In 2011, the Coffee Cultural Landscape of Colombia (CCLC) was inscribed in the UNESCO World Heritage List. Several studies have been undertaken to increase its knowledge and promote its conservation and sustainable development; however, there still exists a gap between the knowledge of the visible features of this landscape and the audible ones, which are associated to anthropophonic, geophonic, and, mainly, to biophonic sound-emitting sources. The perception or recording of the audible features in a place has been recently termed as soundscape and is studied by a relatively novel discipline known as ecoacoustics. This chapter is, therefore, aimed to discuss the potential opportunities and challenges of applying ecoacoustic methods—particularly non-negative matrix factorization and acoustic indices—to enrich the study of the CCLC. Essential concepts for both the CCLC and ecoacoustics are also briefly explained, along with an outline of future work directions in short- and long-term perspectives.
TopIntroduction
In July 2011, the World Heritage Committee approved the inscription of the Coffee Cultural Landscape of Colombia (CCLC) on the World Heritage List of significant sites as “an outstanding example of a centenary cultural, sustainable and productive landscape [...] where natural, cultural and economic elements are homogeneously combined” (UNESCO, 2011, p. 238-239). Such a unique combination of nature, culture and economy can be observed in a typical view of the CCLC as the one shown in Figure 1, where a brightly-painted rustic house appears surrounded by coffee plantations and some patches of remaining native forest on the steepest slopes, along with simple facilities for self-sufficient farming such as food crops (mainly plantain and others such as guava, yuca and corn), a small hen house and reduced open areas for cattle pasture.
Figure 1.
A typical view of the CCLC along the route connecting the municipalities of El Cairo and Argelia, Valle del Cauca. Photo courtesy of Steven Mons
The CCLC includes parts of fifty-one municipal jurisdictions in the departments of Caldas, Quindío, Risaralda and Valle del Cauca. According to the public policies defined by the Colombian government to preserve the CCLC (CONPES, 2014), the main aspects to take into account in its preservation include i) cultural diversity (architecture, traditions and artistic manifestations), ii) nature (ecology, biodiversity, mineral resources and natural hazards), iii) social conditions (labor market, poverty, housing), iv) agriculture (coffee production and trade), v) tourism (touristic offer, transport infrastructure) and vi) spatial planning. Regarding nature and particularly biodiversity in the CCLC, most of the attention has been given to the landscape —i.e. the visible features of the land— and less to the so-called soundscape (Pijanowski et al., 2011): the ones that can be heard. Several taxonomic groups are vocally active and compose a significant part of the soundscape; for instance, frogs, birds and insects. Natural phenomena, such as wind and rainfall, along with anthropogenic sounds, complete the audible scene.
The current availability of recording devices for long-term and remote acoustic monitoring has given rise to the new disciplines of Bioacoustics and Ecoacoustics, whose difference, according to (Towsey, 2020, min. 4:36), is that the first one focuses at the species level while the second deals with an overall view of the soundscape. Most of the analyses in both disciplines start by computing the spectrogram (also known as sonogram) of an audio recording which, in turn, is decomposed into regions of interest or parts and characterized by estimating different acoustic indices (Sueur et al., 2014). Among the decomposition techniques, those of nonnegative matrix factorization (Cichocki et al., 2009), and dictionary learning are widely applied; regarding the acoustic indices, many of them are based on the concept of entropy (Silvestrini, 1998), which is a measure of the disorder or heterogeneity in a system and, therefore, used as an estimator of the biodiversity under the assumption that “the more entropic is the soundscape, the more biodiverse is the place”.
This chapter is aimed at presenting a conceptual overview of the methods for ecoacoustic analysis and characterization as well as at discussing its potential applications for enriching the study of the CCLC and, thereby, bridging the gap between the knowledge of its landscape and soundscape. The remaining part of the document is organized as follows. Essential concepts of the CCLC and Ecoacoustics are described in section Background, followed by a brief summary of the Biodiversity in the CCLC. The subsequent section presents an Overview of ecoacoustic methods. Afterwards, the potential applications of ecoacoustic methods to study the CCLC are discussed in the section entitled Considerations, opportunities and recommendations. Finally, some Future research directions are given, closing with a general Conclusion in the last section.