The Status of Canopy Density and above Ground Biomass along the Northern Coastal Forest Zone of Tanzania

Canopy density and forest biomass estimation are critical for understanding of the carbon cycle, climate change and detecting health status of the forest ecosystems. This study was conducted on the coastal forests reserves in Zanzibar and mainland Tanzania. A systematic sampling design was used to establish a total of 110 temporary sample plots in all study sites. The stratification of the forests was adopted to identify closed forest patches with less anthropogenic effects. The study assessed the forest canopy density and above ground biomass with relative carbon stock for closed forest classes. Jozani Chwaka Bay National Park in Zanzibar recorded higher average canopy densities of 63% followed by Ngezi (46%), Pugu forests (26%) and Kazimzumbwi (16%). However, Ngezi forest had higher forest biomass than all study sites with the overall mean AGB of 138.5 tAGB/ha equivalent to carbon stock of 67.9 tC/ha. Tree species, Bombax rhodognaphala (Msufi mwitu) and Antiaris toxicaria (Mgulele) recorded the highest biomass of 1099 tABG/ha and 703 tAGB/ha (equivalent to 538 tC/ha and (345 tC/ha)) respectively. The study revealed that about 35% of the total closed forest patches at Pugu FR were covered by lower canopy density which accounted about 490 ha. Kazimzumbwi FR was dominated by lower canopy density which represented about 64% of the total forest cover area (1750 ha).

Investigation of tropical coastal forest regeneration after farming and livestock grazing exclusion

It is critical to understand how forests regenerate after the exclusion of human induced disturbances because the regenerating species drive the renewal of resources and ecosystems,which in turn support human beings locally and globally.This study of forest regeneration was conducted in the tropical coastal forest ecosystems of Tanzania at Uzigua Forest Reserve(24,730 ha)in the Pwani Region.We collected data from adult trees in 47 sampling plots(25×25 m)randomly established in closed forest sites(control)and in sites disturbed by farming and livestock grazing.Sapling and seedling data were collected and analyzed in 2×2 m nested subplots.Plots in the closed forest had higher mean basal area and volume for adult trees than those in sites disturbed by farming and livestock grazing.Plots in sites disturbed by farming had the highest Shannon–Wiener index for seedlings and saplings,followed by closed forest and livestock grazed sites.Closed plots and farmed plots had higher Simpson’s index for seedlings and saplings than in grazed sites.Plots in farmed and livestock-grazed sites had a higher Simpson index for adult trees than in closed sites.Equitability of seedlings and saplings was highest in closed forest sites,followed by farmed and livestock grazed sites.Plots disturbed by farming had higher equitability for adult trees than in livestock-grazed and closed sites.Moreover,plots disturbed by farming and grazing had a higher importance value index for seedlings than in closed sites.Plots in closed forests had higher sapling importance values than in farmed and grazed sites.Again,plots in closed forest had a higher importance value for adult trees than in farmed and grazed sites.The differences in tree species subcategories of regeneration across land-use indicates that farming and livestock grazing disturbances create heterogeneous microhabitats,which positively or negatively affects regeneration capacity of species after exclusion.

Distribution and ecology of lesser pouched rat,Beamys hindei,in Tanzanian coastal forests

The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal forests is not well known.Therefore,we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns.Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps.Data on ecology were obtained from monthly capture–mark–recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period.The results indicate the presence of B.hindei in 3 forests where it was not previously recorded.The population abundance estimates ranged from 1 to 40 animals per month,with high numbers recorded during rainy seasons.Reproduction patterns and sex ratios did not differ between months.Survival estimates were not influenced by season,and recruitment was low,with growth rate estimates of 1 animal per month.These estimates suggest a stable population of B.hindei in Zaraninge Forest.Further studies are recommended to establish the home range,diet and burrowing behavior of the species in coastal forests in East Africa.

