基于植被覆盖度的剑川县森林城市创建潜力研究

利用ENVI软件,基于像元二分模型法的剑川县2013年和2021年冬季Landsat 8影像,结合归一植被指数,计算剑川县不同时期植被覆盖度,利用决策树分类方法获得2013年和2021年两个时期的植被覆盖动态变化特征。结果表明,8年来剑川县高覆盖度植被区域面积不断增加,生态环境得到不断改善。分析剑川县各乡镇生态特色,结果表明,剑川县文化底蕴深厚,具有较好的森林城市创建潜力。     

异龄林生长的动态分析——兼小兴安岭和牡丹江林区冷杉异龄林的生长分析

异龄林既是一个自然生态系统,又是一个复杂的森林经营系统。一个经营工作者要对异龄林进行高效率的经营,就必须掌握现实林的动态变化规律,以便有目的地制定经营措施。异龄林系统从经营角度出发,可以划分成如下三个组成单元:进界生长量、向上生长量和枯损量。上述三个单元的相互作用构成了异龄林系统的动态变化规律。本文的主要目的就是通过对上述三个生长单元的动态进行模拟,寻找出异龄林的动态变化规律,所用方法是对每个生长单元用多个数学模型进行拟合,再通过统计量分析和实际验证从中选出最理想的模型,并据此对现实异龄林的动态进行预测。证明了以曲线形式反映异龄林的动态变化远优于线性形式。所用材料取自黑龙江省小兴安岭和牡丹江林区的冷杉(Abies nephrolepis)为主的异龄针阔混交林。     

厦门城市森林马尾松宽带更新改造技术研究

厦门城市森林中马尾松劣质林分比例大,采用不同改造方式试验表明:宽带采伐更新改造效果较好,阔叶树种造林成活率高,幼林生长比较快,适宜阳性、强阳性和中性偏阳树种。且宽带更新改造技术较简单,可操作性强,便于推广应用。     

天水市近30年林地动态变化遥感监测研究

[目的]以甘肃省天水市为例,基于遥感影像变化监测技术,探讨黄土高原丘陵沟壑与小陇山-西秦岭山地交接过渡区域近30年来森林(林地)资源空间分布规律、时间变化趋势及变化影响因素。[方法]以1988—2015年5期夏季Landsat TM/OLI遥感影像为主要数据源,结合辅助数据和外业实地样本点,以光谱特征和指数特征为特征变量,分别利用随机森林(RF)和参数优化支持向量机(POSVM)分类器对土地覆盖类型进行分类,然后基于分类后比较法进行森林资源动态变化监测。[结果]分类结果表明,两种分类器的分类效果均较好,且随机森林分类器在分类精度、效率和稳定性方面明显优于参数优化支持向量机分类器。变化监测结果表明,近30年来森林资源总体变化趋势为林地面积先减少后增加。1990—1996年,林地面积减少0.74%;1996—2002年,林地面积减少2.74%;2002—2008年,林地面积增加1.06%;2008—2015年,林地面积增加8.89%。[结论]本研究采用的基于非参数分类器分类后比较法的变化监测技术是复杂地形地貌过渡区森林资源动态变化监测的一种有效途径,在分类结果分析统计的基础上,得出研究区森林资源变化的总体趋势:以2002年(2002年影像)为界,林地总体趋势为先减少后增加,2002年后林地面积增加显著。     

Temporal patterns of seedling mortality by pine weevils (Hylobius abietis) after prescribed burning in northern Sweden

Damage by the large pine weevil, Hylobius abietis (L.), is a major threat to conifer plantations throughout Eurasia, but damage is usually less severe in northern areas. However, pine weevil damage seems to increase if the sites are burnt. The aim of this study was to determine the effects of variations in the time of planting (with respect to the total age of the clear-cut and the time since burning) on pine weevil damage to seedlings on burnt sites in northern Sweden. The study also explored whether there is an optimal time for planting at which damage levels are reduced to acceptable levels. Ten sites were selected in an inland area of northern Sweden where pine weevils are normally scarce. The sites were dry–mesic and represented a range of times since clear-cutting and since burning. The sites were planted in June 1998, 1999 and 2000 with 1-year-old container-grown seedlings of Norway spruce [Picea abies (L.) Karst.]. Pine weevil damage was reduced if planting was done no earlier than 3 years after clear-cutting and no earlier than 2 years after burning. Planting too soon after burning, irrespective of the age of the clear-cut, resulted in unacceptably high damage levels.     

