生长在矿区废弃地的栾树混交幼林生物量研究

对湖南湘潭锰矿矿业废弃地营造林的3．5-4．5年生栾树、杜英混交林进行了生物量研究．结果表明:林分密度为3 240株／hm2,栾树单株生物量为1 175-1 958 g,杜英为544-909 g;林分生物量为3125-5211．00 kg／hm2,林分净生产量为893．00- 2085．48 kg／(hm2·a)．现林木生命力强,生长旺盛,林分生产潜力大．为矿区废弃地的植物修复提供了优良树种．     

Estimated stocks of organic carbon in mangrove roots and sediments in Hinchinbrook Channel,Australia

Aboveground and belowground root biomasses (Babove and Broot) were measured for young, isolated Rhizophorastylosa on Iriomote Island, Japan. The relationship between these two parameters was significant and given as the equation, Broot(g dry weight) = 0.394 × Babove(g dry weight) – 485 (r = 0.986). Multiple regression analyses also revealed good correlation between diameter and biomass of prop roots (Dprop and Bprop) and between prop root and root biomasses. Consequently, root biomass could be estimated from the measurements of diameter and biomass of prop roots using the multiple regression equation, Broot(g dry weight) = 80.0 ×Dprop(cm) + 0.86 ×Bprop (g dry weight) – 251. The relationship between DBH (diameter at breast height) and prop root biomass was also adequately described using an allometric equation.In Hinchinbrook Channel, Australia, redox potential (measured as Eh) and organic carbon stocks in the top 5cm of mangrove sediments were measured along a 600m transect from the frequently inundated, Rhizophora dominated zone on the creek edge, towards higher grounds, where Ceriops spp. became increasingly dominant. Eh values were about –60mV near the creek edge and increased to 260mV on higher grounds. Organic carbon stocks showed an opposite trend to Eh, with the values decreasing from about 360tCha–1 to 160tCha–1. At 18 sites, representing six different habitats, organic carbon stocks were also measured along with the DBH of mangrove trees. DBH was converted into aboveground biomass and then into root biomass using the equations obtained in the study on Iriomote Island. The average organic carbon stocks in the top 50 cm of sediments, aboveground biomass and root biomass were 296tCha–1, 123 tCha–1 and 52 tCha–1, respectively, and accounted for 64%, 25% and 11% of the total organic carbon stock.     

日光温室内作物干物质积累预测新方法研究

介绍了一种有效结合神经网络和作物生长模型预测目光温室内作物干物质积累的方法，该方法既解决了经验模型的解释性和广适性差的缺点，又解决了机理模型难以理解和使用、输入多而输出欠稳定的不足。以有效光照积累和有效积温作为输入参数，以作物的干物质积累作为输出参数建立神经网络，利用大量实测数据对神经网络结构进行训练，建立作物干物质积累与有效光照累积和有效积温之间的关系，从而对干物质积累进行预测。并以目光温室内黄瓜为例，采用此方法对其进行干物质积累的预测，与实际测量结果相比较，误差率不超过10％。     

The vertical distribution of fine roots of five tree species and maize in Morogoro,Tanzania

In order to assess the possibility of root competition in agroforestry, the vertical distribution of fine roots (< 2 mm in diameter) of five tree species in pure two-year-old stands was compared to that of mature maize.Cassia siamea, Eucalyptus tereticornis, Leucaena leucocephala andProsopis chilensis had a rooting pattern similar to that of maize, i.e. a slow decline in fine root mass from 0–100 cm soil depth.Eucalyptus camaldulensis had its roots evenly distributed down to 100 cm. On an average, the fine root biomass of the tree species was roughly twice as that of the maize. We conclude that the studied tree species are likely to compete with maize and other crops with a similar rooting pattern for nutrients and water.     

