亚热带草地资源综合评价的数学模型

本文在前人工作的基础上,对亚热带草地资源评定因素进行了筛选与合理组合,编排了各评定因素的多层次评判顺序,组建了综合评价草地资源的模糊数学模型。首次应用数学模型对我国亚热带草地资源进行了综合评价。为验证该数学模型的灵敏度,笔者列举了我国南方四个草地类型,作了具体计算。结果表明,数学模型本身具有较高的灵敏度,完全可以用于评价我国南方天然草地资源。     

海洋中的热带雨林——珊瑚礁

红树林和珊瑚礁是热带和亚热带海域中富有特色的浅水海洋生物群群落,被认为是所有生物群落中最富有生产能力、种类繁多、美学上极富盛名的生物群落之一.珊瑚与藻类共生而形成完整的生态系统,为鱼类资源提供生存环境和营养供应地.在已知的海洋鱼类中有1/4生活在珊瑚礁带中,故具有海洋中热带雨林之美称.但是,它的生长极为缓慢,一般所看到的形体可谓是千年锤造之作,一旦破坏,礁鱼将失去栖身地.     

Response of soil fauna to simulated nitrogen deposition： A nursery experiment in subtropical China

We studied the responses of soil fauna to a simulated nitrogen deposition in nursery experimental plots in Subtropical China. Dissolved NH4NO3 was applied to the soil by spraying twice per month for 16 months, starting January 2003 with treatments of 0, 5, 10, 15 and 30 gN/(m2·a). Soil fauna was sampled after 6, 9, 13 and 16 months of treatment in three soil depths (0-5 cm, 5-10 cm, 10-15 cm). Soil available N increased in correspondence with the increasing N treatment, whereas soil pH decreased. Bacterial and fungal densities were elevated by the N treatment. Soil fauna increased in the lower nitrogen treatments but decreased in the higher N treatments, which might indicate that there was a threshold around 10 gN/(m2·a) for the stimulating effects of N addition. The N effects were dependent on the soil depth and sampling time. The data also suggested that the effects of the different N treatments were related to the level of N saturation, especially the concentration of NO3- in the soil.     

环境视点

正冬日里的一把火——金红的水杉柏科水杉,中国特产的孑遗珍贵树种,第一批列为中国国家一级保护植物的稀有种类,有植物王国"活化石"之称。它的适应力很强,生长极为迅速,且对二氧化硫有一定的抵抗能力,是亚热带地区平原绿化、荒山造林的优良树种。每当岁未春来之际,羊城各大公园的水杉,渐渐的脱绿披黄,树技上的叶片变成金色的羽毛,迎风摇曵。冬日暖阳之下,飞红流金,枝条层层舒展,与湖畔倒影相映更是一幅绝妙的图画。让我们都来广州采红吧!(梁宇星)     

速读

<正>美国总统奥巴马批准30亿美元用于联合国气候基金紧随美国与中国达成气候协议之后,美国总统奥巴马宣布,美国政府将拿出30亿美元用于联合国气候基金帮助贫穷国家对抗气候变化,这一措施可能是美国政府迄今为止在气候变化问题上力度最大的一个项目。奥巴马总统提出的这30亿美元基金相当于联合国绿色气候基金预计融资规模的三分之一,该基金皆在减缓气候变化对世界最贫困国家的影响。     

戴云山土壤微生物碳源利用效率的海拔变异规律及影响因素

微生物碳源利用效率（CUE）是指微生物将吸收的碳（C）转化为自身生物量C的效率,土壤微生物CUE的研究对深入认识土壤C循环过程十分重要.利用¹⁸ O-H₂ O-DNA标记法,研究戴云山不同海拔（980~1765 m）天然林土壤微生物CUE、微生物生长速率（C_growth）和呼吸速率（C_respiration）的变化特征和影响机制.结果表明,微生物CUE在0.1~0.4之间变化,并随海拔升高而增加;微生物CUE与C_growth、C_respiration和单位微生物生长正相关,而与呼吸熵负相关,说明随海拔的增加,微生物通过增加个体生长和抑制个体呼吸来提高CUE;温度是影响CUE的主要因素,微生物CUE与温度负相关,说明随海拔增加,温度下降是促进土壤微生物CUE升高的关键因素.     

宜宾树叶开发利用及其前景

宜宾植被为亚热带常绿阔叶林,植物资源十分丰富,目前对树叶开发利用主要是茶叶、挥发油、蚕桑、中药材等。本文论述了宜宾植物资源开发的种类、经济效益及其前景。     

Adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) in paddy soils cultivated for various years in the subtropical China

The adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity (CEC) of the soils are important factors controlling the adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ).The 15-Year paddy soil had the highest adsorption capacity for Pb(Ⅱ),followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu(Ⅱ) than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu(Ⅱ) and Pb(Ⅱ).These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu(Ⅱ) and Pb(Ⅱ) but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu(Ⅱ) (36.7% to 42.2%) and Pb(Ⅱ) (50.4% to 57.9%) were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.     

亚热带常绿阔叶林凋落叶分解过程中氮和磷在不同雨热季节的释放动态

为理解植物—土壤之间的养分联系,采用凋落物分解袋法,研究季节性降雨期间常绿阔叶林区最具代表性的马尾松(Pinus massoniana)、柳杉(Cryptomeria fortunei)、杉木(Cunninghamia lanceolata)、香樟(Cinnamomum camphora)、红椿(Toona ciliata)、麻栎(Quercus acutissima)等6种凋落叶第一年不同雨热季节分解中氮(N)、磷(P)动态及释放与富集特征.结果显示,凋落叶的N浓度随雨季的变化动态取决于树种,但除红椿以外的其它5种凋落叶在分解初期N浓度变化不明显,在雨季时期显著升高(P<0.05);6种凋落叶P浓度动态比较一致,表现为分解初期P浓度稍微下降,在雨季时期显著升高(P<0.05).历经一年的分解,红椿N、P释放率最大(分别为81.79%、54.19%),香樟N富集率最大(131.45%),马尾松的P富集率最高(268.75%),且6种凋落叶N、P释放/富集率动态均在雨季最明显.凋落叶分解过程中C/N、C/P呈现下降趋势,而N/P变化规律不一致.这些结果均表明,季节性降雨显著(P<0.05)影响凋落叶N、P动态,雨季温湿度的改变可影响N、P释放过程.