Relationship of occurrence of Fruhstorferiola tonkinensis Will. and plant communities on riversides in northern Guangdong Province, China

Plant communities on riversides in northern Guangdong Province were investigated with all-survey method, where a kind of native grasshopper Fruhstorferiola tonkinensis Will. broke out severely. 108 plant species belonging to 43 families were identified, and some plant indexes in those plant communities including their name, average height, congregation index, total coverage rate, phenological phase and biod were noted. In addition, plant comparability, plant abundance, quantity character and attribute symbol of dominant species in plant communities on riversides were studied. The results showed that the arrangement and distribution of vegetations on riversides offered a favorable habitat for F. tonkinensis. Moreover, the density of first instar nymphs of F. tonkinensis in plant communities was calculated. The results of partial correlation analysis (PCA) about the relationship between plant communities and occurrence of F. tonkinensis showed that Pterocarya stenoptera C. DC. was the most palatable plant to F. tonkinensis, presenting a very significantly positive correlation between coverage rate of P. stenoptera and occurrence of F. tonkinensis. The partial correlation coefficient (PCC) was 0.856072 (F=32.92012, P=0.0001). Bambusa flexuosa was a non-preferable plant of F. tonkinensis, presenting a significantly negative correlation between them, and the partial correlation coefficient was ?0.607920 (F=0.16173, P=0.0211). Those results would help us to propose some approaches for the ecology control of F. tonkinensis on riversides in northern Guangdong Province.     

大果马蹄荷(Exbucklandia tonkinensis)群落的纬度地带性

大果马蹄荷主产南亚热带至中亚热带南缘,南至海南岛,北至罗霄山脉中段的井冈山、桃源洞地区,是常绿阔叶林的特征种。以纬度地带性(海南霸王岭、广东黑石顶、广东南岭、江西金盆山、江西井冈山、湖南桃源洞)为依托,选定6个具代表性的大果马蹄荷群落开展群落生态学研究,结果表明:(1)各样地物种多样性较高,尤以金盆山蕨类植物9科10属11种、种子植物42科78属128种和桃源洞蕨类植物9科11属12种、种子植物41科79属134种最为丰富。群落组成的优势科主要为金缕梅科、壳斗科、樟科、山茶科、杜鹃花科、山矾科等。(2)从区系特征和环境梯度看,大果马蹄荷群落以南亚热带为分布中心,向南或向北其物种多样性Simpson指数、Shannon-Wiener指数及相应的均匀度指数均呈下降趋势,其中霸王岭、黑石顶、南岭、金盆山、井冈山、桃源洞的Shannon-Wiener指数分别为3.453、4.021、4.130、3.790、3.415、3.712。(3)群落相似性聚类分析显示群落随纬度和随海拔高度形成两个梯度系列,一是以黑石顶、金盆山、井冈山、桃源洞的纬度地带性为一支,相似性系数0.51;二是以南岭和霸王岭聚成海拔梯度较高的另一支,但其相似性系数0.50,为0.33—0.48。(4)大果马蹄荷群落种类组成在区系性质上很相似,具有明显的南亚热带特征;同时,受海拔、地形、气温、降雨条件等因素的影响,种子植物属的热带成分随纬度增加而呈波动性下降趋势。(5)大果马蹄荷种群在各群落中的重要值水平和径级结构表现出一致性,在纬度地带性差异上无明显的相关性。霸王岭大果马蹄荷的径级结构为增长型,但重要值排名为32,说明向南分布该种群优势度明显下降;在南岭、黑石顶、金盆山、桃源洞该种群优势度较大,且为稳定型种群;在井冈山该群落受到人为干忧,大果马蹄荷的重要值排名第1,但为衰退型种群。     

