Niche shifts of nonnative plants can occur when they colonize novel climatic conditions. However, the mechanistic basis for niche shifts during invasion is poorly understood and has rarely been ...captured within species distribution models. We quantified the consequence of between-population variation in phenology for invasion of common ragweed (Ambrosia artemisiifolia L.) across Europe. Ragweed is of serious concern because of its harmful effects as a crop weed and because of its impact on public health as a major aeroallergen. We developed a forward mechanistic species distribution model based on responses of ragweed development rates to temperature and photoperiod. The model was parameterized and validated from the literature and by reanalyzing data from a reciprocal common garden experiment in which native and invasive populations were grown within and beyond the current invaded range. It could therefore accommodate between-population variation in the physiological requirements for flowering, and predict the potentially invaded ranges of individual populations. Northern-origin populations that were established outside the generally accepted climate envelope of the species had lower thermal requirements for bud development, suggesting local adaptation of phenology had occurred during the invasion. The model predicts that this will extend the potentially invaded range northward and increase the average suitability across Europe by 90% in the current climate and 20% in the future climate. Therefore, trait variation observed at the population scale can trigger a climatic niche shift at the biogeographic scale. For ragweed, earlier flowering phenology in established northern populations could allow the species to spread beyond its current invasive range, substantially increasing its risk to agriculture and public health. Mechanistic species distribution models offer the possibility to represent niche shifts by varying the traits and niche responses of individual populations. Ignoring such effects could substantially underestimate the extent and impact of invasions.
The invasive weed Ambrosia artemisiifolia (common ragweed) constitutes a great threat to public health and agriculture in large areas of the globe. Climate change, characterized by higher ...temperatures and prolonged vegetation periods, could increase the risk of establishment in northern Europe in the future. However, as the species is a short-day plant that requires long nights to induce bloom formation, it might still fail to produce mature seeds before the onset of winter in areas at northern latitudes characterized by short summer nights. To survey the genetic variation in flowering time and study the effect of latitudinal origin on this trait, a reciprocal common garden experiment, including eleven populations of A. artemisiifolia from Europe and North America, was conducted. The experiment was conducted both outside the range limit of the species, in Sweden and within its invaded range, in Croatia. Our main hypothesis was that the photoperiodic-thermal requirements of A. artemisiifolia constitute a barrier for reproduction at northern latitudes and, thus, halts the northern range shift despite expected climate change. Results revealed the presence of a north-south gradient in flowering time at both garden sites, indicating that certain European populations are pre-adapted to photoperiodic and thermal conditions at latitudes up to, at least, 60° N. This was confirmed by phenological recordings performed in a region close to the northern range limit, the north of Germany. Thus, we conclude that there exists a high risk for establishment and spread of A. artemisiifolia in FennoScandinavia in the near future. The range shift might occur independently of climate change, but would be accelerated by it.
Seed germination, growth, flowering and yields of kiwano (Cucumis metuliferus E. Meyer Ex. Naudin) were examined in eastern Slavonia during 2021 growing season. The objective of this study was to ...determine agro-morphological diversity within kiwano growing under different weed management practices and sowing time. The experiment was arranged as a 3 x 3 factorial design with three replications. Factors included three weed management options (wheat straw mulch, cultivation and un-weeded control) and three planting dates (early, mid and late May). A typical summer weed community that develops during experiment dominated with bristly foxtail (Setaria verticilata (L.) P. Beauv.) and redroot pigweed (Amaranthus retroflexus L.) while the others were with lower relative density and frequency per unit area and with the lower impact on the crop. Weed control was very effective compared to weedy check. However, sowing date appears as a critical factor in kiwano production, influencing not only emergence, growth and flowering, but also fruit number and size. This study concluded that mid sowing time and cultivation as a weed control measure has a highest agronomic potential for a kiwano production following by mid and early sowing time with mulch as a weed control measure.
