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1.
Woody plant demographics provide important insight into ecosystem state-shifts in response to changing fire regimes. In Australian tropical savannas, the switch from patchy landscape burning by Aborigines to unmanaged wildfires within the past century has been implicated in biodiversity declines including the fire-sensitive conifer, Callitris intratropica. C. intratropica commonly forms small, closed-canopy groves that exclude fire and allow recruitment of conspecifics and other fire-sensitive woody plants. C. intratropica groves provide a useful indicator of heterogeneity and fire regime change, but the mechanisms driving the species’ persistence and decline remain poorly understood. We examined the hypothesis that C. intratropica population stability depends upon a regime of frequent, low-intensity fires maintained by Aboriginal management. We combined integral projection models of C. intratropica population behaviour with an environmental state change matrix to examine how vital rates, grove dynamics and the frequency of high- and low-intensity fires contribute to population stability. Closed-canopy C. intratropica groves contributed disproportionately to population growth by promoting recruitment, whereas singleton trees accounted for a larger proportion of adult mortality. Our patch-based population model predicted population declines under current fire frequencies and that the recruitment of new groves plays a critical role in the species’ persistence. Our results also indicated that reducing fire intensity, a key outcome of Aboriginal burning, leads to C. intratropica population persistence even at high fire frequencies. These findings provide insight into the relationship between ecosystem composition and human–fire interactions and the role of fire management in sustaining the mosaics that comprise ‘natural’ systems.  相似文献   

2.
Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) is a ladybird native to Australia, preying on mealybugs and soft scales, and has been utilized worldwide as a biological control agent. It has long been recognized that C. montrouzieri that was introduced into the main island of Japan had failed to become established. The present study monitored yearly and seasonal occurrence of C. montrouzieri adults in citrus groves at Shizuoka Prefectural Fruit Tree Research Center in Shizuoka City, central Japan in 2008–2012 by using sticky traps and beating citrus trees. Adults of C. montrouzieri were continuously captured for 5 and 4 years in a pesticide-free citrus grove and a neighboring reduced-pesticide grove, respectively. Larvae of C. montrouzieri were observed consuming a cottony scale, Pulvinaria aurantii Cockerell, on citrus trees. These results provide unequivocal evidence for the ladybird’s establishment in central Japan. The number of trapped ladybird adults exhibited four peaks a year: in mid-April, early to late June, mid-August, and late September to early October. Adult numbers in each grove varied largely across years, showing a great increase followed by a rapid decline during a period of 4 years. Factors affecting the seasonal/yearly occurrence of C. montrouzieri adults in citrus groves are discussed.  相似文献   

3.
Serangium japonicum Chapin (Coleoptera: Coccinellidae) chiefly attacks whiteflies. This study monitored the adult occurrence of the ladybird and the citrus whitefly Dialeurodes citri (Ashmead) (Hemiptera: Aleyrodidae) in citrus groves in central Japan using sticky traps, thereby examining temporal relationships in their abundance. Many S. japonicum adults were captured in a pesticide-free grove where D. citri adults were very abundant, with few adults in neighboring (organic, reduced pesticide, and conventional) groves harboring small numbers of D. citri. The whitefly adults exhibited a large peak in numbers in late May to early June. Two peaks of the ladybird adult numbers were detected in late May to early June and late June to mid-July, ?6 to 7 days, and nearly 1 month after the peak in whitefly adult numbers, respectively. The ladybird adults found during the first peak period would be those that visited citrus trees mainly for oviposition, and the adults caught during the second peak period would be those that newly emerged after consuming immature whiteflies at the larval stage. Based on a yearly change in adult numbers in the pesticide-free grove, i.e., a large increase in S. japonicum numbers followed by a rapid decline in D. citri numbers, the ladybird’s role in controlling the whitefly is discussed.  相似文献   

4.
Six new genera, three tribes and one subfamily are added to the list of known hosts for the enigmatic endoparasitic fungus Myrmicinosporidium Hölldobler. Aphaenogaster senilis, Cataglyphis hispanica, Crematogaster auberti, Goniomma hispanicum, Messor barbarus, Tapinoma nigerrimum and Tapinoma simrothi were collected from olive groves and detected as infected with spores of the fungus. Pheidole pallidula and Tetramorium semilaeve were also found to be infected. The finding of seven hosts (seven genera, three subfamilies) from a single olive grove is an evidence that the fungus has a phylogenetically wide host spectrum and is, therefore, a generalist microparasite. Portugal is also a new country for Myrmicinosporidium.  相似文献   

