Abundance Of Native Plant Species Research Articles

Species diversity, primary productivity, and photosynthetic pathway in grasslands of eastern Pennsylvania

AbstractWe examined the relationship between primary productivity and diversity for grassland, meadow, and savanna (GMS) vegetation in northeastern Pennsylvania, USA, where the landscape is primarily forests, agriculture, and urban or suburban development. We surveyed primary productivity, plant species diversity, invertebrate order diversity, and avian abundance and species diversity for 14 grasslands and open areas that were actively managed and three that apparently occurred naturally. Four grasslands were dominated by warm‐season grasses with the C4 photosynthetic pathway, nine were dominated by C3 grasses, forbs, and shrubs, and four had a mixture of both types. We found hump‐shaped relationships for plant species richness and bird species richness as a function of productivity but not for invertebrate order richness. Richness of invertebrates and birds increased linearly with the number sampled at each site. The number of plant species declined with increasing proportion of warm‐season grasses, as did the number of invertebrate orders collected in sweep samples, avian abundance, and avian species richness. Multiple regression showed that both landscape and vegetative characteristics influenced the bird community. Bird species richness increased with the area of the sites, the ratio of area to edge, and the distance to the nearest open area. There was no evidence for the influence of the relative abundance of native plant species on bird or invertebrate richness. GMS restoration of farmlands and mine lands with plantings of warm‐season grasses, while possibly beneficial for some forms of wildlife, seems to be less effective in maintaining the diversity of invertebrates and birds than a mixture of warm‐season grasses, cool‐season grasses, forbs, and shrubs.

Urban native vegetation remnants support more diverse native bee communities than residential gardens in Australia's southwest biodiversity hotspot

Native bees are declining in many regions, often associated with loss of natural habitat. Urbanisation replaces natural vegetation with a highly-modified landscape, where residential gardens are a major component of urban greenspace. While many cities retain native vegetation remnants within the urban matrix, these are often small, isolated and degraded. However, there is little empirical evidence on the capacity of residential gardens to provide equivalent or beneficial habitat for native bees, and which local and landscape factors influence bee assemblages. We surveyed bee assemblages in the southwest Australian biodiversity hotspot at seven residential gardens and seven bushland remnants over two years. We recorded 153 species/morphospecies of native bees. Native bees were more abundant in bushland remnants than residential gardens. Abundance of the introduced honeybee Apis mellifera was generally high, and did not differ between habitats. Bushland remnants hosted more species, and rare and unique species, than did residential gardens. Native bee body-size and nesting guilds varied in their response to habitat type. Native bee abundance and richness increased with abundance of native plant species, but decreased with total flower species richness. Native bee species richness was negatively impacted by urbanisation (built space and isolation from bushland reserves). There were no significant relationships between honeybee abundance and local and landscape factors. Our study demonstrates that while residential gardens can host native bees, urban bushland remnants harbour a more comprehensive suite of species and are key for the conservation of native bee populations.

Floristic Diversity in Secondary Forest under Munduruku Indigenous Agroextractivism

Aims: Knowledge is currently low about composition, richness and abundance of native plant species from secondary forests in traditional communities in the Tapajós River Basin, Western Amazon. These forests are of great importance to indigenous populations being niches of resistance to the advances of monocultures. The objective of this work was to evaluate the floristic composition of a secondary forest with typical indigenous extractive interventions.
 Study Design: The secondary forest studied located in indigenous Village. This forest had 15 years of natural regeneration and was therefore an anthropized forest, where the indigenous people removed wood, fibers, oils and fruits, thus characterizing the agroextractivism on this environment and a very particular floristic composition always in evolution.
 Place and Duration of Study: The research was in Santarem city, Pará state, in Ipaupixuna Village (02°32´46” S, 54°20'15” W) between June 2019 to December 2019.
 Methodology: The research had a descriptive approach for floristic study, but in the same time had a quantitative point of view with the use of regression analysis. The parameters evaluated were: 1. Species abundance, 2. Floristic Richness; 3. Plant diversity measured by the Jentsch Mixing Coefficient; 4. Relations between Circumference & Height of trees. The size of the sampled area was 1 (one) hectare of secondary forest.
 Results: A high abundance was found for Tapirira guianensis Aubl followed by Buchenavia huberi Ducke and Bellucia grossularioides (L.) Triana. Fabaceae was the family of greatest quantitative expression in this 15-year-old secondary forest in indigenous landscapes followed by Arecaceae.
 Conclusion: The secondary forest studied of 15 years of natural regeneration and random anthropogenic interventions by agroextractivists activities of Munduruku Indigenous people showed medium floristic richness and low floristic diversity. Interventions to enrich this secondary forest with plant species with high economic potential can bring environmental and economic benefits to these indigenous people.

