scholarly journals ‘The Best of Two Worlds’—Combining Classifier Fusion and Ecological Models to Map and Explain Landscape Invasion by an Alien Shrub

2021 ◽  
Vol 13 (16) ◽  
pp. 3287
Author(s):  
Nuno Mouta ◽  
Renato Silva ◽  
Silvana Pais ◽  
Joaquim M. Alonso ◽  
João F. Gonçalves ◽  
...  

The spread of invasive alien species promotes ecosystem structure and functioning changes, with detrimental effects on native biodiversity and ecosystem services, raising challenges for local management authorities. Predictions of invasion dynamics derived from modeling tools are often spatially coarse and therefore unsuitable for guiding local management. Accurate information on the occurrence of invasive plants and on the main factors that promote their spread is critical to define successful control strategies. For addressing this challenge, we developed a dual framework combining satellite image classification with predictive ecological modeling. By combining data from georeferenced invaded areas with multispectral imagery with 10-meter resolution from Sentinel-2 satellites, a map of areas invaded by the woody invasive Acacia longifolia in a municipality of northern Portugal was devised. Classifier fusion techniques were implemented through which eight statistical and machine-learning algorithms were ensembled to produce accurate maps of invaded areas. Through a Random Forest (RF) model, these maps were then used to explore the factors driving the landscape-level abundance of A. longifolia. RF models were based on explanatory variables describing hypothesized environmental drivers, including climate, topography/geomorphology, soil properties, fire disturbance, landscape composition, linear structures, and landscape spatial configuration. Satellite-based maps synoptically described the spatial patterns of invaded areas, with classifications attaining high accuracy values (True Skill Statistic, TSS: 0.895, Area Under the Receiver Operating Curve, ROC: 0.988, Kappa: 0.857). The predictive RF models highlighted the primary role of climate, followed by landscape composition and configuration, as the most important drivers explaining the species abundance at the landscape level. Our innovative dual framework—combining image classification and predictive ecological modeling—can guide decision-making processes regarding effective management of invasions by prioritizing the invaded areas and tackling the primary environmental and anthropogenic drivers of the species’ abundance and spread.

Insects ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 677
Author(s):  
Stefan Möth ◽  
Andreas Walzer ◽  
Markus Redl ◽  
Božana Petrović ◽  
Christoph Hoffmann ◽  
...  

This is a reply to the comment from Schausberger [...]


2013 ◽  
Author(s):  
Georgia C.A. French ◽  
Joanna K Bluemel ◽  
David Rowat

Background: The whale shark feeding aggregation in the Seychelles has been studied in detail since 2002, including aerial survey and collection of environmental data. In these coastal waters previous tagging studies have shown whale sharks spend considerable time in the top 10m of water (44-60% of daylight hours). Although protected locally there is currently no management structure to conserve them outside of protected areas. This is the first attempt to develop Temporary Protected Areas using statistical modeling of their ecological distribution to conserve the aggregation. Methods: Data on whale shark occurrence and distribution were collected via standardized aerial surveys from microlight aircraft that also recorded locations of surface-feeding schools of fish and environmental variables. These data were input into Geographical Information System (GIS) software to create density distribution maps; further layers generated included distance from the coastline, and chlorophyll-a (Chl-a) concentration (from MODIS satellite imagery). MAXENT ecological modeling software and Kernel Density Estimate analysis were used to produce a habitat suitability map and probability distribution estimate. The MAXENT model was tested using pseudo-absence data in a binomial generalized linear model. Results: Chl-a concentration, distance from coast and fish schools were all found to influence whale shark presence and Maxent results closely matched those from the Kernel Density Estimate analysis. Predictions of suitable habitat for whale sharks avoided higher Chl-a concentrations, but showed positive correlations with schools of fish, possibly acting as a direct indication of zooplankton abundance. Whale sharks preferentially selected feeding areas close to the coast. Conclusion: Maxent and Kernel Density Estimates can provide useful tools to guide the development of appropriate conservation and management of this species that take into consideration temporal behavior and ecology.


2013 ◽  
Author(s):  
Georgia C.A. French ◽  
Joanna K Bluemel ◽  
David Rowat

Background: The whale shark feeding aggregation in the Seychelles has been studied in detail since 2002, including aerial survey and collection of environmental data. In these coastal waters previous tagging studies have shown whale sharks spend considerable time in the top 10m of water (44-60% of daylight hours). Although protected locally there is currently no management structure to conserve them outside of protected areas. This is the first attempt to develop Temporary Protected Areas using statistical modeling of their ecological distribution to conserve the aggregation. Methods: Data on whale shark occurrence and distribution were collected via standardized aerial surveys from microlight aircraft that also recorded locations of surface-feeding schools of fish and environmental variables. These data were input into Geographical Information System (GIS) software to create density distribution maps; further layers generated included distance from the coastline, and chlorophyll-a (Chl-a) concentration (from MODIS satellite imagery). MAXENT ecological modeling software and Kernel Density Estimate analysis were used to produce a habitat suitability map and probability distribution estimate. The MAXENT model was tested using pseudo-absence data in a binomial generalized linear model. Results: Chl-a concentration, distance from coast and fish schools were all found to influence whale shark presence and Maxent results closely matched those from the Kernel Density Estimate analysis. Predictions of suitable habitat for whale sharks avoided higher Chl-a concentrations, but showed positive correlations with schools of fish, possibly acting as a direct indication of zooplankton abundance. Whale sharks preferentially selected feeding areas close to the coast. Conclusion: Maxent and Kernel Density Estimates can provide useful tools to guide the development of appropriate conservation and management of this species that take into consideration temporal behavior and ecology.


