Time filter

Source Type

Yao Z.,Northeast Forestry University | Liu Z.,Northeast Forestry University | Wang Z.,Helan Mountains National Nature Reserve of Inner Mongolia | Hu T.,Helan Mountains National Nature Reserve of Ningxia | Li Z.,Helan Mountains National Nature Reserve of Ningxia
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Feral yak were introduced into the Helan Mountains on the border between Ningxia Hui and Inner Mongolia Autonomous Regions, China, by the Buddhist monks of Tibet about two hundred years ago. The feral yak population was estimated to be around 200 individuals at present. The plant species composition of the diet of feral yak was studied in order to better understand seasonal variation from November to December 2008 and from April to May 2009. We collected 5 - 10 g fecal pellets of feral yak from each dung piles in Halawu drainages, and then mixed them to form a single, species-specific composite sample. Using this method, we obtained 500 g dung in winter and 498 g in spring during the whole study area. The composition in the diet was determined by fecal microhistological analyses. The results showed that feral yak consumed 20 plant species (genera) belonging to H families in winter. The main families in the winter diet were Graminea (59. 10%) and Compositae (26.05%). The major plant species of winter diet included Stipa spp. (35. 86%), Artemisia frigida (23.96%), Agropyron cristatum (8.28%), Cyperus fuscus (7.60%), Chloris virgata (6.81%) and Phragmites australis (6.58%), accounting for 89.09% of the whole diet. The graminoid category accounted for a large proportion of the feral yak's diet in winter. Shrubs made up the second largest proportion. In spring, the main families in the diet were Graminea (52.76%) and Cyperaceae (18.80%), among which 21 plant species (genera) belong to H families. Stipa spp. (22. 72%), Cyperus fuscus (18. 80%), Agropyron cristatum (13. 23%), Setaria viridis (9. 93%) and Thalictrum aquilegifolium (6.46%), Artemisia frigida (6.31%) were main components in spring diet, contributing 77.45% of the whole diet. The graminoid category predominated in the diet during spring, accounting for 52.76% of the total diet. Forbs made up 36.98% of the diet. Haplophyllum ragacanthoides and Asterothamnus centrali-asiaticus primarily occurred in feces sampled in winter, while Artemisia sacrorum, Potentilla spp. and Ammopiptanthus mongolicus appeared in feces collected in spring. The feral yak also consumed small amounts of Ranunculaceae and Leguminosae, both in winter or spring. The contribution of several plant species eaten by feral yak was different between in winter and in spring. Chloris virgata and Artemisia frigida decreased to 2.28% and 6.31% from 6.81% and 23.96% respectively in spring, while Setaria viridis and Oxytropis spp. increased from 1. 57% and 0.94% to 9.93% and 4.43%. Stipa spp. was the prevalent species of all plant species recorded as eaten by feral yak in winter (35. 86%) and spring (22. 72%). Although food niche width in winter (4.785) was lower than in spring (7.770), the Shannon-Wiener diversity index (-2.848) and Pielou's evenness index (-0. 951) were higher in winter than in spring (-3. 403,-1. 180, respectively). Although feral yak also consumed large amounts of Stipa spp., other plant species consumed by feral yak differed from those of yak on the Tibet Plateau, which may reflect adaptations for geographical range, vegetation, and other factors. The main components in feral yak diet were not similar to sympatric ungulates (blue sheep and red deer) in winter, when shared food resources become limited, and thus feral yak are unlikely to compete with these other ungulates during that season.

Zhao C.,Northeast Forestry University | Su Y.,Helan Mountains National Nature Reserve of Inner Mongolia | Liu Z.,Northeast Forestry University | Liu Z.,Key Laboratory of Conservation Biology | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

