COBISS: 1.01 CAVE PROTECTION AS A KARST CONSERVATION TOOL IN THE ENVIRONMENTALLY SENSITIVE LAGOA SANTA KARST, SOUTHEASTERN BRAZIL VARSTVO PODZEMNIH JAM KOT ORODJE ZA OHRANITEV KRASA V OKOLJSKO OBčUTLJIVEM KRASU LAGOA SANTA V JUGOVZHODNI BRAZILIJI Augusto S. AULER1 Abstract UDC UDK: 551.442:502.13(81) Izvleček UDK UDK: 551.442:502.13(81) Augusto S. Auler: Cave protection as a Karst conservation Augusto S. Auler: Varstvo podzemnih jam kot orodje za tool in the environmentally sensitive Lagoa Santa Karst, ohranitev Krasa v okoljsko občutljivem krasu Lagoa Santa v Southeastern Brazil jugovshodni Braziliji Karst areas in densely populated and industrialized areas in Kraška območja v gosto poseljenih in industrijskih predelih Brazil are under severe environmental pressure due to urban- Brazilije so zaradi urbanizacije, kamnolomov, onesnaženosti ization, quarrying, groundwater pollution, groundwater over- in prekomernega črpanja podzemnih voda ter vandalizma jam pumping and cave vandalism. Although karst terrains receive pod velikim okoljskim pritiskom. čeprav kraški tereni v okviru no specific protection according to Brazilian environmental brazilske okoljske zakonodaje niso posebej zaščiteni, so jame law, caves, regardless of rock type, are classified as belonging to del pripadnosti družbi, zato jih je treba podrobno preučevati the society, and must be studied in detail to have their signifi- in določiti njihov pomen ter temu primerno stopnjo zaščite. cance (and related level of protection) determined. Most caves Večina jam (več kot 90 %) ima bodisi največjo bodisi visoko (>90 %) are of either maximum or high significance, which re- mero pomembnosti, kar pomeni zaščito ne samo jam, am- sults in protection of not only the cave but also of an associated pak tudi njihovih tamponskih območij. Ker pa je definicija buffer zone. Given the very conservative definition of cave (a jame že precej zastarela (vsaka naravna votlina, ki je dovolj natural void large enough to allow a human being to enter), velika, da vanjo vstopi človek), to pomeni, da v kateri koli iz- hundreds of caves will exist in any given outcrop and the amal- danki obstaja na stotine jam, zaradi združevanja tamponskih gamation of buffer zones tends to yield an integrated area that območij pa pogosto nastajajo povezana območja, ki obsegajo covers most of the karst surface. In the Lagoa Santa Karst, Bra- večino kraškega površja. Na kraškem območju Lagoa Santa, zil’s most urbanized and industrialized karst area, cave preser- najbolj urbanem in industrijskem predelu Brazilije, je ohran- vation is presently the most effective approach to protecting itev krasa tako trenutno najbolj učinkovit pristop k varovanju karst heritage. However, other karst features not connected to kraške dediščine. Toda drugi kraški pojavi, ki niso povezani z existing caves (e.g., covered karst, karst aquifers with no acces- obstoječimi jamami (npr. pokriti kras, kraški vodonosniki brez sible caves, dolines with no associated caves) receive no specific dostopnih jam, vrtače brez dostopnih jam idr.), niso deležni protection. Although this heterogeneous level of protection nobene posebne zaščite. čeprav lahko ta raznovrstna stopnja may yield non-preserved karst areas, the remaining zones tend zaščite privede do tega, da bodo določena kraška območja to be surrounded by protection belts, imposing severe restric- ostala nezaščitena, so preostala območja povečini obdana z tions on urban and mining development and associated sourc- zaščitnimi pasovi, ki zelo omejujejo urbani razvoj in rudarstvo es of potential damage. ter z njima povezane morebitne vire škode. Key words: Environmental policy, cave protection, karst pres- Ključne besede: okoljska politika, varstvo jam, ohranitev kra- ervation, Lagoa Santa Karst. sa, kraško območje Lagoa Santa. 1 Instituto do Carste, Rua Aquiles Lobo 297, Belo Horizonte, MG, 30150-160, Brazil, e-mail: [email protected] Received/Prejeto: 06.03.2016 ACTA CARSOLOGICA 45/1, 131–145, POSTOJNA 2016 Augusto S. Auler Introduction Karst terrains are especially sensitive and vulnerable areas ual integration with the nearby metropolis of Belo Hori- in which environmental problems can be magnified (van zonte. A significant number of lime and cement plants Beynen & Townsend 2005; Calò & Parise 2006). Due to were installed and several new urban developments were the fertile nature of the soil, many such areas experienced approved, which led to an increase in both economic early colonization, resulting in centuries of uncontrolled activity and threats to karst environments. However, in agricultural and urban activities that caused degradation recent years, efforts have been undertaken towards the of the karst landscape and karst waters (Drew & Hötzl establishment of conservation