Disturbance Legacy on Soil Carbon Stocks and Stability within a Coastal Temperate Forest of Southwestern British Columbia, Canada

Although it has been recognized that soils play a critical role in carbon storage and that coastal temperate forests have considerable potential to sequester soil organic carbon (SOC), studies related to SOC stocks and stability are scarce in these ecosystems. Forest disturbances may leave legacies on SOC properties and may further compromise SOC storage capacity of these ecosystems. In the Pacific Spirit Regional Park of southwestern British Columbia, we compared SOC stocks and stability among three second-growth forests that have been affected by disturbances of different magnitudes. We collected data on soil chemical and physical properties to estimate SOC content and assess SOC stability. We found that SOC stocks in the forest characterized by low magnitude disturbance were greater than those of the forest characterized by high magnitude disturbance (8.2 ± 1.3 kg·Cm-2 versus 5.3 ± 0.1 kg·Cm-2 to 30 cm depth). SOC was less stable in the highly disturbed forest and subsequent vegetation changes might have further reduced SOC stability. Our results provide insight into the role of disturbance history in the current SOC storage capacity of coastal temperate rainforests of British Columbia.

Effects of forest cover types and environmental factors on soil respiration dynamics in a coastal sand dune of subtropical China

Trees on sand dunes are more sensitive to environmental changes because sandy soils have extremely low water holding capacity and nutrient availability. We investigated the dynamics of soil respiration(Rs) for secondary natural Litsea forest and plantations of casuarina,pine, acacia and eucalyptus. Results show that significant diurnal variations of Rsoccurred in autumn for the eucalyptus species and in summer for the pine species, with higher mean soil respiration at night. However, significant seasonal variations of Rswere found in all five forest stands. Rschanged exponentially with soil temperatures at the 10-cm depth; the models explain 43.3–77.0% of Rs variations. Positive relationships between seasonal Rsand soil moisture varied with stands. The correlations were significant only in the secondary forest, and the eucalyptus and pine plantations. The temperature sensitivity parameter(Q10 value) of Rsranged from 1.64 in casuarina plantation to 2.32 the in secondary forest; annual Rswas highest in the secondary forest and lowest in the pine plantation. The results indicate that soil temperatures and moisture are the primary environmental controls of soil respiration and mainly act through a direct influence on roots and microbial activity. Differences in root biomass, quality of litter,and soil properties(pH, total N, available P, and exchangeable Mg) were also significant factors.

Thinning and in-stream wood recruitment in riparian second growth forests in coastal Oregon and the use of buffers and tree tipping as mitigation

Many aquatic habitats in coastal Oregon have been impacted by historic land use practices that led to losses of in-stream wood and associated degraded fish habitats. Many of these streams are now bordered by stands of dense second growth forests（30–80 years） that are incorporated into riparian buffer zones with low wood recruitment and storage. Thinning in riparian zones is one management option to increase the rate of large tree growth and eventually larger in-stream wood, however, it raises concern about impacts on current wood recruitment, among other issues. Using a forest growth simulation model coupled to a model of in-stream wood recruitment, we explore riparian management alternatives in a Douglas-fir plantation in coastal Oregon. Alternatives included：（1） no treatment,（2） single and double entry thinning, without and with a 10-m buffer, and（3） thinning combined with mechanical introduction of some portion of the thinned trees into the stream（tree tipping）. Compared to no treatment, single and double entry thinning on one side of a channel, without a 10-m buffer, reduce cumulative instream wood volume by 33 and 42 %, respectively, after100 years（includes decay）. Maintaining a 10-m buffer reduces the in-stream wood loss to 7 %（single entry thin）and 11 %（double entry）. To completely offset the losses of in-stream wood in a single entry thin（on one or both sides of the stream）, in the absence or presence of a 10-m buffer,requires a 12–14 % rate of tree tipping. Relative to the notreatment alternative, cumulative in-stream wood storage can be increased up to 24 % in a double-entry thin with no buffer by tipping 15–20 % of the thinned trees（increased to 48 % if thinning and tipping simultaneously on both sides of the stream）. The predicted increases in in-stream wood that can occur during a thin with tree tipping may be effective for restoring fish habitat, particularly in aquatic systems that have poor habitat conditions and low levels of in-stream wood due to historic land use activities.

