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1.
施氮量和行距对冬小麦产量及生理特性的影响 总被引：5，自引：0，他引：5
为探明不同栽培措施对小麦产量的调控差异,以强筋小麦济麦20和中筋小麦中麦8号为试验材料,采用三因素裂区设计,以施氮量为主区,设150、210、270 kg·hm-23个水平;以行距为裂区,设12、20cm 2个水平;以供试品种为小裂区,设济麦20和中麦8号2个水平,在高产栽培条件下研究不同施氮量和行距对冬小麦产量的影响及其生理基础。结果表明,济麦20和中麦8号,2种小麦籽粒产量均在270kg·hm-2施氮量水平下得到显著提高;在210 kg·hm-2或270 kg·hm-2施氮量条件下,20 cm行距更有利于2个小麦品种高产的形成。随着施氮量增加或行距增大,2个小麦品种旗叶SPAD值和净光合速率均在270 kg·hm-2施氮量和20 cm行距条件下保持较高值,可积累更多光合产物,为实现高产奠定基础。因此,本试验条件下,济麦20和中麦8号均在270 kg·hm-2施氮量、20cm行距组合下达到高产。本研究得到了小麦高产的最佳施氮量和行距组合,这对我国冬小麦高产栽培具有一定的指导意义。 相似文献
2.
为分析氮素水平对弱筋小麦植株氮素吸收利用的影响,以弱筋小麦品种宁麦13和扬麦13为材料,设置不同施氮水平(N 105、210和315 kg·hm-2),应用~(15)N示踪分析技术研究弱筋小麦植株氮素积累、转运与利用的变化。结果表明,弱筋小麦开花期、成熟期植株及成熟期籽粒氮素积累量均随施氮量增加而显著增加;来源于肥料氮和土壤氮均随施氮量增加而增加,且来源于土壤氮比例显著高于肥料氮。籽粒蛋白质含量随施氮量的增加而增高。弱筋小麦花后营养器官氮素向籽粒的转运率为29.44%～41.25%,对籽粒氮素积累的贡献率为36.51%～60.89%,均随施氮量的增加而降低。2个小麦品种的氮肥生产效率、氮肥利用效率均表现为N105N210N315,且N315处理的氮素收获指数低于N105、N210处理,即弱筋小麦籽粒氮肥生产效率、氮肥利用效率随施氮量的增加而降低。本试验条件下,保证弱筋小麦籽粒品质的同时,又有相对较高的籽粒产量、氮肥生产效率和氮素利用效率,适宜的施氮量应在105～210 kg·hm-2之间。 相似文献
3.
施氮量对不同品质类型小麦子粒蛋白质组分含量及加工品质的影响 总被引：5，自引：4，他引：1
选用强筋小麦济麦20、中筋小麦泰山23和弱筋小麦宁麦9号,利用反相高效液湘色谱（RP-HPLC）方法测定了施氮量对不同品质类型小麦子粒蛋白质组分含量和高分子量谷蛋白亚基（HMW-GS）、低分子量谷蛋白亚基（LMW-GS）含量的影响,并分析其与子粒加工品质的关系。结果表明,随施氮量增加,强筋小麦济麦20和中筋小麦泰山23的子粒蛋白质含量及各组分含量均呈先增加后降低的趋势,施氮量为N 240 kg/hm2时,蛋白质各组分含量较高,加工品质较好; 过量施氮抑制了HMW-GS合成,这是过量施氮导致强筋和中筋小麦子粒蛋白质品质变劣的原因之一。随施氮量增加,弱筋小麦宁麦9号子粒的蛋白质各组分含量显著增加,加工品质变劣。增施氮肥,3个品种的谷蛋白和醇溶蛋白含量的增加幅度显著高于清蛋白+球蛋白含量,这是施氮改善强筋和中筋小麦子粒加工品质的主要原因。济麦20和泰山23两品种的总蛋白质含量及醇溶蛋白含量无显著差异,但强筋小麦济麦20的谷蛋白含量、贮藏蛋白、HMW-GS、LMW-GS、谷蛋白大聚合体（GMP）含量及谷蛋白与醇溶蛋白含量的比值（Glu/Gli）和HMW-GS与LMW-GS含量的比值（HMW/LMW）高于中筋小麦泰山23,这是强筋小麦济麦20加工品质形成及其面团形成时间和稳定时间显著高于泰山23的重要原因。 相似文献
4.