Effect of pruning intensities of three woody leguminous species grown in alley cropping with maize and cowpea on an alfisol

Field trials were carried out on an Oxic Paleustalf in the humid zone of southwestern Nigeria withLeucaena leucocephala (Lam.) de Wit,Gliricidia sepium (Jacq.) Steud. andSesbania grandiflora (L.) Pers. alley cropped with maize and cowpea. The three leguminous woody species were grown in hedgerows spaced at 2 m. Trials were carried out one year after establishment of the hedgerows using a split-plot design with four replications. TheLeucaena trial had twenty pruning combinations consisting of five pruning heights (25, 50, 75, 100 and 150 cm) and four pruning frequencies (monthly, bi-, tri- and six-monthly). TheGliricidia andSesbania hedgerows were subjected to nine pruning intensities consisting of three pruning heights (25, 50 and 100 cm) and three pruning intensities (monthly, tri- and six-monthly).For the three woody species, biomass, dry wood and nitrogen yield from the hedgerow prunings increased with decreasing pruning frequency and increasing pruning height. Biomass, dry wood and nitrogen yields were in the following orderLeucaena >Gliricidia >Sesbania.The various pruning intensities had no effect on survival ofLeucaena plants. Pruning frequency had a larger effect than pruning height on survival ofGliricidia andSesbania plants. With monthly pruning, about 25 percent of theGliricidia and all of theSesbania plants died within six months of repeated pruning. Even with lower pruning frequencySesbania plants showed lower survival rates thanGliricidia orLeucaena.The various pruning intensities of all the hedgerow species had more pronounced effects on the grain yield of the alley cropped cowpea than on maize grain yield. Higher maize and cowpea yields were obtained with increasing pruning frequency and decreasing pruning height.IITA Journal paper number 335     

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.     

3S技术在鄱阳湖洲滩植被研究中的应用

为了给鄱阳湖洲滩植被的监测、保护与合理利用提供必要的依据 ,将 RS技术 (Landsat-7ETM+ )与 GPS技术、GIS技术相结合 ,对鄱阳湖洲滩植被的分布、面积与生物量进行了研究 ,据假彩色合成图描绘了鄱阳湖洲滩植被图 .结果表明 :(1) Landsat-7ETM+假彩色合成图显示 ,鄱阳湖洲滩植被主要分布于该湖的南部和西部 ,东部只有少量分布 ,北部几乎无分布 ;(2 )到 2 0 0 0年 4月 16日止 ,鄱阳湖洲滩植被总面积为 10 18.74km2 ,占全湖总面积的 3 3 .65 % ,其中单位面积生物量≥ 4kg/ m2 的植被面积为 44 4.5 3km2 ;(3 ) ETM+ 4的亮度值 X与单位面积生物量 Y间的回归方程为 Y=-4 897.11+ 87.68X;(4 )全湖洲滩植被总生物量为3 .81× 10 6 t,洲滩植被平均单位面积生物量为 3 .73 60 kg/ m2 .     

论我国林业生物质能源林培育与发展

能源危机和生态环境压力使世界发达国家纷纷转向发展和利用生物质能源,发展生物质能产业也是我国缓解能源供应压力和解决环境问题的途径之一。林业生物质能资源培育是一项系统工程,要从统筹资源培育和产业发展、进行现状及发展潜力调查评价、制定资源培育及产业发展总体规划、加强科技和加强优惠财税政策等方面做好工作;同时,处理好产业与生态、森林多目标培育的关系,处理好国家、企业和能源林经营者三者之间的关系,以促进我国林业生物质能产业健康快速发展。     

长江中上游马尾松水土保持林生长过程模型研究

将乔木、灌木和草本层次结构合理、郁闭度为0．68左右，蓄水固土功能最优的林分定义为马尾松水土保持林的优良林分，从制表单元、编表样本、模型建立到数表编制，系统地论述了长江中上游马尾松水土保持林优良林分生物量生长过程表的制表过程．为长江中上游水土保持林的经营提供了决策依据．     

河南省森林碳储量及动态变化研究

利用河南省1949—2003年间8次森林资源清查资料,建立不同优势树种生物量与蓄积量之间的回归方程,对河南省54a来森林的碳储量进行了推算。结果表明:河南省54a间森林的总碳储量虽然存在一定的波动现象,但总体呈上升的趋势。全省森林的总碳储量由1949年的2 863.91万t C增加到2003年的4 673.43万t C,共增加1 809.52万t C,年均增加33.51万t C。阔叶林占全省各时期森林总碳储量的80%以上,栎类和杨树两个树种占主导地位。河南森林幼、中龄林占的比重较大。全省森林平均碳密度为22.86~23.64t C/hm2,远低于全国、世界的平均水平。