Forest cover change and its driving forces in Fagita Lekoma District,Ethiopia

This study investigated forest cover change and the driving forces behind it in Fagita Lekoma District of Ethiopia that resulted in increased forest cover, which might be uncommon outside this case study area. The LULC change analysis was made from 2003 to 2017 based on Landsat images. Socioeconomic analysis was carried out to identify the major driving forces that resulted in LULC change. A questionnaire survey, focused group discussion, key informant interviews and field observation were employed to analyze the link between LULC change and the driving forces. The 15-year period(2003–2017)image analysis revealed that the coverage of forest lands,built-up areas and grassland has increased by 256%, 100% and 96%, respectively, at the expense of cultivated lands and wetlands. The increased forest cover is due to the woodlots expansion of Acacia decurrens Willd, which are designed for sustainable livelihoods and a land revitalization strategy in the study area. Rapid population growth, an increasing demand for charcoal and subsequent market opportunities, preferred qualities of A. decurrens or black wattle to halt land degradation as well as to improve land productivity, have been identified as the major driving forces of forest cover change. Chi squared analysis revealed that: a comparative cash income from the sale of A. decurrens; a dependency on natural forests; the distance from the district administrative center; the size of the active labor force, and the area of land owned have significantly affected the cover change. The major forest cover change is due to the expansion of A. decurrens plantations that have socioeconomic and environmental implications to improve rural livelihoods and revitalize the land. Thus, the positive experiences identified in this study should be scaled-up and applied in other similar settings.     

Assessing impact of climate change on forest cover type shifts in Western Himalayan Eco-region

Climate is a critical factor affecting forest ecosystems and their capacity to produce goods and services. Effects of climate change on forests depend on ecosystem-specific factors including dimensions of climate (temperature, precipitation, drought, wind etc.). Available information is not sufficient to support a quantitative assessment of the ecological, social and economic consequences. The present study assessed shifts in forest cover types of Western Himalayan Eco-region (700?4500 m). 100 randomly selected samples (75 for training and 25 for testing the model), genetic algorithm of rule set parameters and climatic envelopes were used to assess the distribution of five prominent forest cover types (Temperate evergreen, Tropical semi-evergreen, Temperate conifer, Subtropical conifer, and Tropical moist deciduous forests). Modelling was conducted for four different scenarios, current scenario, changed precipitation (8% increase), changed temperature (1.07°C increase), and both changed temperature and precipitation. On increasing precipitation a downward shift in the temperate evergreen and tropical semi-evergreen was observed, while sub-tropical conifer and tropical moist-deciduous forests showed a slight upward shift and temperate conifer showed no shift. On increasing temperature, an upward shift in all forest types was observed except sub-tropical conifer forests without significant changes. When both temperature and precipitation were changed, the actual distribution was maintained and slight upward shift was observed in all the forest types except sub-tropical conifer. It is important to understand the likely impacts of the projected climate change on the forest ecosystems, so that better management and conservation strategies can be adopted for the biodiversity and forest dependent community. Knowledge of impact mechanisms also enables identification and mitigation of some of the conditions that increase vulnerability to climate change in the forest sector.     

Fire Environment Mechanism of Lightning-groundfire for Daxing''''anling Mountains

Ground fire is an igniting phenomenon that is difficult to control and lightning is the main cause of ground fire. The mechanism of lightning-ground fire is very complex. Daxing'anling Mountains forest region is the place that lighting-groundfire occurs more often and regularly. Our study on lightning-groundfire of this zone in 2002 shows: much more soil near the surface and the ground fuel is the matter preconditions of lightning-groundfire, and the weather conditions hasten the occurrence of lightning-groundfire. Especially in the conditions with low precipitation, long time drought, increasing surface temperature, relative humidity depressing and fuel dryness, lightning-groundfire is easy to occur. Lightning-groundfire has spatiotemporal character. Lightning-groundfire occurs mostly in primary forest zone, such as conifer forest, broadleaf forest, conifer and broadleaf mixed forest. Lightning-groundfire often burns slowly, for a long time and completely, and it has the characteristics of high conceal     

一个世纪来黑龙江省森林景观动态研究

With the help of GIS tool of ARC/INFO,ARCVIEW and FRAGSTATS,the map of forest resource distribution of Heilongjiang Province was analyzed in 1896,1949 and 1981.Using total area,mean patch size,patch density,coefficient of patch size variation,mean patch fractal dimension and mean shape index,we studied the change of forest landscape pattem and the change of each patch types in this region.As a result,the total area of forest landscape and mean patch size decreased sharply,the quantity and density of patches increased,the juxtaposition of patches weakened,the shape of patch tended to become regular,and the border of patch simplified.All these showed that the forest landscape of this area tended to fragment gradually,and the fragment of Korean pine forest is the severest.the diversity of whole forest landscape and the eveness of landscape types distribution reduced gradually.Human impact,instead of climate change and forest community succession,is the most important reason for such dramatic chages.     