施氮量对不同品质类型小麦产量和加工品质的影响 总被引：15，自引：6，他引：9
为了明确施氮量与不同品质类型小麦的产量和品质的关系,选用强筋小麦济麦20、 皖麦38和中筋小麦京冬8、 中麦8共2种品质类型4个小麦品种,研究了施氮量对其产量性状和加工品质的影响。结果表明,在施氮量N 0-360 kg/hm2的范围内,增加氮肥用量可以有效缓解叶绿素降解,抑制旗叶全氮含量降低,缓解叶片衰老,延长旗叶功能期; 强筋小麦品种比中筋小麦品种旗叶叶绿素含量和氮素含量下降缓慢。子粒产量和蛋白质产量随施氮量的增加逐渐提高,施氮N 270 kg/hm2时达到最大值,增加到360 kg/hm2时子粒产量和蛋白质产量均开始下降。强筋小麦蛋白质产量和子粒产量高,中筋小麦穗数、 穗粒数多,千粒重高。施氮有利于子粒出粉率、 硬度、 蛋白质含量和沉降值的提高。施氮N 180 kg/hm2时可以显著延长面团形成时间和稳定时间,降低吸水率,面包总体评分最高。强筋小麦硬度大,蛋白质含量、 出粉率和沉降值高,面团形成时间和稳定时间长,面包体积大、 评分高。 相似文献
5.
减氮对半冬性中筋小麦产量、NUE及氮代谢关键酶活性的影响 总被引：3，自引：0，他引：3
为了研究半冬性中筋小麦在减氮条件下籽粒产量、氮效率(NUE)及氮代谢关键酶活性的差异与调控效应,于2012年-2013年以半冬性中筋小麦徐麦30、保麦1号为供试品种进行池栽试验。研究表明,施用氮肥增加了穗数和粒数,扩大了小麦库容(公顷粒数),而粒重却有所下降,但穗数和粒数的增加幅度大于粒重的降低幅度,从而提高了单位面积籽粒产量。施氮量从270 kg·hm-2降至225kg·hm-2,籽粒谷丙转氨酶(GPT)活性略有提升,而单株氮素积累量、花后剑叶硝酸还原酶(NR)和谷氨酰胺合成酶(GS)、籽粒GS活性均呈下降趋势,籽粒产量有所降低,但差异未达显著水平。减氮影响了植株对氮素的吸收,对氮肥表观利用率(RE)有降低效应,但增强了氮肥偏生产力(PFP)和氮素生理效率(PE),对NHI影响较小。在兼顾生产成本、生态和效益的条件下,将氮肥用量从270 kg·hm-2减少至225 kg·hm-2,更有利于半冬性中筋小麦的可持续高效生产。本研究为小麦合理施氮及提高氮肥利用效率提供科学依据。 相似文献
6.
