森林病虫损害的可持续控制

森林病虫的控制的控制应遵循效益原则,对病虫所造成的森林综合损失实行可持续控制,并自觉将其纳入整个森林事业的可持续发展体系之中,正确认识病虫在森林生态系统中的功能和对人类的利用价值。建立森林综合效益评价标准体系以及一系列适合于森林病虫损害控制的管理体制和技术手段。是效益原则下的森林损失可持续控制的实现途径。     

土地荒漠化及其防治对策

列举了土地荒漠化的危害及其对人类社会可持续发展的影响，分析了影响其发生、发展的自然和人为因素，提出了沙漠化土地的治理对策。     

井冈山植物资源特点与保护对策

江西井冈山因水热条件优越，森林覆盖率达80．1％，具有植物资源以常绿植物为主、群落类型丰富多样、起源古老、珍稀濒危特有特种多、地带性强等特点。提出了强化管理适度开发、谨慎选项全程监控、引导生态旅游、区域联合共谋发展等保护对策。     

民勤绿洲荒漠过渡区辐射特征与热量平衡规律研究

根据巴丹吉林沙漠与腾格里沙漠交汇处的民勤绿洲荒漠过渡区的长期连续实测资料 ,分析了该地区的辐射特征 ,研究了热量平衡各分量的变化特征及热量平衡规律。在绿洲荒漠过渡区 ,其太阳辐射、净辐射和反射辐射具有明显的日进程和季节变化规律 ;太阳辐射月总量最大值 (12 0 2 3 3kW·m- 2 )出现在 8月份 ,最小值(5 2 0 6 5kW·m- 2 )出现在 11月份 ;流动沙丘表面的反射率高于有植被覆盖的红柳和白刺灌丛沙丘表面的反射率 ,在植被生长季节更为明显 ,反射率日最大值分别为流动沙丘 (37 5 % ) >白刺沙丘 (2 9 7% ) >红柳沙丘 (2 7 9% ) ;流动沙丘表面接受的净辐射是植被覆盖区的 5 0 %～ 70 %左右。在绿洲荒漠过渡区生态系统的热量平衡中 ,占比例最大的是潜热通量 ,其次为感热通量和土壤热通量。随着荒漠化程度的加深 ,生态系统反射率增加 ,净辐射减少 ,而且热量平衡中感热通量和土壤热通量所占比例增加 ,而潜热通量比例减小。     

Nitrogen-fixation dynamics in a cut-and-carry silvopastoral system in the subhumid conditions of Guadeloupe, French Antilles

This paper summarizes several studies on N recycling in a tropical silvopastoral system for assessing the ability of the system to increase soil fertility and insure sustainability. We analyzed the N₂ fixation pattern of the woody legume component (Gliricidia sepium), estimated the recycling rate of the fixed N in the soil, and measured N outputs in tree pruning and cut grass (Dichanthium aristatum). With this information, we estimated the N balance of the silvopastoral system at the plot scale. The studies were conducted in an 11-year-old silvopastoral plot established by planting G. sepium cuttings at 0.3 m × 2 m spacing in natural grassland. The plot was managed as a cut-and-carry system where all the tree pruning residues (every 2-4 months) and cut grass (every 40-50 days) were removed and animals were excluded. No N fertilizer was applied. Dinitrogen fixation, as estimated by the ¹⁵N natural abundance method, ranged from 60-90% of the total N in aboveground tree biomass depending on season. On average, 76% of the N exports from the plot in tree pruning (194 kg [N] ha^–1 yr^–1) originated from N₂ fixation. Grass production averaged 13 Mg ha^–1 yr^–1 and N export in cut grass was 195 kg [N] ha^–1 yr^–1. The total N fixed by G. sepium, as estimated from the tree and grass N exports and the increase in soil N content, was about 555 kg [N] ha^–1 yr^–1. Carbon sequestration averaged 1.9 Mg [C] ha^–1 yr^–1 and soil organic N in the 0-0.2 m layer increased at a rate of 166 kg [N] ha^–1 yr^–1, corresponding to 30% of N₂ fixation by the tree. Nitrogen released in nodule turnover (10 kg [N] ha^–1 yr^–1) and litter decomposition (40 kg [N] ha^–1 yr^–1) contributed slightly to this increase, and most of the recycled N came from the turnover or the activity of other below-ground tree biomass than nodules. This revised version was published online in June 2006 with corrections to the Cover Date.     

Forest Fires and Prevention Strategies in Northwestern Region of China

The paper described the natural conditions and forest types in Northwestern Region of China. Most forests in the region are distributed in subalpine areas. It is important to protect the existent forests in the region for maintaining ecological balance. According to the statistics results of 1991~2000, the paper analyzes the forest fires distribution and fire severity. Annually the numbers of forest fires range from 52 to 240. The incidence rate of forest fires in Northwestern Region is under 0.33 per ten thousand ha. There are 0.67-64.4 ha burned area per ten thousand ha forest. The main reasons for forest fires lie in the dry weather conditions, many firebrands, and high fuel loading. The strategies of fire management in the region are to stress the fire education in forest regions, strength the firebrands' management, emphasize the fuel management, and improve the fire monitoring and fire control ability.     

南方经济林经营管理策略

根据南方经济林生产现状,分析了南方经济林生产与管理中存在的问题,结合国内外市场对经济林产品需求,提出了保障南方经济林健康,稳定,持续发展的经营管理策略。     

小悍蟋若虫滞育的光周期调控及其季节适应策略

就光周期对小悍蟋T a rta rog ry llusm inuscu lus若虫发育及成虫繁殖的影响进行了调查.结果表明,在30℃恒定长日(LD16 h∶8 h)条件下,小悍蟋若虫63 d内全部供试个体完成羽化,而在恒定短日(LD 12 h∶12 h)条件下,小悍蟋若虫120 d之内仍只有90%的个体完成羽化;将孵化后第7 d和第35 d的若虫自短日条件向长日条件转移,能够促进小悍蟋若虫的发育,而反方向的转移则对小悍蟋若虫的发育几乎不起影响.这表明小悍蟋若虫存在滞育现象,短日条件诱导滞育,长日条件解除滞育,并且低龄若虫对长日条件比较敏感.光周期不仅影响小悍蟋若虫发育,而且也影响成虫的繁殖.长日条件下的成虫产卵量显著多于短日条件下的成虫产卵量.但是,光周期对成虫产卵前期间无明显影响.     

福州国家森林公园环境容量评估及其管理策略研究

选择适合的森林公园环境指标评价体系,计算福州国家森林公园的生态容量,并与实际的游客量进行比较,得出福州国家森林公园有待进一步加大森林公园的开展力度。提出应该从森林旅游产品、旅游交通、旅游营销以及旅游管理方面加以改进。     

昆明掌鸠河引水工程云龙水库库区水源林保护与经营对策

正在建设的云龙水库是昆明市掌鸠河引水工程的核心工程,对昆明的建设和经济发展意义重大。通过对掌鸠河流域自然环境及云龙水库工程的介绍,分析了云龙水库库区水源林的基本格局,指出了该区现有森林作为水源林功能转变存在的主要问题。据此,提出了科学划分水源地治理和保护区域、建设结构合理的水源涵养林,以及建立有效的水源林生态补偿机制等的一系列保护和经营对策,为云南省高原湖泊水源林的保护和经营奠定了基础。