Competitive Advantage of Broussonetia papyrifera Growing in a Native Area as Suggested by Structural Diversity.

Paper mulberry (Broussonetia papyrifera) is currently an invasive species on several continents. However, little is known about whether paper mulberry has a competitive advantage over its surrounding trees in its native distribution range, subtropical regions of China. Here, we determined the relative intraspecific and interspecific competitive capacity of paper mulberry in three subtropical deciduous broad-leaved forests using the indices of structural diversity including the mixing index, the tree-tree interval index, and the diameter/height differentiation index. It was found that more than 80% of mingling index values were not greater than 0.25, suggesting a stronger competitiveness of paper mulberry relative to other tree species. The tree-tree interval index values ranged between 1 m and 2 m, suggesting a strong competition between paper mulberry and its neighbors. Moreover, more than 60% of the height differentiation index and diameter differentiation index values were positive, suggesting that the reference paper mulberry had a slight competitive advantage over neighboring trees in both the horizontal and vertical planes. These collectively suggest a competitive advantage over other tree species in the native distribution range, which may play a significant role in the ecological invasion of paper mulberry. Our findings not only help to reveal the invasion mechanism of paper mulberry, but also provide an important reference for the management and utilization of paper mulberry in invaded areas.

Predicting the potential distribution of four endangered holoparasites and their primary hosts in China under climate change.

Climate change affects parasitic plants and their hosts on distributions. However, little is known about how parasites and their hosts shift in distribution, and niche overlap in response to global change remains unclear to date. Here, the potential distribution and habitat suitability of four endangered holoparasites and their primary hosts in northern China were predicted using MaxEnt based on occurrence records and bioclimatic variables. The results indicated that (1) Temperature annual range (Bio7) and Precipitation of driest quarter (Bio17) were identified as the common key climatic factors influencing distribution (percentage contribution > 10%) for Cynomorium songaricum vs. Nitraria sibirica (i.e., parasite vs. host); Temperature seasonality (Bio4) and Precipitation of driest month (Bio14) for Boschniakia rossica vs. Alnus mandshurica; Bio4 for Cistanche deserticola vs. Haloxylon ammodendron; Precipitation of warmest quarter (Bio18) for Cistanche mongolica vs. Tamarix ramosissima. Accordingly, different parasite-host pairs share to varying degree the common climatic factors. (2) Currently, these holoparasites had small suitable habitats (i.e., moderately and highly) (0.97-3.77%), with few highly suitable habitats (0.19-0.81%). Under future scenarios, their suitable habitats would change to some extent; their distribution shifts fell into two categories: growing type (Boschniakia rossica and Cistanche mongolica) and fluctuating type (Cynomorium songaricum and Cistanche deserticola). In contrast, the hosts' current suitable habitats (1.42-13.43%) varied greatly, with highly restricted suitable habitats (0.18-1.00%). Under future scenarios, their suitable habitats presented different trends: growing type (Nitraria sibirica), declining type (Haloxylon ammodendron) and fluctuating type (the other hosts). (3) The niche overlaps between parasites and hosts differed significantly in the future, which can be grouped into two categories: growing type (Boschniakia rossica vs. Alnus mandshurica, Cistanche mongolica vs. Tamarix ramosissima), and fluctuating type (the others). Such niche overlap asynchronies may result in severe spatial limitations of parasites under future climate conditions. Our findings indicate that climate factors restricting parasites and hosts' distributions, niche overlaps between them, together with parasitic species identity, may jointly influence the suitable habitats of parasitic plants. Therefore, it is necessary to take into account the threatened holoparasites themselves in conjunction with their suitable habitats and the parasite-host association when developing conservation planning in the future.

A noteworthy case of rewilding Chinese yew from a garden population in eastern China.