施氮量对2个粒色小麦产量及加工品质的影响 总被引：1，自引：0，他引：1
为探究施氮量对2个不同粒色小麦品种产量和加工品质的影响,采用裂区试验设计,以白粒小麦中麦8号和黑粒小麦漯珍1号为试验材料,测定2个品种的SPAD值、产量及产量构成因素和部分加工品质指标。结果表明,在同一施氮水平下,2个品种旗叶的SPAD值随时间推移呈先升高后降低的趋势,均在花后20 d和施氮量300 kg·hm~(-2)处理下有最大值,分别为57.52和63.55,增施氮肥可以有效缓解小麦旗叶叶绿素的降解,延长旗叶功能期。在120~300 kg·hm~(-2)的施氮量范围内,除中麦8号的穗粒数在施氮量300 kg·hm~(-2)处理下有最大值外,籽粒产量及产量构成因素随施氮量增加呈先增加后降低的趋势。随施氮量的增加,容重、硬度、出粉率和吸水率逐渐增加;蛋白质含量、沉降值、湿面筋含量、形成时间、稳定时间及粉质评价值呈先升高后降低趋势,最高值出现在施氮量240 kg·hm~(-2)的处理;漯珍1号的籽粒蛋白质含量、沉降值、湿面筋、吸水率、形成时间和粉质评价值均高于中麦8号,而容重、硬度、出粉率和稳定时间反之。2个品种在施氮量240 kg·hm~(-2)处理下既提高了产量又改善了部分加工品质。本研究结果为不同粒色小麦优质高产栽培提供了理论依据。 相似文献
7.
追氮时期和施钾量对小麦氮素吸收运转的调控 总被引：10，自引：3，他引：7
【目的】氮肥追施时期和钾肥用量是影响小麦高产高效的重要因素,研究这两个营养元素的相交效应,为小麦的合理施肥提供理论依据。【方法】以强筋小麦‘济麦20’为供试品种,设置盆栽试验。同位素示踪技术进行研究。氮肥用15N标记,追施氮肥时期设返青期和拔节期两个施肥时期。施钾量设K2O 0(K0)、50(K1)、100 kg/hm2(K2)三个水平。于开花期采集全株样本,成熟期将植株分为籽粒和植株两部分,分析氮素含量,计算氮素吸收、分配以及氮素利用率。【结果】虽然追氮时期和施钾量互作对‘济麦20’籽粒蛋白质含量的影响未达到显著水平,但钾肥对小麦氮素吸收、运转及分配的影响因追氮时期不同而有所差异。不施钾(K0)返青期追氮处理,小麦植株氮素积累量、氮素转移量及贡献率均达到最高; 在施用K2O 50 kg/hm2处理(K1)下,拔节期追施氮肥能有效提高小麦开花期植株氮素积累量、成熟期植株和籽粒来自土壤的氮积累量、氮素转移量及贡献率,并最终显著提高产量。由此,提高了小麦氮素积累量、转移量、籽粒产量、氮肥生产效率及收获指数,在施用钾肥100 kg/hm2(K2)条件下,两个追氮时期处理均不利于‘济麦20’氮素利用效率及籽粒产量的提高。【结论】本试验条件下,在K2O 50 kg/hm2施用量、拔节期追施氮肥条件下更有利于强筋小麦‘济麦20’对氮素的吸收、利用和高产的形成。 相似文献
8.
通过大田小区试验,研究了稳定氮肥不同用量对夏玉米产量、养分累积量、氮肥利用效率及经济效益的影响。结果表明,与不施稳定氮肥相比,稳定氮肥施氮量90、150、210 kg·hm-2和270 kg·hm-2分别增产36.7%、62.1%、76.6%和81.9%,地上部氮素总累积量分别增加39.0%、60.3%、79.0%和113.4%,经济效益分别增加36.1%、61.2%、72.7%和77.1%;与农民习惯施用氮肥相比,高量稳定氮肥用量210 kg·hm-2和270 kg·hm-2分别增产7.3%和10.5%,地上部氮素总累积量分别增加3.2%和23.0%,经济效益分别增加9.7%和11.4%。施用稳定氮肥促进夏玉米对氮素的吸收累积,高量210 kg·hm-2和270kg·hm-2处理较习惯施氮提高总吸氮量。施用稳定氮肥各处理氮肥表观利用率和农学效率显著高于农民习惯施氮,偏生产力高于农民习惯施氮,生理效率除270 kg·hm-2处理外,高于农民习惯施氮。稳定氮肥施氮量在210 kg·hm-2时,能较好地协调玉米高产与稳定氮肥合理利用的统一。 相似文献
9.
