河南长江流域防护林工程水土保持效益评价

涵养水源和保育土壤是森林的主要生态功能。通过采用森林生态系统服务功能实物量、价值量评估方法对长防林工程实施区域森林的水土保持效益进行的评价,结果表明,长防林工程实施后林地可调节水量12.936亿m3,固土0.135亿t,林地的水土保持效益价值达126.247亿元。经过20年的长防林工程建设,项目区内森林资源快速增长,水土流失面积大幅度减少,工程建设对生态环境的改善起到了明显的作用。     

放牧压力对草原砂质栗钙土微生物量C,N,P影响的研究

对不同放牧压力下草原砂质栗钙土微生物量C、N、P进行较为系统地研究。结果表明：就土壤原土来看,随着放牧压力的增大,土壤微生物量C,N先增加后减少;土壤微生物量C在放牧率2.67只羊/hm2时相对较高,微生物量P随着放牧压力的增大逐渐降低。     

Decreasing of methanogenic activity in paddy fields via lowering ponding water temperature: A modeling investigation

Methane (CH₄) is a potent greenhouse gas and the huge CH₄ fluxes emitted from paddy fields can prejudice the eco-compatibility of rice cultivation. CH₄ production in submerged rice crops is known to be highly influenced by water temperature. Hence, lowering ponding water temperature (LPWT) could be an option to mitigate CH₄ emissions from paddy environments when it is possible either to irrigate with slightly colder water or to increase ponding water depth. However, paddy soil is a complex environment in which many processes are simultaneously influenced by temperature, leading to a difficult prediction of LPWT effects. For this reason, LPWT efficiency is here theoretically investigated with a one-dimensional process-based model that simulates the vertical and temporal dynamics of water temperature in soil and the fate of chemical compounds that influence CH₄ emissions. The model is validated with literature measured data of CH₄ emissions from a paddy field under time-variable temperature regime. Based on modeling results, LPWT appears promising since the simulated reduction of CH₄ emissions reaches about −12% and −49% for an LPWT equal to −5 °C during the ripening stage only (last 30 days of growing season, when rice is less sensitive to temperature variations) and −2 °C over the whole growing season, respectively. LPWT affects CH₄ emissions either directly (decreasing methanogenic activity), indirectly (decreasing activity of bacteria using alternative electron acceptors), or both. The encouraging results provide the theoretical ground for further laboratory and field studies aimed to investigate the LPWT feasibility in paddy environments.     

Limited effects of land use on soil dissolved organic matter chemistry as assessed by excitation–emission fluorescence spectroscopy and molecular weight fractionation

Dissolved organic matter (DOM) in soil solution represents a complex mixture of organic molecules and plays a central role in carbon and nitrogen cycling in plant–microbial–soil systems. We tested whether excitation–emission matrix (EEM) fluorescence spectroscopy can be used to characterize DOM and support previous findings that the majority of DOM is of high molecular weight (MW). EEM fluorescence spectroscopy was used in conjunction with MW fractionation to characterize DOM in soil solution from a grassland soil land management gradient in North Wales, UK. Data analysis suggested that three distinct fluorescence components could be separated and identified from the EEM data. These components were identified as being of humic‐like or fulvic‐like origin. Contrary to expectations, the majority of the fluorescence signal occurred in the small MW (<1 kDa) fraction, although differences between soils from the differently managed grasslands were more apparent in larger MW fractions. We conclude that following further characterization of the chemical composition of the fluorophores, EEM has potential as a sensitive technique for characterizing the small MW phenolic fraction of DOM in soils.     

草地土壤分离能力季节变化特征及其影响因素

土壤分离能力是土壤侵蚀机理模型的重要参数.受土壤性质、植被根系等因素影响,土壤分离能力呈现显著的季节变化.为研究草地土壤分离能力季节变化特征及其影响机制,以建植一年的柳枝稷、无芒雀麦草地及对照裸地为研究对象,以20 d为周期,测定土壤密度、黏结力和根系密度,并采集原状土样进行水槽实验(τ=6.5-23.4Pa),测量土壤分离能力,并运用相关分析、回归分析等方法,研究土壤性质及植被根系对土壤分离能力季节变化的影响.结果显示:柳枝稷和无芒雀麦草地具有类似的季节变化特征,而裸地与二者差异明显.4月中旬至6月下旬,草地土壤分离能力较大,此后土壤分离能力迅速下降;7月中旬直至10月上旬,草地土壤分离能力较低;10月下旬,土壤分离能力小幅回升;裸地土壤分离能力7、8月份较低,其余时间较高.裸地土壤分离能力试验期均值为柳枝稷草地的10.6倍,无芒雀麦草地的23.7倍.草地土壤分离能力的季节变化受根系密度和土壤黏结力的影响,随着根系密度与土壤黏结力增大,土壤分离能力呈指数形式降低,而土壤密度对土壤分离能力季节变化的影响并不显著.试验区内草地土壤分离能力可用水流剪切力、根系密度、根径和土壤黏结力等参数进行模拟(R2=0.636).研究结果可为土壤侵蚀机理模型的推广应用,以及小流域水土保持措施配置等工作提供科学依据.     