5.
The study was carried out in a four-year-old super-high density olive grove in Central Italy to compare leaf gas exchanges of Spanish Arbequina and Italian Maurino olive cultivars. Overall, from mid July to mid November, Maurino had a slightly higher maximum light-saturated net photosynthetic rate (P Nmax) than Arbequina. The lowest and the highest P Nmax values were recorded at the end of July and in mid November, respectively. Current-season leaves showed similar or slightly higher P Nmax values than one-year-old leaves. During the day Maurino always had slightly higher values or values similar to Arbequina, with the highest P Nmax being in the morning. Maurino had similar or higher dark respiration rate (R D) values compared to Arbequina. During the day, in both cultivars the R D was lower at 9:00 than in the afternoon. The pattern of the photosynthetic irradiance-response curve was similar in the two genotypes, but the apparent quantum yield (Y Q) was higher in Maurino. In both cultivars intercellular CO2 concentration (C i) tended to increase when P Nmax decreased. The increase in C i corresponded to a decrease in stomatal conductance (g s). The transpiration rate (E) increased from mid July to the beginning of August, then decreased in September and increased again in November. Particularly in the morning, the current-season leaves showed similar or slightly higher E values than the one-year-old leaves. During the day, in both cultivars and at both leaf ages, E was higher in the afternoon. No effects on leaf gas exchanges due to the presence or absence of fruit on the shoot were found. Overall, there was satisfactory physiological adaptation for Arbequina to the conditions of Central Italy and for Maurino to the superintensive grove conditions.  相似文献   

6.
Since the 1980s, giant bamboo groves consisting mainly of naturalized Phyllostachys pubescens have been expanding in Japanese rural landscapes (satoyama). Using aerial photographs, I evaluated changes in bamboo grove distribution between 1947 and 2006 at Mount Hachiman, Ohmi‐hachiman City in western Japan, where there is an area of satoyama landscape adjacent to the suburbs. I also quantitatively determined the natural and artificial factors that accelerated bamboo grove expansion using a multiple logistic regression analysis with stepwise procedure. I attempted to describe the positions of bamboo groves in Japanese satoyama landscapes. The area of bamboo groves in the survey area expanded after 1967. The bamboo groves are located at the base of mountain slopes and on alluvial fans adjacent to residential areas, where they are most susceptible to human interferences (mainly disturbance). They mark the boundary between agricultural fields and secondary forests. The model analysis indicated that the abandonment of lands adjacent to bamboo groves caused bamboo‐grove expansion. As forests and agricultural land were abandoned, bamboo, mainly P. pubescens, invaded these areas by rhizomatous clonal growth. Bamboo grove expansion in Japanese satoyama landscapes is dependent on the type of land use, topography, and existing vegetation as well as the invasive life‐history traits of P. pubescens.  相似文献   

7.
Butterfly communities can be modified by the activities of large mammals. The wild boar (Sus scrofa) is one of the most common mammals in Europe and has notably expanded its distribution range in recent decades. The present work aimed to investigate the possible effect of wild boar rooting activity on butterflies in olive groves inside the “Cilento, Vallo di Diano and Alburni” National Park. Butterflies were surveyed in five Rooted (R) and five Control areas (C). Transects were made from April to September in 2011 and 2012. Forty-three species and 3659 individuals were found, of which 39 species and 2426 individuals were detected in C areas and 31 species and 1233 individuals in R areas. A community-level approach showed a significantly higher abundance, richness and Shannon–Wiener index in C than in R. An ecological-level approach indicated that more specialised butterflies were significantly more affected by wild boar activity. Finally, the response of single species was investigated: two species (Colias croceus and Polyommatus icarus) were significantly more represented in R, whereas six species (Aricia agestis, Hipparchia statilinus, Lasiommata megera, Melanargia arge, Pyronia cecilia and Thymelicus acteon) were significantly more abundant in C. Three species considered at risk (M. arge; Annex II of Directive 92/43/EEC; H. statilinus and T. acteon: European Red List) were less represented in rooted areas. Overall, the intensive wild boar activity negatively correlated with butterflies in the olive groves studied.  相似文献   

