Tropical Tree Growth and Longevity: Validation of Growth Simulation,a Bootstrapping Model

ABSTRACT

Growth Simulation, an analytical modeling technique, has been increasingly used in ecological studies and practical forestry applications where dendrochronology is not applicable. The technique uses randomly sampled diameter increments from tagged trees over a known time interval to assemble a statistical sample of lifetime growth trajectories. We carried out a validation of Growth Simulation using a temperate species in order to compare indirect model outputs with direct tree ring analysis. Rings were measured on sample disks cut from 55 pine branches ranging in age from 8–36 years. Assessments included lifetime growth rates, growth rate with respect to diameter and age, periodic annual increment (PAI), cross-referencing of rings by date, and autocorrelation of growth over successive periods. Tree ring analysis and Growth Simulation showed close correspondence for all parameters tested (maximum, median, and minimum growth rates; longevity estimates). Growth Simulation is found to be a robust and informative technique for studies of tropical tree growth, and is especially useful where analysis of tree rings is not feasible or when bootstrapping analysis of ring data is of interest.     

Using ecological trajectories to track long-term taxonomic and functional changes in benthic shallow soft-bottom communities (Bay of Saint-Brieuc,English Channel)

1. Taxonomic and functional trajectories of benthic assemblages were studied in shallow soft-bottom sediments in the bay of Saint-Brieuc (Western English Channel). Changes were assessed at different spatial and temporal scales using a macrobenthic dataset based on 38 stations sampled in 1987 and 2019, coupled with data from one station sampled annually between 2005 and 2019 as part of the European Water Framework Directive monitoring programme.
2. Taxonomic trajectories indicated 1) changes in the structure and distribution of benthic assemblages, 2) an homogenization of the assemblages, and 3) significant functional shifts.
3. Fishing activities and nutrient enrichment are probably strong drivers of the observed changes, as suggested by the higher mortality rate of fragile, flexible, tubiculous and burrowing species, and the increase in the abundance of opportunistic species in the assemblages. Certain populations of macroinvertebrates seem jointly controlled by climate change and by the aforementioned local factors of disturbance.
4. The Community Trajectory Analysis framework appears as a new and interesting method to track ecological changes in marine ecosystems by measuring change with respect to a baseline state, to help define ecological recovery (station returning to the initial ecological state) and departure (station presenting increased changes over time), and to analyse trajectory similarity.
5. According to the degradation of habitat over time, we identify the need for the implementation of knowledge-based conservation strategies, especially within Natura 2000 sites.

     

Measurement of the Motion of Fertilizer Particles Leaving a Centrifugal Spreader Using a Fast Imaging System

Although mechanically simple, centrifugal spreaders used for mineral fertilization involve complex physics that cannot be fully characterized at the present time. We are developing sensors to evaluate the spatial distribution of the fertilizer on the ground based on the measurement of initial flight conditions of fertilizer granules after their ejection by the spreading disk. The techniques developed are based on the analysis of images of the area around the disk showing the granule ejection. A high resolution – low cost imaging system for the analysis of high speed particle projection developed for this specific purpose is presented in this paper. The system, based on a camera and a sequence of flashes, is used to characterize the centrifugal spreading of fertilizer particles ejected at speeds of approximately 30ms^–1. It automatically computes the direction of ejection and velocity of each granule observed in the image. Multi-exposure images collected with the camera installed perpendicular to the output flow of granules are analyzed to estimate the trajectories of the fertilizer granules, using different motion estimation methods.     

食品双螺杆挤出机内物料停留时间及其分布研究

应用流体分析软件对熔体在食品双螺杆挤出机中的三维等温流场进行了模拟计算,给出了粒子的运动轨迹,在此基础上作出了物料在挤出机内的停留时间分布曲线。这种模拟方法与传统的实验方法相比有着极大的优越性,为食品双螺杆挤出机挤出机理的研究提供了一个新思路,并可将该方法推广到与之相近的流体分析中。     

Abandonment of traditional terraced landscape: A change detection approach (a case study in Costa Viola,Calabria, Italy)

This paper presents the results of a change‐detection study of the historical agricultural terraced landscape in “Costa Viola” (Calabria, South Italy). During the last century, because of the loss of economic competitiveness, it has undergone progressive abandonment, followed by landscape degradation. Taking into consideration the very steep slopes of Costa Viola and the need to analyse with high precision the historical evolution of the terraced landscape, research methods were implemented coupling advanced geomatic techniques with in situ detailed surveys. Based on historical aerial photographs, orthophotos, and numeric cartography, we analysed the land use/land cover change in the period 1955–2014 using photogrammetric and geoprocessing techniques, focusing particularly on trajectories in agricultural terraces. Area covered by active terraces decreased dramatically between 1955 and 2014, from 813.25 to 118.79 ha (−85.4%). The implemented spatial database was built in a free open‐source software taking into consideration spatial accuracies and completeness. Spatial comparison among land use/land cover maps was carried out using a postclassification comparison technique that can provide complete cross‐tabulation matrices. These data were compared with socio‐economic statistics concerning demography and trends of farms with vineyards. The evolutionary dynamics of the active agricultural terraces were also analysed trough the definition of 6 types of spatio‐temporal patterns recognised in the analysed period. These methods allowed to highlight the ongoing dynamics of abandonment of agricultural terraces in relation to their main causes and effects. Although tailored for the specific case study, they can be applied to many other terraced agricultural landscapes presenting similar characteristics and problems.     