网球体能训练重点的决策研究

为了能科学地确定训练的重点，为网球教练员和运动员训练决策提供依据。综合使用测试法、变异系数和TOPSIS法对浙江省现役网球运动员体能的测试数据进行处理。结果：男队训练重点排序为：力量、爆发力、灵敏、速度、耐力；同理，女队训练重点的排序为：力量、爆发力、灵敏、耐力、速度；最后对每位运动员亟待加强指标进行排序。结论：变异系数和TOPSIS法计算的结果简单明了，节省资源，适宜不同专项、不同训练指标的训练过程的有效监控。     

化肥减氮及有机肥配施对水稻产量及土壤养分含量的影响

本文旨在研究等磷、钾量条件下，化肥减氮及有机肥不同用量配施对水稻产量及土壤养分的影响，试验共设6个处理，分别为T1∶80%N+20%有机肥；T2∶80%N+40%有机肥；T3∶70%N+60%有机肥；T4∶70%N+80%有机肥；T5∶60%化肥+100%有机肥；CK：100%N+0，对水稻生育期株高、群体动态、产量、构产因子以及秋季土壤养分含量进行分析，结果表明：1化肥减氮20%时，不会对水稻造成明显减产，且当有机肥配施量为500kg·mu-2时，水稻籽粒产量最高，为775.19kg·mu-2，比CK增产17.20%；2有机肥的施用能提高水稻基本苗，对水稻穗长有显著提高效果，对空秕率影响较大，对枝梗数影响最小；3化肥减氮+有机肥配施可以提高土壤肥力，增加土壤有机质含量，提高土壤碱解氮、速效钾含量。     

土壤中根皮苷和根皮素对桃幼苗的影响

以一年生桃嫁接苗为试材,在盆栽条件下研究了苹果园土壤中特征酚酸类物质——根皮苷和根皮素对桃苗生物量、根系活力、根系保护性酶活性和MDA含量的影响。结果表明,根皮苷对桃幼苗的伤害显著,与对照相比,鲜质量、干质量分别降低了16.66%和21.58%,根系活力降低了33.04%,SOD、POD活性分别降低了40.80%和31.10%,MDA含量提高了116.34%。根皮素对桃苗的影响不大。高锰酸钾处理明显缓解了根皮苷对桃苗的伤害,苹果园土壤中的根皮苷含量降低了57.80%,提高了桃苗的生物量、根系活力和保护性酶活性,降低了MDA含量。综上,老龄苹果园土壤实测含量的根皮苷(0.343mg·kg~(-1))可降低桃苗的生物量,适量的高锰酸钾能缓解根皮苷的伤害作用。     

澳大利亚社区农园的发展及其对我国的启示

在一些发达国家,社区农园向人们提供了接触自然、放松身心的场所,已受到越来越多市民的喜欢。而我国社区农园的发展仍处于探索期,借鉴国外社区农园对于我国社区农园的发展有很大的裨益。对澳大利亚社区花园的发展状况进行了详细介绍。以三个分别位于居住区、校园、公园的社区花园为例,根据案例分析社区农园对孤独人群、老年人、儿童、残疾人这些弱势群体带来的益处,阐明其对人们身心健康的改善以及对社会可持续发展的重大意义。文末根据澳大利亚社区农园发展的成功经验和我国城市发展的现状,提出我国建设社区农园需要面临的挑战。     

黄土坡面结皮对土壤水稳性团聚体的稳定性和可蚀性的影响

为了探析微地形下土壤受雨滴打击后产生的结皮类型及团聚体组成差异。通过人工模拟降雨,研究坡面不同位置的结皮土壤水稳性团聚体分布特征、稳定性以及土壤可蚀性的变化情况。结果表明：（1）土壤水稳性团聚体以大团聚体（粒径>0.25 mm）含量为指标,原状土、结构结皮、沉积结皮、过渡带结皮>0.25 mm粒级的水稳性团聚体分别占37.28%、43.58%、36.69%、40.34%;（2）以降雨历时5 min为例,原状土、结构结皮、沉积结皮、过渡带结皮的水稳性团聚体的破坏率分别为：51.49%、46.00%、62.76%、51.02%;（3）原状土、结构结皮、沉积结皮、过渡带结皮的水稳性团聚体的平均重量直径分别为：0.15、0.20、0.14、0.17 mm;（4）原状土、结构结皮、沉积结皮、过渡带结皮土壤可蚀性K值的大小分别为：0.223、0.200、0.229、0.205。微地形下产生结皮差异使得水稳性团聚体分布有所区别,因此土壤水稳性团聚体稳定性和可蚀性存在差异。