Responses of plant community to the linkages in plant-soil C:N:P stoichiometry during secondary succession of abandoned farmlands,China

Succession is one of the central themes of ecology;however,the relationship between aboveground plant communities and underground soils during secondary succession remains unclear.In this study,we investigated the composition of plant community,plant-soil C:N:P stoichiometry and their relationships during secondary succession after the abandonment of farmlands for 0,10,20,30,40 and 50 a in China,2016.Results showed that the composition of plant communities was most diverse in the farmlands after secondary succession for 20 and 50 a.Soil organic carbon and total nitrogen contents slightly decreased after secondary succession for 30 a,but both were significantly higher than those of control farmland(31.21%-139.10%and 24.24%-121.21%,respectively).Moreover,C:N ratios of soil and microbe greatly contributed to the changes in plant community composition during secondary succession of abandoned farmlands,explaining 35.70%of the total variation.Particularly,soil C:N ratio was significantly and positively related with the Shannon-Wiener index.This study provides the evidence of synchronous evolution between plant community and soil during secondary succession and C:N ratio is an important linkage between them.     

土壤有机磷降解菌的筛选、鉴定及其生长特性研究

【目的】从土壤中筛选有机磷降解菌,并对其进行鉴定和生长特性研究,为研制具有降解土壤有机磷功效的生物有机肥提供高效稳定的菌种。【方法】用解磷圈法和液体摇瓶培养法,分别以植酸钙和卵磷脂为惟一磷源,从采自陕西杨凌的农药厂排污渠、棉花地、果园、菜地等不同生态类型土壤中分离筛选有机磷降解菌,对其进行生理生化特征分析和分子生物学鉴定,并确定其最适生长温度和初始pH值。【结果】从采集的不同利用类型的土壤中共初筛分离出了25株有机磷降解菌,复筛选出解磷率较高的Z2-3、Z3-5、Z3-8、Z4-1 4株植酸钙降解菌和L5-2、L7-1 2株卵磷脂降解菌。其中Z2-3、Z3-5、Z3-8和Z4-1在植酸钙液体培养基中的解磷率分别达到64.2%,71.5%,67.2%和58.1%,L5-2和L7-1在卵磷脂液体培养基中的解磷率分别为76.7%和84.1%。生理生化特征测定结果和分子生物学分析结果表明,Z2-3、Z3-5、Z3-8、Z4-1、L5-2、L7-1株菌依次为变形假单胞菌(Pseudomonas plecoglossicida)、恶臭假单胞菌(Pseudomonas putida)、荧光假单胞菌(Pseudomonas fluorescens)、荧光假单胞菌(Pseudomonas fluorescens)、成团泛菌(Pantoea agglomerans)和土壤短芽孢杆菌(Brevibacillus agri)。植酸钙降解菌和卵磷脂降解菌的最适生长温度分别为28~35和28℃,最适初始pH值分别为8.0~8.5和7.5。【结论】分离、筛选、鉴定出了解磷率较高的6株有机磷降解菌,获得了其最适生长温度和最适初始pH值。     

石油烃类污染物降解动力学和微生物群落多样性分析

为了探讨不同初始浓度石油污染土壤堆腐化修复机制,以石油降解菌剂和腐熟鸡粪为调理剂,研究了初始浓度分别为5 000(T1)、10 000(T2)和50 000 mg/kg(T3)的石油污染土壤堆腐化修复过程石油烃类污染物降解动力学特征和微生物群落多样性。结果表明:堆腐化修复过程石油烃类污染物降解符合一级反应动力学,反应常数分别为0.012、0.094和0.050 d-1,半衰期分别为6.79、7.37和13.86 d。整个堆腐过程石油烃类污染物平均降解速率分别为112.08、230.05和887.93 mg/(kg·d)。3个处理的孔平均颜色变化率(average well color development)和碳源利用率(除芳香烃类化合物外)随堆腐进程的推进逐渐升高,在堆腐中、后期达到最大,T3处理显著高于T1、T2处理。多聚物类和糖类代谢群是堆腐体系中的优势菌群。主成分分析表明3个处理的微生物群落差异显著(除第9天外),起分异作用的碳源主要是糖类和羧酸类。微生物群落的丰富度指数和均一度指数随堆腐进程的推进逐渐升高并在堆腐后期达到最大,与T1处理相比,T3处理分别高了0.21%和17.64%,差异达到显著水平(P0.05)。微生物群落优势度指数在中期达到最大,T1处理分别比T2、T3处理高2.12%和9.44%,3个处理间差异不显著(P0.05)。堆肥结束时3个处理的种子发芽指数(seed germination index,SGI)分别比堆腐初期提高了18.26%、20.42%和36.41%。该研究结果为黄土高原不同程度石油污染土壤堆腐化修复的应用提供参考依据和理论基础。     

线辣椒叶面喷施沼液的效应

对线辣椒叶面喷施不同浓度沼液的结果表明,喷施沼液可使可溶性糖有不同程度的提高,以喷施沼液浓度75%的处理为最佳,达到了8.83%;辣椒素含量也显著高于对照;vC含量最高的达到了139.42 mg/100 g;农艺性状较对照有所改善,产量也有不同程度的提高,其中以喷施沼液浓度50%的处理产量最高,干重达到了4 796.40 kg/hm^2,较对照增产25.42%.可见,线辣椒叶面喷施沼液能有效改善其品质并提高产量.     

