Remote sensing as surrogate for phylodiversity and functional processes along land use and elevation gradients
Final Report Abstract
The modification of land use systems has led to a dramatic loss of biodiversity with consequences for ecosystem functionality. As it is time consuming to quantify biodiversity and functional processes we need simple indicator systems for routine monitoring across large areas. Here, new developments in remote sensing provide promising information such as spectral or structural variables for predicting the status of biodiversity as well as certain processes even in areas with rough terrains. In our knowledge transfer project in Ecuador we tackled this challenge by matching field survey on different taxonomic groups and opto-structural information from remote sensing to develop and test remote sensing indicators for biodiversity and functional processes. We focused on different measures of biodiversity (species diversity, phylodiversity, and functional diversity) of important groups of organisms (trees, ants, and birds) that are relevant for the functional processes of herbivory and predation in forests. Tree phylodiversity at the clade level increased with increasing elevation, even though tree species richness did not change. Our results suggest that the dispersal of evolutionary old plant lineages with extra-tropical origins influenced the recent composition of trees in the Andes. We found that the abundance of ants and the two functional processes decreased with increasing elevation. Furthermore, ant incidence and richness were strongly related to the predation rate of artificial caterpillars. These results suggest that ant incidence and richness – relatively easily measurable metrics – can serve as bio-indicator for the process predation on insectivorous larvae. We additionally studied patterns of interspecific changes in the size of morphological traits of orthopteran assemblages collected along the elevation gradient at Mt. Kilimanjaro. Morphological traits changed both along a temperature and productivity gradient. The results emphasize that morphological adaptations within species assemblages go beyond changes in body size and include other ecologically relevant morphological traits as well. We tested the ability of airborne and satellite-borne multispectral remote sensing data to model environmental habitat proxies related to different measures of biodiversity. We found that textural metrics that depict different aspects of habitat heterogeneity are able to better model point-based measures of bird diversity than predictors derived from discrete-return Lidar products. We further tested whether these remote sensing data were able to model also diversity measures of other taxonomic groups. The benefit of structural remote sensing predictors often considerably increased the modelling success. Similarly, we were also able to model functional aspects of the forest using Landsat-8 data. Thus, multispectral data of operational satellite systems could replace costly airborne laser-scanning for modeling certain aspects of biodiversity. Our multi-taxa approach therefore suggests that such a remote sensing-based indicator system could be easily transferred to other ecological aspects to guarantee comprehensive monitoring across space and time. Finally, our knowledge transfer workshop was successful in teaching geostatistical methods to calculate and implement spatially explicit indicators for biodiversity at the non-university partners which will be used as an effective tool on monitoring alterations in functional biodiversity and ecosystem processes caused by environmental changes in Ecuador.
Publications
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2016: Contrasting performance of Lidar and optical texture models in predicting avian diversity in a tropical mountain forest. Remote Sensing of Environment 174, 223–232
Wallis, C.I.B., Paulsch, D., Zeilinger, J., Silva, B., Curatola Fernández, G.F., Brandl, R., Farwig, N., Bendix, J.
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2016: Phylogenetic, niche conservatism does not explain elevational patterns of species richness, phylodiversity and family age of tree assemblages in Andean rainforest. Erdkunde 70, 83–106
Tiede, Y., Homeier, J., Cumbicus, N., Peña, J., Albrecht, J., Ziegenhagen, B., Bendix, J., Brandl, R., Farwig, N.
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2017: Ants as indicators of environmental change and ecosystem processes. Ecological Indicators 83: 527–537
Tiede, Y., Schlautmann, J., Donoso, D.A., Wallis, C.I.B., Bendix, J., Brandl, R., Farwig, N.
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2017: Introduction to the Special Issue “Functional monitoring in megadiverse tropical ecosystems”. Ecological Indicators 83: 524–526
Farwig, N., Bendix, B., Beck, E.
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2017: Remote sensing improves prediction of tropical montane species diversity but performance differs among taxa. Ecological Indicators 83: 538–549
Wallis, C.I.B., Brehm, G., Donoso, D.A., Fiedler, K., Homeier, J., Paulsch, D., Süßenbach, D., Tiede, Y., Brandl, R., Farwig, N., Bendix, J.
