科尔沁沙地土壤化学特性研究

通过对科尔沁沙地典型区域农牧交错带气候、土壤、植被以及天然草地类型的调查,在调查区内共布设52个样点,根据土壤的酸碱度、有机质和养分状况,运用SAS语言进行聚类分析,将这52个样点按照由边缘到中心的顺序分为3类：即外围沙丘带土壤类,中央过渡带土壤类和内部草甸带土壤类,结果表明,3类土壤的化学特性呈现出由边缘到中心递增的趋势,但土壤的养分含量总体水平不高。     

乌兰布和沙漠典型草本植物群落特征

草本植物是乌兰布和沙漠植物群落的重要组成部分,研究草本植物群落特征及植物物种多样性,为认识和保护乌兰布和沙漠地区植物多样性资源提供理论依据和实践基础。根据样方调查资料,采用植物群落物种组成和多样性指数的多种计算方法,分析乌兰布和沙漠典型草本植物群落的物种组成和多样性特征。结果表明,乌兰布和沙漠典型草本植物群落的植物组成种类较少,调查结果仅有24种,隶属于8科,优势科为禾本科和藜科;草本植物群落多样性指数的平均值较小,物种多样性水平总体较低,生态优势度、物种多样性及均匀度在不同群落间差异较大;草本植物群落各多样性指数呈现出基本一致的变化趋势。乌兰布和沙漠的草本植物群落类型多样,但群落组成结构简单;优势种与次优势种的重要值之间的差距随群落内物种数量的增加而减小;草本植物群落多样性指数较小,草本植物物种的分布不均匀,普遍呈斑块化分布。     

Comparative laboratory evaluation of the acute and chronic toxicology of diflubenzuron,hexaflumuron and teflubenzuron against II instar desert locust (Schistocerca gregaria) (Orthoptera: Acrididae)

The acute and chronic toxicities of three benzoylphenyl ureas, diflubenzuron, hexaflumuron and teflubenzuron were assessed under laboratory conditions against two-day-old second (II) instar Desert Locust, Schistocerca gregaria (ForskÅl) nymphs. Following exposure by ingestion of a single precise dose applied to short pieces of spring barley, nymphs were monitored for two moults until the fourth (IV) instar. Analysis of acute response data gave three significantly different LD₅₀ statistics (P < 0·05), 68·0, 26·6 and 0·71 μg per nymph respectively for diflubenzuron, hexaflumuron and teflubenzuron. The probit regression slopes also differed significantly, indicating distinct tolerance distributions for the three compounds, the narrowest response being to diflubenzuron and the widest range of response being to teflubenzuron. The timing of death was found to vary between the compounds; most nymphs died during the first moult following treatment with either hexaflumuron or teflubenzuron. However, the majority of nymphs that died after exposure to diflubenzuron did so after completing the first moult after treatment, but before the second. The mean development times of nymphs during the II and especially third (III) instars were significantly longer (P < 0·05) than those of the controls following exposure to diflubenzuron and hexaflumuron. Teflubenzuron had no significant effect (P < 0·05) on the duration of the II instar. The potential of the three compounds to control S. gregaria populations in the field is discussed with particular reference to the timing and nature of acute and chronic responses.     

制种玉米连作恒量施磷对灌漠土与潮土中磷素利用的影响

[目的]研究恒量外源磷施用对玉米种子生产的影响,为合理施磷提供依据。[方法]通过大田定位与实验室分析相结合,选用河西走廊石灰性潮土及灌漠土定位施肥。[结果]制种玉米连作8a,恒量磷二铵525kg/(hm^2·a)施用,除无机态二钙磷(Ca_2-P)外,2种不同土类总磷(T-P)、速效性磷(Av-P)、总无机磷(T-IP)、总有机磷(T-OP),以及其他各分级无机、有机磷组分均显著增加。无机磷占全磷总量65.2%~70.2%,有机磷占全磷总量6.5%~11.4%。无机磷中十钙磷(Ca₁₀-P)>八钙磷(Ca8-P)>铝磷(Al-P)>铁磷(Fe-P)>闭蓄态磷(O-P)。有机磷中活性有机磷(MLO-P)>高稳性(HRO-P)>中稳性有机磷(MROP)>活性有机磷(LO-P)。随连作年限增加,灌漠土Ca₁₀-P在连作第5a达到最大,Al-P,O-P均持续增加;潮土Ca₁₀-P持续增加,Fe-P,O-P在连作第5a达到最大,磷增加量为3.94%~37.28%。0—60cm土层,两种土类无机磷各组分含量均呈现由表层至下层递减特点,但不同分级磷在不同土层所占比例不同,Ca₁₀-P,Al-P,O-P,MRO-P底聚,Ca_2-P,HRO-P表聚,制种玉米连作生产8a,磷肥最大表观利用率为4.89%,磷素活化系数<2%,外源磷肥以174.3kg/(hm^2·a)残余在土壤中。[结论]制种玉米连作,总磷转化率低,磷素移动缓慢,大部分以溶解性较低的磷素形态在土壤表层积累,但随连作年限增加,土壤对磷素的固持及转化率下降,表现底聚趋势,对生态环境健康存在极大风险,应减量或停止施磷。潮土磷肥施用应采取更加合理措施。     

