Satellite imagery as a tool to evaluate ecological scale

Methods for detecting scale and dispersion of plant cover developed by Carilieet al. (1989,Landscape Ecology 2: 203–213) were adapted to information obtained from satellite imagery. Scales were found to be on the order of 100 m in the shrub-steppe area of southeastern Washington. General agreement between the remotely sensed data and plant cover using the variance and correlation methods of Carlileet al. indicate that remote sensing information can be used in the design of field studies for measuring the processes controlling plant cover in semi-arid areas; the agreement also suggests that the methods have broad applicability in the determination of scale and dispersion.     

Modeling multi-scale spatial ecological processes under the discrete event systems paradigm

A multi-scale spatial ecological model of a wet sclerophyllous forest subject to recurrent fires is presented. The model is specified in a Discrete Event Systems framework (DEVS) (Zeigler, 1990) interfaced with a Geographic Information System (GIS), and includes the ability to simulate landscape dynamics at several levels of resolution simultaneously. This is achieved by encoding a modular hierarchical representation of the forest landscape components into a set of nested, interconnected, and spatially referenced dynamic models. The results of the landscape dynamics simulations are displayed as sequences of maps through time, illustrating the potential of this modeling methodology for dealing with complex hierarchical structures that operate at several spatial and temporal resolutions.Research work supported by Junta Nacional de Investigaçäo Científica e Tecnológica, Portugal, and the Advanced Resource Technology Program, University of Arizona, USA.     

Some remarks on recent developments in landscape ecology as a transdisciplinary ecological and geographical science

Condensed version of a lecture at the Seminar on Landscape Ecology: Theoretical and Practical Perspectives in Italy, organized by the Italian Society of Ecology and the Italian Section of IALE — Parma 25th May 1990.     

植物措施在近自然河道规划中的应用——以浙江海宁生态河道规划设计为例

浙江海宁在近几年的近自然河道模式整治中,主要通过河道疏浚、边坡整理和植物措施等进行河道的治理和生态修复,植物措施作为河道生态建设的关键组分在工程和实践中发挥着重要作用。文章从生态河道植物措施的规划设计理念、原则及具体设计实践进行分析,并结合当地实际,提出郊区、农村河道的生态治理注意事项。     

Application rate and plant species affect the ecological safety of sewage sludge as a landscape soil amendment

Recycling sludge as a soil amendment has become a viable option for sludge disposal. However, such application can lead to soil pollution because of its enrichment in contaminants, especially heavy metals. To identify an effective means to ensure the ecological safety of sewage sludge landscape utilization, a glasshouse experiment was conducted by mixing sewage sludge at 0%, 15%, 30%, 60%, and 100% (V/V) amendment ratios to landscape soils and planting five common landscape plants (Aphelandra ruellia, Syngonium podophyllum, Schefflera odorata, Alocasia macrorrhiza, and Dianella ensifolia). Sludge amendment significantly improved fertility and moisture retention capacity of soil, but dramatically increased the contents of Cd, Pb, Cu, and Zn. Compared with lateritic red soil (CK), sludge amended-soils increased the relative growth rate of landscape plants and enhanced their nutrient uptake and heavy metals accumulation. A rate of 30% or less of sludge application showed positive growth effects for all five landscape plants, and did not cause potential ecological risks of heavy metals to landscape soils. However, rates of 60% or higher posed very high potential ecological risk in multiple metals, particularly in Cd. Interestingly, S. odorata, A. ruellia and A. macrorrhiza could alleviate the ecological risks of Cd, Cu and Zn, respectively, and these results were confirmed by data of relative changes in heavy metal contents in post-experiment soil. Our results suggest that attention to reducing the environmental risks of heavy metals in sludge utilization as landscape soil-amendments should not only be paid to controlling the application dosage of sludge but also to planting suitable plant species.     

