Photosynthetic Physiology Of Damaged Schima Superba Resprouts Following The2008Ice And Snow Storm

The event of extreme climate is a hotspot issue in ecology. It is important to study theeffect of extreme climate on ecosystem. The topical extreme event of the2008ice stormcaused huge damage to the social economic development and ecological system of subtropicalareas. Schima superba Gardn et Champ, one of the typical components of subtropicalevergreen broad-leaf forest community, suffered from severe damage.Taking Schima superbtrees damaged in2008ice strom as object, this paper made a systematically research ofphotosynthetic physiology characteristics in different patterns of Schima superba (uprooted anddecapitated trees). The photosynthesis, chlorophyll fluorescence parameters and photosyntheticindexes was studied in different segment, different age and seasonal variation. Our objectivewas to measure the photosynthetic characteristics of resprouts on damaged Schima superba innatural regeneration after the extreme disturbance and provide the basic theory for theresprouts ecology in the subtropical regions. The main results were showed as follows,1.The photosynthetic physiology characteristics of Schima superb for the same damagedstyle in different segmentThe photosynthetic ability for the basal segment in uprooted trees and the top segment indecapitated trees were higher than other segments. Their initial stage for light response curvesand CO2response curves were steep curves. Apparent quantum yield (AQY), carboxylationefficiency (CCE) and Rp for basal segment in uprooted trees were0.129,0.129and6.84mmol·m-2·s-1·kPa-1higher than that of other segment. AQY, CCE and Rp for top segment indecapitated trees were0.125,0.072and5.64mmol·m-2·s-1·kPa-1higher than that of othersegment. Meanwhile, leaves in the basal segment in uprooted trees and the top segment indecapitated trees had a higher light compensation point (LCP) and a lower light saturationpoint (LSP). The leaves which had a wide ecological rotate had a strong light-adaptation ability.The maximal photochemical efficiency of PSⅡ(Fv/Fm), effective photochemical efficiency ofPSⅡ(Fv'/Fm'), potential activity of PSⅡ(Fv/F0), the chlorophyll (a+b) content (Chl(a+b)), the chlorophyll a/b ratio (Chla/b), carotenoids (Car), leaf mass per area (LMA), nitrogen content(N) and phosphorus content (P) of uprooted trees were highest in basal segment, followed bythose in middle segment, and those in top were the lowest. For the decapitated trees, Fv/Fm,Fv'/Fm', Fv/F0, Chl (a+b), Chl a/b and Car were highest in middle segment, while LMA, N and Pcontent were highest in top segment.2.The photosynthetic physiology characteristics of Schima superb for the same damagedstyle in different ageThe photosynthetic ability for2-year-old leaves was higher than that of1-year-old leavesand young leaves. The net photosynthetic rate (Pn) and transpiration rate (Tr) for2-year-oldleaves were18.81%(p>0.05),29.88%(p<0.05) higher than1-year-old leaves,46.35%(p<0.05),67.82%(p<0.05) higher than young leaves. Light response parameters indicated,ability of young leaves using the low light was weakest. The maximum net photosynthetic rateto light of young leaves was significant lower than that of1-year-old leaves and2-year-oldleaves, LCP and LSP of young leaves were also lower than that of other age leaves. Themaximum net photosynthetic rate to light of2-year-old leaves was significant higher than thatof1-year-old leaves for uprooted and decapitated trees. F_v/F_m, F_v'/F_m', F_v/F₀, LMA, N and Pcontent of uprooted and decapitated trees were highest in2-year-old leaves, followed by thosein1-year-old leaves, and those in young leaves were the lowest. Chl (a+b) and Car of youngleaves were also the lowest. Chl a/b of young leaves were the highest indicated that as themesophyll development, the proportion of chlorophyll (a) was decline.3.Seasonal variation of photosynthetic physiology characteristics for the damaged SchimasuperbThe photosynthetic ability of damaged trees were highest in summer and lowest in winter.Pn, Tr, AQY, LCP, LSP, the maximum net photosynthetic rate to light and the maximum netphotosynthetic rate to CO2of damaged trees showed that summer> autumn> spring> winter.Chl (a+b), LMA, soluble sugar content, starch content and soluble protein content of damagedtrees showed a gradual increase tendency from January to October. While Chl a/b of damagedtrees decreased. N and P content curves showed the form of "N" all the year, and the uprooted trees had a small range. Correlation matrix between the Pn and the environment factors, pathcoefficient of enviromental factors for the damaged trees showed that low temperature highhumidity and high CO2concentration, high humidity, low temperature high CO2concentrationand low temperature high CO2concentration were the most sensitive environmental factorseffecting on the Pn of the uprooted trees for spring, summer, autumn and winter. High humidity,high humidity, low temperature and low temperature high CO2concentration were the mostsensitive environmental factors effecting on the Pn of the decapitated trees for spring, summer,autumn and winter.4. The photosynthetic physiology characteristics of Schima superb for the differentdamaged styleThe photosynthetic ability of uprooted trees was higher than that of decapitated trees. Theaverage annual of Pn, Tr, the maximum net photosynthetic rate to light and the maximum netphotosynthetic rate to CO₂were11.08%,97.52%,14.43%and9.65%higher than that ofdecapitated trees. F_v/F_m, F_v'/F_m', Fv/F0of uprooted trees were3.53%,22.53%and10.68%higher than that of decapitated trees in summer. With higher LCP and lower LSP, leaves ofuprooted trees had a thin ecological rotate and low light-adaptation ability. Chl (a+b) and Chla/b of uprooted trees were8.12%and21.33%higher than that of decapitated trees, while Carwere56%lower than that of decapitated trees.