Three-of-heaven (Ailanthus altissima (Mill.) Swingle) is considered as one of the most invasive plant species worldwide in rural and urban environment. Although tree-of-heaven is commonly observed ...throughout the city of Osijek (Croatia), its prevalence and frequency has not been documented. This study has been conducted from May to September 2022 in the streets of Osijek to determine the distribution, abundance and competitive advantage of this species. A survey was performed by sampling randomly selected 20 quadrats in each city district, having together 140 phytocoenological records, and presence-absence of tree-of heaven was recorded in each plot. Where present at urban habitats, the number of threes were recorded and categorized approximately by the diameter at breast height (dbh). Habitats were distinguished as follows: alleys, abandoned private areas, public areas, ruderal sites, cracked walls and road edges. Risk assessment analysis were prepared by combining quantitative (number of trees per plots) and qualitative (four categories: biological characteristics and dispersal abilities, ecological amplitude and distribution, ecological impact, and difficulty to control) data. There was e recorded a total of 189 tree-of-heaven, occurring both as solitary plants or in developed stands. The habitat types with the highest rate of tree-of-heaven are abandoned private areas (34%) followed by public areas (31%). Out of the total, 55% of the recorded tree-of heaven are young individuals belonging to the very small and small diameter classes, and are mainly present on abandoned private and public areas. Ecological impact and biological characteristics are primary course of its landscape spread.
Pajasen (Ailanthus altissima (Mill.) Swingle) je jedna od najinvazivnijih biljnih vrsta širom svijeta kako u ruralnim, tako i u urbanim područjima. Premda je pajasen široko rasprostranjen na području grada Osijeka (Hrvatska), njegova prevalencija i frekvencija još do sada nije zabilježena. Istraživanje je sprovedeno od svibnja do rujna 2022. na osječkim ulicama kako bi se utvrdila njegova distribucija, abundacija i kompetitivna sposobnost. Istraživanje je obavljeno metodom slučajno odabranih kvadrata unutar svakog gradskog kvarta, što je ukupno iznosilo 140 fitocenoloških snimaka. Naplohama gdje je utvrđen pajasen, pobrojane su sve individue i kategorizirane su prema obujmu prsnog promjera stabla. Plohe su razvrstane kao: ulice, napušteni privatni posjedi, javne površine, ruderalna staništa, napuknuti zidovi i rubovi puteva. Procjena rizika pripremljena je kombinacijom kvantitativnih (broj individua po plohi) i kvalitativnih kategorija (biološka obilježja i sposobnostširenja, ekološke amplitude i rasprostranjenost, ekološki utjecaj i poteškoće u suzbijanju). Utvrdili smoukupno 189 stabala pajesena, koji su bili prisutni i kao solitarna drva a također i oblikujući nakupine. Od urbanih staništa, s najvećim postotkom (34 %) pajasen je utvrđen na napuštenim privatnimposjedima a zatim slijede javne površine (31 %). Od ukupno zabilježenih vrsta, 55 % pajasena sumladice koje pripadaju kategoriji stabala s vrlo malim ili malim promjerom debla i uglavnom surašireni na napuštenim privatnim posjedima i javnim površinama. Ekološka i biološka obilježjapajasena primarno su zaslužna za njegovo širenje urbanim prostorima grada Osijeka.
A field experiment was conducted to evaluate various weed management options on garlic (Alium sativum L.) production in Northeastern Croatia.
This study focus on how different strategies of weed ...control affects weed community composition and economic benefit of weed management. An experiment was arranged as a complete block design with three different weed management strategies: chemical control (PRE EM and POST EM), mechanical control (three times during the season), and combination of chemical and mechanical treatments, together with weeded checks. Data on
weed density, fresh above weed biomass and garlic yield per m2 were collected at the end of the growing season, and were subjected to statistical and economic analysis. The mayor weeds found in the experimental plots were: Sorghum halepense, Ambrosia artemisiifolia, Cirsium arvense and Chenopodium album. The various weed growth (density and biomass) and yield varied with application of weed management practices. Significantly lower values of weed density and fresh above weed biomass were recorded on plots with mechanical and combination of chemical and mechanical treatments compared to weeded check. Chemical application gave in this study insufficient weed control and resulted in lower yields compared to
the mechanical treatments and combination of mechanical and mechanical weed control. The best cost: benefit ratio was observed on treatment with combination of chemical and mechanical weed control and can be successfully applied to boost up the bulb yield in garlic and to harvest
the maximum profit for farmers.
