Ramirez_Road-ecology_1152212852
Transcription
Ramirez_Road-ecology_1152212852
Journal of Maps, 2006, 181-190 Land Cover and Road Network Map for the Monarch Butterfly Biosphere Reserve in Mexico, 2003 M. ISABEL RAMÍREZ1 , RUTH MIRANDA2 , RAÚL ZUBIETA3 and MARGARITA JIMÉNEZ4 1 Unidad Académica Morelia, Instituto de Geografı́a, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro, 8701. CP 58190, Morelia, Michoacán, MÉXICO; isabelrr@correo.unam.mx 2 Departamento de Geografı́a y Ordenación del Territorio, Universidad de Guadalajara, Av. de los Maestros y Mariano Bárcena, CP 44260, Guadalajara, Jalisco, MÉXICO; ruthm@csh.udg.mx 3 Departamento Geografa Fı́sica, Instituto de Geografı́a, Universidad Nacional Autónoma de México, Circuito Exterior s/n. Ciudad Universitaria, CP 04510, México DF, MÉXICO; rrzubieta@yahoo.com.mx 4 Comisió Nacional para el Uso y Conocimiento de la Biodiversidad, Liga Periférico-Insurgentes Sur 4903, CP 14010, México DF, MÉXICO; margaritaffl@yahoo.com.mx (Received 6th July 2006; Accepted 27th August 2006) Abstract: To preserve the monarch butterfly (Danaus plexippus L.) overwintering sites in Mexico, the fir forests used for the main colonies have been protected by three presidential decrees, in 1980, 1986 and 2000. The territory of the current Monarch Butterfly Biosphere Reserve (MBBR) belongs mainly to communal properties (ejidos and indigenous communities). Contrary to expectation, this protected area is still facing severe disturbance and loss of forest cover, because of intensive illegal and legal logging, and subsistence farming activities. Roads are landscape elements well known as a cause of disturbance and deforestation. Therefore, the aim of this map is to illustrate the road network and land cover relationship in the MBBR, taking into account the land tenure. The roads vector layer was obtained by photointerpretation of one meter resolution digital aerial photograph mosaics from March 2003, and one meter resolution Ikonos pansharpened images from March 2004, as well as field work, using GPS georeferenced tracks. Land cover polygons were constructed by visual interpretation of January 2003 Landsat ETM+ color composites, simultaneously verified with the aerial photograph mosaics. The final 1:75000 map shows very high human pressures over the reserve forests. This is expressed by a high density road network, composed mainly of tertiary roads opened to wood extraction, in many cases illegally, and incompatible with the protection category of these forests. 181 ISSN 1744-5647 http://www.journalofmaps.com Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al 1. Introduction The Monarch Butterfly Biosphere Reserve (MBBR) in central Mexico is home to one of the world’s most spectacular ecological phenomena: millions upon millions of monarch butterflies each autumn fly from Canada and United States to winter on a few hectares of fir forests. Since this overwintering habitat was first described in 1976, three presidential decrees have been issued to protect it (1980, 1986, and 2000). The first decree did not delimit specific boundaries. The 1986 decree designated 4,481 hectares as “core zone” in which all logging was prohibited, and 11,629 hectares as “buffer zone” in which limited logging was permitted. The 2000 decree extended the protected area to 56,259 hectares, under Biosphere Reserve category (Diario Oficial, 2000), with 13,552 hectares in core and 42,707 hectares in buffer. Nevertheless, severe forest loss and disturbance have been ongoing, and threaten the butterfly overwintering phenomenon (Brower et al., 2002; Ramı́rez et al., 2003). The forest loss and disturbance is due to forest extraction and farming activities, which require ways to access and transport products. Roads provide social and economic benefits, since they decrease the transportation costs, and allow communication and movement of goods and services between communities. Moreover, roads are necessary for beneficial forest activities, including appropriate forest management, fire and pest control, recreation, and wild life conservation (Tchikoué, 