【作者】 龚固堂；

【导师】 张健；

【作者基本信息】 四川农业大学 ， 森林培育学， 2011， 博士

【摘要】 四川盆地是长江上游最重要的农业区,农业开发历史悠久,长期不合理的经济活动导致了原生常绿阔叶林植被的消失殆尽。为了控制水土流失和解决群众烧柴问题,四川从20世纪70年代在盆地丘陵地区广泛开展了植被恢复；至九十年代后期,该区森林覆盖率达到了22.7%,水土流失得到了一定程度的遏制。但由于多种因素限制,营建了大面积的针叶纯林。目前,大多针叶纯林处于中幼林阶段,林分密度过大,林下灌草盖度低,天然更新不良,地力下降,林分稳定性差,水上保持能力弱。本文针对四川盆地主要生态问题和防护林存在的科学问题,在中尺度流域、小流域和林分尺度开展了防护林空间配置与结构优化研究,主要研究结果如下：1中尺度流域森林覆盖率和林种优化布局应用森林流域水文模型(FCHM)对研究区平通河流域和刘家河流域森林水文过程进行了模拟。结果表明：由于森林的覆盖,两个流域都能减少地表径流,但对径流的再分配存在差异。平通河流域随着森林覆盖率的增加能够增加多年平均河川径流量,径流正效应比较明显；而刘家河流域则相反,呈明显的负效应。选择林分结构、土壤类型、坡度等12个指标对平通河流域的林业用地小班水源涵养功能进行了等级评价,以加权的林地土壤饱和蓄水量为指标确定流域适宜森林覆盖率。平通河流域林种结构优化布局后增加了用材林和经济林面积,这样更合理地利用了流域内丰富水资源,达到了流域削洪增枯的目的。2小流域尺度上地块—林分类型优化配置采用物元分析法对官司河流域土地适应性进行了评价,在综合考虑流域生态效益、经济效益、社会效益和林分稳定性基础上,用层次分析法得到了该流域主要森林类型的面积权重。结合面上样带调查资料,进行了地块—林分类型优化配置,对现有林分类型和相应小班进行了调整。官司河流域地块—林分类型优化配置后针叶纯林面积大大降低,针阔混交林比例达到39.9%。3川中丘陵区适宜森林类型和林分结构通过对川中丘陵区4种柏木林分类型的研究表明：在林冠截留、枯落物持水量、土壤最大持水量和土壤抗蚀性方面,栎柏混交林明显优于其它3种林分类型。根据对郁闭度与灌草生物量、郁闭度与灌草盖度的研究,郁闭度0.6-0.7,灌木盖度35-50%,草本盖度>45%的柏木纯林水土保持效果较好。对川中丘陵区8种主要群落类型的生物多样性进行了研究,结果表明：灌木和草本层生物多样性都明显高于乔木层。8种群落类型的M. Godron稳定性指数远离稳定坐标点(20/80),均处于一定的不稳定阶段。4林分结构优化调控技术针对研究区普遍存在低效人工马尾松纯林、人工松柏混交林和人工柏木纯林的问题,开展了开窗补阔、生态疏伐和带状改造技术试验研究。开窗补阔试验结果表明：香樟、台湾桤木在柏木纯林中生长较好,栓皮栎在松树纯林中生长较好。采用3种处理强度对中龄马尾松纯林进行了生态疏伐试验,结果表明：疏伐强度以中度疏伐为宜,有利于适宜灌草盖度的形成和天然更新。设计了4种采伐带宽对柏木纯林进行了改造试验,结果表明：柏木纯林带状改造的采伐宽度以6 m或8 m为宜。更多还原

【Abstract】 In order to mitigate soil erosion and provision of firewood for local farmers, vegetation recovery programs were implemented starting from 1970s. With forest cover of 22.7%, extensive protection forests were established by the end of 1990s. At present, these forests turned into middle age, but their water and soil conservation functions were quite poor due to pure coniferous forests, over-dense stand, low coverage of grasses or shrubs, weak natural regeneration and community stability.In consideration of current ecological issues and scientific problems in protection forest systems in Sichuan Basin, the study was focused on the optimization of spatial allocation and stand structure of protection forests in medium-sized watershed, small watershed and stand scale. The main results were found as following.1 Suitable forest cover and optimization of spatial allocation of forest categories in medium-sized watershedThe hydrological process of forest watersheds was simulated by applying of forest catchment hydrological model (FCHM) in Pingtonghe and Liujiahe watersheds. The result has indicated the surface runoff decreased due to the existence of forests in both two watersheds; the annual catchments runoff enhanced with the increase of forest cover in Pingtonghe watershed, but it decreased in Liujiahe watershed.12 indicators (stand structure, soil type, slope, etc.) were selected to evaluate the classes of water conservation capacity of forest subcompartments, and the weighted soil saturated water-holding capacity was applied to identify the suitable forest cover in Pingtonghe watershed. After optimization of spatial allocation of forest categories in the watershed, the total area of timber forest and economic forest increased; thus, the water resource in the watershed was made full use and the flooding peak could be reduced during rainy season.2 Optimal site-stand type match in small watershedThrough matter element analysis, the land suitability was evaluated in Guangsihe small watershed, the area weight of the main forest types was calculated by analytic hierarchy process (AHP) with integrating of ecological, economic and social benefit as well as stand stability. Combining the results from field survey, the optimal site-stand type match was implemented, and partial current forest types and forest subcompart-ments were regulated. After the optimal match in Guangsihe small watershed, the area of pure coniferous forest decreased, but the mixed forest between coniferous and broad-leafed species increased to 39.9%.3 Suitable stand types and stand structure in central Sichuan hilly areasThe study on hydrological effects of the four cypress stand types has indicated that oak-cypress mixed forest was the best one in terms of canopy interception, litter water-holding capacity, maximal soil water-holding capacity, as well as reduction of surface runoff and sediment yield. Through analysis of the relationship between canopy closure and biomass of shrubs and grasses, canopy closure and coverage of shrubs and grasses, cypress monoculture in the central Sichuan hilly areas, the stand type with canopy closure of 0.6-0.7, shrub coverage of 35-50% and grass coverage>45%, was much better than other types in terms of water and soil conservation. Study on 8 main vegetation communities in the areas has shown that the biodiversity in shrub and grass layers were higher than that of in arbor layer. The M. Godron stability index of the 8 communities was far from the stable coordinate point (20/80), all the communities were in unstable stage to some extent.4 Regulation techniques for optimization of stand structureThree techniques were studied to regulate stand structure of the cypress and pine monoculture. The results from open-and-beating up with broadleafed species has indicated that the survival rates of camphor and Taiwan alder grew well in cypress forest; oak performed well in pine forest. Three treatments was tested for thinning in middle-aged pine monoculture, the result has shown that medium intensity thinning was the better option for management of middle-aged pine monoculture. Four treatments were designed in transformation of cypress monocultur. The result has indicated that cutting band with 6 m and 8 m were most suitable in improvement of low-function cypress monoculture.更多还原