Poljski pokus je proveden na području sjeveroistočne Hrvatske s ciljem evaluacije različitih strategija suzbijanja korova u češnjaku (Alium sativum L.). Predmet ovog istraživanja bio je utvrditi kako različite strategije suzbijanja korova utječu na korovnu zajednicu u češnjaku i kakav je ekonomski učinak svakog od istraživanih tretmana. Pokus je postavljen po slučajnom blok rasporedu sa tri različita tretmana suzbijanja korova: kemijsko (sa PRE-EM i POST-EM primjenom), mehaničko (tri puta tijekom vegetacijske sezone) i kombinaciju kemijskog i mehaničkog suzbijanja. Zakorovljena, kontrolna varijanta je također bila uključena u pokus. Dobiveni podatci o gustoći korova, svježoj nadzemnoj biomasi korova i prinosu češnjaka prikupljeni su na kraju vegetacijske sezone te statistički i ekonomski analizirani. Najznačajniji korovi tijekom provedbe pokusa bili su: Sorghum halepense,
Ambrosia artemisiifolia, Cirsium arvense and Chenopodium album. Primjenjene strategije suzbijanja korova različito su utjecale na gustoću i nadzemnu
biomasu korova te na prinos češnjaka. Signifikantno manja gustoća korova i njihova nadzemna biomasa u usporedbi sa zakorovjenom kontrolom utvrđena je na parcelama s mehaničkim suzbijanjem korova i s kombinacijom mehaničkog i kemijskog suzbiljanja. Aplikacija herbicida u ovom pokusu nije se pokazala uspješnom i ostvarila je na kraju vegetacijske sezone signifikantno niži prinos u odnosu na ostale tretmane. Tretman s najboljem omjerom troškova i koristi jest kombinacija kemijskog i mehaničkog suzbijanja korova i može se preporučiti farmerima kao uspješna strategija za postizanje visokog pronosa i ostvarenja maksimalnog profita.
Field margins are pollinator-friendly habitats and important refuges for many pollinators. As a valuable food resource throughout the vegetation season, not just when crop species are in flower, ...field margins need to be protect or restore in areas of intensive farming. This paper examines the floristic and functional structure of weed communities on field margins in the northeastern part of the Republic of Croatia. A phytocoenological survey was conducted during the summer period of 2017 and 2018. A total of 32 field margins was analyzed for species richness, abundance and their role for entomofauna. Floristically rich field margins consist of 72,6% plant species beneficial to pollinators. Foraging period can be stretching throughout the year, but stabile and high flowering period is from May to end of September. Among highest ranked honeybee plants, several invasive species with significant relative abundance are: Solidago gigantea, Asclepias syriaca and Amorpha fruticosa who pose a serious threat to plant biodiversity. Positive role of vegetation from field margins was not valuable for pollinators only, but they also serve as supply the substrates that provide a shelter and nesting sites.
Entrepreneurial skills are necessary for all graduates who are planning their own start-up business. Those skills are asked more and more by employers, even from fresh graduates of technical ...backgrounds. This paper compares two extracurricular programs involving students of four different, all non-economics programs from Croatia and the USA. Several challenges were identified during the research. Preparing and executing entrepreneurial educational programs for students with very uneven level of relevant foreknowledge was one of them. Integration of classroom and e-learning methods and achievement of an effective combination of being educational, interesting and attractive in the same time were additional challenges. Gender of the participants, previous education, entrepreneurial background of their families and immediate plans upon the graduation were determined as influencing variables on their satisfaction with the program.