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since the catastrophic fire took place on the northern slope of Great Xing‘an Mountains in 1987. Forest canopy density, which has close relation to forest productivity, was selected as a key factor to find how much the forest quality was changed 13 years after fire, and how fire severity, regeneration way and terrain factors influenced the restoration of forest canopy density, based on forest inventory data in China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. The results showed that fire severity which was inversely correlated with forest canopy density grade was an initial factor among all that selected. Regeneration way which did not remarkably affect forest canopy density restoration in short period, may shorten the cycle of forest succession and promote the forest productivity of conophorium in the future, Among the three terrain factors, the effect of slope was the strongest, the position on slope was the second and the aspect was the last.     

Growth Process of Eucalyptus urophylla × E.grandis Stand Based on Logistic Equation

Eucalyptus is the most valuable cultivated forest genus in the tropical and subtropical areas nowadays. It has been a challenge for foresters to model growth due to the genetic variations, management regimes, and multiple products generated from the plantations. In this paper, Logistic equation was used to study the stock growth process of E. urophylla × E. grandis plantation at age of 14 with 6 spacing treatments. And the biological interpretation of the parameters of Logistic equation was analyzed. The re...     

Spatial pattern analysis for quantification of landscape structure of Tadoba-Andhari Tiger Reserve,Central India

Landscape structure is often regarded as an important factor that governs the distribution and abundance of species.Therefore it is critical to understand the landscapes and their dynamics.Patterns of landscape elements strongly influence the ecological characteristics.This study was designed to document and map the current status of the tropical dry deciduous forest of the Tadoba-Andhari Tiger Reserve(TATR),Central India,(using IRS P6 LISS IV data)and to describe its landscape structure at three levels of organization viz.landscape,class,and patch.The study area was classified into 10 land cover classes that include 6vegetation classes.The landscape structure was analyzed using FRAGSTATS using 12 set of indices.The TATR landscapes have a total of2,307 patches with a mean patch size of 25.67 ha and patch density of 1.7patches per km2.Amongst all land cover classes,mixed bamboo forest is dominant—it occupied maximum area(77.99%)—while riparian forest is least represented(0.32%).Mixed forest has maximum number of patches among all vegetation classes.Results have shown that despite being dominant in the area,mixed bamboo forest has low patch density(0.25/100 ha).Dominance of mixed bamboo forest is attributed to large patch sizes and not to the number of patches.This study has focussed on the approach of integrating satellite forest classification and forest inventory data for studying forest landscape patterns.     

Assessing forest fragmentation in north-western Himalaya: a case study from Ranikhet forest range,Uttarakhand, India

The northwestern Himalaya harbors high levels of biodiversity due to its unique topography, climatic conditions and heterogeneity. Forest fragmentation is one of the major threats causing a decline in biodiversity in the Himalayan region. We assesses forest fragmentation and changes in land use land cover(LULC) patterns using multi-temporal satellite data over a time span of four decades(1976–2013). Fragmentation analysis using the Landscape Fragmentation Tool(LFT) reveals a decrease in core and edge areas by 14 and 2.3 %, respectively; while an increase in non-forest, patch area and perforation area by 2.1, 0.4, and 14 %, respectively. The LULC dynamics show that the areas under dense forest and scrub forest have decreased by 2.8 % and 1.9 %, respectively; and there is an increase in open forest, crop land and fallow land area by 2.6, 1.7 and 2.1 %, respectively. The quantification of landscape heterogeneity is undertaken with the help of landscape metrics computed using FRAGSTATS at class and landscape level, showing signs of increased fragmentation. Our study provides baseline database that can support the future biodiversity conservation and sustainable forest management initiatives.     

Species composition and minimum sampling area of a riparian mixed broadleaved-Korean pine forest in Changbai Mountain Nature Reserve

Riparian areas are unique although often small component of the overall watershed landscape. The structure of riparian forests along Erdaobai River on the north slope of Changbai Mountain were investigated by using field data collected from eight sampling transects perpendicular to the Erdaobai River channel. Two kinds of species-area saturation curves were used to examine the relationship between species number and minimum sampling area. The results showed that riparian gymnosperms accounted for a high proportion of all gymnosperms in the Changbai Mountain Nature Reserve while riparian ferns and angiosperms accounted for a relatively low proportion. The average minimum sampling areas of riparian forest that included 60%, 80%, and 90% of the community species pool were about 85, 185, and 328 m 2 , respectively; while those for nonriparian forest were about 275, 390, and 514 m 2 , correspondingly.     