近30年来滇中城市群生态用地变化轨迹时空演变特征及其驱动机制

[目的]生态用地在维持生态平衡和支撑经济发展方面发挥着重要作用。研究滇中城市群生态用地的时空演变特征和驱动机制对优化生态安全格局、推进云南生态文明建设、筑牢国家西南生态安全屏障具有重要现实意义。[方法]利用Google Earth Engine(GEE)云平台对滇中城市群1990—2020年生态用地进行识别的基础上,采用变化轨迹分析、热点分析和地理探测器对滇中城市群生态用地时空变化轨迹和驱动机制进行了探索。[结果](1)滇中城市群生态用地变化以非生态用地与林地互换为主,并集中发生在林地和非生态用地的过渡地带,而生态用地内部之间(林地和草地)的转换主要发生在研究区北部和南部的山地区域。(2)生态用地变化以低频次变化为主,高频次较少,频次变化在元江干热河谷、金沙江干热河谷区域、滇东滇东南喀斯特地带表现出明显的聚集效应。(3)耕地面积变化是影响滇中城市群生态用地变化的主要驱动力,社会经济因素对生态用地的影响力显著高于自然因素,在自然环境、耕地扩张、生态修复政策等多重驱动下,多因子交互作用对生态用地变化更具解释力。[结论]滇中城市群生态用地破碎,自然环境的改变和人类活动的日益增强极易导致生态用...     

Reconciling the dichotomy between single species and ecosystem conservation: black kites (Milvus migrans) and eutrophication in pre-Alpine lakes

In recent times there has been a growing dichotomy between preservation of single species and broader, ecosystem-based approaches to conservation. Freshwater habitats are among the most highly human-impacted ecosystems. We used a long-term data set on black kites (Milvus migrans), a threatened raptor dependent on aquatic habitats, to explore ways to reconcile single species and biodiversity-driven approaches to conservation. In the pre-Alpine lakes of northern Italy, black kite populations showed medium-low density, extremely low breeding success and widespread declines. Spatio-temporal variations showed density and breeding success to be positively related to ecosystem productivity (as estimated by phosphorus concentrations in lakes), availability of aquatic habitats and grassland, and to be negatively related to extent of farmland and fish harvest by professional fishermen. Fish species richness, used as a surrogate of biodiversity, was highest in one oligotrophic lake, but on average increased with increasing ecosystem productivity (i.e. lake eutrophication). Given expected future declines in ecosystem productivity, kite conservation will be helped by enhancing populations of alternative prey in terrestrial habitats (e.g. through incentives for grassland), and higher regulation of fish harvest. On the other hand, ecosystem management may profit from the use of black kites or other aerial piscivores as indicators of biodiversity and of diffuse ecosystem stress, such as sustainability of fishing practices.     

Use of multivariate techniques to identify vegetation units and monitor change on a livestock production system in a semi‐arid savanna of the eastern Cape

Species composition data of the grass layer were determined from point surveys along permanently demarcated transects. These data were separated into vegetation units using multivariate techniques. The repeatability of this classification was tested on data collected over a period of time. The results indicate that classification based on composition data collected from a single sampling period was adequate for practical purposes provided certain precautions were taken. Change in vegetation was assessed by ordering sites from repeated measurements and tracing site trajectories through ordination space. The trends along the axes were strongly correlated with assessed condition score.     

Distribution,structure and function of Nordic eelgrass (Zostera marina) ecosystems: implications for coastal management and conservation

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Regionalisation of the muscle fascicle architecture in the equine longissimus dorsi muscle

REASON FOR PERFORMING STUDY: The longissimus dorsi is the largest muscle in the equine back and plays an important role in locomotor ability and performance in the horse. In vivo studies suggest that the mechanical function varies between different muscle segments, in part determined by anatomy. It is possible therefore that variations in function reflect variations in the anatomy of the longissimus dorsi along its length. OBJECTIVES: To identify if there are regional variations in muscle architecture of the longissimus dorsi. METHODS: Computed tomography scans were obtained from 8 cadaver backs to identify the cross-sectional area and volume of the muscle. The 3D orientations of the muscle fascicles were quantified in situ by their direction cosines using a magnetic digitisation system. RESULTS: Mean +/- s.e. volume of the muscle was 2.34 +/- 0.18 l for each side and mean length of the vertebral column from T4 to L6 dorsal spinous processes was 56.57 +/- 2.0 cm. There were significant differences in the cross-sectional area and the moment arm lengths between muscle segments (P<0.05). In the lumbar region, the mediolateral moment arms were 2-3 times greater than the dorsoventral moment arms. There were significant variations in the direction cosines (n = 7129) between muscle segments and between different regions within each segment (P<0.05). POTENTIAL RELEVANCE: These observations indicate that the muscle fascicle architecture predisposes the longissimus dorsi to different functions both along its length and between different regions within each segment. Detailed 3D anatomical measures of the structure with in vivo measures of function (back motion and muscle activity) will be investigated in further studies.