中国农业废弃物沼气化资源潜力评价

通过构建农业废弃物沼气化利用潜力估算模型,确定各种农业废弃物沼气化转化参数,估算了2009年中国种植业、畜牧业生产和人类生活所产生的农作物秸秆、畜禽粪便和人粪尿等生产和生活废弃物的量,结果表明2009年全国农作物秸秆量达到89886.75万t、畜禽粪便量达到399115.6万 t,人粪尿达到25333万 t,在35℃条件下沼气化资源潜力为5832.675亿m3,相当于4.14亿t标准煤.研究种植业、畜牧业等农村生产和生活产生的废弃物数量及其沼气化利用的资源潜力计算方法,对摸清我国农业废弃物数量、沼气化利用潜力具有重要意义.     

鸡粪与水稻秸秆混合厌氧发酵特性研究

【目的】研究温度、原料配比对鸡粪与水稻秸秆混合原料厌氧发酵产气特性的影响,为提高厌氧发酵的产气效率提供依据。【方法】采用自行设计的可控性恒温沼气发酵装置,以不同配比(0.5∶1,1∶1,2∶1,3∶1)的鸡粪与水稻秸秆为发酵原料,在总固体(TS)质量分数为8%的情况下,研究各配比鸡粪与水稻秸秆在25,30,35,40℃下的厌氧发酵情况,并用SAS软件对温度、鸡粪与水稻秸秆配比和累积产气量的关系进行多元回归分析。【结果】25~40℃条件下,各配比鸡粪与水稻秸秆均能正常发酵产生沼气,发酵时间随温度上升而下降,鸡粪与水稻秸秆各配比对发酵时间无显著影响;随着温度的升高,除鸡粪与水稻秸秆配比为1∶1时的累积产气量升高外,其余配比处理的累积产气量均呈先增加后降低的变化趋势。通过模型分析,可知在发酵温度为35.5℃,鸡粪与水稻秸秆的配比为1.86∶1时,累积产气量最大可达9 290.9 mL。【结论】确定了鸡粪水稻秸秆沼气发酵的最佳温度和最适配比,为提高厌氧发酵的产气速率提供了依据,也为秸秆的合理利用提供了条件。     

Functional ecology of soil organisms in tundra ecosystems: towards the future

The need to understand the functional linkages between Arctic/alpine soil communities and the major soil processes is stressed. Soil organisms are classified into broad functional groups and it is suggested that the functional success of any organism can be defined by its position along four axes, namely population responsiveness, dispersability, ecophysiological flexibility and resource use flexibility. Each of these axes is defined by reference to a spectrum of relevant ecological attributes. The resilience and response of tundra communities to change are discussed and the possible alteration in community structure and function that may result from shifting climate patterns are reviewed. The interrelationship between the spatial distribution patterns of organisms and their dispersability is highlighted and the significance of the thermal environment in moderating the competitive interaction between species is emphasised. The advantages and disadvantages of various approaches to studying the effect of climate change on Arctic/alpine community structure and function are contrasted. In particular, the manipulative experimental approach is distinguished from the comparative approach that makes use of measurements taken along geographical/ecological transects as analogues for climate change.     

植被恢复土壤抗蚀性响应及其评价研究

以农地为对照,对黄土高原西部地区陕西千阳天然次生林侧柏(B),20年(C20)和5年(C5)生刺槐林,撂荒5年(H5)、苜蓿草地(M)5种不同植被恢复模式土壤结构特性及抗蚀性进行研究.结果表明,与对照相比,不同植被恢复模式土壤结构系数、土壤有机质含量、水稳性团聚体含量提高.以模糊隶属度函数模型对研究区域抗蚀性定量评价,不同植被类型土壤抗蚀性指数分别为:侧柏0.92,20年刺槐0.82,5年剌槐0.62,5年撂荒地0.49,苜蓿0.46,农地0.20.土壤抗蚀性大小顺序为:侧柏>刺槐20>刺槐5>荒5>苜蓿>农地.通过不同的植被恢复,土壤抗蚀性比对照有了明显提高,土壤生态功能得到改善.     

黄土沟壑区植被恢复中土壤生物学特性的响应及其评价

摘要：了解不同植被恢复类型对土壤生物学特性的影响。以农地为对照,该研究通过对侧柏天然次生林、不同林龄（5,20,30年）刺槐人工林、荆条灌丛和苜蓿草地6种不同植被恢复类型土壤生物学特性的探索研究。结果表明,与对照相比,不同的植被恢复类型土壤生物学特性均有明显增强,土壤微生物量及土壤酶活性显著提高。采用土壤微生物量碳、氮、磷和尿酶、碱性磷酸酶、过氧化氢酶、蔗糖酶7项指标计算该区域土壤生物学特性,进行土壤生物学特性等量评价。不同植被恢复模式土壤生物学特性的大小顺序为：30年刺槐、20年刺槐、侧柏、荆条、5年刺槐、苜蓿、农地。该区采用刺槐恢复模式效果较优于苜蓿及荆条、侧柏模式。