越南植物Michelia tonkinensis(木兰科)的模式考订

Michelia tonkinensis A. Chev.这个名称在发表时未指定模式,曾被处理为M. balansae (Aug. DC.) Dandy的异名。在查阅了其原白和原始材料后,确认采自越南北部Tuyen Quang省的标本——Fleury 37.667 (P)是该种唯一的原始材料,应该作为模式看待,同时确认Michelia tonkinensis是一独立的种,不应该处理为M. balansae的异名。此外,还提供了M. tonkinensis的异名、俗名、描述、分布及查阅的标本等综合信息。     

Photosynthesis and growth adaptation of Pterocarya stenoptera and Pinus elliottii seedlings to submergence and drought

To uncover adaptation capacities of two flooding-tolerant plant species, Pterocarya stenoptera (a native species) and Pinus elliottii (an exotic species from southeastern USA), to alternating submergence and drought, we investigated their physiological and growth responses to water stress. Water treatments, including control, continuous flooding (CF), and periodic flooding and drought (PF), were applied to seedlings in order to simulate water level fluctuation in the hydrofluctuation zone of the Three Gorges Reservoir Region. Results showed that net photosynthetic rate (P_N), stomatal conductance, and intrinsic water-use efficiency of both plant species were negatively affected under CF and PF compared with the corresponding controls. The P_N of both species under PF was comparable to that under CF. At the end of the experiment, the ratio of intercellular to ambient CO₂ concentration was not statistically different between water treatments, while that of P. elliottii was significantly higher than that of P. stenoptera. Although P. stenoptera formed lenticels under flooding conditions, P. elliottii seedlings allocated more mass to leaves and increased the relative growth rate of height to enhance the photosynthetic efficiency. Our results illustrated that P. stenoptera and P. elliottii seedlings developed different adaptive strategies in response to flooding, both CF and PF. Therefore, both P. stenoptera and P. elliottii are promising candidates for the vegetation reconstruction of the riparian zones in the Three Gorges Reservoir Region.     

薇甘菊对内伶仃岛植被危害的相关分析

对广东内伶仃岛群落受薇甘菊危害的植物种类分析表明,58种乔木、小乔木和灌木种不同程度地受薇甘菊的影响,约占样地中木本种类的67%;其中受薇甘菊影响最大的主要是小乔木和阳生性灌木.薇甘菊危害与群落类型的关系表现为,由5、6个优势种组成的结构复杂的具有较大郁蔽度的群落受薇甘菊的危害轻微,而仅由2个优势种组成结构简单且郁蔽度很小的群落受薇甘菊的危害较严重.薇甘菊危害与群落结构的相关分析表明,群落垂直高度越大、片层越丰富,群落中薇甘菊的盖度越小;群落物种越丰富,群落密度越大,个体受害比例越小;群落中其他藤本盖度越大,个体受薇甘菊危害的程度越高.     

Effects of longleaf pine planting density and other factors on stand structure and associated wildlife habitat

The primary objective of many longleaf pine (Pinus palustris) restoration programs is to enhance or restore habitat for wildlife dependent on herbaceous plant communities. Because herbaceous cover is inversely related to canopy cover, restoration programs often place restrictions on longleaf pine planting density. However, the influence of planting density on understory plant communities has been inadequately evaluated. Therefore, we initiated a study to examine the relative influences of planting density and other factors on overall understory composition and forage availability for white‐tailed deer (Odocoileus virginianus) and northern bobwhite (Colinus virginianus) in nine longleaf pine stands throughout the Coastal Plain of Alabama during 2017–2018. We found that coverage of herbaceous plants decreased 3.5%, coverage of woody plants decreased 2.4%, and coverage of northern bobwhite forage plants decreased 1.9% for each 1 m²/ha increase in longleaf pine basal area. However, planting density was not a significant predictor of current basal area, nor coverage of any functional group of plants we examined, likely because current longleaf pine density averaged only 46% (range = 30–64%) of seedling planting density. We did not detect an effect of prescribed fire on stand condition or understory plant communities, likely due to variability in fire timing and frequency. Our findings related to planting density were likely a function of low longleaf pine survival, which is not uncommon. Because of this and the inherent variability in growth rates for young longleaf pine stands, restoration programs should consider placing greater emphasis on post‐planting monitoring and management than planting density.     