Short-Term Vegetation Responses to Invasive Shrub Control Techniques for Amur Honeysuckle (Lonicera maackii [Rupr.] Herder)

Invasive shrubs in forest understories threaten biodiversity and forest regeneration in the eastern United States. Controlling these extensive monotypic shrub thickets is a protracted process that slows the restoration of degraded forest land. Invasive shrub removal can be accelerated by using forestry mulching heads, but evidence from the western United States indicates that mulching heads can promote exotic species establishment and mulch deposition can reduce native plant species abundance. We compared the effectiveness of the mulching head and the “cut-stump” method for controlling the invasive shrub Amur honeysuckle (Lonicera maackii), as well as their impacts on native plant community recovery, in mixed-hardwood forests of Indiana. After two growing seasons, mulching head treatment resulted in greater L. maackii regrowth and regeneration. The recovery of native plant abundance and diversity following shrub removal did not differ between the two methods. However, mulch deposition was associated with increased abundance of garlic mustard (Alliaria petiolata), an invasive forb. Increasing mulching head treatment depth reduced L. maackii regrowth, but additional study is needed to determine how it affects plant community responses. The mulching head is a promising technique for invasive shrub control and investigating tradeoffs between reducing landscape-scale propagule pressure and increased local establishment will further inform its utility.

Functional trait variation predicts distribution of alien plant species across the light gradient in a temperate rainforest

Several interspecific studies have related functional traits to alien plant invasiveness. Few studies have explicitly addressed how intraspecific variation in functional traits influences alien plant distribution across environments. In an old-growth temperate rainforest, we evaluated alien plant distribution across the light gradient, its relationship with native plant diversity and abundance, and variation in functional traits related to light capture that could explain the ecological breadth of alien plant species across the light gradient. In addition, we estimated possible ecological and phylogenetic constraints to intraspecific variation in these functional traits. In sixty 8-m2 plots we recorded light availability together with richness and abundance of alien and native plant species. We measured in 14 alien plant species three functional traits (specific leaf area, chlorophyll content and root/shoot ratio) and calculated their coefficient of variation. We estimated ecological constraints by measuring correlations among traits that could limit functional responses to light. We assessed phylogenetic constraints by calculating the phylogenetic signal of those functional traits. Richness and abundance of alien plant species were positively associated with light availability, while abundance was negatively related to native plant species abundance. Dominance of alien species increased with light availability, but some of them were dominant even in the shade. Phenotypic variation of functional traits was positively associated with ecological breadth and dominance of alien plant species. We found little evidence of ecological or phylogenetic constraints on functional trait variation. Light availability and functional trait variation correlated with the distribution and dominance of alien plants in this temperate rainforest. Alien plant species showed considerable phenotypic variation in low light, which may facilitate colonization of the forest understory. This process would not be hindered by ecological or phylogenetic constraints. Intraspecific variation in functional traits can render insightful information on current and future alien plant distribution across environmental gradients.

Strong fitness differences impede coexistence between an alien water fern (Azolla pinnata R. Br.) and its native congener (Azolla rubra R. Br.) in New Zealand

Despite considerable evidence that alien plants impact the fecundity, productivity and abundance of native plant species, support for alien plant species causing the widespread decline of native species is rare. Coexistence theory proposes that the outcome of competition between two species can be predicted through the invasion criterion, measured as a positive population-level growth rate of each competitor when that species is rare. Here we make use of coexistence theory to examine the likelihood of persistence of a native water fern (Azolla rubra) following invasion by an alien congener (Azolla pinnata) which has apparently displaced the native wherever their ranges overlap in New Zealand. We evaluate coexistence between the two water fern species using experimental measurements of population-level growth rates. We show that the alien A. pinnata has a higher fitness than A. rubra, which hinders coexistence between the two species. These experimental results match the rapid expansion of A. pinnata and the apparent decline of A. rubra observed in nature. Our study predicts that A. pinnata is capable of replacing its native congener, highlights the importance of fitness differences in invasion success, and demonstrates the value of experimental analyses of species coexistence for predicting longer-term invasion dynamics and impacts. Using experiments to test coexistence mechanisms between alien and native species is a valuable approach to predict invasion outcomes and one that can lead to insights on the long-term impacts of alien species, including extinction, on native species populations.

Long-term investigations and experimental manipulations: Useful perspectives for applied vegetation studies

Long-term investigations and experimental manipulations: Useful perspectives for applied vegetation studies

Livestock grazing supports native plants and songbirds in a California annual grassland.

