West Guangdong is an important ecological barrier in Guangdong province, so understanding the spatial patterns and sources of heavy metal pollution of forest soil in this region is of great significance for ecological protection. In this study, the concentrations of heavy metals (Cd, Pb, Cu, Zn, and Ni) in forest soil were determined. Geostatistics, single-factor pollution index (PI), potential ecological risk index (RI), principal component analysis (PCA), and Pearson's correlation analysis were used to evaluate and analyze the characteristics of heavy metal pollution of forest soil. The results showed that the average concentration did not exceed the critical value. Cd, Pb, and Cu were enriched in southwest Xinxing County, while Zn and Ni were enriched in most areas of the Yunan and Yuncheng districts. Two groups of heavy metals from different sources were identified by PCA and a correlation analysis. Cd, Pb, and Cu in their respective enrichment areas were mainly from marble and cement production, whereas Zn and Ni were primarily from transportation and chemical fertilizer. Most of the study area was safe or slightly polluted while the heavy metal-enriched areas were moderately to severely polluted. The potential ecological risk was at a lower level in the study area but moderate in southwest Xinxing County. In summary, human factors impact the spatial patterns and ecological risks of heavy metals in forest soil. This study provides a scientific basis for forest soil pollution control and ecological protection.

森林可燃物载量调查专业性强,工作量大.无人机多光谱遥感可获取较大范围森林影像,为计算森林地表可燃物载量提供新的思路.试验区建立在广东省佛山市高明区,测得试验区平均地表可燃物载量高达每公顷39.33 t,且湿地松林Pinus elliottii地表可燃物载量最高.研究发现NDVI及EVI两种植被指数与森林地表可燃物载量之间存在中等强度的相关性,并建立了NDVI(X)与森林地表可燃物载量(Y)的回归模型:Y=-5.9354X+8.4663,以及EVI(X)与森林地表可燃物载量(Y)的回归模型:Y=-5.8485X+6.7271.研究还发现NDVI与地表可燃物载量的线性关系更为显著.

 The survey of forest combustible load is highly professional and requires lots of work. UAV multi-spectral remote sensing can obtain large-scale forest images, offering a new thinking for calculating the fuel load of forest surfaces. The test area was established in Gaoming district, Foshan city, Guangdong province. The average surface fuel load in the test area was measured up to 39.33 tons per hectare, and the slash pine forest surface fuel load was measured as the highest one. The study found that there was a moderate correlation between vegetation indices of NDVI & EVI and the fuel load of the forest surface. The regression model of NDVI ( X ) and the forest surface fuel load ( Y ) was established: Y = - 5.935 4 X + 8.466 3, and the regression model of EVI ( X ) and the forest surface fuel load ( Y ): Y = - 5.848 5 X + 6.727 1. The study also found that the linear relationship between NDVI and the surface fuel load was more apparent.

伴随着全球气候变暖的加剧,森林火灾的严重程度也将大幅增加,尤其是伤亡人数的增加,引起政府及学者们的高度关注.为此,开展森林防灭火督导、强化责任落实,把森林防灭火工作落到实处具有重要意义.本文通过对河源市、梅州市开展森林防灭火督导工作,解析了森林防灭火工作的成效与亮点,指出了目前森林防灭火工作存在的一些问题,结合广东省森林防灭火特点,在森林火灾示范建设、火灾隐患排查、严格火源管控、营造防火氛围、完善应急分级响应机制、加强两支队伍建设等方面提出了做好森林防灭火工作的建议与对策.

Stocks and stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) in ultisols are not well documented for converted forests. In this study, Ultisols were sampled in 175 plots from one type of secondary forest and four plantations of Masson pine (Pinus massoniana Lamb.), Slash pine (Pinus elliottii Engelm.), Eucalypt (Eucalyptus obliqua L’Hér.), and Litchi (Litchi chinensis Sonn., 1782) in Yunfu, Guangdong province, South China. Five layers of soil were sampled with a distance of 20 cm between two adjacent layers up to a depth of 100 cm. We did not find interactive effects between forest type and soil layer depth on soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) concentrations and storages. Storage of SOC was not different between secondary forests and Eucalypt plantations, but SOC of these two forest types were lower than that in Litchi, Masson pine, and Slash pine plantations. Soil C:P was higher in Slash pine plantations than in secondary forests. Soil CNP showed a decreasing trend with the increase of soil depth. Soil TP did not show any significant difference among soil layers. Soil bulk density had a negative contribution to soil C and P stocks, and longitude and elevation were positive drivers for soil C, N, and P stocks. Overall, Litchi plantations are the only type of plantation that obtained enhanced C storage in 0–100 cm soils and diverse N concentrations among soil layers during the conversion from secondary forests to plantations over ultisols.

