辽宁省退耕还草现状问题与建议

针对辽宁省退耕还草现状,阐述实施退耕还草成效,并依据当前退耕还草存在的问题提出了有关建议。     

Seasonal changes of understorey herbage yield in relation to light intensity and soil moisture content in a Pinus pinaster plantation

The relationship of understorey herbage yield with light intensity and soil moisture content was investigated in a 20-year-old Pinus pinaster plantation in Kilkis of Macedonia, northern Greece, in three seasons (fall, winter and spring). The plantation was thinned at three density levels, high, medium and low (2500, 1750 and 1000 trees/ha respectively) and it was seeded with Dactylis glomerata. In addition, two fertilization levels (0 and 110 N+150 P₂O₅ kg/ha) and grazing intensity levels (0 and 0.8 sheep/ha/yr) were applied in a split-split plot experimental design. It was found that herbage yield was highest in the ungrazed and fertilized low tree density stands in all seasons. In the medium tree density stand, although light was lacking, fertilized plots produced higher herbage yield as compared to unfertilized low tree density stands while fertilization is of no use in close stands if herbage production is the goal. Animals seemed to prefer fertilized and medium density stands. Third degree polynomial equations were the best to explain herbage variation through the seasons both in fertilized and unfertilized plots.     

迁西县退耕还林的效益分析

退耕还林工程是我国为解决水土流失、土地沙化等生态环境问题而采取的重大举措,也为我国的林业建设发挥了巨大的作用。本文以河北省迁西县为例,采用实地调查和问卷调查相结合的方式,分析和研究迁西县在退耕还林工程实施前后的各项效益,包括生态效益、经济效益和社会效益,结果显示,退耕还林在迁西县林业发展中取得了显著效益。     

Dynamics of Zn between soil and plant in Northeast Leymus chinensis grassland

A study was conducted to determine the dynamic of Zn content between soil and plant in the natural protection zone of Leymus chinensis grassland in Changling County (44°30′–44°45′N; 123°31′–124°10′E), Jilin Province, China. Results showed that the total Zn content was lower, available Zn content had a moderate level in the soil, and the plants was not lack of Zn. During the growing season, content of total Zn and available Zn in soil showed a down-trend distribution along the soil profile. Content of total Zn had a significantly positive correlation with that of the organic matter, but it was negatively correlated to soil pH. Monthly dynamic of the average content of total Zn showed a “V” type curve in the growing season from May to August, and July was the nadir. The trend of the average content of available Zn was similar to the content of total Zn, but was down after August; Zn content variation in the organs and litter of L. chinensis was great, with the order of root>rhizome >leaf>stem>litter. The ratio of available Zn content in A layer versus B layer was more than 2 times that of the total Zn, which indicated that the soil of A layer had higher enrichment capacity of available Zn. The enrichment of Zn in the root of L. chinensis was 44.17 times as that in the soil. The absorbing intensity of root had a significantly negative correlation with the activity of Zn in the soil (r=−0.8800, p<0.01). Biography: ZHOU Xiao-mei (1966–), female, Ph.D., associate professor of Jilin Normal University, Siping 136000, P.R. China.     

西藏草原5种主要有毒植物营养成分

采用国家标准法对西藏天然草原茎直黄芪(Astragalus strictus)、甘肃棘豆(Oxytropis kansuensis)、毛瓣棘豆(Oxytropis sericopetala)、瑞香狼毒(Stellera chamaejasme)和藏橐吾(Ligularia rumicifolia)5种主要有毒植物不同物候期常规营养成分和矿质元素含量进行测定。结果显示,在5种植物中,粗蛋白平均含量以茎直黄芪最高,其次为甘肃棘豆,且两者粗蛋白含量均超过19%;茎直黄芪中花期粗蛋白含量最高,花前期最低,花期和花果期差异不显著(P0.05);而甘肃棘豆中粗蛋白含量以花前期最高,花果期最低,花前期和花期差异不显著。粗纤维平均含量由高到低依次为毛瓣棘豆、藏橐吾、茎直黄芪、甘肃棘豆和瑞香狼毒,且均以花果期最高,花前期最低。5种植物Mg、Fe、Cu、Mn和Zn含量均以花前期最高,花期次之,花果期最低;但Se含量花果期相对较高。由此得出,茎直黄芪和甘肃棘豆营养较为丰富,具有潜在饲用价值,毛瓣棘豆、瑞香狼毒和藏橐吾营养价值偏低。     

