Topography and soil content contribute to plant community composition and structure in subtropical evergreen-deciduous broadleaved mixed forests

Topography and soil factors are known to play crucial roles in the species composition of plant communities in subtropical evergreen-deciduous broadleaved mixed forests.In this study,we used a systematic quantitative approach to classify plant community types in the subtropical forests of Hubei Province(central China),and then quantified the relative contribution of drivers responsible for variation in species composition and diversity.We classified the subtropical forests in the study area into 12 community types.Of these,species diversity indices of three communities were significantly higher than those of others.In each community type,species richness,abundance,basal area and importance values of evergreen and deciduous species were different.In most community types,deciduous species richness was higher than that of evergreen species.Linear regression analysis showed that the dominant factors that affect species composition in each community type are elevation,slope,aspect,soil nitrogen content,and soil phosphorus content.Furthermore,structural equation modeling analysis showed that the majority of variance in species composition of plant communities can be explained by elevation,aspect,soil water content,litterfall,total nitrogen,and total phosphorus.Thus,the major factors that affect evergreen and deciduous species distribution across the 12 community types in subtropical evergreendeciduous broadleaved mixed forests include elevation,slope and aspect,soil total nitrogen content,soil total phosphorus content,soil available nitrogen content and soil available phosphorus content.

Complications of Fibrin Glue in Pterygium Surgery with Amniotic Membrane Transplant

Purpose:To compare the complications and the recurrence rate between fibrin glue (TISSEEL) and Vicryl 8-0 sutures in amniotic membrane transplant during pterygium surgery.Methods:Patients who underwent pterygium surgery with amniotic membrane transplant (AMT) in the Wang Eye Clinic (Doraville,USA).were randomly categorized into two groups:one group received TISSEEL and the other group received Vicryl 8-0 sutures.All procedures for both groups were performed by one ophthalmologist.Twenty-four patients (24 eyes) participated in the TISSEEL group (22 eyes with primary surgery and 2 eyes with surgery for recurrence) and 19 patients (19 eyes) took part in the suture group (18 primary eyes and 1 recurrence).The patients with recurrent pterygium in both groups had not received AMT previously.Post-operatively,patients were followed up for one week and then one year to check for any signs of complications and recurrence.Results:Conjunctival inflammation occurred in 3 eyes (12.5%) in the TISSEEL group,and 6 eyes (31.6%) in the suture group.(P<0.05,Chi-square test).In the TISSEEL group,1 eye (4.2%) showed recurrence,while there were no recurrences in the sutures group.There were 3 dry eyes (15.8%) in the suture group and 2 dry eyes (8.3%) in the TISSEEL group (P>0.05).No dislocated conjunctival grafts,Dellen,inflammation,infection,bleeding,pyogenic granuloma,or scleromalacia was observed in either group.Conclusion:Pterygium surgery with AMT had less conjunctival inflammation and dry eye in patients receiving fibrin glue than those with Vicryl 8-0 sutures.

Effects of Different Drip Irrigation Fertilizers on Nutrient Levels in Celery and Soil under Drip Irrigation

This study was conducted to investigate the effects of different fertilizers on nitrogen, phosphorus and potassium ＇absorption and distribution by celeo, and the changes of soil nutrients in the 0 -40 cm soil layer under drip irrigation, so as to provide a theoretical basis for nutrient management of greenhouse celery culti- vation and special fertilizer development. With celery as an experiment material and the ratio of conventional fertilization as control treatment, the effects of different ratios of nitrogen, phosphorus and potassium on nutrient absorption by celery and changes of soil nutrients were investigated by plot experiment in greenhouse. The results showed that the contents and distribution proportions of N and P in leaf were higher than those in stem, while for K, the content and distribution proportion were higher in stem than in leaf. The absorption amount of K was the highest in celery, followed by N, and the absorption amount of P element was the least. The mean ratio of N, P and K in celery was 1：0.556： 1.609. There were evident dynamic changes in contents of soil available nutrients in the 0 -20 cm soil layer in various growth stages of celery under different drip irrigation fertilizers. The contents of soil available nutrients were higher on the 28＇h , 47~ and 83＇h d ＂after fieht planting, while those before field planting and after harvest were lower. So the amounts of soil available nutrients were closely related to the growth stage of celery. In the whole growth period of celery, the mean input amounts of N, P205 and K20 were 805, 1 049 and 916 kg/hm2 , respectively, but the absorption amounts of nutrients by celery were far less than inputs, and the amounts of N, P205 and K20 absorbed by celery＂ were only 23% -26% , 10% and 31% -35% of the appli- cation amounts, respectively. The apparent balance of N, P2 O5 and Kz O were 613,943 and 609 kg/hm2 , respectively, indicating excess fertilization in this experi- ment. Under this experiment condition, Tj （ N： PzOs： K20 = 1 ： 0.63： 1.08） favored increase of celery yield and absorption of nitrogen, phosphorus and petassium by celery. The results will provide a scientific basis for study and utilization of special fertilizer for drip irrigation on celery. Key words Drip irrigation; Fertilizer for drip irrigation; Celery; Soil nutrient; Apparent balance

Syntheses and Co-Fluorescence of Complexes of Eu (III)/Gd (III) with Thienyltrifluoroacetonate, Terephthalic Acid and Phenanthroline

A series of complexes of europium (III)/gadolinium (III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen) were synthesized by coprecipitation. The resulting complexes including Eu2(TPA)(TTA)4Phen2, Eu1.4Gd0.6(TPA)(TTA)4Phen2, Eu1.0Gd1.0(TPA)(TTA)4Phen2 and Eu0.8Gd1.2(TPA)(TTA)4Phen2 were characterized by elemental analysis, IR spectroscopy and thermal stability analysis. The results of analysis indicate that the complexes obtained have similar binuclear structure with each other. The thermal stability analysis indicates that the complexes Eu2(TPA)(TTA)4Phen2and Eu1.0Gd1.0(TPA)(TTA)4Phen2 possess good thermal stability, which melt at ~241&deg;C and decompose at ~370&deg;C - 430&deg;C corresponding to the formation of the complexes. The fluorescence spectra of Eu2(1-x)Gd2x(TPA)(TTA)4Phen2 (x = 0 - 1) complex powders and their doped silica gels were studied. The co-fluorescence effect of Gd3+ ions in complex powders is different from that of their doped silica gels. The optimum concentration of Gd3+ for complex powders and their doped silica gels is 0.5 and 0.3 (molar fraction), respectively. The co-fluorescence distinction of Gd3+ ions for complex powders and their doped silica gels is preferably interpreted from the proposed binuclear structure together with monomolecular compositions of the complexes for the first time. Both intermolecular energy transfer and intra molecular energy transfer in cross binuclear monomolecular EuGd(TPA)(TTA)4Phen2 are thought to be responsible for the co-fluorescence effect of the complex powders;yet only the latter is thought to be responsible for the co-fluorescence effect in silica gels, for the complex molecules in this case are isolated from each other.

厄瓜多尔水资源时空分布及变化规律

根据厄瓜多尔水资源综合规划中水资源调查评价成果（1971~2010年系列），研究了厄瓜多尔水资源时空分布特征及变化规律。厄瓜多尔水资源量丰富，但时空分布不均匀，东部地区和安第斯山脉两侧山坡径流较大，西部沿海及安第斯山脉内部的高原盆地径流相对较小；中部和西部地区水资源年际和年内变化大，东部地区水资源年际和年内变化小，水资源出现连丰或连枯情况。