Fuelbreaks are important proactive measures in wildfire prevention and mitigation. Among the most popular ones are the shaded fuelbreaks widely used in western countries and the green fire barriers developed in China forestry sector. While shaded fuelbreaks are considered a main strategy for reducing the distribution of fuel loads in a specific wildland zone, creating green fire barriers involves the dense planting of evergreen broad-leaved trees in a stripped area of flammable plant communities to prevent and block the spread of surface and crown fires. Unlike the shaded fuelbreak technique, the hazard reduction function of a green fire barrier originates from the traits of low-flammability trees and the unique structure formed by the prescribed plantation. Surface fire is mitigated by inhibiting the growth of surface fuels within the strip, whereas crown fire is attenuated and eventually blocked by significantly altering the heat transfer efficiency during an external fire attack. As often demonstrated in practice, the extensive application of this technique in fire-prone areas not only plays a role in mitigating the occurrence of wildfire and its impact on the local environment, but also somehow moderates the local meteorology and wind patterns. These two main fuelbreak approaches are key ecological fire protection techniques that simultaneously achieve prevention and control of accidental forest fires, forest health management and ecological maintenance. As two typical strategic measures, the effective fusion of these approaches can generate multiple economic treatment prescriptions for fire prevention and control at different vegetation scenes subjected to any potential heat sources. The derivatives of these fuelbreak approaches provide systematic tools for constructing both a fire resilient landscape and a green living environment with tolerable fire risk and controllable fire losses.

桉树Eucalyptus spp.人工林蓄积调查是林业生产经营的重要工作,无人机机载激光雷达能够自动获取大面积桉树人工林的激光点云数据,为计算桉树蓄积量提供新的方法.研究通过试验样地实际数据,建立了桉树树高(X)与胸径(Y)的回归模型:Y=3.6116e0.0674X,并结合激光雷达软件获取的株数、树高估算样地总蓄积量.比较激光雷达测量与实地测量结果发现,激光雷达测量的株数比实测株数少27.09％,平均树高高8.67％,平均胸径大8.25％,总蓄积量小22.68％.因此,对于大尺度获取桉树成熟林的总蓄积量V,可以使用V=V0/(1-22.68％)对激光雷达测量的总蓄积量V0进行修正.

森林防灭火工作事关国家生态安全、人民生命财产安危和社会大局稳定.针对广东森林生态建设现状以及森林防灭火面临新形势,剖析了目前存在的森林大火风险、扑火安全风险、应急能力风险等.最后针对广东森林防灭火工作存在的实际问题,有的放矢提出了森林防灭火工作的对策.

Cadmium (Cd) is a toxic metal and found in various soils, including forest soils. The great spatial heterogeneity in soil Cd makes it difficult to determine its distribution. Both traditional soil surveys and spatial modeling have been used to study the natural distribution of Cd. However, traditional methods are highly labor-intensive and expensive, while modeling is often encumbered by the need to select the proper predictors. In this study, based on intensive soil sampling (385 soil pits plus 64 verification soil pits) in subtropical forests in Yunfu, Guangdong, China, we examined the impacting factors and the possibility of combining existing soil information with digital elevation model (DEM)-derived variables to predict the Cd concentration at different soil depths along the landscape. A well-developed artificial neural network model (ANN), multi-variate analysis, and principal component analysis were used and compared using the same dataset. The results show that soil Cd concentration varied with soil depth and was affected by the top 0–20 cm soil properties, such as soil sand or clay content, and some DEM-related variables (e.g., slope and vertical slope position, varying with depth). The vertical variability in Cd content was found to be correlated with metal contents (e.g., Cu, Zn, Pb, Ni) and Cd contents in the layer immediately above. The selection of candidate predictors differed among different prediction models. The ANN models showed acceptable accuracy (around 30% of predictions have a relative error of less than 10%) and could be used to assess the large-scale Cd impact on environmental quality in the context of intensifying industrialization and climate change, particularly for ecosystem management in this region or other regions with similar conditions.

