I.1 GENERAL INTRODUCTION
Tropical mountain (or montane) forests occur in tropical temperate to cold altitudinal belts and range from evergreen species-rich broadleaf forests to species poor open wood-lands (RICHTER 2008). In total 3.3 Mio km2 are covered worldwide with tropical mountain forests, representing 21% of all tropical forests (SCATENA et al. 2010).
Tree species composition, distribution and structure of tropical montane forests depend on altitude, climate, soil type, edaphic conditions, geologic history and topographic heterogeneity (HOMEIER 2008; RICHTER 2008). Besides being hotspots of biodiversity1 (BARTHLOTT
et al. 2005) and centers of endemism (KESSLER & KLUGE 2008), tropical mountain forests provide important ecosystem services such as freshwater production, hydropower generation, soil stabilization and provision of food, fodder, timber and non-timber forest products (H ÖL-SCHER 2008). During the last years, human pressure has increased considerably on montane ecosystems, putting in danger the continued generation of the ecosystem servic-es (GRADSTEIN et al. 2008; HÖLSCHER 2008). In many parts of the world, tropical montane forests are severely threatened as they occur on soil conditions suitable for agriculture and pasture (KAPPELLE & BROWN 2001 in MULLIGAN 2010). Conversion of natural forests to agriculture and pasture land is the most important threat to tropical mountain forests (S CATE-NA et al. 2010) and results in loss of vegetation cover and decrease of air and soil humidity and stability (KAPPAS 1999).
Protected areas are an important means to manage and reduce human impact in tropical mountain forests (MOSANDL & GÜNTER 2008). According to RODRÍGUEZ -RODRÍGUEZ et al. (2011), 32.4% of the world‟s terrestrial protected areas outside Antarctica are designated for mountain protection.2 However, not all of them are effectively managed so that they cannot cope with the human induced threats they are facing (HOCKINGS 2004;
WIENS et al. 2009).
Sustainable management and effective conservation planning of protected areas are only possible if detailed, site-specific baseline data are available, if the data are scientifically ana-lyzed and the results used in the management process (HARMON 1994; MARGULES & P RES-SEY 2000;OLDELAND et al. 2010).
1 Biodiversity shall be understood here as the “variability among living organisms from all sources including, inter alia, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of eco-systems” (Article 2 of the Convention on Biological Diversity).
2 RODRÍGUEZ-RODRÍGUEZ et al. (2011) used in their study the nationally designated protected areas from the World Database on Protected Areas of 2010.
Baseline data are also of high importance for monitoring and evaluation of the actual pres-sures of a site, of the conservation status and of the effectiveness of management. Further-more they enable to assess progress towards global goals like the Strategic Plan for Biodiver-sity 2011-2020 of the Convention on Biological DiverBiodiver-sity and the biodiverBiodiver-sity conservation target of the Seventh Millenium Development Goal (“Environmental Sustainability”).
Especially in developing countries, baseline data of protected areas and their scientific analy-sis are missing (NAUGHTON-TREVES 2005;STOLL-KLEEMANN 2010). Only East Asia and Eu-rope delivered adequate data about protected forests for the Global Forest Resources Assess-ment (FRA) 2010 (FOOD AND AGRICULTURE ORGANIZATION 2010). Only 4% of all develop-ing countries provided for the FRA 2000 information about protected forests based on de-tailed mapping (1:25,000-1:50,000) and nationwide field sampling (SAKET 2002). In tropical mountain forests data gathering is hampered by rugged terrain and limited infrastructure to and inside of protected areas.
Baseline data of protected areas and their surroundings comprise ecological data e.g. data on natural vegetation patterns or floristic compositions, and socio-economic data, e.g. data on human impact. They are analyzed to improve the understanding of the patterns and processes in a site and to determine the prevalent socio-economic pressures and their impacts on vegeta-tion.
In the following baseline data and their analysis for sustainable management of montane pro-tected areas are described in detail.
Changes in the spatial pattern of land cover and land use3 entail negative consequences for the biological and physical processes inside a mountain forest (TOWNSEND et al. 2009). Forest conversion to agriculture or pasture land has severe consequences for biodiversity, hydrology, soil characteristics and local climate (NAIR et al. 2010). Thus, analysis of actual land cover and land use is important for conservation planning and monitoring purposes (HELMER et al. 2002).
Furthermore effective conservation plans require best estimates of the spatial distributions of species and of patterns of biodiversity and endemism (HERNÁNDEZ et al. 2006). Spatial expli-cit data about species occurrences are still scarce in most of the important conservation re-gions worldwide (BONN &GASTON 2005).
As tropical mountain forests vary considerably around the globe (RICHTER 2008), site-specific data about species composition, vegetation-environment relationships and spatial distribu-tions of the main vegetation types must be analyzed to derive adequate management strategies
3 While land cover is related to the different feature types on the Earth‟s surface, land use refers to the human activity or economic function of a piece of land (LILLESAND &KIEFER 2008).
or conduct vegetation type-specific sensitivity analysis to environmental change (e.g. climate change or land conversion) (GUISAN et al. 2006).
