Ecotonal changes and altered tree spatial patterns in lower mixed-conifer forests, Grand Canyon National Park, Arizona, U.S.A.

This research analyzes patch development and determines tree spatial patterns along the lower mixed-conifer ecotone on the North Rim of Grand Canyon National Park in Arizona (U.S.A.). Patterns of patch development were interpreted from spatial analyses, based on tree age and size, and past records of disturbance and climate. Five plots in the ecotone between mixed conifer forests and monospecific stands of ponderosa pine (Pinus ponderosa) were studied for patterns of patch development. The methods used include: (1) size-structure analyses, to compare species patch development; (2) dendrochronological dating of tree establishment; (3) tree ring master chronology, to determine periods of suppressed growth, compared to a Palmer Drought Severity Index; and (4) spatial analyses by species composition, size and age, with univariate and bivariate analyses of spatial association and spatial autocorrelation. We found an increased density of shade-tolerant and fire-intolerant species namely clusters of pole-sized white fir, and fewer large ponderosa pine. This revised version was published online in May 2005 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modelling land cover transitions: A solution to the problem of spatial dependence in data

Raster-based spatial land cover transition models (LCTMs) are widely used in landscape ecology. However, many LCTMs do not account for spatial dependence of the input data, which may artificially fragment the output spatial configuration. We demonstrate the consequences of ignoring spatial dependence, thus assigning probabilities randomly in space, using a simple LCTM. We ran the model from four different initial conditions with distinct spatial configurations and results indicated that, after 20 simulation steps, all of them converged towards the spatial configuration of the random data set. From an ecological perspective this is a serious problem because ecological data often exhibit distinct spatial configuration related to ecological processes. As a solution, we propose an approach (region approach) that accounts for spatial dependence of LCTM input data. Underlying spatial dependence was used to apply spatial bias to probability assignment within the model. As a case study we applied a region approach to a Vegetation Transition Model (VTM); a semi-Markovian model that simulates forest succession. The VTM was applied to approximately 500,000 ha of boreal forest in Ontario, at 1 ha pixel resolution. When the stochastic transition algorithms were applied without accounting for spatial dependence, spatial configuration of the output data became progressively more fragmented. When the VTM was applied using the region approach to account for spatial dependence output fragmentation was reduced. Accounting for spatial dependence in transition models will create more reliable output for analyzing spatial patterns and relating those patterns to ecological processes.This revised version was published online in May 2005 with corrections to the Cover Date.     

Integration of pharmacokinetic–pharmacodynamic for dose optimization of doxycycline against Haemophilus parasuis in pigs

The aims of this study were to establish optimal doses of doxycycline (dox) against Haemophilus parasuis on the basis of pharmacokinetic–pharmacodynamic (PK‐PD) integration modeling. The infected model was established by intranasal inoculation of organism in pigs and confirmed by clinical signs, blood biochemistry, and microscopic examinations. The recommended dose (20 mg/kg b.w.) was administered in pigs through intramuscular routes for PK studies. The area under the concentration 0‐ to 24‐hr curve (AUC_0–24), elimination half‐life (T_½ke), and mean residence time (MRT) of dox in healthy and H. parasuis‐infected pigs were 55.51 ± 5.72 versus 57.10 ± 4.89 μg·hr/ml, 8.28 ± 0.91 versus 9.80 ± 2.38 hr, and 8.43 ± 0.27 versus 8.79 ± 0.18 hr, respectively. The minimal inhibitory concentration (MIC) of dox against 40 H. parasuis isolates was conducted through broth microdilution method, the corresponding MIC₅₀ and MIC₉₀ were 0.25 and 1 μg/ml, respectively. The Ex vivo growth inhibition data suggested that dox exhibited a concentration‐dependent killing mechanism. Based on the observed AUC_24 hr/MIC values by modeling PK‐PD data in H. parasuis‐infected pigs, the doses predicted to obtain bacteriostatic, bactericidal, and elimination effects for H. parasuis over 24 hr were 5.25, 8.55, and 10.37 mg/kg for the 50% target attainment rate (TAR), and 7.26, 13.82, and 18.17 mg/kg for 90% TAR, respectively. This study provided a more optimized alternative for clinical use and demonstrated that the dosage 20 mg/kg of dox by intramuscular administration could have an effective bactericidal activity against H. parasuis.     

Challenges in developing and implementing a decision support systems (ETÇAP) in forest management planning: a case study in Honaz and Ibradı, Turkey

Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans.     

Determining spatial feed distribution in sea cage aquaculture using an aerial camera platform

Within this paper we describe an unmanned aerial vehicle (UAV) based method to estimate the spatial feed pellet distribution in salmon fish-cages and exploit it within a case study to determine the radial pellet distribution for different rotor spreaders and blower configurations. Compared to previously used methods, capturing pellets thrown from a rotary feed spreader in rows of Styrofoam boxes, the UAV based method is simpler and faster to setup and allows to cover a larger portion of the sea cage surface area. We compare results obtained with the Styrofoam box method with results we obtained by an automatic analysis of aerial videos taken by the UAV during feeding experiments. The employed method helps to gain insight into the spatial feed pellet distribution in full-scale salmon fish-cages where the feeding pipe and actual fixation of the spreader may influence the dynamic behaviour of the feeding system. This can also be seen as a step towards a continuous measuring of the feed pellet distribution, particularly in view of possible future feeding systems that may allow to adapt the feed pellet distribution to the actual fish distribution.     