远程林火视频监控系统是怀集县森林重点火险区综合治理三期工程的建设重点.怀集县远程林火视频监控系统由林火视频监控前端、传输网络和后端监测中心的组成,设计了各组成部分的功能,并对系统的建设与实现进行了详述.系统共建设了36处林火监控视频前端,监测范围覆盖了全县1200 km2的林地.系统投入使用后,森林火灾受害率从2014年的0.43‰下降到2017年后的0.01‰以下,极大提高了怀集县森林防火预警监测及应急处置能力,有效降低了森林火灾隐患.

森林生态系统是重要的碳库,在减缓全球气候变暖中具有独特的功能。林火干扰作为非连续的生态因子,是全球生物地球化学循环的驱动因子,可显著改变生态系统的结构和功能以及养分循环和能量传递,引起森林碳库和碳分配格局的变化,进而影响森林演替进程及固碳能力。本文阐述林火干扰对森林生态系统碳库影响的国内外研究方法进展,重点论述林火干扰导致的直接碳损失以及通过森林净初级生产力和土壤呼吸的改变间接影响森林碳循环和碳平衡;并分别阐明林火干扰对植被碳库、凋落物碳库和土壤有机碳库的影响,林火干扰通过直接改变植被覆盖度进而影响植被碳库和营养元素周转,最终影响植被的碳固定及碳从植被向土壤的转移,导致不同碳库之间的重新分配。通过探讨净初级生产力变化对林火干扰的响应,揭示林火干扰对植被碳库循环的间接且长期影响的机制;在林火干扰对生态系统凋落物碳库的影响方面,主要探讨林火干扰后凋落物生产量在不同林火强度和环境梯度下的变化;在林火干扰对土壤有机碳库的影响方面,通常在小尺度范围内影响土壤有机碳库垂直分布变化的主要原因可能是地形条件的变化,而在相对大的区域尺度下,气候、土壤质地、地形、植被及人类活动和管理水平及其交互作用均可影响土壤有机碳库的空间迁移和形态转化,从而导致不同区域范围的土壤有机碳库分异。在此基础上,指出目前研究存在的问题,并提出林火干扰对森林碳库影响的定量化研究路径:1)深入开展林火干扰对森林生态系统碳库循环的影响机制研究; 2)加强"植被-土壤-水-微生物-气候"的系统研究; 3)完善不同时空尺度下林火干扰对森林碳库周转过程的定量化研究; 4)深入探讨林火干扰与森林生态系统碳元素的相互作用关系及影响机制。

由林火生态学观念出发,展示林火生态基本要素和在生态保护中的地位,研讨林火管理目标定位和工作策略.目前管理体系中过于看重森林资源特性,忽视其自维持生态系统特性,相应产生对火源管理和火灾现象处置的极端理念,造成目前不计代价、有火必救和救必彻底的森林消防管理格局.缺少必要的可燃物管理主导的森林生态维护,仅仅着力于林火应急响应力量提升和火灾的控制,必然引起森林生态健康失衡,更因长期可燃物积累导致难以控制超大规模火灾的发生并由此产生难以估量的火灾损失及处置和善后费用,这已被近年国内外典型火灾案例所证实.加强森林可燃物管理和相关防火技术的落实,有利于维护森林生态健康的长期稳定,有效降低重特大火灾发生的概率,实现人与森林生态和谐与共和可持续发展的根本目标.

The depth-specific soil texture map with high-resolution (i.e. <= 10 m) is essential for soil management and forest silviculture. The objective of this research was to develop a modelling method to generate high-resolution soil texture maps at five depths (D1: 0-20, D2: 20-40, D3: 40-60, D4: 60-80, and D5: 80-100 cm) in Yunfu, a typical area of Udults Zone, South China. Taking a coarse-resolution soil texture (CST) map with a 1: 2,800,000 scale and nine topo-hydrologic variables derived from a digital elevation model (DEM) with 10 m-resolution as input candidates, a series of artificial neural network (ANN) models for five depths were built and evaluated by a 10-fold cross-validation with 385 soil profiles from the Yunfu forest. The results indicated that the optimal model for five depths engaged five, five, five, four, and four DEM-generated variables as inputs, respectively, and model accuracies for estimating sand and clay contents varied with root mean squared error (RMSE) of 6.8-9.7%, R-2 of 0.56-0.72, and relative overall accuracy (ROA) +/- 5% of 54-81%, which were better than most of other researches. An extra independent validation with 64 soil profiles outside of the model-building area also indicated that the optimal models had adequate capabilities for generalization with RMSE of 9.2-12.2%, R-2 of 0.33-0.47, and ROA +/- 5% of 37-53%. The depth-specific sand and clay content maps with 10 m-resolution generated from the optimal models in Yunfu showed more detailed information than the CST map, and could reflected the influence of the DEM-derived topo-hydrologic variables. Based on the generated maps, horizontal characteristics of soil texture in the study area exhibited an obvious process of clay translocation from the topsoil (D1) to subsoil (D2-5), a maximum accumulation of clay in D4, and a dominant sandy soil in the topsoil (D1). Thus, the modelling method, i.e. developing ANNs with k-fold cross-validation, can be used to generate depth-specific soil texture maps in Udults Zone, South China. In addition, the generated high-resolution maps can clearly show the changes of soil texture in three-dimension.