2002; Forman, 2003). Nevertheless, roads produce short and long term negative effects on the ecosystems they go through. Some of these effects are direct loss of vegetation and soil; changes in hydrologic patterns, microclimatic conditions, floristic composition and wildlife behavior; increased risk from landslides, and human access leading to excessive resource extraction (Spellerberg, 1998; Forman, 2003). Therefore, the road structure, density, function, and effects have become important aspects of environmental analysis. Mitigating the negative effects of roads through planning, conservation, management, and environmental policies represents a large challenge to science and society (Forman and Alexander, 1998). The most recent official maps of the MBBR (updated through 1995 aerial photographs) (INEGI, 2000), and their finest scale (1:50000) are not sufficient to explore the present road network of the reserve forests. Thus the objective of this work is mapping the current MBBR roads at detailed scale (1:25000) in relation to the forest condition, and to the land 182 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al ownership. 2. Study Area The map covers a rectangle of 140,000 hectares straddling the border between the states of Mexico and Michoacan. The bounding coordinates are 19◦ 18’ to 19◦ 45’ North and 100◦ 08’ to 100◦ 24’ West. Within this area, 54,489 hectares belong to the MBBR main area: 12,963 hectares of core zone, and 41,526 of buffer zone. That represents 97% of the Reserve; the remaining 3% (1,770 hectares) is in an isolated area, at Cerro Altamirano, 30 km north of the main block (Figure 1). The road analysis is focused at the protected area. The MBBR is in the Transverse Volcanic System, which was formed by Tertiary and Quaternary volcanic activity. Thus andesitic and basaltic rocks are predominant, and the soils are mainly andosols, acrisols and luvisols. These soils are poor for agriculture, but suitable to support forest vegetation. This area is characterized by its temperate-humid ecosystem, composed of conifer (Abies, Pinus and Cupressus) and broad-leaved (Quercus, Alnus, Arbutus, etc.) forests (Azcárate et al., 2003). Although the MBBR has official protected status, the land is in private rather than government ownership. The whole MBBR is divided in more than 100 properties. Of these, 70 are communal properties (57 ejidos and 13 indigenous communities), one is federal property, one is state land, three are in dispute, and the remaining are single owner private lands (CONANP, 2001). They are part of six municipalities of Michoacan and four of Mexico State. Ownership boundaries do not coincide with MBBR boundaries: many individual properties include areas within both the core and buffer zones, and some extend outside the reserve boundaries (Figure 1). 183 Journal of Maps, 2006, 181-190 360000 Ramı́rez, M.I., Miranda, R. et al 380000 U.S.A. MEXICO MICHOACAN 2200000 2200000 C. Altamirano 2180000 2180000 2160000 MEXICO STATE 2160000 Gulf of Mexico Pacific Ocean Mexico State Michoacan Map area MBBR Core zone MBBR Buffer zone Land property State border 2140000 2140000 UTM Zone 14 Datum WGS84 Ellipsoid GRS80 0 360000 10 Km 380000 Figure 1: Localization of the Monarch Butterfly Biosphere Reserve, and its relationship with land property. 3. Materials and Methods To generate the base map, we used digital topographic and vector layer maps, both at 1:50000 scale (INEGI 2000), and two meter resolution digital orthophotos from 1994 produced by the Mexican National Institute of Geography, Statistics, and Informatics (INEGI). Our work was developed 184 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al over mosaics of one meter resolution digital aerial photographs (DAP) from March 2003 (Peralta et al., 2001; Honey et al. 2004). We also used Ikonos pansharpened images from March 2004 and Landsat images from January 2003, 1 and 30 meters resolution, respectively (Figure 2). For the road map, we used the INEGI’s roads vectors and their classification, and we updated them by interperting the DAP mosaics and Ikonos images visually on the computer screen. We considered four categories: 1) paved roads, well engineered, covered by asphalt or concrete; 2) gravel roads, some engineering, covered by gravel or compacted sand; 3) earthen roads, hardly any engineering, without any cover; 4) foot paths, abandoned earthen roads or paths opened by hand tools maintained by frequent walking. Simultaneously, we visually interpreted Landsat 453 and 752 color composites to obtain the land cover map, verifying each delimited polygon using the DAP mosaics and Ikonos images. 