Seed Ageing and Smoke: Partner Cuesin the Amelioration of Seed Dormancyin Selected Australian Native Species

1997 ◽  
Vol 45 (5) ◽  
pp. 783 ◽  
Author(s):  
Shauna Roche ◽  
Kingsley W. Dixon ◽  
John S. Pate

Seed germination of many Australian native plant species has consistently proven to be fractious. With the discovery of smoke-mediated germination, it is now possible to better understand the heterogeneity in germination patterns for a wide range of species both in situ and ex situ. In the present study, over 180 species were examined as to viability and smoke responsiveness of freshly collected seed. Soil storage and a number of commonly used seed pre-treatments were employed in combination with smoke to examine both longevity in artificially constructed seed banks, and the role of seed ageing in improved germination. Methods of smoke application for commercial use were also investigated. Viability decline over 1 year varied between 10% and 80%. Reductions of as little as 15% were found to compromise the ability of a number of species to successfully recruit in consecutive seasons. When fresh seed was used,almost 70% of species tested responded positively to smoke whether applied prior to or after sowing. Variation in success between the two methods confirmed earlier conclusions that substances contained in plant-derived smoke may be inhibitory at high concentrations for particularly sensitive species. Only 10% of species under investigation recorded optimum germination with seed ageing alone but when smoke was applied as a treatment after soil storage, 60% of species responded positively. Implications for horticulture, rehabilitation, seed bank research and habitat management are discussed.

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4960 ◽  
Author(s):  
Chelsea K. Janke ◽  
Laura A. Wendling ◽  
Ryosuke Fujinuma

Australian native species grow competitively in nutrient limited environments, particularly in nitrogen (N) limited soils; however, the mechanism that enables this is poorly understood. Biological nitrification inhibition (BNI), which is the release of root exudates into the plant rhizosphere to inhibit the nitrification process, is a hypothesized adaptive mechanism for maximizing N uptake. To date, few studies have investigated the temporal pattern and components of root exudates by Australian native plant species for BNI. This study examined root exudates from two Australian native species,Hibiscus splendensandSolanum echinatum,and contrasted with exudates ofSorghum bicolor, a plant widely demonstrated to exhibit BNI capacity. Root exudates were collected from plants at two, four, and six weeks after transplanting to solution culture. Root exudates contained three types of organic acids (OAs), oxalic, citric and succinic acids, regardless of the species. However, the two Australian natives species released larger amount of OAs in earlier development stages thanS. bicolor. The total quantity of these OAs released per unit root dry mass was also seven-ten times greater for Australian native plant species compared toS. bicolor. The root exudates significantly inhibited nitrification activity over six weeks’ growth in a potential nitrification assay, withS. echinatum(ca. 81% inhibition) >S. bicolor(ca. 80% inhibition) >H. splendens(ca. 78% inhibition). The narrow range of BNI capacity in the study plants limited the determination of a relationship between OAs and BNI; however, a lack of correlation between individual OAs and inhibition of nitrification suggests OAs may not directly contribute to BNI. These results indicate that Australian native species generate a strongly N conserving environment within the rhizosphere up to six weeks after germination, establishing a competitive advantage in severely N limited environments.


2004 ◽  
Vol 52 (2) ◽  
pp. 141 ◽  
Author(s):  
V. P. Thomson ◽  
M. R. Leishman

Australian soils are naturally low in nutrient concentrations, particularly nitrogen (N) and phosphorus (P). Native plants are well adapted to low-nutrient soils, and can be adversely affected when exposed to higher concentrations of nutrients. The Hawkesbury Sandstone soils in northern Sydney are naturally low in nutrients, but often receive additional nutrient input from urban stormwater run-off. Increases in soil nutrients in urban bushland are associated with the presence of exotic species, and the decline in the diversity of native species. This study tested the hypothesis that high concentrations of nutrients, in particular P, in the disturbed soils of urban bushland, reduce survival of native plants. We examined the survival of native species under five different nutrient concentrations that are typical of nutrient-enriched urban bushland soil, in two glasshouse experiments. The experiments examined both survival of seedlings and survival of 6-month-old plants. We used native species that are adapted to both nutrient-poor and nutrient-rich soils. In general, the survival of native plants decreased with increasing nutrient concentrations. At soil total-P concentrations >200 mg kg–1, most plants died. Seedlings were more sensitive to added nutrients than the 6-month-old plants. Species that were from higher-nutrient soil had consistently higher survival than species from low-nutrient soils, under the nutrient addition treatments. These results suggest that at high soil nutrient concentrations typical of stormwater-affected urban bushland, native plant species of low-nutrient soils will be unable to survive. If ecological restoration works are to be done in such areas, replanting with more mature plants from naturally high-nutrient habitats is likely to be the most successful. However, restoration of these areas may have limited success and they are likely to remain dominated by exotic plant species.


