

基于压力—状态—响应(P-S-R)模型构建土地生态安全预警评价指标体系,运用熵权法和RBF模型对2000—2016年广东省土地生态安全进行评价与预警研究,同时分析2012年广东省21地级市土地生态安全空间格局。结果表明:(1)广东省土地生态安全水平总体呈波动上升趋势,其中2000—2006年处于重警状态,2007—2009年处于高警状态,2010—2012年处于中警状态。2013—2016年,若不出现较大变故,全省土地生态安全将仍保持这一发展趋势,平稳中略有上升,仍处于中警状态;(2)2012年广东省土地生态安全基本上呈粤北、粤西警情高,珠三角和粤东警情低的格局;(3)影响广东省土地生态安全的主要因素包括自然灾害受灾面积比重、公路密度、建成区面积比重、人均GDP、经济密度、农民人均纯收入、自然保护区面积比重等,这些是今后调控的重点。     

新疆干旱区于田绿洲生态安全评价及影响因子研究

以新疆克里雅河流域于田绿洲为研究靶区,运用压力—状态—响应(PSR)模型,从时间尺度上对1999—2010年绿洲生态安全状况进行评价并进行影响因子分析。结果表明:于田绿洲生态安全综合指数大致上呈现递增趋势,1999—2005年处于不安全状态、2006—2010年由临界安全状态向较安全状态转变。限制性因子分析表明:影响于田绿洲生态安全的主要限制因子是第三产业占GDP比重、单位耕地农业总产值、人均粮食产量、境内公路里程、农牧民人均纯收入、城镇化程度、耕地面积比重。研究表明于田绿洲生态安全现状良好,评价结果将为维持及进一步改善生态状况提供科学依据。     

基于熵值法和灰色预测模型的耕地生态安全诊断

[目的]弥补已有耕地生态安全诊断中指标体系及评价方法的不足,分析耕地生态安全水平。[方法]在界定耕地生态安全内涵的基础上,构建了基于PSR模型的评价指标体系,采用熵值法和灰色预测模型,对四川省耕地生态安全水平进行了诊断。[结果]1999—2013年四川省耕地生态安全水平总体不断提高,耕地生态安全等级经历了"临界安全—较安全"的演变历程,但2013年"较安全"水平不高;压力指数总体上呈现下降趋势,状态指数呈现波动下降趋势,响应指数呈现上升趋势;单位耕地化肥负荷、人均耕地面积、单位耕地农药负荷、土地垦殖率、水土流失程度等是耕地生态安全等级提升的关键制约因素;2014—2018年四川省耕地生态安全水平呈现稳步上升趋势。[结论]基于PSR模型的评价指标体系能更准确地反映耕地生态安全各要素之间的关系;熵值法和灰色预测模型能有效挖掘耕地生态安全存在的问题,适合用于耕地生态安全评价。     

耕地生态安全动态评价及障碍因子诊断——以黄河下游沿黄县区为例

[目的] 对黄河流域下游耕地生态安全进行动态评价,并诊断其人为障碍因子,旨在发现人类不合理行为对下游耕地生态安全造成的危害,为黄河下游生态保护和高质量发展提供现实科学依据。[方法] 以黄河下游沿黄49县区为研究对象,基于PSR模型构建耕地生态安全评价指标体系,运用物元可拓、马尔科夫链模型等方法开展研究。[结果] ①2000—2018年黄河下游沿黄县区耕地生态安全等级整体呈上升趋势,由Ⅳ级提升到Ⅰ级,其中2010年后变化尤为明显; ②2000—2018年各县区耕地生态安全等级由不稳定向稳定过渡,在空间上呈现由东北部高,中西部低向东北—西南部高,中部低转变的特征,且空间差异持续缩小; ③人均耕地面积、人口密度、单位耕地面积化肥使用量是影响黄河下游沿黄县区耕地生态安全等级的主要人为障碍因子。[结论] 研究期内黄河下游沿黄县区耕地生态安全等级总体呈上升趋势,各县区耕地生态安全等级空间差异持续缩小,受人类活动因素影响较大。未来应从壮大新型农业经营主体、实施归雁工程、构建智慧耕地平台三方面促进黄河流域耕地生态安全等级的提高。     

2007-2017年洞庭湖平原耕地生态安全评价及障碍因子诊断

[目的] 研究洞庭湖平原耕地生态安全状况,并诊断其障碍因子,为区域耕地合理利用和耕地污染治理提供参考依据。[方法] 基于DPSIR模型构建洞庭湖平原耕地生态安全评价指标体系,从县域尺度,采用基于熵权的改进TOPSIS模型测度洞庭湖平原2007—2017年耕地生态安全指数,并采用障碍度模型诊断耕地生态安全状态的主要障碍因子。[结果] 2007—2017年洞庭湖平原整体耕地生态安全程度处于临界状态,整体安全指数在研究期内波动上升但增速缓慢;不同县（区、市）耕地生态系统安全变化特征不一;中低产田改良比例、秸秆还田比例、测土配方施肥比例、农药使用强度、地膜使用强度、化肥施用强度、农业自然灾害成灾比例等是制约耕地生态安全的主要障碍因子。[结论] 为改善洞庭湖平原耕地生态安全状况,应大力实施全域土地综合整治,加强农业面源污染治理。     

基于熵权TOPSIS法与ARIMA模型的四川省耕地生态安全动态预测预警

耕地生态安全预警研究能够有效引导耕地资源可持续利用。以四川省21个地市州为研究对象,构建了基于DPSIR模型的耕地生态安全预警评价指标体系,采用改进的熵权TOPSIS法进行警情分析,并运用ARIMA模型模拟未来5年警情变化趋势。结果表明:(1)ARIMA模型拟合度高,能够较好地拟合2015—2019年四川省耕地生态安全发展趋势;(2)总体而言,2005—2019年四川省耕地生态安全警情由"重警"变为"中警",预警指数由0.397(2005年)上升至0.501(2019年),最高值为0.524(2014年),总体呈波动上升的态势,表明出现严重生态安全问题的可能性小。(3)就各子系统而言,2005—2019年耕地生态安全压力系统是影响警情的变化的主要系统,该系统中预警值呈波动下降趋势,警度将升至"巨警"状态;驱动力、状态、影响与响应系统,预警值则逐年增大,警度等级逐年降低。(4)未来5年,四川省各地市州耕地生态安全压力区域差异明显,不同的区域应对措施不同,一二级区域将是以后调控的重点区。     

基于DPSIR模型的渭河干流甘肃段生态安全评价

[目的] 分析渭河干流甘肃段生态安全现状,为该流域生态文明建设提供理论依据。[方法] 通过DPSIR模型构建渭河干流甘肃段生态安全评价指标体系,运用组合赋权法确定指标权重,并利用障碍模型诊断障碍因子。[结果] ①渭河干流甘肃段生态安全指数呈先降后升的趋势,生态安全等级由Ⅳ（较危险）经Ⅴ（危险）先向Ⅳ（较危险）再向Ⅲ（预警）转变;②项目层指数变化幅度较小,驱动力、压力和影响指数波动下降,状态和响应指数波动上升,生态安全状况整体有所好转;③人口增长率、经济增长率、植被覆盖率、城镇污水处理率和农业用水利用率是影响渭河干流甘肃段生态安全的主要障碍因子。[结论] 未来应注重经济、政治、文化、生态环境四者的有机统一,进一步推动经济与生态的和谐发展。     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

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     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.