农牧交错带适度人口规模与人口再分布初步研究——以阴山北部丘陵区武川县为例

农牧交错带即是国家一直重视的区域也是众多专家学者高度关注的区域,作为一个生态脆弱区,人口、环境与社会经济的协调发展一直是寻根问底的问题。在众多的研究成果中多从生态环境优化、土地利用、经济发展等角度进行了探讨。本文在众多学者研究基础上,测算了土地适度人口规模、经济适度人口规模,并进一步测算了武川县乡城人口转化的进程与规模,从理论与现实角度展示了控制人口,加快转化的必要性。     

广东康禾自然保护区亚热带常绿阔叶林立木结构及碳密度分布特征

在广东东源县康禾自然保护区林分起源相同的典型亚热带常绿阔叶林区域,在物种多样性有明显差异的3个群落分别设置1 hm2的样地,研究异质多样性下亚热带常绿阔叶林的立木结构及碳密度分布特征.研究结果表明,随着植物群落丰富度或个体数的增大,二次平均胸径和平均胸径指标都逐渐减小,而样方立木的总胸径和胸高断面积则逐步增加.生态优势度较低但多样性指数较高的群落1和群落2内,植物种类或个体数的增加使群落蓄积量得以增加,群落3则不然.生态优势度高、物种多样性相对较低的群落,林分蓄积和碳密度更高.这项研究结果提示,立木结构指标与林分碳储量没有直接相关关系,而立木多样性高的群落碳储量不一定高;大径级和具有生态优势的种类对亚热带常绿阔叶林蓄积量和碳储量的保持与增加具有主要贡献作用.     

化控处理时期对玉米植株-根系形态及产量的影响

为进一步明确化控处理时期对玉米冠层、根系形态及产量的影响,2017和2018年在吉林省西部开展2年大田试验,供试品种为‘富民985’,2年均喷施乙烯利类型的化控试剂;其中2017年种植密度为7万和9万株/hm~2,在8和10叶期(T(8+10))、8和16叶期(T(8+16))分别进行化控处理;2018年在8叶期(T(8))、8和16叶期(T(8+16))、16叶期(T(16))分别进行化控处理,种植密度为6和9万株/hm~2。结果表明:1)玉米增密后,倒伏率增加;化控处理可缩短植株节间长,降低株高和穗位高,降低倒伏率,其中T(8+16)处理最为显著;2)化控处理后穗位以上叶片叶面积呈现下降趋势,其中T(8+16)处理能够降低15%以上,从而提高透光率,利于下层叶片进行光合作用;3)化控处理增加玉米根系投影面积和最大扩展宽度,降低顶部夹角,使根系更加平展,增强抗倒伏能力,其中T(8+16)处理效果较为理想;4)T(8+16)处理能增加玉米产量,其中2017年T(8+16)处理与CK相比增加6.5%的产量。所以在玉米群体结构建成的8～9和15～16叶期,运用乙烯利类型化控试剂2次,能够改善穗上群体结构,增强茎秆和根系的抗倒伏能力,维持后期群体结构物质生产能力,提高玉米产量。     

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical,hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers(F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.     

不同经营措施对鄂南毛竹笋用低产林形态特征及产量的影响

采用2 100～2 550、2 700～3 150、3 300～3 750株/hm² 3个立竹密度和复合肥、饼肥、配方肥3种施肥种类双因素试验设计,分析不同处理间鲜笋地径、笋高及鲜质量差异,研究不同经营措施对鄂南地区毛竹笋用低产林竹笋形态特征及产量的影响。结果表明：采取经营措施后,竹林竹笋产量显著高于CK。立竹密度和施肥种类的交互作用对毛竹笋地径有显著影响,其中,以高密度、复合肥处理的地径值最大,为9.65 cm,随着毛竹林立竹密度的增大,其形态特征由“胖、矮” 型逐渐变为 “瘦、高” 型。立竹密度对毛竹笋产量的影响较施肥种类更为明显,较低立竹密度的竹林更有利于竹笋产量的提高。在不同处理中,产量最高的为低密度、复合肥处理,毛竹笋产量为2 174.40 kg/hm²;产量最低的为高密度、饼肥处理,为1 299.15 kg/hm²。在自然立竹密度处理中,以配方肥的产量最高,为1 721.55 kg/hm²,综合考虑经营成本等因素,在该地区毛竹笋用林的经营初期可考虑施用配方肥。     

密度和施肥与小麦面筋含量交互效应分析

采用五因素二元正交旋转试验设计,进行密度、氮肥、磷肥、钾肥、锌肥对小麦面筋含量影响的研究.结果表明,氮肥、磷肥单效应对小麦面筋含量有一定的影响.密度和氮肥、氮肥和锌肥、磷肥和钾肥都有显著的互作效应.在试验条件下,当密度为150万株·hm-2、施氮量为75kg·hm-2、施磷量为56.25kg·hm-2、施钾量为37.5kg·hm-2、不施用锌肥,小麦面筋含量可达25.97%.     

