The Horticultural Trade and Ornamental Plant Invasions in Britain

Abstract:  Ornamental horticulture has been recognized as the main pathway for plant invasions worldwide. We examined the link between propagule pressure created by the presence of ornamental plants in the market and their ability to escape from cultivation and establish in the wild. A random sample of 534 non-native ornamental species on sale in nineteenth century Britain showed that 27% of these species were recorded growing outside cultivation and 30% of those were established. Species that had escaped from cultivation were more frequently on sale both in the nineteenth century and today than nonescaping species. We used logit regression models to identify biological and socioeconomic variables that affect species' abilities to escape cultivation and become established. Frequencies in the market in the nineteenth century and today were good explanatory variables that distinguished escaping from nonescaping species, whereas for the transition from casual to established status these two socioeconomic variables were either absent or only of weak significance. Biological characteristics that increased the probability that a species would escape from cultivation were species height, a European native range, and being an annual. Climbing plants and species intolerant of low temperatures were less likely to escape. In contrast, the establishment probability was greater if the species belonged to a genus native to Britain and increased as the number of continents in a plant's native range increased. Annual plants had a reduced probability of establishment. Market presence, prices, and the date of introduction are among the socioeconomic factors that have had important effects on the observed course of invasions.     

Eradication of the non-native Poa pratensis colony at Cierva Point,Antarctica: A case study of international cooperation and practical management in an area under multi-party governance

The on-going introduction of non-native species to Antarctica due to expanding human activity presents an increasing threat to biodiversity. Under the Protocol on Environmental Protection to the Antarctic Treaty, all introduced non-native species should be removed from the Antarctic Treaty area. The non-native grass Poa pratensis was first introduced to Cierva Point (Danco Coast, Antarctic Peninsula), along with substantial quantities of non-Antarctic soil, in the mid-1950s. Consistent with the Protocol, in January 2015 an internationally coordinated team undertook the eradication of the grass. Immediately prior to removal of P. pratensis, factors affecting its establishment, persistence and impacts upon local indigenous species was examined within the international management framework of the Antarctic Treaty System. The underlying soil had a high organic content of 15.5%, which may have contributed to the successful establishment of P. pratensis and restricted, at least initially, its vegetative growth to the enriched area. Examination of P. pratensis expansion from the original introduction sites showed that the plant colony intricate root system facilitated little or no coexistence of other native plants within its extent. The non-native plant colony also constituted a novel habitat for soil fauna within Antarctic terrestrial environments. The P. pratensis plant colony provided an unfavorable habitat for two of the locally endemic soil invertebrates, Cryptopygus antarcticus and Belgica antarctica. These observations led to the selection of an appropriate eradication approach, where the plants were targeted for physical extraction along with all underlying soil. During the eradication, c. 500 kg of soil and plant material from the P. pratensis colony was removed from the site. Monitoring one year later showed no evidence of re-establishment. Consistent with the Committee for Environmental Protection ‘Non-native Species Manual’, we recommend development and implementation of rapid response protocols following the discovery of a non-native plant colony to limit future impacts on indigenous species and local habitats.     

Distribution of14C-TNT and derivatives in different biochemical compartments ofPhaseolus vulgaris

¹⁴C-TNT was used to quantify the uptake rate and metabolic turnover of TNT inPhaseolus vulgaris. Seventeen plants were analysed by a special cell fractionation method with polar and nonpolar solvents and enzymes. We obtained three cytoplasmic fractions and five cell wall derived fractions. The recovery rate was 72% as measured by liquid scintillation counting.¹⁴C partitioned almost in equal amounts with approximately 50% in the cytoplasm and in the cell wall. The majority of the TNT-metabolites are present in the cytoplasm as was shown by GC/ ECD and thin layer chromatography. The¹⁴C in the cell wall is bound probably resulting in long-term immobilisation of these metabolites. We conclude that plants may also be a model for nitroaromatic turnover and immobilisation in soil components.     