2016 ◽  
Vol 35 (2) ◽  
pp. 136-147 ◽  
Author(s):  
Marek Gális ◽  
Jela Galková ◽  
Jozef Straňák

AbstractThis study characterises an impact of secondary landscape structure on the introduction of non-native plant species during the years 2008 and 2010−2012. The field mapping was realised in the cadastral area of the Topoľčany town. The area of study consists of built-up area with surrounding agricultural land. During the period of our research, we identified the presence of total 55 non-native plant species, including 21 invasive, 11 casual and 23 naturalised. The highest dominance occurred in elements of ruderal vegetation without trees (22) and in the vegetation protection of aquatic dams (15). Several species were observed in a wide range of landscape elements. The occurrence in many structurally different types of habitats confirmed the ability of non-native species to tolerate a wide range of biotic and abiotic conditions.


PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0237894
Author(s):  
Amy E. Kendig ◽  
Vida J. Svahnström ◽  
Ashish Adhikari ◽  
Philip F. Harmon ◽  
S. Luke Flory

Infectious diseases and invasive species can be strong drivers of biological systems that may interact to shift plant community composition. For example, disease can modify resource competition between invasive and native species. Invasive species tend to interact with a diversity of native species, and it is unclear how native species differ in response to disease-mediated competition with invasive species. Here, we quantified the biomass responses of three native North American grass species (Dichanthelium clandestinum, Elymus virginicus, and Eragrostis spectabilis) to disease-mediated competition with the non-native invasive grass Microstegium vimineum. The foliar fungal pathogen Bipolaris gigantea has recently emerged in Microstegium populations, causing a leaf spot disease that reduces Microstegium biomass and seed production. In a greenhouse experiment, we examined the effects of B. gigantea inoculation on two components of competitive ability for each native species: growth in the absence of competition and biomass responses to increasing densities of Microstegium. Bipolaris gigantea inoculation affected each of the three native species in unique ways, by increasing (Dichanthelium), decreasing (Elymus), or not changing (Eragrostis) their growth in the absence of competition relative to mock inoculation. Bipolaris gigantea inoculation did not, however, affect Microstegium biomass or mediate the effect of Microstegium density on native plant biomass. Thus, B. gigantea had species-specific effects on native plant competition with Microstegium through species-specific biomass responses to B. gigantea inoculation, but not through modified responses to Microstegium density. Our results suggest that disease may uniquely modify competitive interactions between invasive and native plants for different native plant species.


2008 ◽  
Vol 1 (1) ◽  
pp. 50-58 ◽  
Author(s):  
Bryan A. Endress ◽  
Catherine G. Parks ◽  
Bridgett J. Naylor ◽  
Steven R. Radosevich

AbstractSulfur cinquefoil is an exotic, perennial forb that invades a wide range of ecosystems in western North America. It forms dense populations and often threatens native plant species and communities. In this study, we address the following questions: (1) what herbicides, rates, and application times are most effective at reducing sulfur cinquefoil abundance while having the least impact on native plants; and (2) does postherbicide seeding with native grass species increase native plant abundance? In 2002, we experimentally examined the effects of five herbicides (dicamba + 2,4-D; metsulfuron-methyl; triclopyr; glyphosate; and picloram) at two rates of application (low and high), three application times (early summer, fall, and a combined early summer–fall treatment), and two postherbicide seed addition treatments (seeded or not seeded) on sulfur cinquefoil abundance, plant community composition, and species richness. Experimental plots were monitored through 2005. Picloram was the most effective herbicide at reducing sulfur cinquefoil density, the proportion of remaining adult plants, and seed production. The effects of picloram continued to be evident after 3 yr, with 80% reduction of sulfur cinquefoil in 2005. In addition, seeding of native grass seeds alone (no herbicide application) reduced the proportion of sulfur cinquefoil plants that were reproductively active. Despite reductions in sulfur cinquefoil abundance, all treatments remained dominated by exotic species because treated areas transitioned from exotic forb- to exotic grass-dominated communities. However, a one-time herbicide application controlled sulfur cinquefoil for at least 3 yr, and therefore might provide a foundation to begin ecological restoration. Herbicide applications alone likely are to be insufficient for long-term sulfur cinquefoil control without further modification of sites through native grass or forb seeding. Integrating herbicides with native plant seeding to promote the development of plant communities that are resistant to sulfur cinquefoil invasion is a promising management approach to ecological restoration.


2021 ◽  
Author(s):  
Ingmar Staude ◽  
Josiane Segar ◽  
Corey Thomas Callaghan ◽  
Emma Ladouceur ◽  
Jasper Meya ◽  
...  

Global commitments to species conservation have failed to halt systematic widespread declines in plant species. Current policy interventions, such as protected areas and legal species legislation, remain insufficient, and there is an urgent need to engage novel approaches and actors in conservation. Here, we propose that urban conservation gardening, namely the cultivation of declining native plant species in public and private green spaces, can be one such approach. Conservation gardening can address key (a)biotic drivers of species decline, act as a critical dispersal pathway and increase the occupancy of declining native species. We identify policy mechanisms to upscale conservation gardening to a mainstream activity by reforming the existing horticultural market into an innovative nature protection instrument. This involves incentivizing the integration of the native seed sector, leveraging existing certification and labelling schemes, promoting consumer access, as well as building citizen-science projects to foster public engagement. Mainstreamed conservation gardening can be an economically viable, sustainable, and participatory measure that complements traditional approaches to plant conservation.