四川省草地贪夜蛾发生为害特点

为探明草地贪夜蛾在四川的发生为害特点,利用田间调查数据对草地贪夜蛾在四川的发生分布范围、受害作物种类、幼虫种群动态和扩散过程进行了分析。结果表明,草地贪夜蛾在四川除阿坝州外的20个市州都有发生,重发区域集中在川东和攀西地区;受害作物以玉米为主,甘蔗、高粱、小麦和油菜零星受害;在攀西地区和川东北地区观察到2个幼虫为害高峰,其余地区只有1个幼虫为害高峰;草地贪夜蛾在攀枝花市和凉山州局部地区为周年繁殖区,其在四川的扩散总体上呈现出由南向北、由东向西的过程。     

传统稻鱼系统生产力提升对稻田水体环境的影响

如何在提升传统农业系统生产力的同时又不破坏其内涵、还对环境不产生负面影响,是一个受到研究者持续性关注的挑战性课题。本研究以具有1 200年历史的全球重要农业文化遗产稻鱼系统为例,研究稻鱼系统鱼的放养密度对生产力和环境的影响,探讨能够显著提升稻鱼系统生产力且又不破坏其传统性(产品优质、环境友好)的途径。研究表明,传统稻鱼系统(RF)(田鱼目标产量375 kg.hm 2)与水稻单作系统(RM)水体的化学需氧量(COD)、总氮(TN)、总磷(TP)及铵态氮(NH4+-N)含量均没有显著性差异。随着田鱼养殖密度提高(鱼产量由750 kg.hm 2提高到3 000 kg.hm 2)和饲料投入的相应增加,稻鱼系统的生产力和经济产出大幅度提高(稻鱼系统的净经济收入增加25.2%~101.4%),但稻鱼系统(RF)水体的COD值及TN、TP和NH4+-N含量均呈现增加的趋势,尤其是当鱼目标产量增至3 000 kg.hm 2时,水体TP含量和COD值显著提高,面源污染风险增加。分析还表明,鱼放养目标产量为2 250 kg.hm 2时,稻鱼系统经济效益最佳,此时净经济收入比传统稻鱼系统增加55.9%,并且不会对水体环境质量产生负面影响。     

Effect of transferring lignocellulose-degrading bacteria from termite to rumen fluid of sheep on in vitro gas production,fermentation parameters,microbial populations and enzyme activity

The digestive tract of termite(Microcerotermes diversus) contains a variety of lignocellulose-degrading bacteria with exocellulases enzyme activity, not found in the rumen, which could potentially improve fiber degradation in the rumen. The objectives of the current study were to determine the effect of inoculation of rumen fluid(RF) with three species of bacteria isolated from termite digestive tract, Bacillus licheniformis, Ochrobactrum intermedium, and Microbacterium paludicola, on in vitro gas production(IVGP), fermentation parameters, nutrient disappearance, microbial populations, and hydrolytic enzyme activities with fibrous wheat straw(WS) and date leaf(DL) as incubation substrate. Inoculation of RF with either of three termite bacteria increased(P0.05) ammonia-N concentration compared with the control group(free of termite gut bacteria). Termite bacteria inoculation had no effect(P0.05) on gas production characteristics, dry matter, organic matter and neutral detergent fiber disappearance, pH, and concentration and composition of volatile fatty acids. Population of proteolytic bacteria and protozoa, but not cellulolytic bacteria, were increased(P0.05) when RF was inoculated with termite bacteria with both WS and DL substrates. Inoculation of RF with termite bacteria increased protease activity, while activities of carboxymethyl-cellulase, microcrystalline-cellulase, α-amylase and filter paper degrading activity remained unchanged(P0.05). Overall, the results of this study indicated that transferring lignocellulose-degrading bacteria, isolated from digestive tract of termite, to rumen liquid increased protozoa and proteolytic bacteria population and consequently increased protease activity and ammonia-N concentration in vitro, however, no effect on fermentation and fiber degradation parameters were detected. These results suggest that the termite bacteria might be rapidly lysed by the rumen microbes before beneficial effects on the rumen fermentation process could occur.     

论人口、环境与可持续发展

运用社会生态学、经济伦理学和人口经济学等跨学科研究方法 ,揭示了人口环境系统的特征、动因及其容量。描述了人口对环境的压力和环境对人口的威胁。预测了全球与中国面临的人口环境挑战。