Conservation of giant panda habitat in South Minshan, China, after ...

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Panda habitat conservationXu et al.354China Conservation and Research Center for the Giant PandaFigure 1. Giant panda (Ailuropoda melanoleuca), observed after the May 12earthquake.100 m to more than 4000 m. Five counties (Dujiangyan,Pengzhou, Shifang, Mianzhu, and Anxian) were includedin the 6093-km 2 study area. The area contains four naturereserves, established between 1993 and 1999, for the conservationof giant pandas, as well as diverse natural ecosystemsand other endangered species (eg golden monkey[Rhinopithecus roxellana] and takin [Budorcas taxicolor]).Two of these reserves are national nature reserves (Longxihongkouand Baishuihe) and two are provincial (state)nature reserves (Jiudingshan and Qianfoshan).Land-cover classificationTo map habitat loss caused by the earthquake and its aftermath(eg landslides and mudflows), we used threeThematic Mapper (TM) images acquired on 19 May 2006,18 September 2007, and 8 July 2008. The first two imageswere provided by the US Geological Survey, and the thirdwas provided by the China Remote Sensing SatelliteGround Station. Although the 2007 image served as theprimary data source for the pre-earthquake stage, cloudsobscured approximately 5% of this image – therefore, weused the corresponding cloud-free areas within the 2006image to complement the cloud-covered sections of the2007 image. The three images were georeferenced to theWGS 84 coordinate system, with a pixel size of 30 m x 30m. A supervised classification was carried out in ERDAS9.1 for the three images. Because forests are the main vegetationtypes used by giant pandas (Liu et al. 2001), and previouslyundisturbed forest habitat was essentially convertedto “bare land” by the earthquake and subsequentlandslides and mudflows, areas within the pre-earthquakeimages were classified as forest, bare land, or “other”, andthat within the post-earthquake image as bare land or“other”. This classification system allowed for pre-earthquakehabitat evaluation and post-earthquake habitatchange detection. Sample points collected in the fieldwere used for image classification and to assess accuracy.For the pre-earthquake images, 60 of the 100 sample pointscollected by researchers between 2005 and2007 were randomly selected for the trainingset, and the remaining 40 for accuracy assessment.For the post-earthquake image, weused 96 sample points collected betweenJune and October 2008, with 60 for thetraining set and 36 for accuracy assessment.The total classification accuracy was 87%and 91%, respectively, for the pre- and postearthquakestages. We overlaid the classificationfrom before and after the earthquake,which revealed the distribution of new bareland created as a result of the earthquake andits subsequent impacts.Changes in giant panda habitatPossible giant panda habitat in the pre-earthquakeimage was evaluated according to a conceptual model(Liu et al. 2001; Xu et al. 2006) and known biologicalrequirements of giant pandas (State Forestry Administration2006). Suitable habitat for the giant panda is considered tobe a function of four main criteria: (1) presence of forestcover; (2) presence of bamboo; (3) elevations between 1000and 3800 m; and (4) slopes of less than 50˚. For the preearthquakeassessment, we combined forest-cover dataobtained from the image classification with slope, elevation,and bamboo presence data. The slope and elevation datawere obtained from digital elevation model data (1:50 000)acquired from The National Geomatics Center of China,and bamboo distribution data were obtained from the ThirdNational Panda Survey (State Forestry Administration2006). The resulting habitat map of pre-earthquake conditionswas overlayed with the bare land distribution resultingfrom the earthquake, revealing the extent of the lost habitat.The total area of lost and remaining habitat was comparedacross different elevations and slopes, between variouscounties and reserves, and inside and outside of individualreserves. We also compared habitat fragmentationacross these areas before and after the earthquake, usinglandscape indices of the number of patches (NP) andmean patch size (MPS) calculated via Fragstats 3.3(McGarigal et al. 2002). A decrease in MPS can indicatean increase in fragmentation of a habitat.Designation of key areas and corridors in theremaining habitat outside nature reservesGiven the large proportion of habitat lost and fragmentedinside the nature reserves, it was important to identify potentialkey habitat outside the nature reserves, so that these couldbecome the focus of conservation efforts, and for the potentialestablishment of future nature reserves. The criteria we usedto select key areas were that they (1) contained large areas ofsuitable habitat, where pandas were distributed, (2) wereadjacent to current nature reserves, and (3) had relatively lowlevels of human disturbance. Corridors were also needed towww.frontiersinecology.org© The Ecological Society of America
Xu et al.Panda habitat conservation355EpicenterPanda distributionEarthquake intensityXXIElevation (m)High: 7206Figure 2. South Minshan (boundary depicted by the red line). The panda distribution area in South Minshan (“Minshan B”) is almostcompletely within the earthquake intensity regions X and XI, the areas most seriously damaged in the May 2008 Wenchuan earthquake.allow pandas to move between isolated habitat patches. Thecriteria for proposed corridors were that they (1) were withina short distance (less than 2 km) of key areas, (2) containedsuitable habitat, and (3) experienced a low amount of humandisturbance (Xu et al. 2006). ResultsCharacteristics of lost panda habitatPanda habitat in the study area decreased from 1536 to1182 km 2 , indicating that 354 km 2 (23%) of panda habitatwas destroyed by the earthquake (Figure 3; Table 1).Of this lost habitat, 88.6% was located between the elevationsof 1200 and 3000 m, and 66.7% lay in areas witha slope greater than 30˚ (Figure 4). After the earthquake,the NP was 4.6 times that of the pre-earthquakeperiod, and the MPS was only 0.17 thatof the pre-earthquake period (Table 1). Thisindicated a sharp increase in patch number anda decrease in patch size after the earthquake.Thus, there was a notable increase in fragmentationof giant panda habitat.Habitat loss was considerably different insideas compared to outside the nature reserves. Thehabitat loss ratio outside nature reserves was13.6%, as compared with 32.5% inside reserves.In post- to pre-earthquake periods, the ratio ofNP was higher – and the ratio of MPS was lower– inside reserves as compared with outside(Table 1). These results suggest that more dam-age to panda habitat occurred inside the nature reservesthan outside such areas. Habitat loss also differed amongthe different nature reserves. Habitat loss inside reservesranged from 15.2% for Qianfoshan Nature Reserve (NR)to 47.8% for Baishuihe NR (Table 1). Among the fourreserves in this study area, two – Longxi-hongkou andBaishuihe – experienced more serious damage than theothers in terms of habitat loss ratio, with 33.7% and47.8% of habitat lost, respectively (Table 1).Characteristics of remaining panda habitatLow: 67After the earthquake, the proportion of remaining habitatand MPS decreased with increasing elevation (Table2), indicating a greater proportion of large, contiguousareas of panda habitat at low elevations. For example,Table 1. Changes in giant panda habitat due to the earthquakewithin nature reserves and outside nature reservesHabitat loss Habitat loss Ratio RatioLocation (km 2 ) (%) of NP of MPSLongxi-hongkou NR 70.15 33.7 9.72 0.07Baishuihe NR 78.59 47.8 4.18 0.12Jiudingshan NR 88.99 27.9 3.84 0.19Qianfoshan NR 11.16 15.2 8.61 0.10Inside reserves 248.89 32.5 4.74 0.14Outside reserves 105.11 13.6 4.32 0.20All 354.00 23.0 4.64 0.17Note: Ratio of NP presents number of patches in the post-earthquake period divided by that ofpre-earthquake. A ratio above 1 means the number of patches has increased.The ratio of MPS presentsmean patch size in the post-earthquake period divided by that of pre-earthquake. A ratiobelow 1 means the mean patch size has decreased.© The Ecological Society of America www.frontiersinecology.org
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