吉林省柳河县林地地类面积动态变化分析

采用2001年和2013年二类调查数据,统计吉林省柳河县8个国有林场和15个乡(镇)林业工作站12年间林地地类面积变化。通过分析,全县12年间林地面积增加2731.1hm 2,主要是退耕退林和有争议林地回收管理力度加大;同时增加了未成林地、无立林地、宜林地、辅助生产林地等面积。

ArcGIS在监测林地地类变化中的应用

以沈阳市沈北新区2016年度林地"一张图"数据为例,结合2016年、2017年2个年度的遥感影像,具体阐述利用ArcGIS监测林地地类变化的方法和步骤,同时对应用的工具进行系统地介绍。该方法可广泛地应用到满足条件的各领域、不同时期的数据对比监测工作中。

关于山西省林地地类划分的思考

林地地类划分是林业调查的基础性工作,科学的林地地类划分标准一定程度上能够直观地反映林业重点建设工程的成效,有利于及时更新统计数据,有利于整个营林活动的合理安排,也有利于整个林业工程的整体布局。文章结合有关技术细则,联系实际,对有林地、疏林地、灌木林地、无立木林地和宜林地的科学划分提出了初步的建议。

基于不同地形因子林地地类时空格局分析——以云南省宜良县为例

林地地类时空格局变化是林地管理及林地保护与利用规划的重要参考,也是行业部门编制森林经营方案的基础;以云南省宜良县林地为研究对象,探究不同地形因子对林地地类变化影响的定量关系,对于揭示林地变化规律,提升林地监管效率具有重要参考。以30 DEM、2006年森林资源二类调查和2020年林地变更成果为数据源,借助ArcGIS分析地形因子高程、坡度、坡向、地形起伏度及地形位指数等对不同林地类型的影响及相关关系。结果表明:研究区林地地类以有林地为主,15年间林地地类时空变化最大的是有林地,其面积净增值为15 469.32 hm^(2),年均增速达1 104.95 hm^(2)/a;2006-2020年林地地类面积总体增加了12 511.97 hm^(2),其中有林地、未成林造林地及无立木林地面积增加明显。综上所述,从时空格局上,林地地类面积随着地形梯度的增大而呈现逐渐减少的规律,不同地形梯度分布的林地地类面积出现先增加后减少的动态趋势,地形因子显著限制林地地类的分布。在林地保护与利用规划中,应综合考虑各地形因子对林地地类分布的影响,从而科学经营森林,有效发挥其多功能效益。

Dynamics of Slope Runoff and Soil Erosion of Different Forest Types in Karst Depression

[Objective] The research was aimed to study the dynamics of slope runoff and soil erosion in different forest types in karst depression.[Method] Precipitation observation sites at the bottom of karst depression and runoff observation sites in different forest types were established to monitor regularly the main indices changes of runoff and soil erosion at fixed position in 4 years.[Result] The surface runoff of different forest types appeared singer peak from February to November,with lowest valley from June to July.The runoff coefficient appeared double peaks from February to May and from July to September.The changing coefficient of runoff appeared three peaks from March to April,from July to August and from September to November.The silt concentration appeared one peak from March to May and The erosion modulus appeared double peaks from March to May and from June to August.Runoff showed annually reduced trend with the growth of forests and the development of vegetation layer＇s structure.There was a positive correlation between the runoff and its silt concentration in different forest types.Precipitation and evaporation had notable positive correlation with the runoff,and similar correlation but not marked with silt concentration.The fitting analysis results of surface runoff and erosion modulus showed that rocky desertification intensified the unevenness of surface runoff and increased the surface runoff and erosion modulus.The penetrability of surface soil in new planted forest was lower than that in young forest,and that in surface soil of different forest types was higher than in bottom soil.[Conclusion] The research provided theoretical basis for the biological management technologies of water and soil conservation and the control of karst rocky desertification in karst regions.

Carbon Sequestration in Forest Vegetation of Beijing at Sublot Level

Based on forest inventory data (FID) at sublot level,we estimated the carbon sequestration in forest vegetation of Beijing,China in 2009.In this study,the carbon sequestration in forest vegetation at sublot level was calculated based on net biomass production (ΔB) which was estimated with biomass of each sublot and function relationships between ΔB and biomass.The biomass of forested land was calculated with biomass expansion factors (BEFs) method,while those of shrub land and other forest land types were estimated with biomass,coverage and height of referred shrubs and shrub coverage and height of each sublot.As one of special forested land types,the biomass of economic tree land was calculated with biomass per tree and tree number.The variation of carbon sequestration in forest vegetation with altitude,species and stand age was also investigated in this study.The results indicate that the carbon sequestration in forest vegetation in Beijing is 4.12 × 106 tC/yr,with the average rate of 3.94 tC/(ha·yr).About 56.91% of the total carbon sequestration in forest vegetation is supported by the forest in the plain with an altitude of < 60 m and the low mountainous areas with an altitude from 400 m to 800 m.The carbon sequestration rate in forest vegetation is the highest in the plain area with an altitude of < 60 m and decreased significantly in the transitional area from the low plain to the low mountainous area with an altitude ranging from 200 m to 400 m due to intensive human disturbance.The carbon sequestration of Populus spp.forest and Quercus spp.forest are relatively higher than those of other plant species,accounting for 25.33% of the total.The carbon sequestration in vegetation by the forest of < 40 years amounts to 45.38% of the total.The carbon sequestration rate in forest vegetation peaks at the stand age of 30–40 years.Therefore,it would be crucial for enhancing the capability of carbon sequestration in forest vegetation to protect the forest in Beijing,to limit human disturbance in the transitional area from the plain to the low mountain area,and to foster the newly established open forest.