Upscaling as ecological information transfer: a simple framework with application to Arctic ecosystem carbon exchange

Transferring ecological information across scale often involves spatial aggregation, which alters information content and may bias estimates if the scaling process is nonlinear. Here, a potential solution, the preservation of the information content of fine-scale measurements, is highlighted using modeled net ecosystem exchange (NEE) of an Arctic tundra landscape as an example. The variance of aggregated normalized difference vegetation index (NDVI), measured from an airborne platform, decreased linearly with log(scale), resulting in a linear relationship between log(scale) and the scale-wise modeled NEE estimate. Preserving three units of information, the mean, variance and skewness of fine-scale NDVI observations, resulted in upscaled NEE estimates that deviated less than 4% from the fine-scale estimate. Preserving only the mean and variance resulted in nearly 23% NEE bias, and preserving only the mean resulted in larger error and a change in sign from CO₂ sink to source. Compressing NDVI maps by 70–75% using wavelet thresholding with the Haar and Coiflet basis functions resulted in 13% NEE bias across the study domain. Applying unique scale-dependent transfer functions between NDVI and leaf area index (LAI) decreased, but did not remove, bias in modeled flux in a smaller expanse using handheld NDVI observations. Quantifying the parameters of statistical distributions to preserve ecological information reduces bias when upscaling and makes possible spatial data assimilation to further reduce errors in estimates of ecological processes across scale.     

The emergence of heterogeneity in invasive-dominated grassland: a matter of the scale of detection

Context

Plant invasions of native ecosystems are one of the main causes of declines in biodiversity via system-simplification. Restoring native biodiversity can be particularly challenging in landscapes where invasive species have become dominant and where a new set of feedbacks reinforce an invaded state and preclude restoration actions. We lack an understanding of the response of invaded systems to landscape-level manipulations to restore pattern and process relationships and how to identify these relationships when they do not appear at the expected scale.

Objectives

To better understand how fire and grazing influence landscape-level heterogeneity in invaded landscapes, we assess the scale at which grazing pressure and seasonality mediate the success of re-introducing a historical disturbance regime, grazing driven by fire (termed pyric herbivory), to an invasive plant-dominated landscape.

Methods

We manipulated grazing timing and intensity in exotic grass-dominated grasslands managed for landscape heterogeneity with spring fire and grazing. In pastures under patch-burn grazing management, we evaluated the spatial and temporal variability of plant functional groups and vegetation structure among and within patches managed with separate grazing systems: season-long stocking and intensive early stocking.

Results

Warm- and cool-season grasses exhibited greater among-patch variability in invasive-plant dominated grassland under intensive early grazing than traditional season-long grazing, but landscape-level heterogeneity, as measured through vegetation structure was minimal and invariable under both levels of grazing pressure, which contrasts findings in native-dominated systems. Moreover, within-patch heterogeneity for these functional groups was detected; contrasting the prediction that among-patch heterogeneity, in mesic grasslands, manifests from within-patch homogeneity.

Conclusions

In invaded grasslands, manipulation of grazing pressure as a process that drives heterogeneous vegetation patterns influences native and non-native grass heterogeneity, but not heterogeneity of vegetation structure, within and among patches managed with fire. Fire and grazing-moderated heterogeneity patterns observed in native grass-dominated grasslands likely differ from invasive grass-dominated grasslands with implications for using pyric herbivory in invaded systems.

     

Climate change adaptation strategies for federal forests of the Pacific Northwest,USA: ecological,policy, and socio-economic perspectives

Conserving biological diversity in a changing climate poses major challenges for land managers and society. Effective adaptive strategies for dealing with climate change require a socio-ecological systems perspective. We highlight some of the projected ecological responses to climate change in the Pacific Northwest, U.S.A and identify possible adaptive actions that federal forest managers could take. The forest landscape, ownership patterns and recent shift toward ecologically based forest management provide a good starting place for conserving biological diversity under climate change. Nevertheless, undesirable changes in species and ecosystems will occur and a number of adaptive actions could be undertaken to lessen the effects of climate change on forest ecosystems. These include: manipulation of stand and landscape structure to increase ecological resistance and resilience; movement of species and genotypes; and engaging in regional, multi-ownership planning to make adaptive actions more effective. Although the language and goals of environmental laws and policies were developed under the assumption of stable climate and disturbance regimes, they appear to be flexible enough to accommodate many adaptive actions. It is less certain, however, if sufficient social license and economic capacity exist to undertake these actions. Given the history of contentious and litigious debate about federal forest management in this region, it is likely that some of these actions will be seen as double-edge swords, spurring social resistance, especially where actions involve cutting trees. Given uncertainties and complexity, collaborative efforts that promote learning (e.g. adaptive management groups) must be rejuvenated and expanded.     

