Spatio-temporal Variations in Plantation Forests'Disturbance and Recovery of Northern Guangdong Province Using Yearly Landsat Time Series Observations(1986-2015)

Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.

Investigation and Analysis of Natural Environment of the Karst Mountain Areas in Northern Guangdong

[ Objective] The aim was to study the natural environment of Karst mountain areas in northern Guangdong. [ Method] Through the col- lection of topography, climate, soil and vegetation data in the Karst mountain areas of Northern Guangdong, combined with field investigation, the natural environment of Karst mountain areas in northern Guangdong was analyzed. [ Result] The Karst topography of the area is widely distributed. Most places were in subtropical climate zone, with high temperature and rainfall in the same period, and abundant precipitation. There was a large area of contiguous distribution of limestone with dissolution area. Vegetations included typical limestone evergreen and deciduous broadleaved mixed forest, limestone shrub and grassy slopes in mountain and hill. Limestone vegetation had typical limestone mixed evergreen broadleaf forest, limestone shrub, limestone hilly mountain grass slope. [ Conclusion] The study provided theoretical basis for the protection of natural environment of Karst mountain areas in northern Guangdong.

Overwintering of Rana dybowskii in Northern Guangdong′s Mountainous Areas

[ Objective] To understand the overwintering of Rana dybowskii under four overwintering modes in northern Guangdong＇s mountainous areas. [Method] The overwintering management of Rana dybowskii was performed under four overwintering modes which were outdoor overwintering in water-land, outdoor overwintering in water, indoor overwintering in dryness, and indoor overwintering in freezer, respectively. The time, temperature and overwintering status were recorded. The Rana dybowskii in each group was weighed before and after overwintering, and the body weight loss and the survival rate were calculated. [ Result] Under the outdoor overwintering in water-land, outdoor overwintedng in water, indoor overwintering in dryness, and indoor overwintering in freezer, the survival rate of Rana dybowskii was 40.0%, 41.5%, 82.0% and 84.5%, respectively. [Conclusion] The temperature, overwintering mode and fatness are the important factors affecting the safe overwintering of Rana dybowskii in northern Guangdong.

Analysis on Hydrogeochemical Characteristics and Their Temporal and Spatial Variation in the Karst Catchment of Lianjiang River,Northern Guangdong Province

[ Objective] The study aimed to discuss the hydrogeochemical features and their temporal and spatial variation in the karst catchment of Lianjiang River, northem Guangdong Province. [ Method] Water samples were collected from 10 sub-drainages of Lianjiang River in July of 2012 and January of 2013, and then major chemical ions in tributaries of Xingzi River and Tongguanshui River were analyzed in detail to discuss the hydrochemistry type, spatial and temporal distribution and its causes of formation in Lianjiang River basin. [ Result] Among chemical ions in the wa- ter samples, Ca2. and HCO^- were dominant in Lianjiang River, accounting for over 70% and 80% of total concentrations of cations and anions re- spectively, followed by Mg2＋ and SO24-. The concentrations of most major ions were higher in winter than those in summer except SO4^2- concentra- tion was much higher in summer than that in winter, which was related to anthropogenic factors. From hydrochemical types, it is seen that HCO3-- Ca2＋ type in summer and HCO3--Ca2＋ ~ Mg2. type in winter were dominant in Lianjiang River, followed by the HCO3--SO4^2- · Ca2＋ type, and only two samples of Xingzi River belonged to HCO3--Ca2＋ Mg2· Na＋ type in winter. The spatial distribution regularity of chemical ions was not obvi- ous in the 10 sub-drainages of Lianjiang River. The concentrations of chemical ions changed greatly in the upper reaches but slightly in the lower reaches of Xingzi River catchment. The concentrations of chemical ions were steady in Tongguanshui River catchment with a smaller area, and it was a little higher in the upper reaches than those in the lower reaches. [ Conclusion] Natural processes, such as lithological heterogeneities and at- mospheric precipitation, contributed to the chemical composition of Lianjiang River catchment, northem Guangdong Province.

