Drought response of a native and introduced Hawaiian grass
TL;DR: Higher Pn and greater biomass allocation to leaves resulted in greater growth for Pennisetum compared to Heteropogon and may explain the success of Pennisettum as an invader of lowland arid zones on Hawaii.
Abstract: The alien grass, Pennisetum setaceum, dominates many of the lowland arid regions that once supported native Heteropogon contortus grassland on the island of Hawaii. Response to drought in a glasshouse was compared between these C4 grasses to test if success as an invader is related to drought tolerance or plasticity for traits that confer drought tolerance. Pennisetum produced 51% more total biomass, allocated 49% more biomass to leaves, and had higher net photosynthetic rates (P
n) on a leaf area basis than Heteropogon. Plants of both species under drought produced less total biomass and increased their allocation to roots compared to well-watered plants, but there was no difference between the two species in the magnitude of these responses. The decline in P
n with decreasing leaf water potential (ψ1) was greater for Pennisetum compared to Heteropogon. Plasticity in the response of P
n to ψ1, osmotic potentials, and the water potentials at turgor loss in response to drought were not different between the two species. Stomata were more responsive to Δw in Heteropogon than in Pennisetum and for well-watered plants compared to droughted plants. Plasticity for the stomatal response to Δw, however, was not different between the species. There was no evidence that the alien, Pennisetum, had greater plasticity for traits related to drought tolerance compared to the native, Heteropogon. Higher P
n and greater biomass allocation to leaves resulted in greater growth for Pennisetum compared to Heteropogon and may explain the success of Pennisetum as an invader of lowland arid zones on Hawaii.
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TL;DR: These comparative studies provide insights into the more general question “Do alien invasive plants usually outperform co-occurring native species, and to what degree does the answer depend on growing conditions?”
Abstract: ▪ Abstract In the search to identify factors that make some plant species troublesome invaders, many studies have compared various measures of native and alien invasive plant performance. These comparative studies provide insights into the more general question “Do alien invasive plants usually outperform co-occurring native species, and to what degree does the answer depend on growing conditions?” Based on 79 independent native-invasive plant comparisons, the alien invaders were not statistically more likely to have higher growth rates, competitive ability, or fecundity. Rather, the relative performance of invaders and co-occurring natives often depended on growing conditions. In 94% of 55 comparisons involving more than one growing condition, the native's performance was equal or superior to that of the invader, at least for some key performance measures in some growing conditions. Most commonly, these conditions involved reduced resources (nutrients, light, water) and/or specific disturbance regimes. I...
1,271 citations
TL;DR: What is required to assess phenotypic plasticity at different levels is described and a new framework can be applied when testing both ecological or evolutionary oriented hypotheses, and therefore promises to bridge the gap between the two perspectives.
Abstract: Invasion biologists often suggest that phenotypic plasticity plays an important role in successful plant invasions. Assuming that plasticity enhances ecological niche breadth and therefore confers a fitness advantage, recent studies have posed two main hypotheses: (1) invasive species are more plastic than non-invasive or native ones; (2) populations in the introduced range of an invasive species have evolved greater plasticity than populations in the native range. These two hypotheses largely reflect the disparate interests of ecologists and evolutionary biologists. Because these sciences are typically interested in different temporal and spatial scales, we describe what is required to assess phenotypic plasticity at different levels. We explore the inevitable tradeoffs of experiments conducted at the genotype vs. species level, outline components of experimental design required to identify plasticity at different levels, and review some examples from the recent literature. Moreover, we suggest that a successful invader may benefit from plasticity as either (1) a Jack-of-all-trades, better able to maintain fitness in unfavourable environments; (2) a Master-of-some, better able to increase fitness in favourable environments; or (3) a Jack-and-master that combines some level of both abilities. This new framework can be applied when testing both ecological or evolutionary oriented hypotheses, and therefore promises to bridge the gap between the two perspectives.
1,147 citations
TL;DR: A two-way classification of nativeness and invasiveness that distinguishes natives, non-invasive non-natives and invasive non-Natives is offered and a simple conceptual model for cases in which high levels of environmental stress should and should not reduce invasibility is offered.
Abstract: Invasion ecology, the study of how organisms spread in habitats to which they are not native, asks both about the invasiveness of species and the invasibility of habitats: Which species are most likely to become invasive? Which habitats are most susceptible to invasion? To set the stage for considering these questions with regard to plants, we offer a two-way classification of nativeness and invasiveness that distinguishes natives, non-invasive non-natives and invasive non-natives. We then consider the current state of knowledge about invasiveness and invasibility. Despite much investigation, it has proven difficult to identify traits that consistently predict invasiveness. This may be largely because different traits favour invasiveness in different habitats. It has proven easier to identify types of habitats that are relatively invasible, such as islands and riverbanks. Factors thought to render habitats invasible include low intensities of competition, altered disturbance regimes and low levels of environmental stress, especially high resource availability. These factors probably often interact; the combination of altered disturbance with high resource availability may particularly promote invasibility. When biotic factors control invasibility, non-natives that are unlike native species may prove more invasive; the converse may also be true. We end with a simple conceptual model for cases in which high levels of environmental stress should and should not reduce invasibility. In some cases, it may be possible to manipulate stress to control biological invasions by plants.