The yak (Bos grunniens), sometimes called "the boat of the plateau", is an endemic species of the Qinghai- Tibet Plateau, famous for its resistance to cold and importance as a form of transport. The total number of adults may be close to 10,000 because the total population was estimated to be around 15,000 in 1995. Nevertheless, the species was listed as "Vulnerable" in the World Conservation Union's Red List of Threatened Animals because it is inferred that it has declined by over 30% over the last 30 years. Poaching, including commercial poaching for meat, has been the most serious threat to wild yaks. The species was listed on CITES Appendix I. Wild yaks have been protected in China since 1962, and are currently listed as a Class I protected animal, which means that they are fully protected by government law. In China, wild yaks are found in a number of large nature reserves, including the Arjin Shan, Chang Tang, Kekexili, Sanjiangyuan, and Yanchiwan Nature Reserves, although none of these reserves provide complete protection from habitat loss or occasional poaching. The yak population in the Helan Mountains is a reintroduced population from Qinghai-Tibet Plateau, and is only distributed in the Halawu Valleys and the surrounding areas, in the Helan Mountain Reserve in Inner Mongolia. Because their habitat selection had not been previously studied, we conducted surveys from December 2009 to January 2010 and from April to May 2010 to study yak habitat selection in winter and spring. Twenty line transects were established along seven valleys. We identified a total number of 103 used plots in winter and 129 in spring. To provide comparison plots for the analysis of habitat selections, we surveyed 188 randomly placed plots in winter and 207 randomly placed plots in spring by systematically placing transects in areas with no obvious evidence of yak use. Data on 18 topographic and biological variables were collected in each plot. In winter, yaks preferred montane coniferous forest, lower altitude (<2000 m), habitat dominated by Ulmus glaucescens, more gentle slopes (<10°), sites closer to the foot of the mountain, areas distant from water resource (>1200 m), moderate distance from human disturbance (2000-4000 m) and abundant hiding cover (>70%). In spring, yak preferred subalpine shrubland and meadow, higher altitude (>3000 m), lower tree density (<1 tree/100 m 2), lower tree height (<3 m), greater distances from trees (>3 m), higher shrub density (>40 trees/100 m 2), short distance to shrub (<1 m) and higher vegetation coverage (>70%). Habitat selection of the yak showed significant differences in vegetation type, landform feature, dominant tree species, shrub type, position on mountain (e. g. top or base), slope direction, distance from human disturbance and distance from water resource between winter and spring. Results of principal components analysis indicated that the first principal component axis accounted for 21. 10% of the total variance in habitat use during winter, with the highest correlation coefficient for distance to nearest tree, dominant tree species, tree height, tree density. In spring, the first principal components axis accounted for 31. 247% of the variance, with highest correlation coefficient for vegetation type, altitude, landform feature, shrub density. Compared to other migrating yak populations distributed in Qinghai-Tibet Plateau, there were significant differences in yak habitat selection between different seasons in the Helan Mountains. Yaks are acclimatized to the particular geography and climate in the Helan Mountains.

Liu Z.,Northeast Forestry University | Liu Z.,Key Laboratory of Conservation Biology | Gao H.,Northeast Forestry University | Teng L.,Northeast Forestry University | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013

Habitat evaluation has an important significance for management of wildlife populations and conservation planning. Geographic Information Systems (GIS) and abundant landscape-level data provide new opportunities for biologists to evaluate wildlife habitat quality. Maximum Entropy (MAXENT) is a recently introduced modeling technique, achieving high predictive accuracy and enjoying several additional attractive properties. With the purpose of predicting habitat for blue sheep (Pseudois nayaur) in the Helan Mountain Range, we collected the occurrence records for this species and the environmental factors, the occurrence records were collected from the study area from 2010 to 2011, and the date of environmental factors were extracted from the Thematic Mapper (TM) image of Helan Mountain in 2007. The method relies on the combined use of GIS and Maximum Entropy (MAXENT) model in this research. GIS was used to produce the data needed in the model, MAXENT can model species geographic distributions with presence-only data, and is suitable for the research because absence data are not available for blue sheep. A map indicated the distribution of habitat suitability of blue sheep in Helan Mountain generated from the data and software. In this paper, the method of Receiver Operating Characteristic (ROC) curve analysis was used to assess the accuracy of MAXENT model, the area under ROC curve (AUC) of the model was 0. 915, indicating that the result of assessment was excellent, and the results showed the relationships between the distribution of blue sheep and the environmental factors, the result of Jackknife test indicated that the mining, slope, altitude and road were the main factors influencing habitat selection of blue sheep. Along with the increase of slope, distance from mine and road, the habitat suitability increased gradually, and habitat suitability decreased gradually with the increasing distance from water. Suitable habitat was mainly distributed in southwest of Ningxia Helan Mountain National Nature Reserve (east part) and lesser distributed in the Inner-Mongolia Helan Mountain National Nature Reserve (west part), with the total area of 1 006.9km2, accounting for 28% of the total assessment area. Blue sheep preferred to use montane savanna dominated and the rugged slopes at elevations of 1 500-2 300 m. There were two factors interfered in achieving accurate results, one was difficult to reach occurrence points for the steep terrain, and the other was that we could not get the information of traffic flow on every road. During the research, we reduced the error by recording the nearest position to the target point and choosing the main road on the maps. The results showed that the most serious human interferences were mining and road, more regulatory actions are needed to be taken in those aspects to improve the habitat's quality as well as promote the progress of the population.

Loading Helan Mountains National Nature Reserve of Inner Mongolia collaborators
Loading Helan Mountains National Nature Reserve of Inner Mongolia collaborators