Landscape Ecology最新文献

Context

Models of human agency within research on land systems and landscapes do not fully account for social and cultural factors in decision making. Conversely, within social theory, parallel concepts of agency do not fully take biophysical and spatial factors into account. This calls for a synthesis of conceptual models addressing human decision making in land systems.

Objectives

The review identifies parallels between social and ecological perspectives on humans as co-constituent parts of complex land systems. On this basis selected models of agency combining insights from social theory and land systems research are outlined and compared, and improved concepts are outlined.

Methods

Elements of agency in modern agricultural land systems are reviewed. A case study illustrating the application of agency concepts in an analysis of decision making among farmers on the Canterbury Plains (New Zealand) is presented. On this basis it is discussed how to improve understandings of human agency in land systems.

Results

The review identifies and compares parallel conceptions of agency, practice and holism in landscape ecology and social theory. Taking the agency of farmers in contemporary agricultural landscapes as an example, theories currently used to characterise and interpret the agency of farmers are discussed and improvements considered. Potentials for improvement of current conceptual models are indicated and discussed, and an improved model of agency is suggested.

Conclusions

Based on the review, the article presents an improved conceptual model of agency in land systems emphasizing the position of agents in social-ecological contexts of action.

Context

Maintaining connectivity is crucial for wildlife conservation in human-occupied landscapes. Structural connectivity modeling (SCM) attempts to quantify the degree to which physical features facilitate or impede movement of individuals and has been widely used to identify corridors, but its accuracy is rarely validated against empirical data.

Objectives

We evaluated SCM’s ability to identify suitable habitat and corridors for onagers (Equus hemionus onager) through a comparison with functional connectivity (i.e., actual movement of individuals) using satellite tracking data.

Methods

We used MaxEnt to predict suitable habitat and evaluated the ability of three SCM approaches: circuit theory, factorial least cost path, and landscape corridors approaches to identify corridors. The performance of the three SCM approaches was validated against independently collected GPS telemetry data.

Results

Onagers selected water sources and dense vegetation while avoiding areas grazed intensely by livestock. The three approaches to SCMs identified similar movement corridors, which were interrupted by roads, affecting major high-flow movement corridors. The SCMs overlapped with functional connectivity by about 21%.

Conclusion

Movement corridors derived from SCMs did not align with the locations or intensity of corridors identified using the functional connectivity model. This finding suggests that SCMs might have a tendency to overestimate landscape resistance in areas with low habitat suitability. Therefore, SCM may not adequately capture individual decisions about habitat selection and movement. To protect corridors linking suitable habitat, data on functional connectivity (i.e., telemetry data) can be coupled with SCM to better understand habitat selection and movements of populations as a consequence of landscape features.

Context

Providing accessible urban green spaces is crucial for planning and ensuring healthy, resilient, and sustainable cities. The importance of visually accessible urban green spaces increases due to inner urban development processes.

Objectives

This article proposes a new index, the Green Window View Index (GWVI) for analyzing and assessing visible vegetation, that promotes an integrated planning of urban green spaces and buildings at different scales and levels. It is defined as the proportion of visible vegetation area in a field of view when looking out of a specific window with a defined distance to the window.

Methods

The method for estimating GWVI consists of three steps: (a) the modeling of the three-dimensional environment, (b) the simulation of the two-dimensional window views using modern rendering engines for three-dimensional graphics, (c) the computation of the GWVI. The method is proposed and tested through a case study of the urban area of Bonn, Germany, using a Digital Terrain Model (DTM), CityGML-based semantic 3D City Model at level of detail (LoD) 2, airborne Light Detection and Ranging (LiDAR) data, and 2D land use data from the official German property cadaster information system (ALKIS).

Results

With an average processing time of 0.05 s per window view, an average GWVI of 26.00% could be calculated for the entire study area and visualized in both 2D and 3D.

Conclusion

The proposed engine generates multi-scale visibility values for various vegetation shapes. These values are intended for use in participatory citizenship and decision-making processes for analysis by architects, real-estate appraisers, investors, and urban as well as landscape planners.

Abstract

Context

Prior research documented relationships between brown-headed cowbird (Molothrus ater) brood parasitism and edge effects, proximity of perches, and nest exposure. Those relationships have not been evaluated in agroecosystems containing extremes of fragmentation and vegetation diversity.

Objectives

We compared three existing hypotheses on how cowbirds locate host nests with two new hypotheses regarding habitat amount and vegetation diversity to determine how the configuration and location of agricultural conservation practices affect grassland bird nest parasitism rates and predicted rates for eight common conservation practices.

Methods

We assessed cowbird parasitism of grassland bird nests on corn and soybean farms in Iowa, USA, and measured perch proximity, nest exposure, edge effects, habitat amount, and vegetation diversity for each nest. We fit a global generalized linear mixed-effects model and compared importance of model parameters using odds ratios. We predicted parasitism likelihood for every subset model and averaged predictions to explore individual effects.

Results

The variables that most influenced parasitism rates included main effects for nest initiation day-of-season (OR = 0.71, CI₉₅ = 0.60–0.84) and the landscape variables of distance to nearest crop edge (0.63, 0.51–0.76) and proportion of grass land cover within 660 m (0.75, 0.57–1.00). We found little support that perch proximity, nest exposure, or native vegetation diversity affected parasitism. We also assessed parasitism likelihood by conservation practice and found no significant differences.