units, leading to selec- 1999; Chen et al. 2009). In recent times, urban and in- tive preservation of areas that retain representative karst dustrial activities, particularly mining, have encroached landscapes. in many karst areas, leading to physical alteration of the A recent (2008) change in cave related environmen- landscape and the potential total loss of karst features and tal laws resulted in a strong emphasis on cave preserva- underground biodiversity (Langer 2001; Parise & Pascali tion without mentioning other karst landforms (Auler & 2003; Sugai et al. 2015, for a recent review see Gutierrez Piló 2015a). However, the strict nature of the law, which et al. 2014). requires a much larger protection buffer zone for each Although each karst landform responds differently underground void of length beyond a few meters, may to environmental changes, the integrative nature of karst potentially encompass much of the surrounding karst terrains means that the system as a whole can be subject landscape. Furthermore, in the scenario of possible cave to irreversible impacts (Ravbar & šebela 2015). Further- destruction, two other cave equivalents must be pro- more, with groundwater flow velocities orders of mag- tected. This situation has created the potential for the nitude higher than in other types of terrains, the trans- permanent preservation of a considerable number of mission of contamination or alterations in water quality caves, making mining expansion difficult. Although this can affect vast areas relatively quickly (Ford & Williams conservative law represents a major economic setback 2007; Vallejos et al. 2015). for mining operations in Brazil, it creates interesting, The Lagoa Santa Karst in eastern Brazil has been although challenging, opportunities for preserving envi- subject to environmental modifications since Portuguese ronmentally significant areas of karst. settlement in the late 17th Century. Prior to that, the slash The current work presents a case study of the heav- and burn agricultural practices of the native population ily populated and industrialized Lagoa Santa Karst as an may have also resulted in modifications in the original example of the present environmental situation of karst vegetation. Caves, in particular, have been targets for ex- areas in Brazil. Caves are currently the only landforms ploitation due to saltpeter mining, commercial and sci- that legally provide protection for karst areas. Although entific paleontological excavations and vandalism. these are an essential part of the karst environment, caves During the late 20th and throughout the 21st Cen- tend to be overemphasized and treated as features not in- tury, increased economic development in Brazil led to tegrated with the surrounding karst system. marked urbanization of the Lagoa Santa Karst, and grad- STUDY AREA The Lagoa Santa Karst is located in the south central into the basal Pedro Leopoldo Member and the upper state of Minas Gerais, approximately 30 km north of the Lagoa Santa Member (Tuller et al. 1992). The lower metropolis of Belo Horizonte, the state capital. The area Pedro Leopoldo Member is characterized by impure derives its name from the town of Lagoa Santa (Sacred limestone with intercalations of pelites and siltstone, Lake), which was an important urban center in the area while the upper Lagoa Santa Member is of purer cal- during the 18th and 19th centuries, prior to the inaugura- carenites and calcisiltites. Chemical analyses reported tion of Belo Horizonte in 1897. by Piló (1998) show a marked increase in silica and a The area displays well-developed karst topogra- decrease in calcium carbonate in the lower Pedro Leo- phy developed on Precambrian carbonate rocks of the poldo Member. The carbonates have thin, nearly hori- Bambuí Group. These carbonate rocks belong to the zontal laminations. Dips in the area normally do not lowermost Sete Lagoas Formation, which is divided exceed 5°. 132 ACTA CARSOLOGICA 45/2 – 2016 CAVE PROTECTION AS A KARST CONSERVATION TOOL IN THE ENVIRONMENTALLY SENSITIVE LAGOA SANTA KARST, ... Fig. 1: Boundaries of the Lagoa Santa Karst, showing the geology and officially recorded caves (red dots) according to the Brazilian government (CECAV 2016) database. Due to clustering of caves, individual red dots may represent several caves. Map source: ArcGIS basemap. Metamorphic siltstones of the upper Serra de Santa the caves are small, shallow occurrences, densely packed Helena Formation outcrop in a few areas and form most in the studied outcrops. Most represent segments of sys- of the northern limit of the karst. To the west and south, tems that were once more extensive, mostly of parage- boundaries are marked by Archean gneisses and migma- netic origin, divided by cliff and massif fragmentation