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Yang Y.,Key Laboratory of Southwest China Wildlife Resources Conservation | Yang Y.,China West Normal University | He X.,Key Laboratory of Southwest China Wildlife Resources Conservation | Xu X.,Key Laboratory of Southwest China Wildlife Resources Conservation | And 2 more authors.
Trees - Structure and Function | Year: 2015

Key message: We examined sexual differences in scaling relationships among twig components in dioecious speciesPopulus cathayanaRehd, and explored the functional adaptation of twigs in female plants. Abstract: Since the evolution of reproductive requirements for disseminating pollen or producing seeds/fruits has led to sexual dimorphisms of twigs in dioecious species, different functional traits among twig components should exist between sexes. To explore sexual differences in scaling relationships among twig components in dioecious species, we took advantage of a field study of Populus cathayana Rehd, a dioecious tree native to China. Lamina mass and area, petiole mass and area, and stem mass were measured for the current-year terminal twigs in 62 (29 females and 33 males) mature P. cathayana trees along an altitudinal gradient (1,400–1,700 m) of the Xiaowutai Mountain, Hebei, north China. The scaling relationships within twig and leaf components were determined using the model type II regression method. Significantly positive correlations among lamina area and petiole mass or lamina mass were found in both male and female trees at the twig and leaf level, and scaling relationships between these traits differed between sexes. An allometric scaling relationship with a common slope <1.0 existed between total leaf area and stem mass, while isometric scaling relationships were between lamina area and petiole mass or lamina mass. Females had larger total leaf area per unit stem mass than males at the twig level, but a thinner and larger blade for a given petiole mass than males at the leaf level. Our results demonstrated that females tended to have more photosynthetic organ area per unit supporting tissue mass than males, which reflects functional adaptation of twigs in female plants to meet their specific reproductive needs. © 2014, Springer-Verlag Berlin Heidelberg.


Hong M.,Key Laboratory of Southwest China Wildlife Resources Conservation | Hong M.,Chongqing University | Yuan S.,Key Laboratory of Southwest China Wildlife Resources Conservation | Yang Z.,Key Laboratory of Southwest China Wildlife Resources Conservation | And 4 more authors.
Mammalian Biology | Year: 2015

The giant panda is an iconic forest-dwelling conservation species worldwide. Preservation of forests is considered essential to keep their populations sustainable in the wild. However, little effort has been made to uncover effects of selective logging on their abundance and habitat selection. In this research, we conducted a field survey during May-November 2012 in Liziping National Nature Reserve, China, to compare trace abundance and microhabitat selection by giant pandas in primary and secondary forests. Our results indicated that forest structure varied significantly in selectively logged forests, especially for tree and bamboo layers. Slope and bamboos are significant variables affecting microhabitat utilization by giant pandas in the two forest types. Significant difference was found in rations of elevations, total trees, total shrubs, total dead bamboos and basal diameter of biennial bamboos between primary and secondary forests, indicating selective logging had an effect on microhabitat selection by giant pandas in the study area. In addition, trace abundance, as indexed by droppings and dropping groups per km, decreased significantly in secondary forests. Selective logging can not only affect the inner structure of forests in giant panda habitats, but also their spatial distribution and microhabitat selection behaviors. The flexibility in microhabitat selection of giant pandas can help them to adapt to surrounding conditions. In the future, conservation attention should be paid to the effects of forest types on habitat selection of captive released giant pandas, and gentle areas in habitats when patrolling and monitoring. © 2015 Deutsche Gesellschaft für Säugetierkunde.


Wang Z.,China West Normal University | Wang Z.,Key Laboratory of Southwest China Wildlife Resources Conservation | Xu X.,China West Normal University | Xu X.,Key Laboratory of Southwest China Wildlife Resources Conservation | And 5 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Dioecious plant species are an important component of terrestrial ecosystems. However, little is known about their ecology, including the factors affecting their distribution. We investigated the ecology of Populus cathayana Rehd, a dioecious and deciduous species that occupies a wide range of habitats in China. We measured the mean diameter at breast height (DBH), population density, sex ratio, size structure, and spatial distribution of male and female P. cathayana populations in a series of forest plots along an altitudinal gradient (1400-1700 m) in the Xiaowutai Mountains. The results showed that the trends in mean DBH and density were significantly different for males and females. There was no significant difference in mean DBH along the altitudinal gradient in female populations and the population density at 1700 m was lower than at other altitudes. Compared with females, the maximum mean DBH for males was observed at 1700 m and was significantly larger than at other altitudes. However, there was no variation in the population density of males associated with altitude. The mean DBH in male and female populations was nearly equal at 1600 m and the density at this altitude was also very similar among male and female populations. The sex ratio (male:female) tended to increase along the altitudinal gradient. Although the sex ratio was close to 1:1 (χ 2 = 2. 94, P > 0. 05) for the entire population (1400-1700 m), the ratio was biased towards females (χ 2 1400 = 5. 91, P < 0. 05) at low altitudes and biased toward males (χ 2 1700 = 6. 56, P < 0.05) at high altitudes. The sex ratio approached 1:1 (χ 2 1600 = 0,P > 0.05) as the altitude tended towards1600 m. Furthermore, the size structure of all male and female P. cathayana populations revealed a steady-state distribution along the altitudinal gradient (except for a decline-state distribution at 1700 m). However, the distribution of the size classes differed between male and female P. cathayana populations. A large proportion of class I and II were observed at 1400 m in female populations but at 1600 m in male populations. In addition, we also found that the distribution of male and female populations was affected by altitude. We observed a random distribution pattern at low altitudes and a clumped distribution pattern in most male and female populations at other altitudes, though we did not detect a difference among the sexes. However, the aggregation intensity between male and female P. cathayana populations differed markedly along the elevation gradient. The aggregation intensity of female populations increased gradually along the elevation gradient whereas the change in aggregation intensity was nonlinear in male populations. Below 1500 m, the aggregation intensity increased with increasing altitude, but then decreased with increasing altitude above 1500 m. This phenomenon may be explained by differences in the adaptability of male and female P. cathayana plants. In summary, we showed that differences in the distribution of male and female P. cathayana populations along an altitudinal gradient. And we conclude that P. cathayana populations are likely to reproduce and survive best at moderate altitudes.


