Study On The Optimum Light Environment Of Updated Tree Species In The Artificial Canopy Of Larix Olgensis Henry

More than 50 quadrats were set up under the zonal clear-cutting areas and artificial crown canopy of larch with different selective-cutting density.Every quadrat was measured for the upper luminous environment indicator by using a canopy analyzer,and then height,varieties and biomass of herbs in quadrats were investigated.Based on it,influences of different environmental indicators under artificial crown canopy of larch(such as gap fraction,canopy coverage and comprehensive illumination)on herbal diversity and biomass were analyzed to draw a conclusion as follows:(1)There was the correlation with varying degree between undergrowth light environmental indicators and 6 indicators of herbal diversity.In terms of herbal diversity,gap fraction and scattered light had the significant influences on herbal diversity.The correlation coefficient size was shown as follows: gap fraction>scattered light.Direct light index,global radiation,and comprehensive light index had the insignificant influences on herbal diversity.In terms of herbal homogeneity,scattered light,canopy coverage,gap fraction,global radiation under canopy and comprehensive light index had the significant influences on herbal homogeneity.The correlation coefficient size was shown as follows: scattered light>canopy coverage>gap fraction>global radiation under canopy=comprehensive light index,while direct light had insignificant influences on herbal homogeneity.In terms of herbal richness,there was no corresponding relation between herbal richness and different light indicators.Undergrowth herbal diversity and homogeneity had the obviously decreased tendency with the increase of light environmental indicators(except for canopy coverage),indicating that most of herbaceous plants under larch plantation are shade plants.The stronger illumination won't increase herbal diversity and homogeneity,but it will increase biomass.Therefore,to increase canopy coverage and reduce canopy light radiation will be good for increasing diversity and homogeneity of undergrowth herbaceous plants.(2)Varieties,height and diversity of undergrowth herbaceous plants presented 30 m clear cutting>20m clear cutting>selective cutting,showing that the broader clear-cutting zones,the more varieties of undergrowth herbaceous plants will be,,mean height is also increasingly high,and then more abundant categories of undergrowth herbaceous plants.The increase of illumination intensity will be good for growth of undergrowth herbaceous plants in selective-cutting forests..But,the effect of afforestation on young trees(3)By analyzing above-ground biomass,underground biomass and total biomass of herbaceous plants,as well as six light indexes,most of herbaceous plants under canopy are herbaceous plants with shade tolerance.Scattered light,canopy transmittance,global radiation under canopy,and too strong comprehensive light and oversized canopy density(canopy coverage)restrain herbal growth and reduce herbal biomass.However,undergrowth herbaceous plants can better absorb direct light.Suitable increase of direct light can promote growth of undergrowth herbaceous plants and also increase herbal biomass.In order to better operate herbaceous plants under the larch,optimal scattered light(ISF)under canopy,comprehensive light index(GSF),gap Fraction VisSkey and total radiation TotBe under canopy and canopy coverage GndCover can be controlled between 0.35-0.4,0.25-0.3,3000-5000 and 0-0.2,thus the biggest biology can be acquired.(4)Above-ground biomass,underground biomass,and total biomass were shown as follows: 30 m of clear cutting zone>20m clear cutting zone >selective cutting areas,showing that that the border clear cutting,the large herbal biomass was increased and growth will be more exuberant.