2012年3—10月在甘肃省河西走廊石羊河绿洲灌区进行大田试验,研究了不同施氮水平[0、140 kg(N)·hm-2、221 kg(N)·hm-2和300 kg(N)·hm-2]对小麦//玉米间作系统生产力、间作优势和水分吸收利用的影响。研究结果表明:当施氮量达221 kg(N)·hm-2时,小麦单作籽粒产量(5 036 kg·hm-2)和水分利用效率(25.13 kg·hm-2·mm-1)达最大值;当施氮量达300 kg(N)·hm-2时,小麦间作籽粒产量(3 078 kg·hm-2)和水分利用效率(39.76kg·hm-2·mm-1)、玉米单作籽粒产量(9 921 kg·hm-2)和水分利用效率(38.96 kg·hm-2·mm-1)、玉米间作籽粒产量(6 895 kg·hm-2)和水分利用效率(46.31 kg·hm-2·mm-1)达最大值;当施氮量为0 kg(N)·hm-2时,小麦相对于玉米的竞争力(0.049)达最大值;当施氮量为300 kg(N)·hm-2时,小麦//玉米间作的土地当量比(1.33)达最大值;当施氮量为140 kg(N)·hm-2时,小麦相对于玉米的水分竞争比率(0.98)达最大值。与单作相比,小麦//玉米间作具有显著的间作产量优势和水分利用优势。间作方式中小麦的竞争能力大于玉米;小麦、玉米两作物对水分生理需求时间有效性差异是小麦//玉米间作高效利用水分资源的基础,合理施氮能促进间作种植产量优势和水分利用优势的发挥。 相似文献
10.
氮硫互作对冬小麦旗叶衰老、产量和氮素利用效率的影响 总被引：2，自引：0，他引：2
试验采用裂裂区设计,小麦品种(烟农19和汶农6号)为主区,施氮(N)量为裂区,设0(N0)、120(N120)、240(N240)kg hm-2三个施N水平,施硫(S)量为裂裂区,设0(S0)、20(S20)、40(S40)、60(S60)kg hm-2四个施S水平。结果表明,汶农6号开花后旗叶超氧化物歧化酶(SOD)活性、旗叶净光合速率、产量和氮素利用效率均高于烟农19。在一定施氮水平下适量施硫显著提高烟农19和汶农6号小麦开花后旗叶SOD活性和可溶性蛋白质含量,提高旗叶净光合速率和开花后干物质积累量,增加植株地上部氮素积累量和籽粒产量;当施氮水平为120 kg hm-2施硫量超过40 kg hm-2和施氮240 kg hm-2施硫量超过20 kg hm-2时,汶农6号植株地上部氮素积累量仍继续增加,但旗叶抗氧化能力和光合同化能力均无明显提高,籽粒产量不再增加,烟农19号旗叶SOD活性、可溶性蛋白质含量和光合速率均降低,植株地上部氮素积累量和籽粒产量均减少。在同一施氮水平下,两小麦品种氮素利用效率总体表现为随施硫量增加而降低的趋势。在土壤有效硫为38.9~42.1 mg kg-1的条件下,适量施用氮肥和硫肥有利于延缓小麦花后旗叶衰老,提高光合同化能力,增加籽粒产量,但不同品种小麦对氮肥和硫肥施用量的响应不同,氮素利用效率较高的品种在较高的氮硫供给水平下仍有较好的光合同化和产量表现,而氮素利用效率相对低的品种对高氮高硫的适应性较差,后期易早衰,影响产量和氮素利用效率。 相似文献
11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响 总被引：2，自引：2，他引：0
【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。 相似文献
12.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
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. 相似文献
13.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
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. 相似文献
14.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
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. 相似文献
15.
《中国生态农业学报》2014,(6)
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, 相似文献
16.
《中国生态农业学报》2014,(7)
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, 相似文献
17.
《中国生态农业学报》2014,(8)
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, 相似文献
18.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
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. 相似文献
19.
I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“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. 相似文献
20.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
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. 相似文献