Detection of dioxygenase genes present in various activated sludge

GOAL, SCOPE AND BACKGROUND: Activated sludge from refineries contains various microorganisms that could utilize aromatics under aerobic conditions due to the oxygenase enzymes. Dioxygenase enzymes are oxygenases, which are involved in the ring cleavage step of aromatic hydrocarbons. In this study, the selected catabolic loci involved in ring cleavage have been monitored in the activated sludge samples at different time intervals. The investigation of the dioxygenase genes in the Effluent Treatment Plants (ETPs) and evaluation of their presence at different time points provides a clue for the aromatic utilizing potential of the inherent microbial flora. METHODS: The catabolic gene loci pheB, xylE, tod-isp, bed and nahG responsible for the enzymes catechol 1,2-dioxygenase, catechol 2,3-dioxygenase, toluene dioxygenase-iron-sulphur protein component, benzene dioxygenase and naphthalene dioxygenase were used respectively. The time dependent change in eubacterial population was demonstrated by the amplification of 16S rDNA product, followed by restriction digestion. The template DNA was obtained from the activated sludge collected from ETPs. The supporting physiological data for the overall performance of sludge was developed using respirometric analysis. The on-site COD and MLSS analysis for ETP was used in final evaluation. The study was carried out with samples collected from three different ETPs and also from a selected ETP at different time intervals. RESULTS AND DISCUSSION: The respirometric studies were carried out with phenol, catechol, toluene, and naphthalene to arrive at the target genotypes for further study by PCR protocol. The respirometric analysis coupled with the COD and MLSS analysis represented the physiological capacity of the various sludges. Initially, the tracking protocol was optimized by using different sludge samples, which were collected from refineries. The selected genotypes were amplified and their presence has been confirmed using Southern analysis. The gene loci tod-isp, bed and xylE were commonly observed at various time intervals of the sludge from the same source. The gene loci pheB and nahG were found to be relatively rare. CONCLUSION: The 16S rDNA PCR products after restriction digestion produced different DNA fingerprint patterns, suggesting that the microbial community composition was diverse in the three sources. Similarly, the presence of the catechol 2,3-dioxygenase, benzene dioxygenase and toluene dioxygenase genes confirmed the aromatic degrading potential in the various sludges. The probes could not pick the nahG and pheB genes. However, the respirometeric assay suggested that the oxidative capacity to use naphthalene as a substrate exists. RECOMMENDATION AND PERSPECTIVE: Our study of the diversity at various time points from the ETP provided an overview of the shifts of the catabolic composition of the sludge. This also depends on the influential parameters like the incoming pollutant level and the environmental conditions that are prevailing and often changing from time to time. The results of direct DNA extraction and PCR amplification do reflect the relative abundance of a particular catabolic genotype, which could be used to monitor the efficiency of treatment.     

Factors Associated with Alien Plants Transitioning from Casual, to Naturalized, to Invasive

Abstract:  To explain current plant invasions, or predict future ones, more knowledge on which factors increase the probability of alien species becoming naturalized and subsequently invasive is needed. We created a database of the alien plants in seminatural habitats in Ireland that included data on taxonomy, invasive status, invasion history, distribution, and biological and ecological plant characteristics. We used information from this database to determine the importance of these factors in increasing the ability of species to become naturalized and invasive. More specifically, we used two multiple logistic regressions to identify factors that distinguish naturalized from casual alien plant species and invasive from noninvasive, naturalized alien species. Clonal growth, moisture-indicator value, nitrogen-indicator value, native range, and date of first record affected (in order of decreasing importance) the probability of naturalization. Factors that distinguished invasive from noninvasive species were ornamental introduction, hermaphrodite flowers, pollination mode, being invasive elsewhere, onset of flowering season, moisture-indicator value, native range, and date of first record. Incorporation of phylogenetic information had little influence on the results, suggesting that the capacity of alien species to naturalize and become invasive evolved largely independently in several phylogenetic lineages. Whereas some of the variables were important for both transitions, others were only important for naturalization or for invasion. This emphasizes the importance of studying different stages of the invasion process when looking for mechanisms of becoming a successful invasive plant, instead of simply comparing invasive with noninvasive alien species. Our results also suggest that a combination of species traits and other variables is likely to produce the most accurate prediction of invasions.     

Population Biology of Gametophytes in Homosporous Polypodiophyta

Modern data on the diversity of morphology and morphogenesis of gametophytes in homosporous ferns, their vegetative reproduction, and the existence of their colonies growing separately, independently of sporophytes, are reviewed. The ontogenetic states of gametophytes are identified and characterized. The problem of gametophyte chemical interactions mediated by antheridiogen, an exohormone, is discussed. These intrapopulation interactions determine the polyvariant character of gametophyte ontogeny and the complex age and sex structure of their colonies.     

污水处理厂中雄激素分布及行为的研究进展

人类及生物体内在自然代谢及药物使用过程中产生的甾醇类激素如果在污水处理厂中未能完全去除或是未加处理直接排放,则会污染受纳水体,并对其中的鱼类等生物造成影响,其中人体内产生的雄激素睾酮的浓度比雌激素雌二醇要高1~3个数量级.本文比较了当前各地污水处理厂中的雄激素分布,阐述了污水处理工艺对雄激素的去除效果;其中,格栅、初沉池等初级处理工艺基本不去除雄激素;厌氧-缺氧-好氧等二级处理工艺通过生物降解等作用可以有效去除80%~100%的雄激素;氯消毒、臭氧等三级处理工艺对雄激素的去除效率相差较大,在-66.7%~70%范围内波动;同时也对去除雄激素的新型材料研究及未来研究方向进行了展望.     