Coastal Protection Forest Construction Project

China’s coastal line starts at the Yalu River in Liaoning in the north and ends at the Beilun River mouth in Guangxi. It is 18,000 kilometres long and crosses 11 provinces, municipalities and autonomous regions, including Liaoning, Hebei, Tianjin, Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong, Guangxi and Hainan. In 1988, the Chinese government outlined the Coastal Protection Forest System Construction Project and defined the coastal line of 11 provinces as the main construction line. The project aims at developing a

The Dependency of Coastal Livelihood on Forest Resources, and Alternative Options in the Periphery of the Sundarbans Reserve Forest, Patharghata, Bangladesh

Dependency on forest resources poses a threat to the environment in Patharghata, Bangladesh. Therefore, this study explores the role of forest resource in the life and livelihood of coastal people as well as to understand the effectiveness of forest and status of forest dependency in and around south-central coast in Patharghata, Bangladesh. We collected data randomly from 105 household heads through both open and close-ended questionnaire. To investigate the forest dependency and people’s perception regarding alternative solutions, Microsoft excel software program has been applied. The findings reveal that usage of fuelwood in cooking, housing structure, fish catching, honey & fodder collection significantly contributes to household dependency on forest resources, while other variables seem to be insignificant. Our study amplifies that the share of forest income to the total household income was only 19% while other earning sources provided 81% income. The result shows that respondent people collect forest resources primarily for cooking purpose with a share of 71% where 9% forest resources are collected as fodder followed by 8% forest resource collection as food and sheltering purposes. Moreover, the study found that using alternative cooking system, artificial instruments, declaring the forest as tourist spot, changes in housing structure, occupation are some effective options to reduce forest dependency. The study concludes that these alternative options need more financial and other support from the government, non-government and other civil society organizations to cut down forest resource dependency.

基于随机森林算法的天津市滨海地区地面沉降模拟

地面沉降的监测与预测,对于保障城市安全和社会可持续发展具有重要意义和现实价值。利用随机森林机器学习模型预测了天津市滨海地区的地面沉降量空间分布,并评估了模型的性能和变量的重要性。基于2020年天津市滨海新区局部地区的地面沉降量、含水层岩性、含水组水位差、水文地质参数等数据来训练和验证随机森林模型。结果表明:随机森林模型能够较好地拟合和预测地面沉降量(R^(2)=0.98,RMSE=0.52 mm);影响地面沉降量最重要的因素是水位差,其次是含水层的岩性(砂-黏比值),最后是相关水文地质参数。上述结果与传统上太沙基原理基本吻合,进一步验证了模型的正确性和可预测性。本研究采用了空间分布数据来训练随机森林模型;根据物理机制,选取了重要控制因素来开展分析;评估了控制因素的重要性程度,并指出了研究的局限性和未来的研究方向,为利用随机森林模型快速有效预测地面沉降提供了重要参考和启示。

台风干扰海岸林受损及灾后恢复的影响因素研究进展

随着气候变暖,台风登陆的强度及频率均呈增加趋势,其对海岸森林的影响也日益严重,从而危及沿海生态安全。但因台风登陆的不确定性、海岸森林恢复的滞后性和数据源受限等影响,当前对台风后海岸森林受损及灾后恢复的影响因素研究仍存在很大的不确定性。台风登陆导致海岸森林枝叶脱落、树干折断和根系裸露等,受树种特征(冠层、树干和根系),林分结构(密度、组成),立地条件(地形、土壤)和台风特征(强度、频率)等影响,海岸森林在不同研究尺度的受损存在明显的空间异质性,单一因素难以完全解释台风后海岸森林的受损格局。台风后部分海岸森林因受损严重而死亡,其余仍以种子萌发、幼苗/幼树生长或萌生更新的方式持续恢复。海岸森林在灾后的恢复周期从几个月到几十年不等,其具体时长与树种更新策略(实生、萌生),森林类型(人工林、天然林),树木受损程度(轻度、重度)及区域水热条件(水分、热量)等有关。未来仍需借助多源遥感数据,并结合台风后的固定样方调查、野外采样和室内样品分析,对海岸森林的受损和恢复格局开展多时空尺度研究,阐明不同受损程度下树木的水分传输和光合产物分配过程及其差异,全面揭示台风干扰对海岸森林的影响机制。