Growth and Nutritional Responses of Juvenile Jeffrey Pine to Post-Planting Fertilization

Abstract

Broadcast fertilization of a three-year-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) plantation growing on an eroded Sierra Nevada site was examined for its capacity to enhance seedling growth. The amendments chosen for the study included controlled release and conventional soluble formulations that contained a variety of N forms, but all featured high N content along with other nutrients. Four application rates were used, and all amendments were distributed around the base of the seedlings as top dressing. Four seasons after treatment application, fertilized seedlings were 129% larger in height, 93% larger in diameter, and 865% greater in shoot volume than unfertilized seedlings overall. Seedling sizes generally increased with application rate, and by a small margin, the controlled release fertilizer outperformed the other formulations. Relative growth analysis suggested that stimulation by the amendments would continue beyond four seasons. Foliar analysis conducted early and again late during the study revealed that N and P concentrations were consistently raised by fertilization, which likely accounts for much of the accompanying growth gains, while Ca, Fe, Mn, B, and Al concentrations were consistently reduced. Either early or late, foliar K was also raised while Mg, S, Zn, and Cu were reduced. Collectively, these results indicate that fertilization with a variety of high N formulations can increase the availability and uptake of critical nutrients sufficiently to impart in Jeffrey pine on low quality sites a substantial growth advantage.     

中国东北地区的立木腐朽菌

简要论述了中国东北地区的立木腐朽菌,共报道危害活立木的木腐菌４９种,对每个种的寄主、腐朽类型及分布进行了报道,它们中多数造成白色腐朽,少数导致褐色腐朽,其中在我国首次报道为森林病原菌的种类有：白黄小薄孔菌Ａｎｔｒｏｄｉｅｌｌａ ａｌｂｏｃｉｎｎａｍｏｍｅａ,奥氏蜜环菌Ａｒｍｉｌｌａｒｉａ ａｓｔｏｙａｅ,亚黑管孔菌Ｂｊｅｒｋａｎｄｅｒａ ｆｕｍｏｓａ,硬栓孔菌Ｆｕｎａｌｉａ ｔｒａｇｉｉ,小孔异担     

Water Conservation Forest Impacts on the Runoff Generation and Sedimentation at Small Watershed Scale in the Miyun Reservoir Watershed

密云水库集水区水源保护林在北京地区饮用水源保护中起着非常重要的作用．本文给出了该区小流域对比实验的初步研究结果,有林小流域和无林小流域对１９９６年７月３０日降雨过程较为一致的径流响应表明,土壤前期含水量对流域产流有较大的影响,在降雨较多土壤含水量较大的情况下该区产流方式可以表现为饱和地表径流．尽管该区以霍顿超渗产流为主,但对于１９９７年７月３１日至８月１日降雨过程,森林流域产流总量为１３９３．８０ｍ３,无林流域为２２０２．４３ｍ３,森林流域减少洪水总量３６．７％,消减洪峰流量达３７３％．然而,１９９７年７月１９日降雨过程森林流域径流洪峰量与洪水泥沙含量均较无林流域高,这表明预处理措施对径流泥沙过程有极为显著的影响     

小黑山自然保护区森林生态系统服务功能及价值评估

以小黑山自然保护区的森林生态系统为研究对象,采用影子工程法、机会成本法、市场价值法等研究方法,对其生态系统服务功能的直接价值和间接价值进行了评估.结果表明,小黑山自然保护区的生态系统服务功能价值达10.52×108元/a,其中直接价值为5 406.89×104元/a,仅占服务功能总价值的5.14%,而间接价值高达99 825.04×104元/a,两者之比为1∶18.46.间接价值中大小顺序依次为:涵养水源水土保持维持生物多样性固碳释氧净化空气科研文化.小黑山自然保护区对维持当地社会经济可持续发展具有举足轻重的作用.     

浙江衢州毛竹林低改后害虫种群变动分析

自20世纪80年代始,衢州市各县(市、区)逐渐推广毛竹低产林改造技术,为竹林增产增效打下了基础。但是,由于改制后的毛竹林地被挖锄,天敌资源锐减,竹林中年年有笋,立竹上终年披叶,使竹子害虫食物条件改善,致使竹子害虫种类、数量增加,危害逐年加重。通过害虫种群变动分析,可以为开展竹林病虫害综合防治提供有效的应对措施。