Chinese yew (Taxus wallichiana var. mairei) is ranked as a rare and endangered plant of first-grade protection of China. It has been widely cultivated in 17 provinces of China over the past few decades. However, little is known about the dispersion, rewilding, and ecological influence of Chinese yew's offspring during cultivation. Here, we report a noteworthy case of this species, via ex situ conservation, which has successfully spread into different secondary forests, thus forming a stable regenerating population in eastern China. The establishment of this yew population, which has > 900 individuals and 7 ha area, can be ascribed to two key ecological factors: (1) secondary forest near the parent yews that provided suitable microhabitats in which progeny yews could germinate and grow, and (2) seed-foraging and transportation by native birds. Thus, this case may offer a pathway for conserving endangered Chinese Taxus species, which can attract frugivorous birds to disperse their seeds. In addition, it is necessary to monitor the growth performance of progeny population in the field.

Potential geographical distribution and environmental explanations of rare and endangered plant species through combined modeling: A case study of Northwest Yunnan, China.

In recent decades, due to the effect of climate change and the interference of human activities, the species habitat index has fallen by 2%. Studying on the geographical distribution pattern and predicting the potential geographical distribution of species are of great significance for developing scientific and effective biodiversity conservation strategies. Plenty of rare and endangered species that need immediate conservation are distributed in Northwest Yunnan. In this regard, this research is conducted in the purpose of predicting the potential geographical distribution of 25 rare and endangered plant species in Northwest Yunnan and analyzing the explanation capabilities of various environmental factors on the potential geographical distribution patterns of these species. Initially, the ecological niche model MaxEnt was employed to predict the potential geographical distribution of target species. Following that, the superposition method was applied to obtain the potential geographical distribution pattern of species richness on the spatial scale of the ecological niche model with a resolution of 0.05° × 0.05°. Ultimately, geographically weighted regression (GWR) model was adopted to investigate the explanation capabilities of various environmental parameters on the potential distribution patterns. The research results showed that the average value of the area under the receiver operating curve (AUC) of each species was between 0.80 and 1.00, which indicated that the simulation accuracy of the MaxEnt model for each species was good or excellent. On the whole, the potential distribution area for each species was relatively concentrated and mainly distributed in the central-western, central-eastern and northern regions of Northwest Yunnan. In addition, the potential distribution areas of these species were between 826.33 km2 and 44,963.53 km2. In addition, the annual precipitation (Bio12), precipitation of coldest quarter (Bio19), and population density (Pop) made a greater contribution to the species distribution model, and their contribution values were 25.92%, 15.86%, and 17.95%, respectively. Moreover, the goodness-of-fit R 2 and AIC value of the water model were 0.88 and 7,703.82, respectively, which indicated the water factor largely influenced the potential distribution of these species. These results would contribute to a more comprehensive understanding of the potential geographical distribution pattern and the distribution of suitable habitats of some rare and endangered plant species in Northwest Yunnan and would be helpful for implementing long-term conservation and reintroduction for these species.

Diversity and distribution of parasitic angiosperms in China.

Parasitic plants are an important component of vegetation worldwide, but their diversity and distribution in China have not been systematically reported. This study aimed to (1) explore floral characteristics of China's parasitic plants, (2) map spatial distribution of diversity of these species, and (3) explore factors influencing the distribution pattern. We compiled a nationwide species list of parasitic plants in China, and for each species, we recorded its phylogeny, endemism, and life form (e.g., herb vs. shrub; hemiparasite vs. holoparasite). Species richness and area-corrected species richness were calculated for 28 provinces, covering 98.89% of China's terrestrial area. Regression analyses were performed to determine relationships between provincial area-corrected species richness of parasitic plants and provincial total species richness (including nonparasitic plants) and physical settings (altitude, midlongitude, and midlatitude). A total of 678 species of parasitic angiosperms are recorded in China, 63.13% of which are endemic. Of the total, 59.73% (405 species) are perennials, followed by shrubs/subshrubs (14.75%) and vines (1.47%). About 76.11% (516 species) are of root hemiparasites, higher than that of stem parasites (100, 14.75%), root holoparasites (9.00%), and endophytic parasites (0.15%). A significant positive relationship is found between the area-corrected species richness and the total species richness, which has been previously demonstrated to increase with decreasing longitude and latitude. Moreover, more parasitic species are found in the southwest high-altitude areas than low areas. Consistently, the area-corrected species richness increases with increasing altitude, decreasing latitude, and decreasing longitude, as indicated by regression analyses. China is rich in parasitic flora with a high proportion of endemic species. Perennials and root hemiparasites are the dominant types. The spatial distribution of parasitic plants is largely heterogeneous, with more species living in southwest China, similar to the distribution pattern of Chinese angiosperms. The positive relationship between parasitic and nonparasitic plant species richness should be addressed in the future.