针对四川凉山州“3·30”森林火灾及扑火人员伤亡事件从客观与主观两方面进行了原因剖析,提出了7个方面的森林防火工作建议与对策.

森林火灾作为森林非连续的干扰因子,是生物地球化学循环的驱动因子,显著改变生态系统的结构和功能及养分循环与能量传递,引起森林碳库与碳分配格局的变化,进而影响森林演替进程及固碳能力.该研究以广东省马尾松(Pinus massoniana)次生林为研究对象,采用相邻样地比较法和空间代替时间法,以野外调查采样与室内试验分析为主要手段,定量研究突发性森林火灾对土壤有机碳密度的影响,探讨森林火灾对土壤有机碳固持的影响机制.结果表明:与对照相比,森林火灾后的幼龄林、中龄林和成熟林的土壤有机碳密度分别为35.12、40.80和52.34 t·hm-2,依次降低了10.93％、8.52％和7.56％.相比对照,幼龄林、中龄林和成熟林土壤剖面(0-60cm)的土壤有机碳密度变化范围分别为5.04-7.76、5.26-10.27和6.33-13.58 t·hm-2,依次降低了2.51％-16.83％、1.31％-11.85％和1.09％-12.50％;森林火灾显著降低了幼龄林和中龄林0-30 cm的土壤有机碳密度,显著降低了成熟林0-20 cm的土壤有机碳密度.马尾松次生林土壤有机碳密度与土壤理化性质具有显著相关关系.通径分析表明,对照样地和过火样地中,土壤全氮含量均对土壤有机碳密度的直接作用最大,土壤细根生物量对土壤有机碳密度的直接作用较小,但其通过土壤全氮含量对土壤有机碳密度的影响均表现在间接作用上.嵌套方差分析表明,土壤深度解释了土壤有机碳密度变异的70.60％,林龄解释了其变异的25.35％,森林火灾解释了其变异的2.34％.研究发现:森林火灾减少了马尾松次生林各林龄的土壤有机碳密度.在水平方向上,随着林龄增长,土壤有机碳密度的减少幅度降低;在垂直方向上,土壤有机碳密度随着土壤土层深度加深而降低,且随林龄增长减少幅度下降.研究森林火灾对森林生态系统土壤有机碳的影响,有助于理解森林生态系统土壤碳固持和碳循环过程,对制定旨在减缓全球变化的科学合理的林火管理策略具有重要意义.

森林火灾是森林生态系统中的重要干扰之一,深刻影响着土壤生物和非生物特性动态变化,进而影响生态系统养分循环和平衡.选择森林火灾典型分布区域,选取相似立地条件的具有南方代表性的不同发育阶段(不同林龄:幼龄林、中龄林和成熟林)的马尾松(Pinus massoniana)次生林,在火烧迹地(过火样地)及相邻未烧林分(对照样地)进行野外调查和采样,定量研究森林火灾对土壤理化性质的影响.森林火灾增加了马尾松次生林不同林龄的土壤容重、土壤pH值和土壤全磷,降低了不同林龄的土壤含水率、土壤全氮和土壤有机碳含量;提高了土壤C/N比,减少了C/P比和N/P比,且土壤含水率、土壤全氮、土壤全磷和土壤有机碳含量均随着林龄增长而增加,土壤容重和土壤pH值随林龄增长而减少.相关分析表明,土壤细根生物量与过火样地的土壤容重和土壤pH值呈负相关,而与土壤全氮、土壤全磷和土壤含水率呈极显著正相关(P<0.01).不同林龄土壤有机碳含量与土壤全氮耦合性较高.嵌套方差分析表明,引起马尾松次生林土壤理化性质变异的原因是不同林龄、不同土壤深度和森林火灾,林龄和土壤深度解释了土壤理化性质的10.80％—69.80％,森林火灾解释了土壤理化性质变异的2.50％—11.20％.森林火灾对不同林龄马尾松次生林的土壤理化性质均产生影响.马尾松次生林土壤含水率、土壤全氮、土壤全磷和土壤有机碳含量均呈现为随土壤土层深度加深而减少的趋势,而土壤容重和土壤pH值则表现为随土壤土层深度加深而增加的趋势.研究结果进一步量化了森林火灾对土壤理化性质的影响,可为火烧迹地恢复、森林碳汇管理、林业可持续发展提供科学支撑.