Temperature modeling of a land-based aquaculture system for the production of Gracilaria pacifica: Possible system modifications to conserve heat and extend the growing season

Temperature control is a major cost for numerous aquaculture systems. Solar thermal engineering techniques can be used to identify inexpensive methods for conserving and capturing heat. Gracilaria pacifica, also known as the culinary ingredient ogo, is currently grown in land-based tanks at a site in Goleta, CA where influent sea water temperatures infrequently reach the 21–28 °C range that provides for optimal growth. The major objective of this study was to explore various designs of a G. pacifica tank culture system that maintain optimal water temperature year round to maximize growth. A model was constructed and calibrated by comparing results to a one-third scale pilot system operated in Davis, CA. For model calibration the most sensitive parameter such as cover optical properties were adjusted first and less sensitive parameters were adjusted later. The pilot system consisted of six tanks, three insulated with foam and a clear polyethylene cover (experimental), and three uninsulated and uncovered (controls). The model had weather data inputs including air temperature, humidity, wind speed, and solar radiation. The model was then compared to a full-scale system operated in Santa Barbara during the winter. The experimental pilot system was 4.93 °C warmer than the control pilot system under optimal weather conditions. The full-scale experimental system was 2.80 °C warmer than the control system under non-ideal conditions. The model demonstrated predictive accuracy under most weather conditions. Furthermore the model is robust enough to accept estimated values for many inputs and still produce accurate results, this suggests a simpler model may be feasible. A polyethylene cover and insulation are not sufficient in general for raising the water temperature to the optimum range during the winter; they may be during other times of the year when more solar energy is available, thereby extending the growing season.     

基于GIS的农村居民点空间分布特征研究----以扶余市为例

科学认识乡村地域结构是全面推进农业农村现代化和乡村振兴的基础。本文以扶余市第二次土地调查调数据为基础，借助ArcGIS空间分析软件，运用规模分析、核密度估算、缓冲区分析，从用地规模、分布格局与土地利用条件方面探讨扶余市农村居民点地域分异特征。研究表明：扶余市以微、小型居民点居多，居民点数量随着规模的增大逐渐减少，居民点之间的距离差异较大，总体呈现大散居、小聚居，不均匀分散分布；农村居民点的平均核密度为0.4个/km2，空间布局呈东南部高密度集聚成片，向西逐渐密度降低，西部零散错落分布；居民点分布呈现较强的城镇指向性，交通用地对居民点有集聚的作用，河流对微型居民点和大型居民点有集聚吸引的功能。     

Geostatistical interpolation and aggregation of crop growth model outputs

Many crop growth models require daily meteorological data. Consequently, model simulations can be obtained only at a limited number of locations, i.e. at weather stations with long-term records of daily data. To estimate the potential crop production at country level, we present in this study a geostatistical approach for spatial interpolation and aggregation of crop growth model outputs. As case study, we interpolated, simulated and aggregated crop growth model outputs of sorghum and millet in West-Africa. We used crop growth model outputs to calibrate a linear regression model using environmental covariates as predictors. The spatial regression residuals were investigated for spatial correlation. The linear regression model and the spatial correlation of residuals together were used to predict theoretical crop yield at all locations using kriging with external drift. A spatial standard deviation comes along with this prediction, indicating the uncertainty of the prediction. In combination with land use data and country borders, we summed the crop yield predictions to determine an area total. With spatial stochastic simulation, we estimated the uncertainty of that total production potential as well as the spatial cumulative distribution function. We compared our results with the prevailing agro-ecological Climate Zones approach used for spatial aggregation. Linear regression could explain up to 70% of the spatial variation of the yield. In three out of four cases the regression residuals showed spatial correlation. The potential crop production per country according to the Climate Zones approach was in all countries and cases except one within the 95% prediction interval as obtained after yield aggregation. We concluded that the geostatistical approach can estimate a country’s crop production, including a quantification of uncertainty. In addition, we stress the importance of the use of geostatistics to create tools for crop modelling scientists to explore relationships between yields and spatial environmental variables and to assist policy makers with tangible results on yield gaps at multiple levels of spatial aggregation.     

不同沙丘下梭梭(Haloxylon ammodendron)主根周围土壤特征的差异性研究

为探明沙漠建群种植物个体周围土壤养分和盐分空间分布及成因,对艾比湖湖区边缘三种类型沙丘下梭梭主根周围土壤含水量,电导率,全量养分和速效养分的变化进行了研究。结果表明:1固定性沙丘在表层(0~10 cm)处土壤含水量最小,流动性沙丘和半固定性沙丘在浅层(10~20 cm)处最小,以距离主根面3m处表现最为显著(P0.05)。2流动性沙丘和半固定性沙丘土壤有机质和全氮的结构性和空间自相关性均较弱,固定性沙丘养分(全量养分、速效养分)的结构性则较好。3三种沙丘土壤养分的空间分布不均,主要以条状和斑块状分布,整体上呈现出一定的集聚趋势,其中流动性沙丘和固定性沙丘集聚范围在0~2 m圈层,但纵向集聚范围中,流动性沙丘以浅层(10~20 cm),固定性沙丘以较深层(20~40cm)出现集聚,形成"肥岛"。4流动性沙丘土壤电导率对沙丘的影响较其他各特征因子占主导地位,半固定性沙丘和固定性沙丘养分因子占主导地位。     

佛山岭南天地旧改项目中开放空间的特色分析

近年来,国内出现了不少基于城市老街区改造为商业街区的项目。通过对佛山岭南天地项目中有代表性的广场、街道、建筑等节点进行调研,选取开放空间的3个特色要素——空间形态和尺度,传统装饰元素,植物和水景布置,探析"新天地"模式中开放空间营造的特色手法,包括保持街巷形态和宜人尺度,增强街区公共属性;保护传统建筑构件,利用传统材料、技术;保留古树,并结合植物和水景布置,形成多层次的景观系统等。