8.
The gene FRIGIDA (FRI) is floral repressor and plays a key role in the timing of Arabidopsis flowering. To study the function of FRI-like genes in bamboo, we isolated a FRI family gene from bamboo Phyllostachys violascens and named it PvFRI-L. Sequence alignment and phylogenetic analysis show that the PvFRI-L protein belongs to the FRL3 (III) subfamily from monocots and contains a conserved FRIGIDA domain. PvFRI-L was located in the nucleus of onion epidermal cells. PvFRI-L was expressed in all tested organs of flowering and non-flowering bamboo plants with a higher expression in non-flowering than in flowering plants. Overexpression of PvFRI-L in Arabidopsis caused late flowering by downregulating flowering locus T and upregulating flowering locus C. A P-box, the binding site involved in gibberellin response, was found only in the promoter region of PvFRI-L but not in that of FRI. Furthermore, PvFRI-L expression in the leaves of Ph. violascens seedlings was downregulated with gibberellic acid treatment. Taking together, our observation suggests that PvFRI-L may be flowering repressor and its delaying floral timing may be regulated by gibberellic acid in bamboo.  相似文献   

9.
Present study revealed the presence of 16 earthworm species belonging to 11 genera and four families viz. Megascolecidae (Amynthus alexandri, Metaphire houlleti, Lampito mauritii, Kanchuria sp1, Perionyx excavatus), Octochaetidae (Eutyphoeus gigas, Eutyphoeus comillahnus, Eutyphoeus orientalis, Octochaetona beatrix, Dichogaster bolaui, Lennogaster chittagongensis, Lennogaster yeicus), Moniligastridae (Drawida papillifer papillifer, Drawida assamensis, Drawida nepalensis) and Glossoscolecidae (Pontoscolex corethrurus) in the soils of five bamboo species [Bambusa balcooa (Sil Barak), Melocanna baccifera (Muli), Bambusa polumorpha (Bari), Bambus cacharensis (Bom) and Bambus bambus (Katabarak)] of West-Tripura. While four earthworm species viz. Metaphire houlleti, Drawida assamensis, Drawida papillifer papillifer and Pontoscolex corethrurus were common to all species of bamboo plantations, the rest showed restricted distribution. Among the earthworm species 4 were exotic (Amynthus alexandri, Metaphire houlleti, Dichogaster bolaui and Pontoscolex corethrurus) and the others were native to the Indian sub-continent. In general, earthworms under the bamboo plantations occurred within temperature range of 21.6 °C–28.0 °C, pH 4.0–7.0, organic matter 0.56–5.99 %, moisture 9.6–31.7 %, water holding capacity 14.6–43.9 % and bulk density 0.7–1.8 g cm?3. The average density and biomass of the earthworms in the studied places were 108 ind m?2 and 44 g m?2 respectively. Earthworm diversity, dominance and evenness indices showed the values 1.00, 0.47 and 0.70 respectively. Earthworm density and biomass showed a negative correlation with temperature whereas those had a strong positive correlation with pH, moisture and organic matter of the soils.  相似文献   

10.
Passer montanus became established in a small area of central North America following its introduction in 1870. P. montanus underwent minimal range expansion in the first 100 years following introduction. However, the North American population of P. montanus is now growing in size and expanding in geographic distribution, having expanded approximately 125 km to the north by 1970. We quantify the distance of spread by P. montanus from its introduction site in the greater St. Louis, Missouri-Illinois, USA area, using distributional (presence) data from the National Audubon Society Christmas Bird Count surveys for the period of 1951 to 2014. Linear regressions of the average annual range center of P. montanus confirmed significant shifts to the north at a rate of 3.3 km/year (P < 0.001) km/year. Linear regressions of the linear and angular distance of range center indicates significant northern movement (change in angle of mean range center; P < 0.001) since 1951. Our results quantify the extent of a northward range expansion, and suggesting a probable spread of this species northward.  相似文献   

11.
Escherichia coli can hardly grow anaerobically on glycerol without exogenous electron acceptor. The formate-consuming methanogen Methanobacterium formicicum plays a role as a living electron acceptor in glycerol fermentation of E. coli. Wild-type and mutant E. coli strains were screened for succinate production using glycerol in a co-culture with M. formicicum. Subsequently, E. coli was adapted to glycerol fermentation over 39 rounds (273 days) by successive co-culture with M. formicicum. The adapted E. coli (19.9 mM) produced twice as much succinate as non-adapted E. coli (9.7 mM) and 62% more methane. This study demonstrated improved succinate production from waste glycerol using an adapted wild-type strain of E. coli with wild-type M. formicicum, which is more useful than genetically modified strains. Crude glycerol, an economical feedstock, was used for the cultivation. Furthermore, the increase in methane production by M. formicicum during co-culture with adapted E. coli illustrated the possibility of energy-saving effects for the fermentation process.  相似文献   