Growth synchrony between leaves and stems during twig development differs among plant functional types of subtropical rainforest woody species.

During the development of woody twigs, the growth in leaf may or may not be proportional to the growth in stem. The presence or absence of a synchronicity between these two phenologies may reflect differences in life history adaptive strategies concerning carbon gain. We hypothesized that sun-adapted species are more likely to be less synchronous between growths in total leaf area (TLA) and stem length compared with shade-adapted species, with a bias in growth in stem length, and that shade-adapted species are more likely to be more synchronous between increases in individual leaf area (ILA) (leaf size) and leaf number (LN) during twig development compared with sun-adapted species, giving priority to growth of leaf size. We tested these two hypotheses by recording the phenologies of leaf emergence, leaf expansion and stem elongation during twig development for 19 evergreen woody species (including five shade-adapted understory species, six sun-adapted understory species and eight sun-adapted canopy species) in a subtropical evergreen broad-leaved forest in eastern China. We constructed indices to characterize the synchronicity between TLA and stem length (αLS) and between leaf size and leaf number (αSN) and we derived the α values from logistic functions taking the general form of A = A(max)/[1 + exp(ß - αB)] (where A is the TLA or average ILA, B is the corresponding stem length or LN at a specific time, and A(max) is the maximum TLA or the maximum ILA of a twig; the higher the numerical value of α, the less synchronous the corresponding phenologies). Consistent with our hypotheses, sun-adapted species were higher both in α(LS) and α(SN), showing less synchronous patterns in the growths of TLA vs stem length and leaf size vs LN during twig development. Moreover, α(LS) and α(SN) were significantly positively correlated with relative growth rates of LN and leaf size across species, as indicated by both analyses of ordinary regression and phylogenetic generalized least squares. The across-species synchronies during twig development show that the temporal dynamics of the leaf size-twig size spectrum is of adaptive significance in plants. We suggest that temporal dynamics of plant functional traits should be extensively studied to characterize plant life history.

Unidirectional monovalve homologous aortic patch for repair of ventricular septal defect with pulmonary hypertension.

BACKGROUND: Severe pulmonary hypertension is a common complication of congenital cardiac defects with large left to right shunt, and the closure of a large ventricular septal defect (VSD) with elevated pulmonary vascular resistance (PVR) is associated with significant morbidity and mortality. A unidirectional monovalve homologous aortic patch was designed to close the large VSD with severe pulmonary hypertension in an effort to decrease the morbidity and mortality. METHODS: Twenty-seven patients (mean age, 15.0 +/- 5.6 years) with large VSD with severe pulmonary hypertension (pulmonary vascular resistance, 15.2 +/- 3.8 Wood units) were repaired with a unidirectional monovalve homologous aortic patch. According to body surface area and the preoperative arterial oxygen saturation, the monovalve homologous aortic patches were fenestrated on the aortic wall with a diameter of 4 to 8 mm. RESULTS: Two patients died of pulmonary hypertensive crisis and cardiac arrest postoperatively. All of the survival patients were followed up (5 months to 10 years) and the cardiopulmonary function was well improved with no late death. Obvious opening and closing of the monovalve was detected by early postoperative echocardiography in seven patients. A small amount of right to left shunt was detected in three patients three months after operation, and in two of them the shunt still existed three years after operation. CONCLUSIONS: Closure of a large VSD in patients with severe pulmonary hypertension could be performed with low morbidity and mortality when a unidirectional monovalve homologous aortic patch was used and the long-term result was satisfactory.