Abstract This paper analyses the floristic biodiversity of weed communities in the arable lands of the Istrian peninsula during a twelve year period (2005–2017). A total of 50 fields were surveyed ...for each sampling time using the seven-degree Braun-Blanquet cover abundance scale in the following agricultural categories: a) permanent crops (vineyards/olive groves), b) alfalfa fields, c) cereals, d) row crops and e) ruderal areas. The taxonomic identification was performed during the full development of vegetation, for cereals in June and July, and for the rest – in August and September. A total of 175 weed species were determined during both study periods with Asteraceae and Poaceae families as the most abundant. Altogether, therophytes were dominant in both surveys, followed by hemycryptophytes and geophytes. Variations in species composition were visible in both study periods (2005 and 2017) as well as in the selected habitat types. Exclusive species were found in addition to those that were common for both surveys. Changes in species composition between 2005 and 2017 referred to the difference in row spacing in earlier period, and ruderal vs. agricultural habitats in the recent survey. The differences in phenological traits between the past and present surveys were greatest for germination season in permanent crops and row crops, flowering start for permanent crops, flowering period for ruderal area and weed height for permanent crops. Significant differences between the past and present survey for other plant traits did not occur.
Changes in floristic composition of weed flora were assessed comparing two phytocoenological surveys carried out during vegetation seasons in 2005 and in 2017 on the Istrian Peninsula. A total of 50 ...fields (row crops, cereals, alfalfa fields, orchards/vineyards and ruderal areas) were surveyed for each of the sampling time using Braun-Blanquet cover-abundance scale. Altogether 175 vascular plant species were recognized in both investigations. The most abundant species in 2005 were Avena fatua, Setaria verticilata, Lolium multiflorum and Veronica persica. In the recent survey these species became very rare or were even not detected in some habitats. In contrast, some species with very low relative abundance or not recorded in the earlier survey were found abundant in 2017. These are: Pastinaca sativa, Conyza canadensis, Picris
echioides, Polygonum aviculare, and Heliotropium europaeum. The species
richness was significantly higher in the earlier survey when 143 (82%) weeds were detected compared to only 97 species (55%) found in 2017. Only 64 species were found in both surveys, and these were considered frequent weeds. The comparison of weed communities
from the earlier to the recent survey reflects the reduction of the weed flora at the regional scale, as well as at the field scale. The mean values of Shannon-Wiener diversity index were also higher in the earlier period and it decreased over time, particularly in row crops, cereals and ruderal habitats. This decrease was related to decline of species richness, and to the increase in inequality in the relative abundance of species. On the whole, canonical correspondence analysis indicated the major variations in species composition between different habitats.
Promjene u florističkom sastavu korovne flore Istre procijenjenje su putem dvije fitocenološke analize vegetacije izvršene tijekom 2005. i 2017. godine. U oba istraživanja pregledano je 50 polja korištenjem kombinirane procjene brojnosti i pokrovnosti vrsta metodom po Braun-Blanquetu. Ukupno je na istraživanom području evidentirano 175 vrsta vaskularne flore. Najvećom abundacijom u 2005. isticale su se Avena fatua, Setaria verticilata, Lolium multiflorum i Veronica persica, dok su u 2017. bile vrlo rijetke ili su čak nestale s nekih staništa. Nasuprot tome, neki korovi koji su bili neznatno zastupljeni ili ih nije bilo u ranijem istraživanju zabilježeni su s visokom abundacijom u istraživanjima 2017. godine. To su vrste Pastinaca sativa, Conyza canadensis, Picris echioides, Polygonum aviculare i Heliotropium europaeum. Floristički su bogatija bila istraživanja iz 2005. godine kada je utvrđeno 143 vrste korova (82 %) u odnosu na istraživanja izvršena 2017. kada je zabilježeno samo 97 vrsta, odnosno 55 % od ukupno evidentirane flore. Zajedničke u oba istraživana razdoblja bile su 64 korovne vrste koje pripadaju tipičnim i frekventnim korovima istraživanog područja. Promjene unutar korovnih zajednica utvrđene su ne samo na regionalnoj razini veći i unutar samih polja. Na to ukazuje i smanjenje Shannon-Wienerova indeksa raznolikosti (H’), posebice u okopavinama, žitaricama i na ruderalnim staništima. Na smanjenje Shannon-Wienerova indeksa raznolikosti utjecala je redukcija broja vrsta kao i njihova nejednaka abundacija. U konačnici, multivarijantna analiza (CCA) potvrdila je fluktuacije u florističkom sastavu korovne zajednice.
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