12.
Extensive research has found that nighttime transpiration (E n) is positively correlated to the vapour pressure deficit (VPD), that suggested E n was highest during the night under high temperatures and low humidity along with high soil water availability, typically for the riparian forest in the extreme arid region of China. This study used the heat ratio method to measure sap velocity (V s) for mature and saplings Populus euphratica Oliv., and then E n was conservatively calculated as total nocturnal sap flow (F s, the product of V s and sapwood area A s) between 01:00 to 06:00. A gas exchange system was used to measure the leaf transpiration rate (T r) and stomatal conductance (g s) of saplings. For mature trees, nighttime V s was extensive and logarithmic correlated to VPD (similar to daytime). For saplings, g s and T r was extensive in different months, and also a strong logarithmic relationship was found between V s and VPD for both daytime and nighttime periods. Both of stem sap flow and leaf gas exchange suggusted the occurrence of E n, whether mature or sapling trees. E n contribution to daily transpiration (E d) was high just as expected for P. euphratica, which was confirmed by proportional E n to E d (E n/E d) means taken in 2012 (24.99%) and 2013 (34.08%). Compared to mature trees, E n/E d of saplings in 2013 was lower with means of 12.06%, that supported further by the shorter duration times and less T r,n (16.64%) and g s,n (26.45%) of leaf, suggesting that E n magnitude is associated to individual the tree size, that effect to stored water of individual trees, although this hypothesis requires further research.  相似文献   

13.
There are three species of Phoenix (Arecaceae) in the territory of the European Union, P. canariensis, P. dactylifera and P. theophrasti, found in wild-native populations, feral, planted and intermediate states, accounting each for thousands of individuals. The EU Habitats Directive has addressed the conservation of P. theophrasti and P. canariensis under the habitat type 9370, ‘Palm groves of Phoenix,’ but neglected to include the wild-growing populations of P. dactylifera palms in southern Spain. In this paper, we survey the habitats and status of both representative native and naturalized populations of Phoenix, in total 103, through fieldwork, image analysis and review of literature. We underline the significance of feral populations and palms originating from ancient abandoned plantations, existing in protected areas as a reservoir of genetic variation. We conclude that, in order to improve their conservation status by adequate protection and conservation management, the concept of Phoenix palm groves in the Habitats Directive should be redefined to include the western group of P. dactylifera and the various habitats of P. canariensis and P. theophrasti that do not appear in the current definition.  相似文献   

14.
A 5-m-deep gravel pit was excavated from 1996 to 1998 in the floodplain between Willow Creek, Alberta, and a grove of balsam poplars ('cottonwoods', Populus balsamifera L.) and water level at the pit was lowered 2.5 m through pumping. This interrupted the infiltration of stream water into the riparian groundwater and imposed drought stress on the cottonwoods. Trees in the drought-affected grove displayed extensive leaf senescence and abscission in late August 1998, while trees in nearby control groves remained green until autumnal senescence in late September. The precocious senescence was accompanied by a two-thirds reduction in leaf stomatal conductance (g s) but mid-day leaf xylem water potentials (ψl) were only slightly reduced (?1.55 vs 1.42 MPa). Pumping ceased in 1999, the pit was partially refilled, and the hydraulic linkage between the stream and the riparian zone recovered. Subsequently in August 1999, g s and ψl were similar for trees in the affected and control groves and senescence phenologies were similar in 1999 and 2000. Annual branch growth increments varied 3-fold across years between 1994 and 1999, but there was no reduction in these growth increments in the drought-affected trees in 1998 or 1999. This study supports the hydraulic linkage between a stream and the adjacent riparian zone in a semi-arid region and demonstrates the vulnerability of riparian cottonwoods to drought due to water table depletion. It also indicates rapid physiological recovery of cottonwoods following restoration of water availability.  相似文献   

