Gertrud Schaab

Forest Fragmentation and Selective Logging Have Inconsistent Effects on Multiple Animal-Mediated Ecosystem Processes in a Tropical Forest

Forest fragmentation and selective logging are two main drivers of global environmental change and modify biodiversity and environmental conditions in many tropical forests. The consequences of these changes for the functioning of tropical forest ecosystems have rarely been explored in a comprehensive approach. In a Kenyan rainforest, we studied six animal-mediated ecosystem processes and recorded species richness and community composition of all animal taxa involved in these processes. We used linear models and a formal meta-analysis to test whether forest fragmentation and selective logging affected ecosystem processes and biodiversity and used structural equation models to disentangle direct from biodiversity-related indirect effects of human disturbance on multiple ecosystem processes. Fragmentation increased decomposition and reduced antbird predation, while selective logging consistently increased pollination, seed dispersal and army-ant raiding. Fragmentation modified species richness or community composition of five taxa, whereas selective logging did not affect any component of biodiversity. Changes in the abundance of functionally important species were related to lower predation by antbirds and higher decomposition rates in small forest fragments. The positive effects of selective logging on bee pollination, bird seed dispersal and army-ant raiding were direct, i.e. not related to changes in biodiversity, and were probably due to behavioural changes of these highly mobile animal taxa. We conclude that animal-mediated ecosystem processes respond in distinct ways to different types of human disturbance in Kakamega Forest. Our findings suggest that forest fragmentation affects ecosystem processes indirectly by changes in biodiversity, whereas selective logging influences processes directly by modifying local environmental conditions and resource distributions. The positive to neutral effects of selective logging on ecosystem processes show that the functionality of tropical forests can be maintained in moderately disturbed forest fragments. Conservation concepts for tropical forests should thus include not only remaining pristine forests but also functionally viable forest remnants.

Potential of remote sensing to predict species invasions A modelling perspective

Understanding the causes and effects of species invasions is a priority in ecology and conservation biology. One of the crucial steps in evaluating the impact of invasive species is to map changes in their actual and potential distribution and relative abundance across a wide region over an appropriate time span. While direct and indirect remote sensing approaches have long been used to assess the invasion of plant species, the distribution of invasive animals is mainly based on indirect methods that rely on environmental proxies of conditions suitable for colonization by a particular species. The aim of this article is to review recent efforts in the predictive modelling of the spread of both plant and animal invasive species using remote sensing, and to stimulate debate on the potential use of remote sensing in biological invasion monitoring and forecasting. Specifically, the challenges and drawbacks of remote sensing techniques are discussed in relation to: i) developing species distribution models, and ii) studying life cycle changes and phenological variations. Finally, the paper addresses the open challenges and pitfalls of remote sensing for biological invasion studies including sensor characteristics, upscaling and downscaling in species distribution models, and uncertainty of results.

The indirect effects of habitat disturbance on the bird communities in a tropical African forest

Tropical forests are increasingly threatened by anthropogenic activities often resulting in habitat and biodiversity loss. To effectively manage and protect these areas, it is important to have an understanding of the factors affecting their biodiversity. Previous research has shown that birds in tropical regions are severely affected by human-induced habitat conversion and disturbance. The effects, however, are often area and guild-specific and the underlying mechanisms are frequently unclear. In this study, we disentangle and quantify the direct and indirect effects of human population density, distance to forest edge, habitat disturbance, and vegetation structure and composition on the total abundance and species richness of birds in Kakamega Forest, Kenya. Specifically, we use structural equation modeling to develop and test path models, which reflect the potential causal relationships between the bird assemblages and the chosen explanatory factors. Relationships were tested on the overall bird community and on five different guilds, classified according to birds’ forest specialization and feeding preferences (i.e. forest specialists, generalists and visitors, and frugivores and insectivores). Results showed that habitat disturbance, caused by logging, had a weak positive direct effect on the bird communities, but also had a strong detrimental indirect effect, particularly on the total abundance and species richness of forests specialists and insectivores. The negative effect was mediated through changes in the forest’s vegetation structure and composition. Shorter distances to the forest edge also had a negative effect, on all bird categories except on forest visitors, which also benefited from higher levels of disturbance. Our study shows that although in some cases habitat disturbance may have no strong direct negative effects it can still negatively influence bird communities in an indirect way. In the case of Kakamega Forest, we suggest that to conserve bird communities it is important to maintain the forest’s compositional and structural diversity by reducing human-induced habitat disturbance, such as illegal logging activities.