Lower Emsian biostratigraphy and event stratigraphy of Ha Giang Province,northern Vietnam

A new species of rugose coral, Sanidophyllum dubium n. sp., and the typical Emsian (Early Devonian) rugose coral Xystriphylloides nobilis are described from the Mia Le Formation in northern Vietnam. The lower Emsian index conodonts ranging from the Polygnathus excavatus zone to the P. nothoperbonus zone are illustrated. The biostratigraphic correlation between northern Vietnam and South China shows that the Mia Le Formation in northern Vietnam is early Emsian in age, and its upper part can be correlated with the lower part of the Shizhou Member of the Yukiang Formation in Liujing, Guangxi and its equivalents in South China. Based on the study of the lower Emsian biostratigraphic sequence, the disappearance of Xystriphylloides nobilis fauna in the overlying bed of the uppermost Mia Le Formation and the extinction of the “tonkinensis fauna” (sensu lato) in the interval between the basal Si Phai Formation and the uppermost Mia Le Formation demonstrate the influence of the Yujiang Event in northern Vietnam.     

Low genetic diversity and weak population differentiation in Firmiana danxiaensis,a tree species endemic to Danxia landform in northern Guangdong,China

Danxia landform, a unique type of petrographic geomorphology, sporadically occurs in southern China. There are about 400 rare or threatened plants and animals in this landform, but little information on genetic aspects of these species has been available. Of them, Firmiana danxiaensis is a dominant tree species endemic to Mount Danxia, a typical Danxia landform in northern Guangdong, China. In this study, we examined genetic diversity and population structure of F. danxiaensis, in comparison with two other narrowly distributed Firmiana species, Firmiana hainanensis and Firmiana kwangsiensis, which grow in non-Danxia-landform regions. Nine microsatellite markers were used to investigate genetic diversity and differentiation in a total of 256 individuals from nine populations of F. danxiaensis, three of F. hainanensis, and one of F. kwangsiensis. The results showed that F. danxiaensis had the lowest genetic diversity (H_E = 0.364 ± 0.019) among the three species, but weak population structure similar to another Firmiana species (F_ST = 0.042 and 0.020, respectively). This low genetic diversity observed in F. danxiaensis is possibly due to confined natural distribution range and strong selective pressure in soils of Danxia landform, which may also be true for other endemic species in Danxia landform. For the long term survival of these endemic species, habitat conservation and anthropogenic introduction to similar habitats such as the adjacent Danxia landform areas should be two major strategies.     

广东省两栖动物新纪录——长肢林蛙

2011年10月,在广东古田省级自然保护区采集到5只长肢林蛙(Rana longicrus),为广东省两栖动物新纪录。长肢林蛙此前仅发现于台湾,主要分布在台湾北部、中部和西部地区。此新纪录的发现对于促进认识长肢林蛙的形态特征及地理分布格局具有重要意义。     

Syntaxonomy of vegetation of the Svyatoi Nos peninsula, Lake Baikal 2. Forests and krummholz in comparison with other regions of northern Buryatia

Using the Braun-Blanquet approach, 7 plant communities of forests and 3 communities of krummholz were distinguished on the Svyatoi Nos Peninsula on the eastern coast of Lake Baikal. Dominant species of these communities areAbies sibirica, Larix sibirica, Pinus sibirica, P. sylvestris, P. pumila andBetula divaricata. The data from Svyatoi Nos were combined with all the available data from the northern part of the Republic of Buryatia (289 relevés) and classified into 23 communities. These have been assigned to the following alliances:Aconito rubicundi-Abietion sibiricae—floodplain forests with tall forbs and the relict occurrence of a few nemoral species,Pino sibiricae-Laricion sibiricae—mesic forests with (sub-Atlantic) boreal species and abundant mosses,Vaccinio-Pinion pumilae—krummholz communities of NE Asian distribution,Cladonio stellaris-Laricion gmelinii—Larix gmelinii dominated open forests on permafrosts with NE Asian distribution, andHieracio umbellati-Pinion sylvestris—xeric forests with southern Siberian species. Phytogeographical affinities of these alliances are discussed and a system of high-ranked syntaxa (orders, classes) is proposed for the northern Buryatian forests and krummholz.     