文峪河流域景观格局动态及其驱动力分析

以文峪河流域为研究对象,分析流域2000—2018年景观格局数量动态的面积、转移及速度特征。从斑块类型尺度与景观尺度2个层面选取景观指数分析流域近18年的景观格局动态,并在流域尺度上沿城市—林区梯度线分析沿线景观格局指数的梯度分布,基于数量统计模型对景观格局动态驱动力进行研究。结果表明,流域耕地、林地、草地面积有所减少,向其余地类支出面积,水域、建设用地、未利用地面积增加,向其余地类吸收面积,不同地类土地转移、变化速度情况不同。不同景观类型的格局动态不同,流域整体景观破碎化程度增加,连通性下降、景观规则度下降、景观核心面积下降,不同景观指数的梯度分布特征不同。自然驱动因子、社会驱动因子对流域景观格局变化均具有驱动作用,文峪河流域的景观动态在过去18年间经历了快速、复杂的变化,社会经济驱动因子是景观格局演变的主要驱动力量,经济与人口发展、产业结构及工业化进程是文峪河流域景观格局演变的重要驱动力量。     

基于GIS的桃山林场森林景观格局研究

以河北省木兰围场国有林场管理局桃山林场施业区内的森林资源为对象,利用GIS技术对其森林景观及分布规律进行分析,结果表明:桃山林场森林景观以混交林为主体,其面积占景观总面积的60.42%,斑块数量占景观斑块总数量的29.01%,优势度达到3.474 5。在斑块规模中,以混交林斑块最大,纯林和荒山荒地也有较大规模,疏林地也有相当规模分布,未成林造林地、宜林沙荒地、灌木林、耕地和其它用地景观规模最小;各类斑块的极差值均较大,斑块大小的分化较强烈。混交林的形状最复杂;其次是未成林造林地、纯林、荒山荒地、灌木林、宜林沙荒地、耕地和疏林地;其它用地的形状规整,边缘形状简单,说明这类景观斑块受人为干较严重。     

基于GIS的白河林业局景观格局演变研究

在CIS的支持下,应用景观生态学的理论和方法,采用景观格局指标定量分析,研究1987．2000年长白山地区白河林业局景观格局的动态演变,探讨区域景观生态过程和森林景观格局演变之间的关系。结果表明：1987～2000年间,经营总面积减少1663．87hm^2,斑块数目增加4240个;受区域自然地理要素的影响和社会经济因素的制约,形成以有林地景观为主导的疏林地、灌木林地、沼泽地、非林业用地等呈补丁状散布之中的区域景观格局;随着人类干扰强度的增加,景观多样性指数上升,斑块密度增加,破碎化程度进一步加强。     

基于GIS和Markov的黄龙山天然林区林地变化研究

以黄龙山林区为研究对象,以其1986年、1997年、2006年森林资源二类调查资料为数据源,运用GIS空间分析模型、土地利用动态度模型对该林区三期林地面积变化及水平空间格局特征进行了分析,并运用马尔可夫(Markov)模型对2015年林地类型分布状况进行了预测。研究表明:研究区林地类型结构以阔叶林和针叶林为主;1986-1997年间,针叶林、阔叶林、农田等面积增加,荒地剧烈减少,反映出该区域天然更新、人工抚育和植树造林以及垦荒造田的发展过程;1997-2006年间,退耕还工程的实施,使农田和荒地减少,阔叶林和灌木林地,特别是针叶林的大幅增加,主要变化趋势为其他土地利用类型转向有林地和灌木林地,土地利用类型向着更加理想的方向转移。Markov模型模拟结果表明,今后9年内阔叶林面积将会由增加转为减少,针叶林面积和针阔混交林面积有所增加,这一结果将在2015年林地变化调查中进行验证。     

永定河流域土地利用景观格局变化研究

以永定河流域为研究对象,对1978～2009年间6期遥感图像的土地利用情况进行解译,运用景观格局指标,分析永定河流域景观格局动态变化．结果表明：32年来永定河流域以农、林、草业景观为主,耕地面积有下降趋势,林地面积2000年最低,后缓慢上升,水域面积近10年下降明显．景观破碎化程度呈不断上升的趋势,多样性指数逐步升高,景观类型均匀度总体有下降趋势,景观类型转移概率矩阵表明,林地最为稳定,干旱河道的变化最大．     

喀什河流域生态景观格局量化分析

以遥感与地理信息技术为基础,编制了喀什河流域生态景观图。在此基础上选取多种景观指数,从景观多样性指数、景观空间构型指数、斑块特征指数3个方面,定量地分析喀什河流域景观格局特征。结果表明：喀什河流域山地景观占全流域的88%。该区域的景观基质为山地景观;流域内部景观高度连接,生态系统稳定;城镇景观、乡村景观和建设用地景观的分布很集中,基本为连片分布,呈聚集状,镶嵌在山地景观和绿洲景观中,分维指数大,破碎度高;景观处于稳定状态,其中山地景观和绿洲景观中最稳定,景观受干扰与斑块伸长程度都较小;从总体上看,喀什河流域的景观单一,多样性指数较小,破碎化程度较低,景观异质性较低,景观优势度较高。     