Conclusions

Our results provide evidence to support the edge effect and habitat amount hypotheses, but not the nest exposure, vegetation diversity, or perch proximity hypotheses.

Context

Understanding landscape functional connectivity is critical for nature conservation in fragmented landscapes. Spatially explicit graph-theoretical approaches to assessing landscape connectivity have provided a promising framework for capturing functional components driving connectivity at the landscape scale. However, existing weighting schemes used to parameterise functional connectivity in graph theory-based methods are limited with respect to their ability to capture patch-level characteristics relevant to habitat use such as edge-effects.

Objectives

We set out to develop a new approach to weighting habitat connectivity as a function of edge-effects exerted by non-habitat patches through better delineation of edge-interior habitat transitions at the patch-level and parameterization of intra-patch movement cost at the landscape scale.

Methods

We leverage the use of raster surfaces and area-weighted exponential kernels to operationalize a mechanistic approach to computing spatially explicit edge surfaces. We integrate map algebra, graph theory and landscape resistance methods to capture connectivity for a range of species specialisms on the edge-interior spectrum. We implement our method through a set of functions in the R statistical environment.

Result

Through a real-world case study, we demonstrate that our approach, drawing on these behaviours, outperforms competing metrics when evaluating potential functional connectivity in a typically fragmented agricultural landscape. We highlight options for the optimal parameterization of graph-theoretical models.

Conclusion

Our method offers increased flexibility, being tuneable for interior-edge habitat transitions. This therefore represents a key opportunity that can help to re-align the fields of landscape ecology and conservation biology by reconciling patch-versus-landscape methodological stances.

Context

Land use/cover change (LUCC) can directly and indirectly affect surface urban heat island intensity (SUHII) and the effects need to be decomposed.

Objectives

To perform long-term trend analyses of contribution indexes (CIs) of land use types to urban heat environment in cities and to deconstruct direct and indirect effects of LUCC on SUHII within geographical regions.

Methods

Mann–Kendall test and Sen’s slope were used to examine the trends of CIs and SUHII in 365 cities during summer of 2005–2019. Structural equation models were established to quantify direct and indirect effects of land use types’ CIs on SUHII in six geographical regions of China.

Results

First, SUHII in 78.08% and 73.70% of the Chinese cities increased during summer daytime and nighttime, respectively. Second, the CI of built-up land significantly increased across more than half of the cities in all the six regions. Third, not all land use types exerted both direct and indirect effects on SUHII. At daytime, the CI of cropland (direct) was the dominant factor in East China (1.386), South-central (− 0.637), and Northwest (− 0.399) regions. At nighttime, the CI of water bodies (both direct and indirect) was the dominant factor in Northwest (0.506) and Northeast (0.697) regions while CI of built-up land (both direct and indirect) determined in North China (0.476).

Conclusions

Separation of direct and indirect effects of land use types on SUHII had practical implications for cities to optimize the structures and functions of ecosystems and to take regionally based actions improving the urban heat environment.

Context

Species distribution models are widely used in ecology. The selection of environmental variables is a critical step in SDMs, nowadays compounded by the increasing availability of environmental data.

Objectives

To evaluate the interaction between the grain size and the binary (presence or absence of water) or proportional (proportion of water within the cell) representation of the water cover variable when modeling water bird species distribution.

Methods

eBird occurrence data with an average number of records of 880,270 per species across the North American continent were used for analysis. Models (via Random Forest) were fitted for 57 water bird species, for two seasons (breeding vs. non-breeding), at four grains (1 km² to 2500 km²) and using water cover as a proportional or binary variable.

Results

The models’ performances were not affected by the type of the adopted water cover variable (proportional or binary) but a significant decrease was observed in the importance of the water cover variable when used in a binary form. This was especially pronounced at coarser grains and during the breeding season. Binary representation of water cover is useful at finer grain sizes (i.e., 1 km²).

Conclusions

At more detailed grains (i.e., 1 km²), the simple presence or absence of a certain land-cover type can be a realistic descriptor of species occurrence. This is particularly advantageous when collecting habitat data in the field as simply recording the presence of a habitat is significantly less time-consuming than recording its total area. For models using coarser grains, we recommend using proportional land-cover variables.

Context

The goal of this work is to describe and explain the conditions that trigger, enable or prevent the implementation of preferred land uses by local communities.

Objective

The questions this paper addresses are as follows: Is there a set of preferred scenarios for land use change? What triggers, enables and prevents the implementation of preferred land uses? What did we learn by using participatory landscape scenarios?

Methods

In order to answer the research questions, we synthesize knowledge from a long-term case study in the buffer zone of the Rio Doce State Park in Brazil by (1) Developing participatory landscape scenarios and spatially explicit models for exploring desirable futures and associated land uses, as seen by local communities; (2) Explaining the conditions that trigger, enable or prevent the implementation of preferred landscape scenarios; and (3) Synthesizing knowledge on research and practice for working towards preferred land use changes.

Results

Preferred scenarios for land use change are agroforestry, animal husbandry, tourism and conservation. Although there is biophysical potential and funding available through multiple social and environmental programs, the Rio Doce State Park’s institutional setting is confusing. Although preferred land use scenarios will likely be implemented, participatory landscape approaches require a new, strategic role and leadership by regional institutions. Universities need to bring in social theories and institutional analysis to educate a new generation of landscape stewards.

Conclusion

We highlight the role of more responsive social agents and their representative institutions, including the changing role of university-based research and practice for working towards sustainable landscape outcomes.

Abstract