Phylogenetic relationships of Pterocarya (Juglandaceae) with an emphasis on the taxonomic status of Iranian populations using ITS and trnH-psbA sequence data

Pterocarya fraxinifolia (Lam.) Spach., a relict tree species of the Juglandaceae family, is native to the Great Caucasus, Anatolia, and to the Hyrcanian forests of the southern Azerbaijan and Northern Iran. In this study, the phylogenetic relationship of the species, sampled in selected Iranian populations, and the global biogeography of the genus Pterocarya were addressed. Leaves were collected from 8 to 10 trees from three geographically isolated habitats. The samples were analyzed with nuclear (internal transcribed spacer [ITS] regions) and chloroplast (trnH-psbA) DNA markers. The obtained results were compared and analyzed with the data registered in NCBI GenBank. It is reported that the ITS regions varied from 644 to 652 for Pterocarya genus, but we did not observe polymorphisms for Iranian Pterocarya. The phylogenetic tree divided the Pterocarya genus in three clades: clade 1 grouping exclusively the samples P. fraxinifolia, clearly separated from the East Asiatic taxa; clade 2 that includes the species P. hupehensis and P. macroptera; clade 3 clustering P. stenoptera and P. tonkinensis. Although the Iranian Pterocarya samples and P. fraxinifolia from the Caucasus were in the same clade, they presented two different secondary structures. The Iranian populations showed the maximum genetic distance with P. stenoptera and P. tonkinensis. Our analysis demonstrates that the traditional division of all the six species sampled throughout their distribution area as well as the phylogeny of the genus Pterocarya needs to be reviewed.     

Forest Invasibility in Communities in Southeastern New York

While biological invasions have been the subject of considerable attention both historically and recently, the factors controlling the susceptibility of communities to plant invasions remain controversial. We surveyed 44 sites in southeastern New York State to examine the relationships between plant community characteristics, soil characteristics, and nonnative plant invasion. Soil nitrogen mineralization and nitrification rates were strongly related to the degree of site invasion (F= 30.2, P < 0.0001 and F= 11.8, P < 0.005, respectively), and leaf C : N ratios were negatively correlated with invasion (R ²= 0.22, P < 0.0001). More surprisingly, there was a strong positive relationship between soil calcium levels and the degree of site invasion (partial r= 0.70, P < 0.01), and there were also positive relationships between invasion and soil magnesium and phosphorus. We found, in addition, a positive factor-ceiling relationship between native species diversity and invasive species diversity. This positive relationship between native and invasive diversity contradicts earlier hypotheses concerning the relationships between species diversity and invasion, but supports some recent findings. Cluster analysis distinguished two broad forest community types at our sites: pine barrens and mixed hardwood communities. Invaders were significantly more abundant in mixed hardwood than in pine barrens communities (Mann–Whitney U = 682.5, P < 0.0001). Even when evaluating the mixed hardwood communities alone, invasion remained significantly positively correlated with soil fertility (calcium, magnesium, and net nitrogen mineralization rates). Soil texture and pH were not useful predictors of the degree to which forests were invaded. Nitrogen and calcium are critical components of plant development, and species better able to take advantage of increased nutrient availability may out-perform others at sites with higher nutrient levels. These results have implications for areas such as the eastern United States, where anthropogenic changes in the availability of nitrogen and calcium are affecting many plant communities.     