浙江慈溪海防林天牛的主要寄主树种与危害防控

[目的]调查慈溪海防林天牛危害树木种类,并研究天牛的防治方法。[方法]2009年,对慈溪主要防护林工程区及城市绿地、市林场开展野外调查,整理出天牛寄主树种名单,并列出遭受严重危害的林木种类。2021—2022年,对天牛寄主树种作了补充调查和资料完善。[结果]据野外调查,浙江慈溪沿海防护林天牛的寄主树种共73种,其中17种受害严重。经连续3年对天牛进行综合防控,林木天牛幼虫平均虫株率从35.70%下降到16.40%;田间林木天牛成虫虫口密度从1153.5头/hm^(2)下降到529.5头/hm^(2),降幅达54.10%,效果十分显著。[结论]综合应用药剂防治、人工杀灭和诱集树引诱集中防治等方法,有利于提高天牛防效。

福建海岸沙地5种防护林土壤微生物群落特征

[目的]探明福建海岸沙地不同防护林对土壤微生物群落的影响及机制,为海岸带防护林森林质量提升提供科学依据。[方法]选择5种主要防护林为对象,分别为次生林、木麻黄(Casuarina equisetifolia)人工林、湿地松(Pinus elliottii)人工林、厚荚相思(Acacia crassicarpa)人工林和尾巨桉(Eucalyptus urophylla×E.grandis)人工林,采用磷脂脂肪酸法(Phospholipids fatty acid, PLFA)比较了不同防护林的土壤微生物群落结构。[结果](1)海岸沙地不同防护林土壤中共检测到18种PLFA生物标记,在尾巨桉和次生林中种类最多,湿地松和厚荚相思人工林最少。(2)土壤总磷脂脂肪酸、革兰氏阳性细菌和革兰氏阴性细菌含量均表现为尾巨桉和次生林较高,厚荚相思和木麻黄人工林较低,土壤真菌含量为尾巨桉林最高,丛枝菌根菌含量为次生林最高,真菌和丛枝菌根菌含量在其他防护林间无显著差异。(3)次生林的土壤微生物多样性和均匀度均高于4种人工林。(4)土壤pH、细根碳氮含量为土壤微生物群落的主要影响因子,其次为土壤全氮和硝态氮含量以及凋落物木质素/氮和细根碳氮比。[结论]不同防护林对土壤微生物群落的影响存在显著差异,在海岸带木麻黄防护林中引种尾巨桉和乡土树种,可以增加土壤微生物多样性,提高森林生态功能。

基于多源遥感数据的福建省海岸带县域森林生态质量评价

【目的】森林生态质量是从生态角度反映森林质量的内涵,对森林的生态功能和生态服务、生长状况以及自我调节功能进行综合测度,以期提高森林改善生态环境、维护生态平衡的能力。【方法】利用中、高分辨率多源遥感数据,获取大范围尺度下能表征森林生态质量的关键指标信息,在此基础上,分析福建省海岸带40个县域的森林生态质量状况。首先,基于2016年2 m分辨率多源遥感数据为主要数据源,利用双层尺度集模型选定最佳分割尺度,多分类器集成算法集,自动选择最优分类算法进行森林类型提取,并结合2020年Sentinel遥感数据及森林分类产品,更新2020年福建省海岸带森林类型精细分布图;其次,利用LandTrendr算法衍生的干扰开始时间特征推算现存森林年龄,通过GEDI冠层高度产品获取海岸带森林冠层高度分布图;在以上关键森林质量指标提取基础上,对遥感手段获取的8项森林生态质量评价指标进行主成分分析,获得福建省海岸带县域森林生态质量综合评价结果。【结果】2020年福建海岸带40个县域约50%的县域森林生态质量处于优良水平,其中仙游县、闽侯县、南安市、霞浦县、柘荣县及厦门海沧区、思明区、集美区、同安区等森林生态质量为优;森林生态质量较差的县域有惠安县、秀屿区、石狮市、福安市、平潭实验区、诏安县。【结论】结合中、高分辨率多源遥感数据,能够发挥遥感大范围监测优点,客观评价福建省海岸带40个县域的森林生态质量;研究结果表明2020年福建沿海县域森林生态质量还存在较大的提升空间,需要针对存在的问题采取相应森林管理措施提升森林生态质量。