Supporting the Monitoring of Cheetahs in Kenya by Mobile Map Apps

The cheetah (Acinonyx jubatus) is Africa’s most endangered large felid. In Kenya, cheetahs are extirpated from 25% of their historic range with 75% of the population residing outside protected areas. Action for Cheetahs in Kenya (ACK) endeavours to understand cheetah ecology and threats in human-dominated landscapes. The NGO is a suitable candidate for benefitting from the development and deployment of mobile map apps on smartphones to support the monitoring of species, also by so-called citizen scientists. The apps enable a digital workflow of data collection, transfer and analysis. This paper describes the process of developing custom mobile map apps from the conceptualizing of a system from data collection to data storage. We discuss the implementation as well as on the ground testing which included a usability study. The software environment from Esri’s platform tools were used but aiming at a low-cost solution which supports both secure monitoring in the field and the management of sensitive data. Due to hardware constraints the implemented system cannot be considered a state-of-the art version, but for ACK it is a big step towards digital data collection by means of an app family and data management in a database. A Web frontend allows for input on cheetah sightings also from outside the organization and serves the purpose of visualizing observation efforts for potential donors. While software development took place mainly in Germany, the usability study following the installation of the mobile app monitoring system targeted twelve ACK staff members on the ground in Kenya. Before the testing the users expected faster and less work in particular in the field and an easier reporting to office staff and streamlined data collection. After testing the mobile apps or the data management routines, answers shifted to pointing out benefits of faster data transfer and in-time data access. The evaluation provided valuable insights in the needs for reaching a routine level and high quality data recording and management.

Communicating Climate Change: Reinforcing Comprehension and Personal Ties to Climate Change Through Maps

ABSTRACT Although climate change is highly prevalent in the media, people in Europe and the United States are often unsure about climate change terms, processes, and its personal consequences. In other words, climate change communication seems to be largely failing so far. Among other communication tools, maps are widely used for explanatory purposes by scientists and the media. Here two questions arise: first, whether high map complexity may be too intricate to be understood and discourage people from deciphering the map; and second, whether personal interest in climate change can be influenced by the phenomenon depicted or the map’s scale. In a survey conducted among 109 students in the USA, 63% of respondents preferred a simple map, but a substantial subset, 37%, asked for complexity to receive more information. Regional phenomena evoked more concern than far-off phenomena (concern level index difference of 0.93 on a 5-ranked Likert scale). The advantage of maps showing local areas could not be statistically confirmed.

Expert opinions on using the third dimension to visualise wind speed uncertainty in wind farm planning

ABSTRACT To date, most studies on uncertainty visualisations have focused on two-dimensional representations. The closing of the software gap between three-dimensional (3D) graphics and geovisualisation presents new opportunities for the visualisation of uncertainty. The goal of our research is to understand the usability and suitability of different visualisation techniques for representing uncertainty in the third dimension. In this paper, we present the perceptions of experts in the fields of renewable energy and climate modelling regarding 3D uncertainty maps. Four different maps, each representing uncertainty of mean wind speed in a different way, were prepared for expert interviews. Interviewees were asked questions about different usability and suitability aspects of the maps for regional planning of wind farms. Their responses provide valuable insights for the usability of the third dimension to represent uncertainty in maps, and the suitability in regional-level planning of wind farms. These exploratory research results can be used to guide the design of controlled user studies to further investigate the usability of the third dimension for uncertainty representations, and the suitability for wind farm planning.