2021 ◽  
Author(s):  
Zhongyi Zhan ◽  
Lili Ren ◽  
Linfeng Yu ◽  
Zhiwen Guo ◽  
Yujie Liu ◽  
...  

Abstract In recent years, the red turpentine beetle (RTB), an invasive pest species, has caused extensive pine mortality in North China. Although some studies have theoretically clarified the interference mechanism of multi-level factors with the development of RTB damage, knowledge about this mechanism from the empirical research is still limited. The aim of this study was to determine whether the primary factors influencing RTB occurrence change during different periods of RTB invasion. Stand-level variables of sample plots were obtained through field investigation and the forest resource survey data including forest stand characteristics, topographic characteristics, and soil properties. Remote sensing classified images were to develop the characteristic variables related to landscape composition and configuration around the sample plots at multiple scales. Generalized linear models (GLMs) and generalized linear mixed models (GLMMs) were used to explore the relative importance of stand-level and landscape-level variables in explaining the severity of RTB damage. Result showed that two stand-level factors, aspect and canopy density, were the best predictors of damage in the early stage of RTB invasion. The landscape-level factor, the proportion of Chinese pine (Pinus tabuliformis) patches, was the main predictor of damage in the middle stage of RTB invasion. The most effective spatial scale at which RTB responded to landscape pattern was 250 m. With the increasing severity of RTB damage, the factors driving RTB invasion have shifted from the stand-level to the landscape-level. This calls for an urgent consideration of multi-scale processes to address the changing disturbance regimes in ecosystem management.


2021 ◽  
Vol 9 ◽  
Author(s):  
Lázaro da Silva Carneiro ◽  
Willian Moura de Aguiar ◽  
Camila de Fátima Priante ◽  
Milton Cezar Ribeiro ◽  
Wilson Frantine-Silva ◽  
...  

Human activities have modified the landscape composition. The changes in the landscape structure can be evaluated by metrics, which are influenced, among other factors, by the number of cover classes used for the landscape classification (thematic resolution). In high thematic resolutions, landscape covers that can influence biological responses are identified and detailed. In low thematic resolutions, this detail level is lower because it aggregates different landscape covers in a few classes. However, how the thematic resolution influences our ability to understand landscape structure on biodiversity is poorly explored, particularly for pollinators. Here we asked how thematic resolution affects the explanatory power of landscape composition on explaining Euglossini bees (richness and abundance) within 15 landscapes composed mainly of coffee and pasture. To address this issue, we quantified the association between five attributes of the euglossine bee community and landscape composition: landscape cover classes (%) and landscape heterogeneity. Moreover, we also evaluated how the thematic resolution influences bee responses to landscape structure. We found a strong and positive influence of landscape heterogeneity in low thematic resolutions (i.e., few cover classes on maps) over the richness and rare species abundance. We also observed that- in addition to the forest cover in the landscape- the pasture cover (%) quantified in high thematic resolution positively influenced the total abundance and abundance of common and intermediate species. Our study highlights the importance of maintaining compositional heterogeneity for the orchid bee community in agroecosystems, and forest cover for the biological requirements and conservation of these pollinators. Moreover, the use of different thematic resolutions showed how specific types of landscape covers influence the euglossine community attributes. This can highlight the species preferences for habitats and landscape covers. Thus, we call the attention of landscape ecologists to the importance of the definition of thematic resolution, as our ability to quantify the association between biological responses and landscape structure may be influenced by the number of classes used when building thematic maps.


Insects ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 351
Author(s):  
Adara Pardo ◽  
David H. Lopes ◽  
Natalia Fierro ◽  
Paulo A. V. Borges

Intensive agricultural practices leading to habitat degradation represent a major threat to pollinators. Diverse management practices are expected to influence wild pollinator abundance and richness on farms, although their effect in perennial crops is still unclear. In this study, we assessed the impact of management on apple (Malus domestica) pollination on an oceanic island, by comparing conventional (with and without herbicide application) and organic apple orchards. Pollinator visitation and pan trap surveys were carried out in six apple orchards in Terceira Island (Azores) and the landscape composition surrounding orchards was characterized. We also quantified fruit set, seed set and apple weight. We found no significant effect of management on insect visitation rates, whereas there was a negative association with increasing surrounding agricultural land. In contrast, management had an effect on species abundance, richness and diversity at the orchard level. Conventional orchards without herbicides showed higher abundance than the rest, but lower richness and diversity than conventional orchards with herbicides. Management had an effect on fruit set, but not on seed set or fruit weight. Our results suggest that management alone is insufficient for the overall improvement of apple pollination on an oceanic island, while landscape composition may play a relevant role.


Sign in / Sign up

Export Citation Format

Share Document