提高石榴外观质量的技术措施

１９９８～１９９９年,以大青皮和大红袍石榴为试材进行了提高石榴外观质量试验。采用合理修剪,穴贮肥水,果园覆盖,疏花疏果、果实套袋等综合技术措施,使两个品种果个增大,着色果比率提高,果面褐斑率、裂果率显著降低,外观质量明显改观。     

不同生态条件下西瓜果实瓜氨酸含量比较研究

为了明确不同西瓜材料在不同生态条件下瓜氨酸含量的差异,用分光光度法分别测定了新疆和海南种植的15份相同西瓜材料果实瓜氨酸的含量,结果表明,15份西瓜材料在新疆地区瓜氨酸含量(鲜质量)范围为1.13~2.46 g·kg~(-1),海南地区瓜氨酸含量(鲜质量)范围为0.62~2.23 g·kg~(-1),两地瓜氨酸含量均较高的2份为‘White wonder’和‘9904’。和海南相比,新疆种植的西瓜果实有较高的瓜氨酸含量,西瓜材料、地区生态环境均能显著影响西瓜果实瓜氨酸含量,并且环境对不同西瓜材料瓜氨酸含量的影响程度存在差异。     

Determination of ecological scale

We suggest that ecological processes and physical characteristics possess an inherent scale at which the processes or characteristics occur over the landscape. We propose a conceptual spatial response model that describes the nature of this ecological scale. Based on the proposed spatial model, we suggest methods for estimating the size of study plots or transects and the distance between replicate plots needed to approach statistical independence. Using data on percent cover for Agropyron spicatum, a common arid-land bunchgrass, we demonstrated four relationships that should hold if the spatial response model is appropriate. These relationships are sample variance increases as functions of (1) transect segment length and (2) intersegment length (transect segment dispersal), and correlation decreases as functions of (3) intersegment length and (4) transect segment length. Based on evaluation of these four relationships, cover for A. spicatum is correlated over the landscape on a scale of 400 to 700 m, and a segment length of 64 to 128 m is most appropriate for measuring cover for this species.     

The social and spatial dynamics of community food production: a landscape approach to policy and program development

Community food production in the form of home gardening, community gardening, school gardening, and urban farming continues to increase in popularity in many parts of the world. This interest has led to public and private investment in community food production and increased need for urban agricultural planning as a way to manage growth and prioritize resource allocation. Municipal planning and thoughtful institutional support for the practice will require program evaluation and greater attention to the spatial composition and configuration of this widely dispersed practice. This article explores the results of community-supported landscape socio-ecological research in Madison, WI (USA) to assess the spatial and social dynamics of community food production. Results indicate that community food production resources are unevenly distributed across the study area. Historic community garden placement does appear to be consistent with community prioritization which dictates placing resources in areas with low median household income. However, home garden presence and recent community garden placement both occur in areas of higher than average median household income. Specific focus is placed on how an understanding of landscape placement and pattern has helped inform attempts to meet municipal and regional objectives in addressing urban food insecurity.     

生态园林对张掖人居环境的影响

本文通过对生态园林特点的分析研究,概括提出了生态园林的自然化、生态化和人性化、人本化的风格是未来生态园林的两大发展主题,进而探索了生态园林对人居环境品质的影响及重大意义。     

Machine learning in landscape ecological analysis: a review of recent approaches

Landscape Ecology - Artificial Intelligence (AI) has rapidly developed over the past several decades. Several related AI approaches, such as Machine Learning (ML), have been applied to research on...     