843 citations
TL;DR: In this paper, the authors present documented input parameters for a process-based ecosystem simulation model, BIOME-BGC, for major natural temperate biomes, including turnover and mortality, allocation, carbon to nitrogen ratios (C:N), the percent of plant material in labile, cellulose, and lignin pools, leaf morphology, leaf conductance rates and limitations, canopy water interception and light extinction.
Abstract: Ecosystem simulation models use descriptive input parameters to establish the physiology, biochemistry, structure, and allocation patterns of vegetation functional types, or biomes. For single-stand simulations it is possible to measure required data, but as spatial resolution increases, so too does data unavailability. Generalized biome parameterizations are then required. Undocumented parameter selection and unknown model sensitivity to parameter variation for larger-resolution simulations are currently the major limitations to global and regional modeling. The authors present documented input parameters for a process-based ecosystem simulation model, BIOME–BGC, for major natural temperate biomes. Parameter groups include the following: turnover and mortality; allocation; carbon to nitrogen ratios (C:N); the percent of plant material in labile, cellulose, and lignin pools; leaf morphology; leaf conductance rates and limitations; canopy water interception and light extinction; and the percent of...
789 citations
TL;DR: Overall, invasive species appear to be better suited than native species to capturing and utilizing light resources, particularly in high-light environments such as those characterized by relatively high levels of disturbance.
Abstract: Growth, biomass allocation, and photosynthetic characteristics of seedlings of five invasive non-indigenous and four native species grown under different light regimes were studied to help explain the success of invasive species in Hawaiian rainforests. Plants were grown under three greenhouse light levels representative of those found in the center and edge of gaps and in the understory of Hawaiian rainforests, and under an additional treatment with unaltered shade. Relative growth rates (RGRs) of invasive species grown in sun and partial shade were significantly higher than those for native species, averaging 0.25 and 0.17 g g−1 week−1, respectively, while native species averaged only 0.09 and 0.06 g g−1 week−1, respectively. The RGR of invasive species under the shade treatment was 40% higher than that of native species. Leaf area ratios (LARs) of sun and partial-shade-grown invasive and native species were similar but the LAR of invasive species in the shade was, on average, 20% higher than that of native species. There were no differences between invasive and native species in biomass allocation to shoots and roots, or in leaf mass per area across light environments. Light-saturated photosynthetic rates (Pmax) were higher for invasive species than for native species in all light treatments. Pmax of invasive species grown in the sun treatment, for example, ranged from 5.5 to 11.9 μmol m−2 s−1 as compared with 3.0−4.5 μmol m−2 s−1 for native species grown under similar light conditions. The slope of the linear relationship between Pmax and dark respiration was steeper for invasive than for native species, indicating that invasive species assimilate more CO2 at a lower respiratory cost than native species. These results suggest that the invasive species may have higher growth rates than the native species as a consequence of higher photosynthetic capacities under sun and partial shade, lower dark respiration under all light treatments, and higher LARs when growing under shade conditions. Overall, invasive species appear to be better suited than native species to capturing and utilizing light resources, particularly in high-light environments such as those characterized by relatively high levels of disturbance.
373 citations
References
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1,570 citations
01 Jan 1951
TL;DR: The grasses of the United States are described in detail in this manual, which is intended to be a guide to gardener’s aid in the management of weeds.
Abstract: Manual of the grasses of the United States , Manual of the grasses of the United States , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,430 citations
TL;DR: The physiological adaptations of species of one successional gradient-from open field to broad-leaved deciduous forest and the nature of successional environments, seed germination, seedling and mature plant development, plant growth, photosynthesis, water use, and the physiological ecology of competition and interference are discussed.
Abstract: Succession is a process of continuous colonization of and extinction on a site by species populations. The process has long been central in ecological thinking; much theory and many data about succession have accumulated over the years. Since nearly all species in all communities participate in successional interactions, and because physiological ecology encompasses everything that a plant does during its life cycle, a complete review of physiological ecology of all species in all successions is not possible. Thus in this review I discuss the physiological adaptations of species of one successional gradient-from open field to broad-leaved deciduous forest. I concentrate on the physiological adaptations of early successional plants to environmental variability and collate the literature on tree physiology to make comparisons with early successional plants. My discussion may not be applicable to seres where there is little difference in physiognomy between early and late successional plants or where the designation of species as early or late successional is unjustified (e.g. for certain desert and tundra habitats). I discuss the nature of successional environments, seed germination, seedling and mature plant development, plant growth, photosynthesis, water use, and the physiological ecology of competition and interference.
1,244 citations
Book•
01 Aug 1999
TL;DR: This revised edition of "the most significant botanical publication on Pacific plants in recent decades" (Flora Vitiensis Nova) includes an extensive addendum providing information on newly described species, nomenclatural changes, and new island records together with a bibliography of important taxonomic references published since the first edition.
Abstract: This revised edition of "the most significant botanical publication on Pacific plants in recent decades" (Flora Vitiensis Nova) includes an extensive addendum providing information on newly described species, nomenclatural changes, and new island records, together with a bibliography of important taxonomic references published since the first edition. The status of 271 species newly listed as endangered or threatened has also been updated.
1,189 citations