多功能土壤改良剂对河西内陆灌区棕漠土的改良效果

[目的]解决棕漠土保水肥能力弱,有机质含量低,制种玉米产量低而不稳的疑难问题,为河西内陆灌区制种玉米产业可持续发展提供技术支撑。[方法]选择甘肃省酒泉市肃州区棕漠土,采用田间试验方法,进行多功能土壤改良剂配方筛选及对棕漠土改良效果研究。[结果]多功能土壤改良剂最佳配比为:有机生态肥∶保水剂∶制种玉米专用肥∶聚乙烯醇为0.978 3∶0.000 9∶0.019 6∶0.001 2。多功能土壤改良剂最佳施用量为68.75t/hm~2,制种玉米理论产量为6.64t/hm~2。施用多功能土壤改良剂与传统化肥比较,棕漠土总孔隙度、毛管孔隙度、非毛管孔隙度、团聚体、饱和持水量、毛管持水量、非毛管持水量分别增加22.75%,22.76%,22.74%,9.50%,22.75%,22.76%和22.74%;有机质、CEC、碱解氮、速效磷和速效钾增加35.01%,21.64%,0.63%,2.26%和2.09%;真菌、细菌和放线菌分别增加93.97%,35.35%,20.78%;蔗糖酶、脲酶、磷酸酶和多酚氧化酶分别增加61.82%,44.64%,40.00%和64.29%;制种玉米增产值和施肥利润增加39.23%和31.82%。[结论]施用多功能土壤改良剂,能有效地改善棕漠土理化性质和生物学性质,提高制种玉米产量。     

库布齐沙漠东缘防沙治沙生态效益评价

[目的]研究库布齐沙漠东缘防沙治沙生态效益,为沙漠化治理效益评价提供科学参考。[方法]通过建立了库布齐沙漠东缘防沙治沙生态效益评价指标体系,采取层次分析法和模糊综合评价法进行生态效益评价。[结果]在生态效益评价指标的权重中,排在前3位的分别是植被盖度、地上生物量、草层高度评价指标,植被因子在沙漠化治理中较其他因子更为重要,植被恢复状况对库布齐沙漠化治理的影响显著;基于模糊综合评价结果可知,研究区防沙治沙生态效益值为53,属于一般状况。当地农户普遍认为防沙治沙明显改善了当地生态环境,大多数农户对沙漠化治理工作认同度较高。[结论]随着生态政策和治理措施的推进,治理效益将呈现良好态势;农户生态环保意识较差,还需加强农户生态环保意识,并提高农民文化水平。     

基于多层次模糊综合评价模型的沙漠绿洲水资源承载力评价与预测

[目的]对腰坝绿洲未来水资源承载力进行评价和预测研究,为该地区水资源的可持续利用及合理管理政策的制定提供决策依据。[方法]取2016年为现状水平年,2020,2025,2030年为规划水平年,根据绿洲发展历史和现状及相关规划,对社会经济发展进行预测,进而对各水平年的需水进行预测。选取9个评价指标构建水资源承载力评价指标体系,建立水资源承载力模糊综合评价模型,对各水平年水资源承载力进行评价分析。[结果]水资源承载力综合评判值2016年仅为0.251 2,表明水资源承载力已达到饱和;至2030年,上升至0.434 4,水资源承载力处于较高的可承载水平,但区内地下水资源开发潜力仍然有限。[结论]现状年水资源承载力处于超载状态,水资源供需矛盾突出,社会经济子系统是水资源承载力提高的主要压力源,通过采取一系列的措施,未来水资源承载力状况将逐渐好转,需采取全面有效的措施使水资源承载力提升至较高水平,将研究区打造成为和谐高效的绿洲。     

