On the growth performance of two competing species in an Andean pasture of southern Ecuador - monitoring and simulations

The megadiverse tropical mountain forests in the southeastern Andes of Ecuador, including their biodiversity and ecosystem services, are severely threatened due to climate warming and the clearing of forests to produce pasture land. The common local practice of recurrent burning for pasture rejuvenation has proven to be non-sustainable, since it enables bracken fern to invade pastures, causing farmers to abandon heavily infested pastures and instead clear new tracts of natural forest. No quantitative information on the growth potential of pasture grass and bracken fern under current and future environmental conditions has yet been available for the Andes of Ecuador. The scientific basis required to understand bracken invasion has yet to be established. This scientific basis would enable the development of sustainable pasture management strategies. Such strategies would, in turn, help protect the remnants of natural forest. Consequently, the present work aims at investigating the growth potential of two competing species under current and future climate conditions. Outcomes provide new knowledge and methodological developments concerning pasture invasion by bracken fern in southern Ecuador. The method entails the development of a new model, the Southern Bracken Competition Model (SoBraCoMo), realistically parameterized and validated. The model code is based on existing Soil Vegetation Atmosphere Transfer (SVAT) and vegetation dynamic models to calculate the potential growth of two main competitors, the southern bracken fern (Pteridium arachnoideum) and the pasture grass (Setaria sphacelata). Extensive field measurements and proper meteorological forcing delivered new site and species-specific parameters for realistic productivity simulations of both species. An experimental site was established to observe pasture and bracken fern development under the practice of recurrent burning, and to provide atmospheric data for a realistic forcing of the developed model. A novel balloon-borne monitoring system was developed to detect species cover and provided new insights into post-fire canopy recovery. The main results demonstrate that, under current environmental conditions, Setaria has a slightly higher competitive growth potential under undisturbed conditions (no grazing, trampling, or light competition). Furthermore, this growth advantage of Setaria should most likely increase due to global warming. Because field observations show bracken infestation, however, other factors than those investigated should be responsible for the bracken fern’s current success. The most likely cause of bracken success to be investigated in the future is cattle browsing; although browsing continuously removes aboveground biomass, this disruption of the upper soil does not affect deep roots and rhizomes of bracken plants. The newly developed SoBraCoMo can now provide an excellent basis to implement new mechanisms like browsing for future simulations

Towards a metadata standard for field spectroscopy

This thesis identifies the core components for a field spectroscopy metadata standard to facilitate discoverability, interoperability, reliability, quality assurance and extended life cycles for datasets being exchanged in a variety of data sharing platforms. The research is divided into five parts: 1) an overview of the importance of field spectroscopy, metadata paradigms and standards, metadata quality and geospatial data archiving systems; 2) definition of a core metadataset critical for all field spectroscopy applications; 3) definition of an extended metadataset for specific applications; 4) methods and metrics for assessing metadata quality and completeness in spectral data archives; 5) recommendations for implementing a field spectroscopy metadata standard in data warehouses and ‘big data’ environments. Part 1 of the thesis is a review of the importance of field spectroscopy in remote sensing; metadata paradigms and standards; field spectroscopy metadata practices, metadata quality; and geospatial data archiving systems. The unique metadata requirements for field spectroscopy are discussed. Conventional definitions and metrics for measuring metadata quality are presented. Geospatial data archiving systems for data warehousing and intelligent information exchange are explained. Part 2 of the thesis presents a core metadataset for all field spectroscopy applications, derived from the results of an international expert panel survey. The survey respondents helped to identify a metadataset critical to all field spectroscopy campaigns, and for specific applications. These results form the foundation of a field spectroscopy metadata standard that is practical, flexible enough to suit the purpose for which the data is being collected, and/or has sufficient legacy potential for long-term sharing and interoperability with other datasets. Part 3 presents an extended metadataset for specific application areas within field spectroscopy. The key metadata is presented for three applications: tree crown, soil, and underwater coral reflectance measurements. The performance of existing metadata standards in complying with the field spectroscopy metadataset was measured. Results show they consistently fail to accommodate the needs of both field spectroscopy scientists in general as well as the three application areas. Part 4 presents criteria for measuring the quality and completeness of field spectroscopy metadata in a spectral archive. Existing methods for measuring quality and completeness of metadata were scrutinized against the special requirements of field spectroscopy datasets. Novel field spectroscopy metadata quality parameters were defined. Two spectral libraries were examined as case studies of operationalized metadata. The case studies revealed that publicly available datasets are underperforming on the quality and completeness measures. Part 5 presents recommendations for adoption and implementation of a field spectroscopy standard, both within the field spectroscopy community and within the wider scope of IT infrastructure for storing and sharing field spectroscopy metadata within data warehouses and big data environments. The recommendations are divided into two main sections: community adoption of the standard, and integration of standardized metadatasets into data warehouses and big data platforms. This thesis has identified the core components of a metadata standard for field spectroscopy. The metadata standard serves overall to increase the discoverability, reliability, quality, and life cycle of field spectroscopy metadatasets for wide-scale data exchange