[Species diversity of Brasenia schreberi community in different habitats].

By using Braun-Blanquet Cover Abundance Scale method, the species diversity of Brasenia schreberi community in Dongshan Town (Suzhou City, Jiangsu Province) and Zhuantang Town (Hangzhou City, Zhejiang Province) was studied, and the results showed that in these two towns, B. schreberi community was of simple species composition and relatively low species diversity. The Shannon-Wiener diversity index, Simpson ecological dominance index, and community evenness index all increased obviously when the habitat shifted from pond center to bank nearby. B. schreberi community was similar in the same type habitats of these two towns, and of much more similarity in pond center than at bank nearby. Compared with Zhuantang Town, Dongshan Town had a greater difference of B. schreberi community between the two habitats.

High RAPD but no cpDNA sequence variation in the endemic and endangered plant, Heptacodium miconioides Rehd. (Caprifoliaceae).

Heptacodium miconioides Rehd. is an endangered species endemic to China and has suffered rapid decrease of distribution range and population size. This species has been disappeared in central China where the modal specimen was collected. We analyzed the genetic variation of the remaining populations to reveal whether the genetic diversity also suffered decrease and to provide some suggestions for conservation. All the nine known remaining populations were sampled. Genetic variation was analyzed based on RAPD markers and two fragments of cpDNA sequence, intergenic spacers of petG-trnP and trnS-trnG. No variation was observed in the two fragments of cpDNA sequence. However, the species exhibited high level of RAPD variation compared to other threatened or rare plants. Measures of genetic diversity within populations were strongly related to the log of estimated population size, indicating that large populations usually have more genetic diversity than that of small ones. About 25% of the variation was partitioned among populations. Significant relationship was observed between differentiation and geographical distance, indicating a pattern of isolation-by-distance. Given for few populations remaining, all the populations should be protected and urgent efforts be paid on the small populations to avoid their local extinction.

[Application of homologous conduits with valves in the treatment of complex congenital heart disease with insufficient pulmonary blood flow in children].

OBJECTIVE: To investigate the effects of homologous conduits with valves in the treatment of complex congenital heart disease with insufficient pulmonary blood flow in children. METHODS: Homologous conduits with valves were used in the right ventricular outflow tract reconstruction among 212 pediatric patients with complex congenital heart disease with insufficient pulmonary blood flow, aged 2.6 (0.5 - 15). The patients were followed up for 2.6 years (6 months to 7 years) and underwent echocardiography to assess the degree of pulmonary insufficiency and calcification of blood vessel. RESULTS: The success rate of operation was 96.5% (204/212). The ratio of right ventricle to aortic pressure was less then 0.55. During the follow-up, echocardiography showed valvular regurgitation and calcification of the blood vessel in 34 patients, 23 (11.2%) being mild, 7 (3.42%) being moderate, and 4 (1.96%) being sever. 170 patients did not show obvious pulmonary insufficiency. CONCLUSION: Application of homologous conduits with valves in the treatment of complex congenital heart disease with insufficient pulmonary blood flow in children shows excellent early results in preventing pulmonary insufficiency.

[Change of component structure of shrubland in Tiantong region, Zhejiang Province under different treatments].

The community diversity of shrubland in Tiantong region, Zhejiang Province was measured by using the methods of species of abundance, Simpson index, Shannon-Wiener index and community evenness index. The beta diversity between before treatments and after treatments was also measured by applying beta diversity index and similarity index. In addition, the changes of species composition and their importance values in the shrubland were analyzed. The results showed that whether in the first or second group of plots, the species composition and their importance values changed in varying degree. Compared with plots before treatments, the species diversity of shrub layer of experimented plots decreased while ecological dominance and community evenness were improved. By means of comparing beta diversity and similarity index, the results also showed that the species composition of experimented plots have changed to various extent.