水氮控制对荒漠草原中小型土壤动物群落的影响

【目的】了解水氮控制对荒漠草原中小型土壤动物的影响,进而从土壤动物角度解读全球变化对荒漠草原的生态效应。【方法】2014年植物生长季,以内蒙古自治区乌兰察布市四子王旗短花针茅荒漠草原为研究对象,设置对照(CK,自然降雨状态)、减雨(R)、增雨(W)、施氮(N)、减雨施氮(R+N)和增雨施氮(WN)6个处理,观测不同处理中小型土壤动物群落和土壤环境参数的变化。【结果】短花针茅荒漠草原共捕获中小型土壤动物333 079.5只/m~2,隶属于节肢动物门的4纲10目47科,主要为弹尾纲(Collembola)、蛛形纲(Arachnida)和昆虫纲(Insecta);优势类群为疣虫兆科(Neanoridae)和等节科(Isotomidae),优势类群和常见类群构成了研究样地中小型土壤动物群落的主体。增雨、增雨施氮有助于提高短花针茅荒漠草原中小型土壤动物个体密度,减雨、减雨施氮处理减少中小型土壤动物个体密度,且水氮交互作用对中小型土壤动物个体密度影响表现显著,而对类群数无显著影响。短花针茅荒漠草原中小型土壤动物具有明显表聚性,各处理下0~10cm土层个体密度和类群数显著高于10~20cm土层(P0.05)。【结论】在未来降雨增加和氮沉降的全球变化背景下,中小型土壤动物个体密度的变化可能会更大。     

新疆主要稻区不同稻水象甲地理种群对常用杀虫剂抗药性测定

【目的】 研究主要稻区稻水象甲Lissorhoptrus oryzophilus田间种群对目前常用杀虫剂的抗性水平,为防治该虫科学用药提供依据。【方法】 以南疆阿克苏稻区温宿县种群(WS)为敏感基线,采用室内点滴法,测定察布查尔(Qapqal)和五家渠(WJQ) 2 个主要稻区稻水象甲田间种群对6种杀虫剂的抗性水平。【结果】 以南疆主要稻区温宿县稻水象甲地理种群为敏感种群,察布查尔(Qapqal)和五家渠2个地理种群(WJQ)对6种供试药剂的敏感性均有不同程度的下降,其中,对95.87%噻虫嗪、97%毒死蜱、97%吡虫啉、95.1%高效氯氰菊酯和98%溴氰菊酯等多数药剂仍处于敏感状态(抗性倍数＜5),对96%氯虫苯甲酰胺的抗性倍数均高于5.92,属于已产生低水平抗性。【结论】 在水稻生长季节应避免重复使用或限用96%氯虫苯甲酰胺,注意与其它药剂混用、轮用,延缓该地区稻水象甲抗药性发生。     

Charcoal production through selective logging leads to degradation of dry woodlands:a case study from Mutomo District,Kenya

Provision of woodfuel is an important ecosystem service of dry forests and woodlands.However,charcoal production through selective logging of preferred hardwood species has the potential to alter the physiognomic composition of the residual or re-growth woodlands and may lead to their deterioration and degradation.This study,conducted through forest inventory in Mutomo District in Kenya,assessed the impact of charcoal production on unprotected dry woodlands in terms of tree density,targeted species basal area,species richness,evenness and Shannon diversity.The parameters of the disturbed woodlands were evaluated for significant differences with those of the neighbouring protected Tsavo East National Park,which served as a reference for an ecologically undisturbed ecosystem.By evaluating a consequence of tree harvesting for charcoal production,this study confirmed the overall significant differences between the protected and unprotected woodlands in all the tested parameters.To confirm if the differences in the land-covers of the woodlands had any influence on their degradation,all mentioned parameters were compared between the four differentiated classes and their respective control plots in the protected areas.At the "land-cover level",the statistically significant difference in the basal area of tree species preferred for charcoal production between the protected and unprotected open trees confirms that the class with a high density of large mature trees is the prime target of charcoal producers.In addition,there seems to be a general trend of lower values of tree species richness,evenness and Shannon diversity for the unprotected woodlands subjected to charcoal production.On the other hand,the disturbed woodlands display the potential to recover through their comparably high saplings density.The findings make an important contribution to the discourse on the impact of charcoal production in dry woodlands,a topic that is highly controversial among researchers.