Resilience and elasticity of intertidal communities in response to harvesting of the alien mussel Mytilus galloprovincialis

Besides the direct impacts of exploitation on target species, indirect effects on non-target species are unavoidable and find expression in changes in community structure. We quantified the effects of experimental harvesting of Mytilus galloprovincialis on intertidal communities on the South African west coast. In the mid- and low-shore, four months of harvesting at intensities greater than F = 0.3 and F = 0.6 respectively, resulted in significant changes in community composition. These changes were driven by progressively greater spatial dominance by the macroalgae Cladophora flagelliformis, Porphyra capensis and Ulva species as harvesting intensity increased. Four months after cessation of harvesting, community structure had not recovered and even areas subjected to as little as F = 0.3 supported significantly altered communities in both zones. The fact that substantial community changes were induced by even low-intensity exploitation is indicative of low resilience to harvesting. The densities and cover of the dominant taxa returned to a pre-harvest state 16 months after the cessation of harvesting, but multivariate analyses indicated that the overall community composition required 32 months for Cover Letter full recovery. Although these communities displayed elasticity within three years, it is recommended that should a M. galloprovincialis fishery be established in the region, harvesting be implemented at a maximum intensity of F = 0.3. This approach would maximise yields and protect associated intertidal communities.     

Plant Interactions with Changes in Coverage of Biological Soil Crusts and Water Regime in Mu Us Sandland,China

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes.     

Legacy effects of afforestation on prairie plant and seed bank communities in a northern Canadian prairie

Afforestation resulting from fire suppression, modified grazing, plantation establishment and climate change poses a threat to northern prairie ecosystems. Trees alter the composition and function of plant and soil fauna communities and can compromise the restoration of afforested prairies. To evaluate the hypothesis that legacies of afforestation persist in restored prairie communities and decrease the potential for restoration, we examined the composition, structure, and diversity of plant and seed bank communities along a 20 year chronosequence of plantation tree removal from a northern fescue prairie in Riding Mountain National Park, Manitoba, Canada. Tree removal increased the abundance of weedy species in the plant and seed bank communities of restored prairies and plant diversity peaked and declined over the 20 year period of passive restoration. As a result, time since tree removal and the encroachment of invasive species were key in explaining the composition of restored prairie communities. Low correlation between the species composition of plant and seed bank communities, including the complete absence of Festuca hallii in restored treatments, demonstrated that legacies of afforestation compromised the potential of seed banks to facilitate prairie restoration. We conclude that tree removal alone is insufficient for the restoration of northern fescue prairies and that, in the absence of active management, the persistence of low-diversity plant and seed bank communities constitutes an important legacy of afforestation and an important barrier to future restoration.     

Genetic differentiation in Pyrenophora teres populations measured with AFLP markers

The genetic structure and occurrence of mating types and forms of Pyrenophora teres, the causal agent of net blotch on barley, was studied among 278 isolates collected from the northern hemisphere and from Australia. Genetic differentiation was high (F_CT 0.238, P = 0.002) between P. teres f. teres (PTT) isolates originating from Northern Europe, North America, Russia and Australia. The P. teres population in Australia was clearly divided into two subgroups (F_CT 0.793, P < 0.001) according to the form identity: PTT and P. teres f. maculata (PTM), with the PTT samples showing a greater degree of differentiation (F_ST 0.573, P < 0.001) among Australian states than the PTM samples (F_CT 0.219, P < 0.001). No differentiation was found among locations within Australian states. Both mating types (MAT1 and MAT2) were equally common (1:1) in several locations in Australia and in Finland. The only exception was Krasnodar, Russia, where only MAT2 was identified. Our results show that the prevalence of sexual reproduction, occurrence of forms of P. teres, and genetic differentiation between geographical regions are highly variable. The paper discusses the various effects and outcomes of population selection in Australia and in the northern barley growing regions.     