15 land cover types were identified: 4 types of dense forest, 4 types of disturbed forest (opened or fragmented), secondary shrubs, dense scrubs, disturbed scrubs, grassland, seasonal crops, irrigated crops, and barren ground. Roads were photointerpreted using the same on-screen 1:10000 scale to obtain a 1:20000 final vector map. Likewise land cover was interpreted at 1:40000 to get a 1:75000 final vector map. Draft maps were verified by field work carried out between July 2003 and March 2004. We visited 46 properties, tracking more than 12.5% of the photointepreted roads. Using the track mode of Garmin GPS units (III+, and eTrexVista), we verified 57% of the paved roads, 37% of the gravel roads, 10% of the earthen roads, and 6% of the footpaths. Estimated positional accuracy of mapped road lines was less than 25 meters, <0.3 mm in scale of 1:75000. Also, we took 228 GPS check points of land cover to estimate accuracy by applying a confusion matrix. The result indicated a map global accuracy of 90%. However, considering DAP mosaics and Ikonos visual validation, most of misclassified points are not map class errors, but heterogeneity within polygons (Figure 2). Despite the finer scale of the road features, the final map combining both layers is presented at 1:75000 scale. 185 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al Figure 2: Example of same view on Peralta’s 1:10000 DAP mosaic (left) and 1:40000 Landsat image (upper right). In DAP mosaics roads, and heterogeneity within main land cover classes can be seen. 4. Conclusions The photointerpretation of the DAP mosaics shows that inside the MBBR there is a road network of 2574 kilometers: 55% are earthen roads, 37% are foot paths, and remaining 8% are paved and gravel roads. Thus, within the Reserve the average road density is 4.7 km/km2 (Ramı́rez et al., 2005). It appears to be associated more strongly with land ownership than with Reserve boundaries, since there is no significant difference between the core 186 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al zone and buffer zone (Table 1). In areas of similar environmental conditions devoted to forest extraction in Mexico, it is recommended that road density be less than 4 km/km2 (40 m/ha) to avoid triggering severe erosion processes (Tchikoué, 2002). Considering only paved, gravel and earthen roads, in this protected area we found 14 properties where density is higher than 4 km/km2 . Even in Ejido Emiliano Zapata, at buffer zone, road density reaches 12 km/km2 (Ramı́rez et al., 2005). The conservation implications of the extensive road network are clear. The map demonstrates that the properties with higher densities of earthen roads and paths are also the properties with a greater extent of disturbed forest. Furthermore, the chaotic road distribution pattern is evidence that many of them have been opened without any planning, and without legal authorization. This is additional evidence of what is considered to be the highest conservation concern for the MBBR: illegal logging (WWF-Mexico, 2004). This study maps the road network and land cover as of 2003; as of summer 2006, illegal logging and road creation are continuing at an untenable rate. Finally, the spatial patterns of forest conservation and forest disturbance are related to property and political boundaries rather than to official protection limits, indicating that current management regulations and enforcement are not adequate. The existing road network is dense enough to compromise the viability of the Reserve; in use and abandoned earthen roads