Mineral Chemical Characteristics of Gabbro-diorite for Shulouqiu Uranium Deposit in Northern Guangdong, China: Constraint on the Magmatic Source

1 Introduction The uranium deposits related with Indosinian and Yanshanian granite have provided the abundant resource of uranium during the past several decades in China.The deposits are mainly distributing in the Guidong granite

Organic Geochemistry of Lead-Zinc Polymetallic Deposits, Northern Guangdong

The characters of organic matter in rocks and ores in the Fankou and Dabaoshan deposits are systematically studied with regard to their implications for mineralization. The results show that kerogens in this area fall mainly into the plutonism field in Van Krevelen’s diagram.Reflectivity of the organic substance was measured to be 3. 06% (Fankou) and 1. 67% (Dabaoshan) , corresponding to the paleo-geotemperatures of 232℃ and 184℃ respectively.The same types of porphyrins and hydrocarbons were recognized in the rocks and ores and hydrocarbon-bearing inclusions are widespread in quartz and calcite, particularly in Dabaoshan. It is thought that the organic matter must have played a critical role in diagenesis and metallization in these deposits and that the hydrothermal solution was most 1ikely to be the type of water-oil hot brine.

The Early Jurassic magmatism in northern Guangdong Province, southeastern China: Constraints from SHRIMP zircon U-Pb dating of Xialan complex

This paper reports SHRIMP zircon U-Pb ages of 196±2 Ma for granite, and 195±1 Ma for gabbro from the Xialan complex in the Meizhou area, northern Guangdong Province. These results shed new light on the calm stage of magmatic activity in southeastern China during 200-180 Ma, and revealed that the back-arc extension induced by the subduction of the western Pacific plate may have begun at 195 Ma at least. Field observation on the fresh outcrops allows us to recognize some features formed by magma mixing. A part of the gabbro has a fine-grained rim of 20-30 cm at the margin, and thins gradually to-ward the granite; numerous dark fine-grained to microcrystalline dioritic enclaves developed in the granite. These enclaves vary in shape and size, dark minerals concentrated at the margin of enclaves, and the contact between enclaves and host rock is either obvious or obscure, or gradational. In addi-tion, needle-shaped apatites are included in the enclaves. The REE patterns of gabbros, as well as the trace element patterns, are generally consistent with those of granitic rocks. The above characters further suggest that in the Early Jurassic the injection of basic magma had melted deep continental crust and produced acidic magma, and the Xialan complex was produced by the mixing of them.

粤北贵东岩体及外围花岗岩地质特征对比及其意义

前人对贵东复式岩体的研究多集中在单个岩体上,而未能对整个岩体地质特征、成矿因素等进行全面对比分析。本文为进一步研究粤北贵东岩体及其外围花岗岩体的铀成矿差异的原因,通过对贵东岩体及其外围花岗岩体的地质特征、岩浆演化期次、矿物学特征及地球化学特征等方面进行系统研究分析。研究结果表明:在岩浆演化过程中,岩浆结晶粒度的变化,反映在矿物成分上含量上,主要表现为石英含量逐渐增加,斜长石含量逐渐减少,并且中长石逐渐被钠长石取代,黑云母被白云母替换而含量降低;贵东岩体中西部与东部花岗岩相比,角闪石、斜长石的含量偏大,自变质和交代蚀变较弱,东部花岗岩的矿物组成中基本不含角闪石,斜长石的含量总体上偏低,自变质和交代蚀变较强;地球化学特征表明西-中部岩体属亚碱弱过铝质的花岗岩体,东部及外围属亚碱弱过铝质-过铝质的花岗岩体,说明西-中部岩体在形成过程中可能有少量幔源组分的加入,认为其并非同源物质不同程度部分熔融产物,而是不同源区物质经部分熔融形成。

粤北地区塘洞岩体地球化学特征及地质意义

塘洞岩体位于粤北地区长江铀矿集区北部,具有较好的铀成矿地质条件。文章通过对塘洞岩体岩相学、地球化学分析,初步探讨了塘洞岩体成因及其形成的构造环境。结果表明:塘洞岩体岩性为中粒二云母花岗岩,具有高硅(SiO_(2)=72.77%~73.83%)、富铝(Al_(2)O_(3)=13.13%~13.82%)、富碱(K2O=5.00%~6.84%,Na_(2)O=1.55%~2.67%),且钾大于钠,贫铁、镁、钙、钛、磷,铝饱和指数(A/CNK=1.08~1.28)大部分大于1.1的特征,属高钾钙碱性弱过铝质-过铝质花岗岩;稀土元素总量较高,属轻稀土富集型(LREE/HREE=8.45~12.86),明显铕负异常(δEu=0.24~0.30);富集大离子亲石元素Rb、Th、U、K、Pb,而贫Nb、Ta、Ti、Zr等高场强元素。塘洞岩体CaO/Na_(2)O=0.16~0.58、Rb/Sr=5.01~8.19、Ra/Ba=0.90~1.94,指示其源区为砂质岩与泥质岩混合,属于S型花岗岩,主要为同碰撞后期在碰撞加厚向伸展减薄构造转换阶段的地壳物质经部分熔融形成的。