15.
The Western European population of wild boar (Sus scrofa) has increased its distribution over the past several decades, and some populations have colonized areas strongly influenced by human activity. Wild boars are known carriers of antibiotic-resistant bacteria acquired from the environment, and urban populations of wild boars may be more exposed than their rural counterparts. In this work, we compared the frequency of antibiotic resistance in indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium) isolated from urban wild boars with that from rural wild boars in NE Spain. We further assessed whether bacterial isolates from the urban wild boars had a higher probability of showing antibiotic resistance when their host was highly associated to urban features. Seventy-two and 100 bacterial isolates from urban and rural habitat, respectively, were screened for antibiotic resistance against a set of antibiotics (13 per bacterial species). We found a significantly higher frequency of E. faecium showing resistance to tetracycline (70.0% vs 36.4%) and high-level resistance to streptomycin (30.0% vs 4.5%) in urban wild boars compared to rural wild boars (p?<?0.05). E. faecalis was more frequently resistant to trimethoprim in urban than rural wild boars (33.3% vs 0.0%, p?<?0.05). In isolates from urban origin, 55.6% of the likelihood of detecting antibiotic resistance depended only on the bacterial species, being more likely in the enterococci than in E. coli. These results suggest that urban wild boars may be more exposed to certain antibiotic-resistant bacteria or antibiotic resistance genes that they may acquire from the urban environment, although implications are uncertain.  相似文献   

16.
17.
Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.  相似文献   

18.
Anthocyanin pigmentation of various organs develops during plant ontogeny in response to adverse and damaging abiotic and biotic stressors (environmental factors). Using the monosome method, the genes responsible for anther and culm anthocyanin pigmentation (Pan1 and Pc2, respectively) were localized to 7D chromosome in introgressive lines from crosses between common wheat Triticum aestivum L. and the species Triticum timopheevii Zhuk. Genetic analysis of ten common wheat genotypes using testers carrying genes Pan1, Pc1 and Pc2 showed that these genotypes contained Pan1 and Pc2 genes. Visual examination of plants from 70 and 76 varieties of respectively winter and spring common wheat revealed anthocyanin pigmentation of anthers and culms in 36 varieties. Pan1 and Pc2 genes were presumably introduced into common wheat from Aegilops tauschii (Eig.) Tzvel., a donor of the D genome.  相似文献   

19.
The axillary bud-break and multiple bud induction were obtained from the nodal explants of field-grown culms of Bambusa tulda in liquid Murashige and Skoog’s (MS) basal medium supplemented with 2.0 mg l?1 6-benzylaminopurine (BAP), 1.0 mg l?1 kinetin (Kn) and 8% coconut water. Multiple shoots regenerated and proliferated in the liquid MS medium fortified with 3.0 mg l?1 indolebutyric acid (IBA). While, in B. balcooa, MS medium supplemented with 2.5 mg l?1 BAP and 1.0 mg l?1 Kn induced axillary bud-break, bud multiplication and subsequently shoot elongation was obtained after three passages in the same medium. A clump with at least three shoots of both these bamboo species was used as propagule for successful root induction in half-strength MS liquid basal medium supplemented with 0.2 mg l?1 IBA. Sympodial type of microrhizomes developed in B. tulda and the regenerants acclimatized in the soil easily. Explants collected in the month of October produced best in vitro regeneration response in these two bamboo species. Endogenous phenol content proved detrimental for efficient shoot regeneration. The clonal fidelity of the regenerants was established by RAPD analysis advocating clonal propagation through axillary meristem culture of B. balcooa and B. tulda is reliable for commercial exploitation.  相似文献   

20.
Bamboo flowering owns many unique characteristics and remains a mystery. To investigate the molecular mechanisms underlying flower development in bamboo, a petal-identity gene was identified as a PISTILLATA homologue named BoPI from Bambusa oldhamii (bamboo family). Expression analysis showed that BoPI was highly expressed in flower organs and gradually increased during flower development stage, suggesting that BoPI played an important role in flower development. Ectopic expression of BoPI in Arabidopsis caused conversion of sepals to petals. 35S::BoPI fully rescued the defective petal formation in the pi-1 mutant. BoPI could interact with BoAP3 protein in vitro. These results suggested that BoPI regulated flower development of bamboo in a similar way with PI. Besides flower organs, BoPI was also expressed in leaf and branch, which revealed that BoPI may involve in leaf and branch development. Similar to other MIKC-type gene, BoPI contained the C-terminal sequence but its function was controversial. Ectopic expression of the C-terminal deletion construct (BoPI- ΔC) in Arabidopsis converted sepals to petals; BoPI- ΔC interacted with BoAP3 on yeast two-hybrid assay, just like the full-length construct. The result implied that the C-terminal sequence may not be absolutely required for organ identity function in the context of BoPI.  相似文献   

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