The impact of rainfall in remobilising particulate matter accumulated on leaves of four evergreen species grown on a green screen and a living wall

Green walls have recently been identified as a green infrastructure (GI) solution to the problem of particulate matter (PM) air pollution. Green wall systems mostly use evergreen plants as the leaves are retained throughout the year; however, researchers have argued that evergreen foliage becomes saturated with PM and fails to capture more due to a long retention time on the leaves. This study evaluated the potential of (simulated) rainfall to remobilise these captured PM and renew the capture ability of the leaf surfaces of four evergreen species (Heuchera villosa Michx, Helleborus × sternii Turrill, Bergenia cordifolia (Haw.) Sternb., Hedera helix L.) used in a living wall and a green screen located along a busy road in Stoke-on-Trent, UK. The approach used compared PM densities on pre- and post-rain exposed leaf surfaces (using leaf halves of the same leaf) and using a paired t-test to identify any significant reduction in PM due to the rainfall. An Environmental Scanning Electron Microscope (ESEM) and ImageJ image analysis software were employed to quantify the PM densities on leaves. The reduction of PM on leaves, following exposure to 16 mm hr⁻¹ simulated rain in six different rainfall durations was estimated in all four species in order to evaluate any variable impact of rainfall on different species of plants. PM wash-off levels on leaves of H. helix by 41 mm hr⁻¹ rain was also evaluated, using the same rainfall durations, to assess any differential impact of rainfall intensity on PM wash-off. This study revealed a significant impact of rainfall in washing the particles off the leaves in all rainfall durations used. A one-way Anova in a Generalised Linear Model showed a differential impact of rainfall in remobilising PM on different species of plants. The rainfall with higher intensity (41 mm hr⁻¹) showed a significantly higher impact on PM wash-off compared to 16 mm hr⁻¹ rain. The results of this study demonstrated the potential of green walls to act as good PM traps throughout the year by recycling their capture surfaces.     

The effect of temperature on growth and dry matter production of lychee seedlings

In lychee (Litchi chinensis Sonn.), high day/night temperatures ($\text{30}\text{25}$, $\text{25}\text{20}$, $\text{20}\text{15}\text{°}\text{C}$ compared to $\text{15}\text{10}\text{°}\text{C}$) increased stem extension, node and leaf production and plant dry weight in seedling selections of 6 cultivars (‘Bengal’, ‘Haak Yip’, ‘Kwai May’, ‘Gee Kee’, ‘Tai So’ and ‘Wai Chee’). The mean daily base temperature for shoot growth (node production) was estimated by linear correlation to be 11.0°C for the seedlings. High temperatures also increased the proportion of leaf and decreased the proportion of root in the total dry weight. There was a strong effect of cultivar on all aspects of growth, but the responses to temperature were similar.This experiment shows that temperatures in many tropical and warm sub-tropical areas where lychees are grown are too high to induce satisfactory vegetative dormancy prior to floral initiation. The assessment of lychee seedlings for low vigour in a heated glasshouse appears to be a useful technique for the initial screening of adapted genotypes (which flower and fruit under warm conditions) prior to field evaluation.     

出菇温度对工厂化瓶栽平菇子实体产量和品质的影响

以黑平8号平菇菌株为材料,采用工厂化瓶栽生产方法,设置不同出菇温度,通过测定原基形成时间、密集度、色泽,子实体颜色、朵形和菌盖光亮度,采收时间、产量和生物学效率等指标,比较不同出菇温度对平菇生长发育的影响。结果:出菇温度越低,原基形成时间越长、颜色越深,子实体朵形越紧凑。随着出菇温度的升高,菌盖光亮度变差,子实体采收时间变短,产量和生物学效率下降;最终确定以16℃为黑平8号在工厂化瓶栽条件下的适宜出菇温度。     

Colonisation as a common denominator in plant metapopulations and range expansions: effects on genetic diversity and sexual systems

Colonisation plays a central role in both the initial occupancy of a region through range expansions as well as in metapopulations, where local extinctions are balanced by re-colonisations. In this paper, we review the effects that colonisation is expected to have on patterns of genetic variation within a species, and we draw attention to the possibility of interpreting these patterns as signatures of colonisation in the past. We briefly review theoretical predictions for the effect of colonisation on both neutral genetic diversity and on variation at genetic loci that regulate the sexual system of plant populations. The sexual system represents a particularly important trait in this context because it is affected by both selection during colonisation, and because it influences gene flow amongst populations. Finally, we introduce four case studies of plant species that show variation in their sexual systems that is consistent with theoretical predictions.