2021 ◽  
Author(s):  
Chris Parker

Abstract I. cylindrica is a serious weed not only in crops but also in natural areas, causing serious economic and environmental damage. The ability of I. cylindrica to effectively compete for water and nutrients, spread and persist through the production of seeds and rhizomes that can survive a wide range of environmental conditions, and its allelopathic effects and pyrogenic nature, allow it to exclude native plant species and other desirable plants and dominate large areas of land.


Author(s):  
M. Celeste Díaz Vélez ◽  
Ana E. Ferreras ◽  
Valeria Paiaro

Abstract Animal dispersers are essential for many non-native plants since they facilitate seed movement and might promote seed germination and seedling establishment, thereby increasing their chances of invasion. This chapter reviews the published literature on seed dispersal of non-native plant species by native and/or non-native animals. The following questions are addressed: (i) Are interactions between non-native plants and their animal dispersers evenly studied worldwide? (ii) Which are the distinctive traits (i.e. geographical origin, life form, dispersal strategy and propagule traits) of non-native plants that are dispersed by animals? (iii) Which are the most studied groups of dispersers of non-native plants around the world? (iv) Does the literature provide evidence for the Invasional Meltdown Hypothesis (non-native plant-non-native disperser facilitation)? (v) What is the role of animal dispersers at different stages of the non-native plant regeneration process? Our dataset of 204 articles indicates that geographical distribution of the studies was highly heterogeneous among continents, with the highest number coming from North America and the lowest from Asia and Central America. Most of the non-native plants involved in dispersal studies were woody species from Asia with fleshy fruits dispersed by endozoochory. More than the half of the animal dispersal agents noted were birds, followed by mammals, ants and reptiles. The dominance of bird-dispersal interactions over other animal groups was consistent across geographical regions. Although most of the studies involved only native dispersers, interactions among non-native species were detected, providing support for the existence of invasional meltdown processes. Of the total number of reviewed articles reporting seed removal, 74% evaluated seed dispersal, but only a few studies included seed germination (35.3%), seedling establishment (5.4%) or seed predation (23.5%). Finally, we discuss some research biases and directions for future studies in the area.


Author(s):  
Elizabeth M. Wandrag ◽  
◽  
Jane A. Catford ◽  
◽  
◽  
...  

The introduction of species to new locations leads to novel competitive interactions between resident native and newly-arriving non-native species. The nature of these competitive interactions can influence the suitability of the environment for the survival, reproduction and spread of non-native plant species, and the impact those species have on native plant communities. Indeed, the large literature on competition among plants reflects its importance in shaping the composition of plant communities, including the invasion success of non-native species. While competition and invasion theory have historically developed in parallel, the increasing recognition of the synergism between the two themes has led to new insights into how non-native plant species invade native plant communities, and the impacts they have on those plant communities. This chapter provides an entry point into the aspects of competition theory that can help explain the success, dominance and impacts of invasive species. It focuses on resource competition, which arises wherever the resources necessary for establishment, survival, reproduction and spread are in limited supply. It highlights key hypotheses developed in invasion biology that relate to ideas of competition, outlines biotic and abiotic factors that influence the strength of competition and species' relative competitive abilities, and describes when and how competition between non-native and native plant species can influence invasion outcomes. Understanding the processes that influence the strength of competition between non-native and native plant species is a necessary step towards understanding the causes and consequences of biological invasions.


Author(s):  
Estella B. Leopold

As each of us siblings—Starker, Luna, Carl, Nina, and i— matured and entered our professional lives in different parts of the country, we carried with us a hankering to have a place in the country, a Shack of our own. It is not merely real estate, of course. Instead, it is a camping place for feeling close to the land, a place to work with the land and to observe the ecosystem and its fauna. To “own,” or as the first peoples saw it, to “belong” on a piece of land is exciting and special—a chance to become acquainted with a few favorite species, then to watch them grow. But of course it is way more than that. As Dad said, he chose his land for its backwardness, but it flourished in splendid isolation under our care. Shack land, as we conceived of it, had the potential of being inhabited by a vast number of native bird species, plus a diverse fauna of mammals, which got richer with time. We were excited that the Shack landscape itself had such physical variety; it had hills and dales, a grand river, a series of tributaries animated by spring and fall floods, a standing bottomland forest coursed by those floods and occupied by lively muskrats, with ducks flying in and out of the sloughs, as well as kingfishers and jays. Even though it was “degraded” agricultural land, Dad and Mother saw it as a land of opportunities for the family. While it had a “reduced level of complexity,” the soil was still there, and we could help improve it, which actually means that the right plants could make it better. Prairie is the perfect model for this kind of restoration and recovery. Dad described the upward flow of energy from soils through the plant community as a kind of circuit. After major disruption and loss of native species, the energy circuit is slowed and altered. He asked, “Can the land adjust itself to the new order?” He was sure it could if we reintroduced the native plant species on that cornfield, on that terrace, on that hill, in order for a genuine prairie, with its very efficient energy-flow, to become reestablished.


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