粤北地区“南华系”沉积时代的重新厘定:来自碎屑锆石年代学的证据

粤北地区横跨湘桂赣和武夷两个地层分区,大地构造上位于华夏地块西部,介于武夷、云开两个微陆块之间。粤北南华纪地层是研究华夏地块新元古代晚期构造演化等问题的重要载体,但该地区南华系的确定和划分较大程度上依赖与周边省份相应岩石地层的岩性组合和层序的对比,而周边省份的相应岩石地层单位的认识近年来发生较大的变化,因此,粤北地区“南华系”的重新厘定显得极为必要。本文对粤北地区原定为“南华系”大绀山组和活道组开展碎屑锆石U-Pb年代学研究,获得最年轻一组锆石加权平均年龄分别为422±4 Ma和430±4 Ma。结合岩性组合、区域地质调查研究成果及文献数据,暂将该地区原定的南华系厘定为下泥盆统。碎屑锆石年龄谱显示,其与周边地区泥盆系均具有450~420 Ma、1000~900 Ma以及~2450 Ma为主的锆石年龄显示,且在800~550 Ma之间形成复杂的次级峰值,可能指示了相似的物源。综上,建议在开展华夏地块新元古代构造演化等研究中,需首先对南武夷-云开地区南华系的沉积层位做细致的认定。

云锦杜鹃在粤北高海拔山区栽培技术研究

为研究云锦杜鹃Rhododendron fortunei在粤北高海拔山区的栽培技术,观察记录了云锦杜鹃在不同抚育模式、不同山势环境的林木保存率和生长差异。结果表明:云锦杜鹃在连续每年割灌除草和施肥2次的抚育模式中的生长表现最优,并在造林第4年实现首次开花;生长在山坳的云锦杜鹃的生长量指标、林木保存率优于生长在山脊的云锦杜鹃,感染病虫害率较低;但是,在开花苗木占比、花芽数量和结果量等指标低于生长在山脊的云锦杜鹃,首次开花时间也晚于生长在山脊的云锦杜鹃。

铸牢中华民族共同体意识视域下粤北民族古籍研究——基于契约文书的考察

契约文书不仅是粤北地区民族经济活动的直接记录,也是粤北各民族交往交流交融的估证材料。以粤北地区民族古籍中的契约文书作为研究对象,从铸牢中华民族共同体意识视角出发,分析契约文书中所体现的粤北各民族经济往来、法律制度、民族交往、社会变迁等方面信息,以及在形式上集中展现的具有多文风、多语种、多载体特点,从不同的视角和层面客观地载录了中华文化在粤北的形成和发展过程。

粤北地区无花果水肥一体化设施栽培技术规程

设施栽培是指利用温室、塑料大棚或其他设施,通过改变或控制农作物生长发育的环境因子(光照、温度、水分、二氧化碳等)对农作物生产进行调控的一项新技术。目前关于广东省设施栽培无花果的报道相对较少,为规范设施无花果栽培技术,种植出高品质无花果,本文总结了粤北地区设施无花果栽培的产地环境、选址建棚、设施栽植、设施水肥管理、无花果整形修剪、病虫草害防治、收获和储藏等技术要点,以期为粤北地区无花果标准化种植提供依据。