随着气候变暖加剧,全球森林火灾灾害发生的频率与强度亦随之增加,世界各地森林火灾潜在的危险将长期存在,严重程度也将大幅增加.森林火灾对森林生态资源和全球气候产生了重大影响,由于其突发性强、破坏性大、处置救助极为困难,是当今世界最为严重的生态灾害和突发性公共事件之一.森林火灾发生发展规律是森林火灾预防与扑救的重要依据,加强其规律研究有利于有的放矢地开展森林防灭火工作.针对气候变化现状及发展态势,结合气候变化背景下国内外森林火灾现状,系统论述了气候变化对我国森林火灾发生发展规律的影响,主要阐述了气象条件影响森林火灾的发生,气候影响森林可燃物,气候影响森林火源,气象影响森林火行为,气候决定森林火灾周期以及气候变化对森林火灾时空分布规律的影响.在全球气候变暖的背景下,从解析我国森林火灾发生规律入手,通过气候变化背景下我国森林火灾发生规律的研究,客观认识我国和各地区森林火灾发生发展规律,从而为国家和地方各级政府有效开展森林火灾灾害防治和应急管理工作、切实保障社会经济可持续发展提供科学决策依据.

[目的]定量研究不同林火干扰对森林生物碳库的变化规律,揭示林火干扰对森林生物碳密度的影响机制,为林火干扰后森林生态系统碳汇管理提供参考依据。[方法]以广东省亚热带2种典型针叶林为研究对象,采用相邻样地比较法,以野外调查采样与室内试验分析为主要手段,定量测定不同林火干扰强度对森林生物碳库（植被碳库和凋落物碳库）碳密度与碳分配格局的影响。[结果]林火干扰对亚热带2种典型针叶林的植被和凋落物碳密度有影响,均表现为对照＞轻度林火干扰＞中度林火干扰＞重度林火干扰。轻度林火干扰对植被碳密度的影响差异不显著（P＞0.05）,而中度和重度林火干扰则显著降低了植被碳密度（P＜0.05）。相同林火干扰强度下,植被各组分碳密度的变化均表现为乔木最大。乔木碳密度在不同林火干扰强度下均呈现为对照＞轻度林火干扰＞中度林火干扰＞重度林火干扰,而草本碳密度则呈现与乔木碳密度相反的变化趋势。林火干扰显著影响乔木和草本碳密度,亦对灌木碳密度产生了影响。不同林火干扰强度对凋落物碳密度的影响有所差异,但不同林火干扰强度均显著减少了凋落物碳密度（P＜0.05）,并随林火干扰强度的增加其减少幅度增大。[结论]林火干扰减少了植被和凋落物碳密度,进而对森林生态系统的碳密度产生重要影响。

以韶关市为例,系统介绍森林防火工作的亮点和成效.韶关市清明节期间以森林防火督导工作为先导,森林防火工作早部署早安排,狠抓森林防火责任和具体工作落实,压实基层森林防火责任,有序开展清明节期间的森林防火工作.最后探索性地提出了适合当地实际,在森林火灾预防、队伍装备建设、制度建设、法律责任追究方面建立健全森林防火长效机制,完善标本兼治的森林防火措施,切实把防火的重点转移到"预防为主"的轨道上来.

森林火烧迹地面积的传统调查方法存在劳动强度大、效率低、数据可靠性不高等问题.为解决上述问题,研究设计了无人机荷载多光谱传感器对森林火烧迹地面积进行调查的方法,并利用野外实验对该方法进行了初步验证.结果表明该调查技术可快速准确获取较大范围的森林火灾火烧迹地面积,精度可达94.44％,提高了火烧迹地调查的效率.