Forest cover changes in the Oregon Coast Range from 1939 to 1993

Understanding the shifts over time in the distribution and amount of forest vegetation types in relation to forest management and environmental conditions is critical for many policy and ecological questions. Our objective was to assess the influences of ownership and environment on changes in forest vegetation from post-settlement historical to recent times in the central Coast Range of Oregon. We evaluated land cover types on 1475 20 m plots, using scanned, geo-referenced historical (1939) and recent (1993) aerial photos. The amount of older conifer cover declined by 63% relative to its former amount, from 36 to 13% of the landscape, during the 54-year period. Dominant ownership of older conifer stands shifted from industrial private to Forest Service lands. Younger conifer stands showed the greatest expansion in cover, increasing more than two-fold, from 21 to 44% of the landscape. Shrub and hardwood cover declined by 16%, from 31 to 25% of the landscape. Shrubs and hardwoods occurred at lower slope positions and closer to streams at the end of the period than at the beginning. Ownership was not an important determinant of the presence of large and very large conifer cover or shrub and hardwood cover in 1939, but was a very important factor affecting the presence of these cover types in 1993. Landscape transitional pathways were distributed among many types and no single transitional pathway was dominant. Even the most stable cover types (hardwood trees and herbs) had low absolute stability, with over 65% of their plots changing to another cover type by 1993. Our research indicates that the importance of ownership as a factor affecting the type of vegetation cover present has increased greatly during this time, whereas the relative influence of environment has lessened considerably. Land owners in the Oregon Coast Range have altered the cover and distribution of vegetation in diverse ways, changing the landscape to one dominated by young conifers, shifting the distribution of younger successional shrubs and hardwoods toward streams, and restricting the location of older coniferous stands to particular ownerships and site types.     

广州市白云区森林景观镶嵌结构的分形分析

利用分形理论建立了广州白云区森林景观镶嵌结构的回归模型。以森林景观各斑块类型的分维数和稳定性指数为依据分析了该区各种森林景观类型的复杂性和稳定性。探讨了影响该区森林景观镶嵌结构的成因。结果表明:白云区森林景观镶嵌结构具有分形特征,其分维数为1.044 3~1.146 1;稳定性指数为0.353 9~0.455 7。该结果定量地反映了白云区森林景观结构形态在人类活动控制下,形状比较规则,结构趋向简单化。     

文峪河流域河岸带植被景观格局分析与规划

以山西吕梁文峪河流域地形图、航片等为基础资料,借助Geoway软件及Visual FoxPro与Microsoft Excel对数据进行处理、转化.选取斑块面积指数、标准差、变动系数、多样性指数、优势度等景观指数对流域总体景观格局进行分析.结果表明,林地和灌草丛对整个流域河岸带植被景观起绝对控制作用,占相当比重的耕地是流域治理中不容忽视的类型;小规模分散分布的村庄是引起流域河岸带景观破碎化的主要原因;水面、草甸等类型对维护河岸带景观多样性有着重要意义.藉此,提出了流域分段治理的规划设计,即在流域上游段,以自然演替优先,辅以人工管理;在中游段,封育管建并重,人为促进更新;在人为干扰严重的下游段,以人工建设为主进行河岸带生态恢复重建.     

1957-2012年滇西北剑湖景观演变特征及驱动因子研究

以1957～2012年具有代表性的6期航空和卫星影像为研究数据,利用ERDAS IMAGINE9．2、ArcMap10、Fragstats3．3等软件,选取一些常用景观指数,分析了1957～2012年剑湖研究区景观演变特征和驱动因子。结果表明,（1）湖泊和农地的面积呈减少趋势,河流、沼泽、鱼塘、农村居民地和有林地的面积呈增加趋势。湖泊和农地分别减少了203．0hm2和44．5hm2,河流、沼泽、鱼塘、农村居民地和有林地分别增加了1．2hm2、84．9hm2、42．2hm2、52．2hm2和67．0hm2。（2）景观类型数量、景观破碎化程度、景观形状复杂程度和景观多样性都呈现逐渐增加的趋势,说明剑湖景观受人为干扰越来越强烈。（3）湖泊主要转移成了沼泽,沼泽主要转移成了鱼塘、农地和有林地,鱼塘转移成了沼泽和农地,农地主要转移成了农村居民地和有林地。（4）人为驱动因子对剑湖景观演变的影响要比自然驱动因子大得多,总体上形成了以人为驱动因子为主、自然驱动因子为辅的景观演变驱动因子格局。