Habitat Suitability Of Francois's Langur (Trachypithecus Francoisi Francoisi) And Its Application In Setting Minimum Area Of Mayanghe National Nature Reserve, China

Francois' langur(Trachypithecus frarccoisi francoisi), a species of Colobinae subfamily, Cercopithecidae family, is an endangered primate that is endemic to the limestone cliffs and caves of the tropical and subtropical zone of northern Vietnam and South-west China.Mayanghe national nature reserve holds the highest abundance of Francois'langur for any single site in the world, making the reserve of global conservation importance and us an excellent for Francois'langur research. We used line-transect survey and interviews to survey and evaluate the habitat use of Francois'langur in October 2008 and June-July 2009 in this reserve, and we also attempted to set the minimum area of this reserve according to our results. In particular, we used method of 3S (GIS, GPS and RS) technology and multivariate statistic to analyze our data.(1)Based on line-transect surveys, we recorded 87 groups of Francois'langur in Mayang River Nature Reserve. Among them,52 groups located in Boyangping, Boshui, Changyiba, Hetongwan, Hongyandi, Siqu, Sanjiaomu, Xinchangba, Xuetangpu, Xuehuagai and Yangjiaba. We also recorded 35 groups in Boyangping, Boshui, Changyiba, Hetongwan, Laosijing, Tanjiachang, Xinchangba, Xuetangpu, Xuehuagai and Yangjiaba according to our interviews.(2)The langurs were mainly distributed along the valleys of the Mayang and Hongdu Rivers and the tributaries, with a higher population density in Mayang River and its downstream, Hongdu River and its tributaries. However, we did not record any monkey groups'activity and use of roosts in the upstream of Mayang River in our field survey and interviews, which may be due to the increasing human disturbance.(3)Francois'langur tended to be found in evergreen broadleaf forest, evergreen broadleaf deciduous forest and shrubby areas in Vegetation types, which were often dominated by Liquidambar formosana and oaks (Quercus spp.), evergreen broadleaf trees (e.g. Cyclobalanopsis glaucat and Quercus multinervis), pyracantha (Pyracantha fortuneand) or southern vibumum (Viburnum fordiae), whereas they tended to avoid the area with pine(Pinus massoniana) and Chinese fir (Cunninghamia lanceolata).(4)Descriptive statistics of individual habitat variables show showed that vegetation types, elevation, slope degree, slope position, tree canopy density, distance to water source, distance to the farmland, distance to the unpaved road and distance to the paved road were the main factors that affect the langurs habitat selection. The sites occupied by the langur tended to have lower elevation, steeper slope degree, middle or upper slope position, and higher tree canopy density, and a closer distance to water and paved road. We did not detect differences between used and control locations in relation to slope aspect, vegetation comprehensive coverage, and distance to the nearest residents and lane road.(5)The results of the habitat evaluation based on Logistic regression model declared that the candidate models consisting of vegetation types, topographic factors is the best approximating model (wi=0.649) with a total accuracy rate was 84.2% (Hosmer and Leweshow test), and it could good reflected the distribution of Francois in the nature reserve. Variables in model included shrub (shrub), broad-leaved forest (broadleaf), coniferous forest (conifor), elevation (ELE), slope degree (SLO) and slope position (POS), which could be descripted by the equation as following: f(x)=-1.207+3.667×shrub+0.456×broadleaf-0.330×conifor+0.007×ELE-0.144×SLO+0.371×POS(6)The larger the minimum suitable area of Mayanghe National Nature Reserve, the larger the prediction probability scale of the suitablbe habitat. For example, the minimum area of the nature reserve is 21322.97 hm2 when the predicted probability scale is 60%, the minimum area is 25137.77 hm2 when the scale is 70%, and the minimum area is 28569.17 hm2 when the scale is 80%. Moreover, when the scale is 90%, the minimum area is 31946.11hm2, which is similar to the total area of the nature reserve.(7)The carring capacity of Francois'langurs in the minimum suitable area, at the same scale, decreased if the langurs'home range increased. For instance, the minimum suitable area can accommodate 120-425 individuals of Francois'langur when the predicted probability scale is 60%, which is enough to protect the langur's current population in this reserve. In consequence, we recommendedthat the minimum area of Mayanghe nature reserve could be set as 21322.97 hm2.