基于RF算法改进BP神经网络的港口吞吐量预测

为提高港口吞吐量预测的合理性和准确性,采用随机森林算法(RF)改进BP神经网络,建立一种基于多变量输入的RF-BP模型,实现对国内10座沿海主要港口总吞吐量的预测。首先采用随机森林算法对多变量输入数据进行特征提取,提高模型的鲁棒性和准确性,筛选出重要特征;然后通过BP神经网络进行回归预测,充分发挥其拟合能力和泛化能力;最后将预测结果与单变量BP神经网络模型、多变量BP神经网络模型、Arima算法等做对比。结果表明,多变量RF-BP神经网络预测的吞吐量数据误差更小,预测结果更加精确。上述模型提高了港口吞吐量数据预测的准确性,对于提升港口应对市场需求的能力、支撑港口战略决策、优化货物运输流程、促进区域经济发展都具有重要意义。

滨海盐碱地防护林带养护管理技术

滨海盐碱地盐渍化程度高,土壤结构差,质地粘重,防护林带养护管理难度大。该文着重从江苏省连云港市徐圩新区的重度滨海盐碱地防护林的养护管理技术的几个方面如林木管理,土壤水分管理,土壤盐分管理,土壤肥力管理,林下植被管理和病虫害防治等进行了讨论,以期为滨海盐碱地防护林带的管护提供措施和理论依据。

山东近海毛虾属虾类渔获量对捕捞压力和气候环境要素的响应

基于1979—2020年山东近海气候环境要素和毛虾属虾类(下文简称毛虾)渔获量数据,运用方差膨胀因子、随机森林模型、广义线性可加模型和相关性分析等方法,研究了山东近海捕捞压力和气候变化对伏季休渔制度实施前后毛虾渔获量的影响,筛选影响山东近海毛虾渔获量的关键气候因子。研究表明,山东近海毛虾渔获量与捕捞努力量之间具有显著的相关性;黄渤海海表温度是影响山东近海毛虾渔获量变动的重要环境要素,毛虾渔获量与黄渤海海表温度呈显著正相关(P<0.05),毛虾渔获量在一定范围内随温度的升高而升高。毛虾种群变动是多种因素共同作用的结果。研究结果可为评估山东省毛虾最大捕捞量、配额制定及为毛虾专项捕捞实施提供科学依据。

基于谷歌地球引擎平台的海上养殖信息提取方法研究——以福建省平潭县为例

海上养殖业对粮食安全有着至关重要的作用。然而,海上养殖的无序扩张和开发,阻碍了海上交通,同时也造成了海洋环境问题。为及时、准确地获取海上养殖信息,满足海岸带调查以及推进海上养殖规范化、科学化,提出一种基于谷歌地球引擎(Google Earth Engine, GEE)平台实现长时间序列下海上养殖区信息快速提取的方法。本研究构建了一个基于随机森林分类的海上养殖区信息提取模型,该模型综合利用了Sentinel-1卫星SAR影像数据的VV和VH极化波段,以及Sentinel-2卫星的多光谱影像数据。此外,模型还融合了4个用于增强养殖区特征的指数,以提高养殖区域信息提取的准确性和效率。这种方法的应用旨在优化海上养殖区的识别过程,通过精确分析和利用不同数据源的互补优势,展现了遥感技术在海洋养殖监测领域的巨大潜力。本研究对2017—2021年平潭县海上养殖区域进行判定与提取,实验结果表明,以养殖密度较低,养殖特征不明显为特征的海上养殖区,基于GEE平台的海上养殖区信息提取方法精度在90%以上,表明在复杂水体背景下对养殖区快速识别取得较好的效果,可为海上养殖科学规划与规范化管理提供有效的参考依据。