For the extraction of land cover and land use information in mountainous areas with difficult access, remote sensing images represent adequate data (WIENS et al. 2009). On georeferenced images the exact location of each land cover/land use unit can be determined and measure-ments of size and distances be made. The spatial, spectral and temporal resolution of the data source has to be defined according to the purpose of the study. Land use units inside montane protected areas are mainly of small size so that medium resolution images do not deliver the desired results due to the mixed pixels (GLEITSMANN &KAPPAS 2005). High spatial resolution satellite images like GeoEye-1 or WorldView-2 would be appropriate for this task (WANG et al. 2010), but they are extreme costly for nature conservation institutions, especial-ly in developing countries.
Digital aerial photographs represent an alternative due to their high spatial resolution (M AD-DEN et al. 1999; WELCH et al. 2002). Extensive aerial photograph archives exist in many countries around the world, also historical ones for retrospective studies (MILLER 1999; F EN-SHAM & FAIRFAX 2002; NUSKE &NIESCHULZE 2005). Extraction of land cover and land use based on aerial photography interpretation in combination with field work has been carried out for several mountain protected areas (BAKER et al. 1995; WELCH et al. 2002; MADDEN et al. 2004). The spatial analysis is undertaken by using Geographic Information Systems (GIS).
GIS store large databases with geo-referenced location and permit analysis and mapping of spatial explicit information (SWENSON 2008). Its use in geographical and also biological re-search has increased considerably during the last years (SWENSON 2008). CASTRO & K AP-PELLE (2000:12) stated that “The future success of decision-making in endemic species pre-servation, ecosystem restoration, (...) in tropical mountain forests strongly depends on the availability of a monitoring and evaluation GIS tool, integrating ecological and geographical information.”
Differences in compositions of vegetation types and vegetation-environment relationships are assessed by statistical analysis of botanical data, for instance by ordination techniques (MCCUNE & GRACE 2002). The botanical data is sampled in the field and stored in databases or can be obtained from herbaria of Botanical Gardens.
Ecological niche modeling (ENM) allows the prediction of the potential spatial distribution of a species or vegetation type. ENM relates known occurrences of individual species or assem-blages of species to environmental factors to predict suitable or unsuitable areas. Especially
mountain areas cannot be sampled entirely, so that ENM is an adequate methodology to extrapolate ecological plot based data to a larger space. Ecological niche models represent a useful tool for conservation and reserve planning (ARAÚJO & WILLIAMS 2000), for modeling the distribution of single species (MCPHERSON &JETZ 2007; BUERMANN et al. 2008; B RAD-LEY & FLEISHMAN 2008), of species richness (SAATCHI et al. 2008; DUBUIS et al. 2011; G UI-SAN &RAHBEK 2011), of endemism (ESCALANTE et al. 2009) and for mapping the sensitivity of species to environmental change (for example: climate change, THUILLER et al. 2005), amongst other applications.
I.2 THIS THESIS
The major objective of the study is to generate and analyze ecological and environmental data that can be used to improve the management of Armando Bermúdez National Park, situated in the Cordillera Central of the Dominican Republic in the Caribbean4. Armando Bermúdez Na-tional Park is one of seven protected mountain forests in the Dominican Republic and holds the highest hydrological and a very important ecological value for the country.
In particular the main objectives of the thesis are:
- to generate an orthorectified aerial photograph mosaic to derive and analyze land cover and land use information;
- to analyze the floristic composition of the main natural mountain forest types and deter-mine the vegetation-environment relationships;
- to develop a predictive model to map the spatial potential distribution of the main natural mountain forest types and analyze the potential distributions;
- to develop a predictive model to map the spatial potential distribution of selected woody species and analyze the potential distributions;
- to map and analyze the patterns of woody species richness and endemism and - to give some recommendations for management.
4MYERS et al. (2000) listed the Caribbean (Bahamas, Greater and Lesser Antilles) in the third place of the most important global biodiver-sity hotspots and in the fifth regarding endemism. In total, 13,000 plant species are known and 6,500 are endemics to single islands (SMITH
et al. 2005). Only 10% of the original vegetation of the Caribbean hotspot remains in a natural state. 13% of the land area (30,000 km2) are protected under different categories. However, many sites are far from pristine and urgently need better management and monitoring (SMITH et al.2005). According to SMITH et al. (2005) montane forests are underrepresented in the protected area system in the Caribbean, thus requiring high conservation priority for the existing ones.
I.3 OUTLINE
Chapter II presents the history of protection of Armando Bermúdez National Park and unfolds relevant physical and socio-economic geographic aspects. Moreover management needs of the site are determined.
In Chapter III the photogrammetric steps to process an aerial photograph mosaic of 295 aerial photographs is described. Then land cover and land use information is extracted and analyzed from the mosaic.
Chapter IV illuminates the floristic compositions of the natural mountain forest types along the altitudinal gradient. The relationship between the occurrence of the natural mountain for-est types in Armando Bermúdez National Park and environmental parameters is determined.
Ecological niche models are built on the most significant environmental variables for the spa-tial prediction of the main forest types.
Chapter V investigates on the spatial distributions of selected woody species and analyzes the patterns of biodiversity and endemism.
Each chapter is finalized with an implication for management and possible further use of the results. Chapter VI provides an overall discussion and outlook, followed by a German and English summary.