Effects of postfire seeding and fertilizing on hillslope erosion in north-central Washington,USA

After the 1998 North 25 Fire in the Wenatchee National Forest, eight study sites were established on steep, severely burned hillslopes to examine the effectiveness of postfire seeding and fertilizing treatments in increasing cover to reduce hillslope erosion, and to measure the nutrient content of the eroded sediment. At each site, four 4 by 9 m plots were located with four randomly applied treatments: seed (winter wheat, Triticum estivum) at 34 kg ha^− 1, fertilizer (75% ammonium nitrate and 25% ammonium sulfate) at 31 kg ha^− 1, seed and fertilizer, and untreated control. Sediment fences were installed at the base of each plot to measure erosion rates and sample the eroded sediments. In addition, precipitation amounts and intensities, surface cover, canopy cover, and nutrient concentrations in the eroded sediments were measured for four years after the fire. Total precipitation was below average during the four-year study period, and most erosion occurred during short duration, moderate intensity summer rainfall events. The overall first year mean erosion rate was 16 Mg ha^− 1 yr^− 1, and this decreased significantly in the second year to 0.66 Mg ha^− 1 yr^− 1. There were no significant differences in erosion rates between treatments. In the first year, the seeded winter wheat provided 4.5% canopy cover, about a fourth of the total canopy cover, on the seeded plots; however, the total canopy cover on the seeded plots did not differ from the unseeded plots. The below average precipitation in the spring after seeding may have affected the winter wheat survival rate. In the fourth year of the study, the mean canopy cover in the fertilization treatment plots was 74%, and this was greater than the 55% mean canopy cover in the unfertilized plots (p = 0.04); however, there was no accompanying reduction in erosion rate for either the seeding or fertilization treatments. Revegetation by naturally occurring species was apparently not impacted by seeding during the four years of this study. The pH of the sediment as well as the concentrations of NO₃–N, NH₄–N, and K was not affected by seeding or fertilizing. The nutrient loads in the eroded sediment were minimal, with most of the nutrient loss occurring in the first postfire year. These results confirm that seeding success is highly dependent on rainfall intensity, amounts, and timing, and that soil nutrients lost in eroded sediments are unlikely to impair the site productivity.     

岗平地黑土草田轮作的生态效应

以玉米连作为对照 ,研究了草田轮作对岗平地黑土的生态效应。结果表明 :在水蚀和风蚀严重的岗平地黑土上实行草田轮作 ,有利于改善土壤的孔隙状况 ,从而改善岗平地黑土的通气有余、持水不足、易于干旱和沙化的状况。草田轮作可以增加土壤微生物的数量 ,增强微生物的总体活性 ,也可以增加土壤的酶活性 ,进而提高土壤的生物活性 ,改善土壤的环境条件。     

优良牧草在肉兔生产中应用的研究

在家兔饲料中添加紫花苜蓿、白三叶、聚合草、多年生黑麦草等四种优良多年生牧草能够增加家兔食欲,提高饲料转化率,促进家兔的生长。其中黑麦草饲喂效果最好,其次为聚合草。牧草混合饲喂的效果好于单独饲喂,其中黑麦草与白三叶混合饲喂效果最好。     

河南省黄河滩区绿色草业工程建设的现状与展望

笔者根据河南省黄河滩区自然条件的特点和畜牧业发展中存在的问题,依据生态学原理探讨了在滩区建设绿色草业工程的必要性和可行性。文章的重点在于提出建立以发展“三元”农业生产结构、发展绿色草业工程、发展绿色畜禽产品小区以及加强生物多样性保护为核心的绿色综合建设措施,其目的是为了改善黄河滩地的生态环境,保护滩地的生物多样性,促进滩区湿地以及周边地区农田和草地的科学化利用,促进滩区农牧业经济的良性循环和可持续发展。     

我国席草生产机械化现状与发展

通过研究分析我国席草生产机械化的发展现状,对目前存在的问题和发展模式的选择做了分析和探索,并对席草生产机械的研发和推广做了展望,试图为席草生产机械化的发展提供研究基础.     

草地牧草物候发育模型的应用研究——以锡林郭勒草原为例

天然草地牧草生长发育受环境条件影响很大,牧草的发育期年际间和年内有很大变化。利用多年牧草物候观测资料,分析了影响草地牧草生长发育的主要气象要素并建立了锡林郭勒草原主要牧草物候发育模型。     

20世纪50年代以来科尔沁沙地景观时空动态变化探析

研究分析了50年来科尔沁流动沙地和半固定沙地景观时空动态变化,并分析了沙地时空动态变化的主要成因。     

鄱阳湖钉螺体内吸虫尾蚴记述

作者从1999-2000年共解剖鄱阳湖草洲钉螺87146只，先后发现裸头类、矛口类、单盘类、微尾类、叉尾类、对盘类、无尾类尾蚴共15种，本文将各种尾蚴的形态特征予以简介。     

对发展大通山区畜牧业的建议

充分利用山区丰富的草地和土地资源 ,结合退耕还草工程 ,引导群众种草养畜 ,放牧与暖棚舍饲相结合 ,使畜牧业生产与生态环境保护同步 ,实现生态和经济良性循环 ,促进山区畜牧业高效和持续发展     

不同水钙磷浓度条件下草鱼对水和饲料中钙磷的吸收利用

本研究结果表明:草鱼对饲料钙磷的消化吸收受水中钙磷浓度的影响。草鱼能直接从水中吸收利用钙磷。鱼体存积的大部分来自于水,而磷则大部分从饲料中获得,草鱼钙磷的利用按Ca/P≈1.6的比值进行。