Integrated Assessment of Forest Cover Change and Above-Ground Carbon Stock in Pugu and Kazimzumbwi Forest Reserves, Tanzania

A study was conducted to estimate the forest cover change, quantify and map tree above-ground carbon stock using Remote sensing and GIS techniques together with forest inventory. Landsat images of 1980, 1995 and 2010 acquired during dry season were used in the estimation of cover changes. Supervised image classification using Maximum Likeli-hood Classifier was performed in ERDAS Imagine software to analyze the images and further analysis was performed in Arc GIS 9.3 software. Stratified sampling procedure was used to select concentric inventory plots in Pugu Forest Reserve (PFR) and Kazimzumbwi Forest Reserve (KFR). Plots were laid according to NAFORMA, and the tree parameters in each sampling plot were collected. A Microsoft Excel spreadsheet was used to compute the above-ground bio- mass for each plot using an empirical equation relating wood basic density and tree height. The above-ground carbon was calculated using a conversion factor of 0.49. Geostatistical method in ArcGIS was used to analyze and map carbon. Results revealed that for the periods 1980-1995 and 1995-2010, Closed Forest in PFR decreased by 4.5% and 25.3% respectively, while for KFR, Closed Forest decreased by 11.9% and 31.3% respectively. The mean carbon density for PFR and KFR were respectively 5.72 tC/ha and 0.98 tC/ha while carbon stocks were 14 730.41 tC and 7 206.46 tC re- spectively. The revealed low carbon densities were attributable to decline in area under Closed Forest in the two Forest Reserves. The study recommends concerted efforts to enhance proper management of the forests so that the two forest reserves may contribute to REDD initiatives.

SITE CLASSIFICATION FOR PROTECTIVE FOREST AFFORESTATION ON THE COAST OF CHINA

Land for protective forest on the coast has special site conditions, and site classification is the scientific basis for seaboard afforestation. The site classification system on the coast zone and islands of China may be classified into five levels-site region (sub - region), district, class, group, and type. The land division for afforestation is carried out by the principle of enviornmental heterogeneity among regions, sub-region and district on large scale, according to the difference of air temperature, moisture and type of coast geomorphy. It may be classified into 7 regions, 12 sub-regions and 55 districts. The medium and small scaled division for site class, group and type, subdivided in a site district, are based on medium topography, topographic climate, micro - relief and soil conditions.

沿海防护林体系建设工程区生态系统服务权衡/协同及驱动力

探究沿海地区的生态系统服务、权衡协同关系及其驱动机制是区域自然资源科学管理及生态合理规划的基础,对有效提升地区生态、经济、社会效益和人类福祉具有重要理论意义。以海防林工程区为研究区,多角度探究区域内固碳、土壤保持、产水量的生态系统服务、关系特征、驱动机制,从而为沿海地区制定合理生态建设规划提供参考。研究结果表明:(1)沿海防护林体系建设工程区在2000—2020年期间生态系统服务水平整体提升,生态建设效果第二期最佳。(2)2000—2020年区域内各生态系统服务间以协同关系为主,土壤保持和产水量协同显著。(3)建设分区、建设分亚区生态系统服务间关系尺度效应主要存在于土壤保持和产水量。(4)权衡协同关系北方主要受气象因子影响,南方受植被、地形地貌因子影响,人类活动对权衡协同关系的影响以负效应为主,驱动因子存在空间异质性。