Xu X.,Key Laboratory of Southwest China Wildlife Resources Conservation | Xu X.,China West Normal University | Li Y.,Key Laboratory of Southwest China Wildlife Resources Conservation | Wang B.,Key Laboratory of Southwest China Wildlife Resources Conservation | And 2 more authors.
Acta Physiologiae Plantarum | Year: 2015

The sex-related spatial heterogeneity of gas exchange rates over the leaf surface under salt stress was investigated in the dioecious species, Populus cathayana Rehd. Cuttings were subjected to two salt regimes: 0 and 75 mM NaCl added to the Hoagland solution, the control and the treatment group, respectively. Measurements of gas exchange parameters were taken from over 40 sites on the surfaces of representative ‘non-stressed’ and ‘salt-treated’ leaves which had the same insertion point for two sexual cuttings. Compared to the control group, the treatment group showed a significant decrease in the mean values of the following: water use efficiency (WUE), Chlorophyll a (Chl a) concentration, chlorophyll b (Chl b) concentration, concentration of carotenoids (Caro), total chlorophyll concentration (TC) in two sexes, and net photosynthesis rate (Pn), stomatal conductance (gs), and stomatal length/width ratio (SR) in females. Also, in the treatment group, females exhibited lower WUE, Pn, gs, E, Chl a, Chl b, TC, and SR than males. Comparison of contour maps showed that the net photosynthesis rate decreased gradually from apical to basal zones over the leaf surface occurred in the two sexes under natural conditions, but under salt stress, the opposite trend was found in females only. The results suggest that the heterogeneity pattern of the gas exchange parameters in response to salt stress between the two sexes is quite different due to different strategies employed by males and females to maintain the photosynthesis rate under salt stress. This heterogeneity phenomenon under salt stress may mainly be attributed to the chlorophyll pigments in males and the stomatal apertures in females. © 2014, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.


Lei M.,Key Laboratory of Southwest China Wildlife Resources Conservation | Yuan S.,Key Laboratory of Southwest China Wildlife Resources Conservation | Yang Z.,Key Laboratory of Southwest China Wildlife Resources Conservation | Hong M.,Key Laboratory of Southwest China Wildlife Resources Conservation | And 4 more authors.
Environmental Science and Pollution Research | Year: 2015

The female giant panda Zhangxiang (pedigree number 826) was born on August 20, 2011 in Wolong Nature Reserve, China. On November 6, 2013, Zhangxiang was transported into the acclimatization enclosure in the Liziping Nature Reserve. Before Zhangxiang left the enclosure into the wild, we conducted the first study to compare microhabitats and foraging strategies between Zhangxiang in the enclosure and giant pandas in the wild. Compared with the latter, microhabitats of Zhangxiang in the enclosure are characteristic of gentler slope, more trees, higher canopy, smaller tree DBH, and lower density of living bamboos. Diet composition and foraging behaviors significantly differed between Zhangxiang and wild giant pandas, perhaps reflecting the combined consequence of environmental conditions (e.g., bamboo species) and individual status (e.g., age, mastication ability, etc.). The difference in microhabitats and foraging strategies between Zhangxiang and wild giant pandas implied that after being released into the natural habitat in the reserve, Zhangxiang will have to adapt to the environmental conditions once again. For future reintroduction, the enclosure can be extended to the Bashania spanostachya forest in the reserve, and captive giant pandas for release can thus normally transit into the wild without human intervention during acclimatization period. For other acclimatization enclosures to be constructed in the future, ecological environment inside, including topography, forests, and bamboos as well, should as possible as can match the habitat that the giant panda to-be-reinforced populations inhabit. © 2015 Springer-Verlag Berlin Heidelberg

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