Bai K.D.,Guangxi Institute of Botany |
Bai K.D.,Chinese Academy of Forestry |
Jiang D.B.,Bureau of Guangxi Maoer Mountain Nature Reserve |
Wan X.C.,Chinese Academy of Forestry
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013
The present study analyzed the photosynthesis-nitrogen relationship in evergreen and deciduous tree species at different altitudes on Mao'er Mountain, Guangxi, and explored whether photosynthetic nitrogen use efficiency (PNUE) was affected by leaf habit and altitude. Deciduous tree species had significanlty higher PNUE than evegreen tree species because of lower leaf mass per area (LMA) and higher photosynthetic rate per mass (Amass), nitrogen content and stomatal conductance (gs) in the former. Tree species at high altitude had significantly lower PNUE than those at middle and low altitudes due to higher LMA and lower Amass and gs in the former. Principal component analysis for PNUE and its related leaf traits suggested that the tree species distribution of evergreen-deciduous and low-middle-high altitude were in the process of natural transition. In addition, PNUE was not related to soil carbon: nitrogen ratio, but significantly positive related to mean annual temperature, suggesting that temperature climate was the main environmental factor that regulated the altitudianl changes in PNUE. Therefore, this differential PNUE that was affected by leaf habit and temperature climate was a mechanism for the bimodal distribution of evergreen tree species along the altitudes on Mao'er Montain.
Bai K.,CAS Institute of Botany |
Bai K.,Chinese Academy of Forestry |
Mo L.,CAS Institute of Botany |
Liu M.,CAS Institute of Botany |
And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015
Nitrogen (N) and phosphorus (P) resorption from senesced leaves are hypothesized to improve plant nutrient conservation. However, whether the availability of nutrients in soil affects the resorption efficiency of N and P is still under debate. The present study investigated N and P contents in mature and senesced leaves of co-existing evergreen and deciduous tree species in evergreen broad-leaved forest at low altitude, beech mixed forest at middle altitude, and hemlock mixed forest at high altitude on Mao’er Mountain, Guangxi. The present study also determined if nutrient resorption was affected by leaf habit and altitude. N resorption efficiency (NRE) and P resorption efficiency (PRE) for the total species averaged 56.5% and 52.1%, respectively, supporting our hypothesis that nutrient resorption from senesced leaves is very important for plant nutrient conservation. NRE and PRE for the total evergreen species averaged 61.8% and 57.0%, respectively. NRE and PRE for the total deciduous species averaged 51.2% and 47.3%, respectively. Evergreen species exhibited significantly higher NRE (P<0.001) and PRE (P<0.01) than deciduous species, which were closely associated with lower N and P contents in senesced leaves in evergreen species. These shifts of NRE and PRE between leaf habits suggested that evergreen species were more conservative than deciduous species in terms of nutrient resorption. On average, at low, middle, and high altitude, NRE was 61.8%, 55.8%, and 52.0%, while PRE was 47.1%, 51.5%, and 57.8%, respectively. As altitude increased, NRE decreased significantly (P<0.01), while PRE increased significantly (P<0.05). NRE was negatively correlated to the soil N:P ratio (r = - 0.41, P<0.05) and mature leaf N:P ratio (r = - 0.37, P< 0.05), whereas PRE was positively correlated to the soil N:P ratio (r = 0.44, P<0.05) and mature leaf N:P ratio (r = 0.47, P<0.01).The pattern of NRE vs. PRE was indicative of the plant adaptation from N limitation at low altitude to P limitation at high altitude. In addition, mean annual temperature was positively related to NRE (r = 0.43, P<0.05) but negatively related to PRE (r = - 0.45, P <0.01), suggesting that air temperature was also an important factor in the regulation of nutrient resorption patterns in tree species. The combined effects of soil and temperature on nutrient resorption indicated that plants were not responding to altitude directly, but rather to a suite of factors such as soil and temperature that co-varied with altitude. Overall, this study suggests that surveying leaf nutrient content and resorption could provide information about plant adaptation to altitude-induced changes in soil and temperature and explain the bimodal distribution of evergreen tree species along the altitudes on Mao’er Mountain. This study also provides insight into the nutrient management and ecosystem onservation in montane forests and delivers information for future meta-studies and model simulations of global leaf nutrient resorption. © 2015 Ecological Society of China. All Rights Reserved.
Bai K.,Chinese Academy of Forestry |
Bai K.,CAS Xishuangbanna Tropical Botanical Garden |
Jiang D.,Bureau of Guangxi Maoer Mountain Nature Reserve |
Cao K.,CAS Xishuangbanna Tropical Botanical Garden |
And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010
The present study investigated the seasonal changes in photosynthetic charateristics of co-occurring evergreen and deciduous broad-leaved trees in a montane evegreen broad-leaved forest in Yunnan Ailao Mountain and a montane decidous beech forest in Guangxi Mao' er Mountain in 2005, and tried to explore the effects of temperature climate differences between the two habiitas on species dominance. In summer, light-saturated photosynthetic rates per leaf area (Amax_a) exhibited no differences either between evegreen and deciodus species in each habitat or between the two habitats. However, as air temperature decreased, Amax_a of evegreen and deciodus species dropped in both habitats, resulting from partly stomatal closures and decreases of photosytem II activities. Stomatal closures could decrease water losses, but decidous spicies had higher degree of stomatal closures than evergreen species and were unavoidable to suffer heavier photoinhibition. Evergreen species could maintain green leaves by promoting photosynthetic water use efficiency through stomatal control and enhancing the ability of photosynthetic apparaturs via photosytem II adjustments. However, low tempertures in winter led to heavy malfunction of stomata and photosytem II and consequent low dominance of evergreen species in montane decidous beech forest in Mao'er Mountain. By contrast, relative warmness in winter helped evegreen species of montane evegreen broad-leaved forest in Ailao Mountain to acculmate more photosynthetic biomass and facilated them to dominate in the communities.