closures need to be enforced to limit the accessibility of remaining conserved forests patches. Road type Core zone Paved Roads Gravel roads Earthen roads Foot paths Total Density (km/km2 ) Length (km) Total Core zone 3 Buffer zone 45 Total 0.1 Buffer zone 0.02 48 9 134 143 0.1 0.1 0.3 290 1129 1419 2.2 2.2 2.6 265 566 699 2008 964 2574 2.0 4.4 2.0 4.4 1.8 4.7 0.1 Table 1: Road length and road density by protected zone at the MBBR 187 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al Acknowledgements We thank WWF-Mexico for financial support, and the Monarch Butterfly Biosphere Reserve staff for field permits. We are especially grateful to the members of the 46 ejidos and communities we visited, especially to those people who guided us. Dr. Lincoln Brower and Dr. Linda Fink, of Sweet Briar College, US, shared us part of the materials, discussed the project and reviewed this manuscript. Carmen Luz, Laura Luna, and Sergio Cano provided help in different activities. Software For land cover and road network visual interpretation Ilwis 3.0 and ArcView 3.2 GIS were respectively used. ArcInfo 8.1 was used for edition and topology building, and, FreeHand MX for designing and construction of final map. References AZCÁRATE, J. G., RAMÍREZ, M. I. and PINTO, M. (2003) Las comunidades vegetales de la Sierra de Angangueo (Estados de Michoacán y México, México): clasificación, composición y distribución. Lazaroa, 24, 87-111. BROWER, L., CASTILLEJA, G., PERALTA, A., LOPEZ, J., BORJÓRQUEZ, L., DIAZ, S., MELGAREJO, D. and MISSRIE, M. (2002) Quantitative Changes in Forest Quality in a Principal Overwintering Area of the Monarch Butterfly in Mexico, 1971-1999. Conservation Biology, 16 (2), 346-359. CONANP (2001) Programa de Manejo Reserva de la Biosfera Mariposa Monarca. Comisión Nacional de Áreas Naturales Protegidas. Mexico. 188 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al DIARIO OFICIAL DE LA FEDERACIÓN (2000) Decreto por el que se declara área natural protegida, con el carácter de reserva de la biosfera, la región denominada Mariposa Monarca México, Noviembre 10, 2000. 6-29. FORMAN, R. T. T. and ALEXANDER, L. E. (1998) Roads and their major ecological effects. Annual Review of Ecology and Systematics, 29, 207-231. FORMAN, R. T. T. (2003) Road Ecology. Science and Solutions. Island Press, USA. HONEY, J., RENDÓN, E., LÓPEZ, J., PERALTA, A., CONTRERAS, I., ÁNGELES, P. and GALINDO, C. (2004) Monitoreo Forestal del Fondo Monarca 2003. WWF-Mxico. Available from: http://www.wwf.org.mx/monarca/archivos foro/Rep Monitoreo Forestal.pdf [Accessed: May 10, 2006] INEGI (2000) Vector layers sets, 1:50000: E14A25, E14A26, E14A35, and E14A36. National Institute of Geography, Statistics and Informatics. Mexico. PERALTA, A., LÓPEZ, J., BROWER, L. P., BOJÓRQUEZ, L., CASTILLEJA, G. and MISSRIE, M. (2001) The use of digital aerial photographs in the study of the overwintering areas of the monarch butterfly in Mexico. ASPRS 18th Biennial Workshop on Color Photography and Videography in Resource Assessment. May 16-18, 2001. Amherst, Mass. U.S. RAMÍREZ, M. I., AZCÁRATE, J. G. and LUNA, L. (2003) Effects of Human Activities on Monarch Butterfly Habitat in Protected Mountain Forests, Mexico. Forestry Chronicle, 79 (2), 242-246. RAMÍREZ, M. I., JIMÉNEZ, M. and MARTÍNEZ, A. (2005) Estructura y densidad de la red de caminos en la Reserva de la Biosfera Mariposa Monarca. Investigaciones Geográficas, 57, 68-80. SPELLERBERG, I. F. (1998) Ecological effects of roads and traffic: a literature review. Global Ecology and Biogeography Letters, 7, 317-333. 189 Journal of Maps, 2006, 181-190 Ramı́rez, M.I., Miranda, R. et al TCHIKOUÉ, H. (2002) Taller Teórico-Práctico: Planeación, proyección, diseño, construcción, mantenimiento y rehabilitación de los caminos forestales. Comisión Nacional Forestal-Universidad Autónoma Chapingo-División de Ciencias Forestales. WWF-MÉXICO (2004) La tala ilegal y su impacto en la Reserva de la Biosfera Mariposa Monarca. Informe interno. May 2004. Available from: http://www.wwf.org.mx/wwfmex/archivos/bm/040601 documenTalaMonrca.php [Accessed: May 10, 2006] 190