禁牧对退化草地恢复的作用

草地是我国重要的农业自然资源之一,但目前草地退化的现象十分严重,超载过牧是主要原因之一。本文就针对草地退化提出的围封禁牧措施对草地植被、土壤及草地生态系统恢复过程中的作用进行综述,发现适度放牧对草地恢复是必需的,但采取长期围封禁牧恢复与重建草地的做法不可取,围栏封育并非恢复退化草地的万全之计。建议在我国要因地制宜,根据草地的退化程度,采取合理的划区轮牧强度和放牧时间,与退化草地生态恢复的围封措施结合,以达到既能恢复退化草地,又可收获畜产品的双赢目的,实现草地生态系统持续平衡发展的目标。     

西南喀斯特地区草地生态系统面临的问题及对策

本文系统阐述了西南喀斯特地区草地生态系统的重要性,并分析了西南喀斯特地区草地生态系统面临的问题,主要为水土流失、土壤贫瘠、土地石漠化、生物多样性减少以及人类不合理利用等,针对上述问题提出了增加栽培草地面积、提高公众环保意识、调整农村产业结构、保持水土、防治石漠化、建立完善的监测评价体系等一系列相应对策,以期为喀斯特地区草地生态系统健康、稳定、持续发展提供一定的科学依据。     

放牧对草地土壤微生物的影响

土壤质量是草地生态系统生产力可持续发展的关键所在。健康的土壤必定拥有丰富的物种多样性、活跃的生命体、高效的内部养分循环及较好的抗干扰能力。土壤微生物作为土壤系统中各种生物进程的主要推动者,其作用不可小觑。因此,我们可以利用土壤微生物的数量、群落结构和多样性等特征监测土壤质量。本文综述了放牧对草地土壤微生物数量、生物量、群落结构和多样性的影响。指出通过了解土壤微生物与放牧行为间的关系,如何评估土壤质量,选取适宜的放牧梯度,完善草地管理模式,并介绍了土壤微生物群落结构和多样性研究方法的利弊。解决两个关键问题：1）土壤微生物的各种特征是如何响应放牧行为的。2）如何通过这些指标评价土壤质量,然后提出合理的放牧模式,改善和维护草地的生产力。     

基于PROSAIL模型的山地草原叶面积指数高光谱反演

【目的】 研究基于PROSAIL模型监测天然草地的动态变化,掌握草地的质量与数量。【方法】 研究使用地物光谱仪连续3年在天山北坡中段的2个山地草原样区采集光谱数据和配套数据,基于PROSAIL模型进行冠层LAI的高光谱反演,重点研究应用不同代价函数、植被种类变化对反演精度的影响。【结果】 多数代价函数反演LAI的决定系数(R²)在0.54~0.55,均方根误差(RMSE)在0.23~0.25,归一化均方根误差(NRMSE)在17~19。在9个来自不同统计类型的代价函数中,常用的RMSE代价函数的反演精度相对不高。将获取的427个样方数据依据种类数分成组,然后用PROSAIL进行LAI反演。种类数越多,RMSE在增大,R²在减少,反演精度越差。但精度的下降幅度不是均匀的,种类数≤2的组和种类数≤3的组之间精度差异最大。【结论】 在利用物理模型反演天然草地的叶面积指数时,不同代价函数获得的反演精度差别比较大;随着植被种类数量的增多,反演的精度是下降的。