Subcellular distribution and chemical form of Pb in hyperaccumulator Arenaria orbiculata and response of root exudates to Pb addition

Solution culture was conducted in order to understand accumulation characteristics and chemical forms of Pb in Arenaria orbiculata (A. orbiculata) and the response of root exudates to Pb addition. The results showed that: 1) Pb contents in the shoot and root of A. orbiculata increased with increasing in Pb concentrations in solution. 2) The contents of Pb chemical forms under Pb addition followed as: HAc extractable fraction (F_HAC)>HCl extractable fraction (F_HCl)>NaCl extractable fraction (F_NaCl)>ethanol-extractable fraction (F_E)>water extractable fraction (F_W). 3) Increased Pb level in the medium caused increases in Pb contents in the four subcellular fractions of shoots and roots, with most accumulation in FIV (Fraction IV, soluble fraction) in shoots and FI (Fraction I, cell wall fraction) in roots. 4) Contents of soluble sugar and free amino acid of root exudates increased with increasing Pb concentration in solution. Significantly positive correlations between Pb and contents of soluble sugar and free amino acid were observed. 5) With Pb concentrations in solution, low molecular weight organic acids (LMWOAs) contents followed the tendency: tartaric acid>acetic acid>malic acid>citric acid. Significantly positive correlation was observed between Pb and citric acid contents. The results indicate that soluble sugars, free amino acid and citric acid in root exudates of A.orbiculata facilitate the absorption and accumulation of Pb, which exist in NaCl-, HCl- and HAc- extractable Pb forms, FI and FIV fractions, resulting in tolerance of A.orbiculata to Pb.     

澎溪河消落带典型植物群落根际土壤无机氮形态及氮转化酶活性

三峡库区消落带是典型的生态脆弱带,其土壤N循环因受到植物根际效应和季节性淹水的影响而具有特殊性.本研究以三峡库区一级支流澎溪河消落带为例,选择4种植被(狗牙根、香附子、苍耳以及玉米)覆盖区,采集植物根际、非根际土壤,分析根际土壤与非根际土壤理化性质、无机氮形态以及7种N素转化相关酶,并比较了4种植物根际效应强度,以反映不同植物覆盖对消落带土壤N循环过程的影响.研究表明:供试植物根际土壤pH值均低于非根际,有机质、全氮、全磷含量均高于非根际,表明植物根际对消落带土壤养分有富集作用;4种植物根际土壤硝态氮、铵态氮、亚硝态氮及14d可矿化氮含量均高于非根际,且土壤硝态氮、亚硝态氮以及14d可矿化氮含量呈现香附子＞狗牙根＞苍耳/玉米;总体上根际土壤N转化酶活性高于非根际,且狗牙根和香附子覆盖区脲酶、亚硝酸还原酶、谷氨酰胺酶、脱氢酶显著高于玉米和苍耳覆盖区;蛋白酶、脲酶、谷氨酰胺酶活性与4种N形态均呈显著相关性,是消落带土壤N转化的主要参与酶类;根际效应分析结果香附子和狗牙根对消落带土壤N转化的根际效应强度大于苍耳和玉米,有利于土壤N素的固定和保持.植物根际效应对消落带土壤N素循环的影响可为消落带植被恢复工程中植被选择提供参考,也为改善消落带土壤退化相关研究提供科学支撑.     

利用文蛤生物标志物评价尾水-海水混合体系污染水平

采用不同浓度（体积比0%～40%,经天然海水稀释而成）的市政污水处理厂（MSTP）尾水对文蛤（Meretrix meretrix）连续培养9d,通过测定9种生化因子水平评价污染暴露对双壳类的生物学效应包括：内脏中的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）、谷胱甘肽还原酶（GR）、谷胱甘肽（GSH）、乙酰胆碱酯酶（AChE）、金属硫蛋白（MTs）、硫代巴比妥酸反应物（TBARs）以及血细胞的溶酶体膜稳定性（LMS）.SOD、CAT除外的所有生化因子均能对尾水污染产生敏感响应,其中,GPx、MTs、AChE和LMS的响应与尾水浓度呈显著相关（P<0.05或P<0.01）,适于作为尾水污染的生物标志物;依据这些生物标志物计算的综合生物标志物响应指数值（IBR_v2=0.61～2.65）随尾水浓度上升而增大,且两者间存在显著相关性（P<0.01）.研究结果表明,基于生物标志物响应值计算IBR指数的方法适于MSTPs尾水-海水混合体系的综合污染评价.