Different Degrees of Plant Invasion Significantly Affect the Richness of the Soil Fungal Community

Several studies have shown that soil microorganisms play a key role in the success of plant invasion. Thus, ecologists have become increasingly interested in understanding the ecological effects of biological invasion on soil microbial communities given continuing increase in the effects of invasive plants on native ecosystems. This paper aims to provide a relatively complete depiction of the characteristics of soil microbial communities under different degrees of plant invasion. Rhizospheric soils of the notorious invasive plant Wedelia trilobata with different degrees of invasion (uninvaded, low-degree, and high-degree using its coverage in the invaded ecosystems) were collected from five discrete areas in Hainan Province, P. R. China. Soil physicochemical properties and community structure of soil microorganisms were assessed. Low degrees of W. trilobata invasion significantly increased soil pH values whereas high degrees of invasion did not significantly affected soil pH values. Moreover, the degree of W. trilobata invasion exerted significant effects on soil Ca concentration but did not significantly change other indices of soil physicochemical properties. Low and high degrees of W. trilobata invasion increased the richness of the soil fungal community but did not pose obvious effects on the soil bacterial community. W. trilobata invasion also exerted obvious effects on the community structure of soil microorganisms that take part in soil nitrogen cycling. These changes in soil physicochemical properties and community structure of soil microbial communities mediated by different degrees of W. trilobata invasion may present significant functions in further facilitating the invasion process.     

Population Genetic Structure Within and among Seasonal Site Types in the Little Brown Bat (Myotis lucifugus) and the Northern Long-Eared Bat (M. septentrionalis)

During late summer and early autumn, temperate bats migrate from their summering sites to swarming sites, where mating likely occurs. However, the extent to which individuals of a single summering site migrate to the same swarming site, and vice versa, is not known. We examined the migratory connectivity between summering and swarming sites in two temperate, North American, bat species, the little brown bat (Myotis lucifugus) and the northern long-eared bat (Myotis septentrionalis). Using mitochondrial and microsatellite DNA markers, we examined population structuring within and among summering and swarming sites. Both species exhibited moderate degrees of mitochondrial DNA differentiation (little brown bat: F_ST(SWARMING)= 0.093, F_ST(SWARMING)= 0.052; northern long-eared bat: F_ST(SWARMING)= 0.117, F_ST(SWARMING)= 0.043) and little microsatellite DNA differentiation among summering and among swarming sites. Haplotype diversity was significantly higher at swarming sites than summering sites, supporting the idea that swarming sites are comprised of individuals from various summering sites. Further, pairwise analyses suggest that swarming sites are not necessarily comprised of only individuals from the most proximal summering colonies.     

Lespedeza cuneata invasion alters soils facilitating its own growth

Lespedeza cuneata (sericea) is an Asian legume introduced to the US in the 1930s for erosion control and forage, but it can strongly reduce the abundance of native grassland plants. One possible explanation for this high invasive capacity is that L. cuneata is able to alter soil conditions to either improve its own growth, or reduce growth of native plants. To test for soil alteration following invasion, we collected soil from a previous 3-year field experiment in which L. cuneata was established in or excluded from randomly selected plots in a restored grassland. These soil history treatments were crossed with soil autoclaving—to disrupt microbial communities potentially important to plant interactions. For each treatment combination, a native plant, Sorghastrum nutans, was grown with L. cuneata or a conspecific in a 12-week greenhouse experiment. Although we found no evidence for competitive effects on the native species, L. cuneata biomass increased when grown in soil with a L. cuneata history as opposed to non-invaded soil (F _{1, 16} = 4.79, P = 0.04). Additionally, nodulation of L. cuneata increased in invaded compared to non-invaded soil (F _{1, 16} = 6.01, P = 0.026). These results indicate that, within three years of invasion, L. cuneata is able to alter soils to facilitate its own growth and suggest that at least part of the invasive success of L. cuneata is linked to altered soil conditions.