粤北丹霞山陡崖可见光-近红外(VNIR)反射光谱特征研究

红色是丹霞地貌核心特征和重要标志,文章基于丹霞山陡崖可见光-近红外(VNIR)反射波谱曲线,分析不同颜色(红色表面、橘色表面和纯净白斑)、不同岩生植物覆盖的陡崖表面反射光谱的特征参数及它们与色调之间的定量关系。结果表明:1)红色表面和橘色表面样品在525和500 nm处的吸收深度、吸收面积与红度和橘度之间的相关性显著,且红色表面和纯净白斑在红度值和吸收特征处的吸收深度和吸收面积上差异明显,是区分这2类表面的有利参数;2)红色表面、橘色表面和纯净白斑在可见光波段的吸收位置具有显著不同,极有可能与这3类地层中的含铁矿物种类及含量的变化有关;3)黑色岩生植物、块状岩生植物和绿色岩生植物3类岩生植物在670 nm处的吸收深度与归一化植被指数(NDVI)均具有较大的差异,可作为区分3类岩生植物的有效指标,且两者具有显著的相关性;非白斑岩生植物覆盖类和白斑岩生植物覆盖类在670 nm处的吸收深度随着NDVI值增大而增加;4)白斑表面附着植被后,纯净白斑在430 nm处的吸收特征消失,在530与690 nm处的吸收特征向短波方向移动。

1988—2018年粤北植被NDVI时空分布特征分析

植被是陆地生态系统的核心组成部分,而归一化植被指数(Normalized Difference Vegetation Index,NDVI)是反映地表植被覆盖和生长状况的重要参数。以粤北为研究区,结合1988—2018年长时间序列NOAA/AVHRR产品数据和高程数据,采用变化率分析法和空间分析法,分析31年间粤北NDVI变化特征及其与地形因子的关联性。结果表明,1988—2018年,粤北NDVI年均值整体呈现出北高南低、西高东低的分布特征,NDVI年均值介于0.20~0.87。其中,连山壮族瑶族自治县NDVI年均值最高,达到0.82,而清远市清城区NDVI年均值最低,仅为0.68。2018年,NDVI年均值达到最高,为0.84;1988年,NDVI年均值达到最低,为0.74。随着高程的增加,粤北NDVI年均值呈现出上升趋势,NDVI分布特征受到人类活动、地形和气候的综合影响。研究结果可为粤北山地城市生态屏障区建设提供重要理论支持。

粤北地区乡镇集中式饮用水水源保护区划分方案优化方法分析——以韶关市乡镇水源地“划、立、治”工作实践为例

饮用水安全与人民群众的生活健康密切相关,集中式饮用水水源保护区的划定是保证水质安全的重要措施。本文以韶关市乡镇水源地“划、立、治”工作实践为例,分析粤北地区乡镇集中式饮用水水源保护区划分方案的优化方法。其间充分调研韶关市乡镇饮用水水源地现状,分析水源保护区划分技术路线,探讨划分方案优化方法,并提出划定后的建设管理建议,为后续乡镇饮用水水源保护提供科学依据。

3种野生杜鹃在粤北造林早期的生长表现

为合理利用野生杜鹃资源,将3年生云锦杜鹃(Rhododendron fortunei)、刺毛杜鹃(Rh. championae)和毛棉杜鹃(Rh. moulmainense)实生苗应用于营造林工程;同时,观察记录3种杜鹃在造林早期的生长表现,以期为这3种杜鹃在景观林营建工程中的应用提供参考。结果表明,3种杜鹃均能适应粤北山地气候环境,造林成活率均达到90%以上。3种杜鹃的年均树高生长量低于常规造林树种,其中云锦杜鹃年均树高生长量低于其他2种杜鹃。刺毛杜鹃、毛棉杜鹃和云锦杜鹃的首次开花树龄分别为:4年生、6年生和8年生;刺毛杜鹃的花量和结果量最多,云锦杜鹃的花量和结果量最少。建议3种杜鹃造林后,连续每年进行抚育,每年割灌除草2~3次和施肥2次。

粤东西北应用型高校产教融合共生系统构建:理论逻辑、现实问题与行动路径

随着国家及各省市产教融合建设试点实施方案及地方本科高校应用型转型的稳步推进,地方与高校产教融合发展趋势不断增强,双方共生关系日益显现。在共生理论视域下,粤东西北应用型高校产教融合通过共生单元、共生模式和共生环境构成共生系统,但共生单元未激活、共生模式动力不足、共生环境不友好是制约当前粤东西北应用型高校产教融合成效的现实问题。针对当前现状,从优化共生单元、强化共生模式、改善共生环境三方面出发,提出粤东西北应用型高校构建产教融合共生系统的行动路径。