Over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species—Western Meadowlark (Sturnella neglecta), Horned Lark (Eremophila alpestris), and Grasshopper Sparrow (Ammodramus savannarum)—at sites in central California during breeding season. In California’s Mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of native bunchgrass and forbs. Livestock grazing, primarily with beef cattle, is the most widely used management tool. Compared with ungrazed plots, grazed plots had higher bare ground, native plant cover, and vertically heterogeneous vegetation. Grazed plots also had less plant litter and shorter vegetation. Higher native plant cover, which is predominantly composed of bunchgrasses in our study area, was associated with livestock grazing and north-facing aspects. Using an information theoretic approach, we found that all three bird species had positive associations with native plant abundance and neutral (Western Meadowlark, Grasshopper Sparrow) or positive (Horned Lark) association with livestock grazing. All species favored flatter areas. Horned Larks and Western Meadowlark occurred more often where there were patches of bare ground. Western Meadowlarks and Grasshopper Sparrows were most common on north-facing slopes, suggesting that these species may be at risk from projected climate change. These findings demonstrate that livestock grazing is compatible with or supports grassland bird conservation in Mediterranean-type grasslands, including areas with high levels of exotic annual grass invasion, in part because grazing supports the persistence of native plants and heterogeneity in vegetation structure. However, conservation of low-lying grasslands with high native species presence, and active management to increase the abundance of native plant species are also likely to be important for sustaining grassland birds long-term.

Non‐native plant species benefit from disturbance: a meta‐analysis

Disturbances, such as fire and grazing, are often claimed to facilitate plant species richness and plant invasions in particular, although empirical evidence is contradictory. We conducted a meta‐analysis to synthesize the literature on how non‐native plant species are affected by disturbances. We explored whether the observed impact of disturbance on non‐native plant communities is related to its type and frequency, to habitat type, study approach (observational or experimental), and to the temporal and spatial scales of the study. To put the results in a broader context, we also conducted a set of parallel analyses on a data set involving native plant species. The diversity and abundance of non‐native plant species were significantly higher at disturbed sites than at undisturbed sites, while the diversity and abundance of native plant species did not differ between the two types of sites. The effect of disturbance on non‐native plant species depended on the measure used to evaluate the impact (species diversity or abundance) and on disturbance type, with grazing and anthropogenic disturbances leading to higher diversity and abundance of non‐native plant species than other disturbance types examined. The impact of disturbance on non‐natives was also associated with study approach, habitat type and temporal scale, but these factors covaried with disturbance type, complicating the interpretation of the results. Overall, our results indicate that disturbance has a positive impact particularly on non‐native plant species (at least when they are already present in the community), and that the strength of this impact depends primarily on the disturbance type.SynthesisEmpirical evidence of the effect of disturbances on plant species richness is contradictory. Here we use a meta‐analysis to synthesize the published literature on how different types of disturbances influence the diversity and abundance of plant species, focusing in particular on non‐native plants. Our study supports the hypothesis that disturbances generally facilitate the diversity and abundance of non‐native plant species, although the strength of this facilitation depends primarily on the disturbance type.

Reducing Biotic and Abiotic Land‐Use Legacies to Restore Invaded, Abandoned Citrus Groves

AbstractLand‐use legacies associated with agriculture, such as increased soil fertility and elevated soil pH, promote invasions by non‐native plant species on former agricultural lands. Restoring natural soil conditions (i.e. low fertility and low pH) may be an effective, long‐term method to control and reduce the abundance of non‐native and ruderal species that invade abandoned agricultural lands. In this study, we examined how soil manipulation treatments of lowering soil fertility with carbon additions and lowering soil pH by applying sulfur affect non‐native and ruderal native plant species abundance in two former citrus groves in central Florida. Non‐native plant biomass was removed by one of two methods (tilling or topsoil removal), and was combined with a soil amendment of sulfur, carbon, sulfur + carbon, or none. The biomass removal treatments significantly decreased non‐native abundance, with topsoil removal as the most effective. Carbon additions did not affect soil fertility or vegetation. Sulfur and sulfur + carbon additions significantly decreased soil pH in both groves for at least 1 year post‐treatment; however, we did not see a significant vegetation response. Overall, our results suggest that removing vegetation by tilling and topsoil removal is an effective method for reducing non‐target species cover. Although we did not see a response of vegetation to our treatments, we were able to restore the initial soil characteristics, which can be a first step toward complete restoration.

Distribution and Abundance of the Invasive Plant Species Chromolaena odorata L. in the Zamboanga Peninsula, Philippines

The ecology of the highly invasive plant species C. odorata is poorly studied in the Philippines in spite of the fact that it is hard to eradicate, a nuisance in plantations, and known to harm farm animals and decimate forage and native plant species. In order to determine the abundance and distribution of the species and its possible relationship with local ecological factors, we estimated in 75 transect lines the percentage cover of C. odorata and other plant species growing around it, and concurrently determined soil parameters (soil type, pH, total nitrogen, total phosphorus, total potassium, and % organic matter) in three Provinces of the Zamboanga Peninsula, Southern Philippines. Multivariate Canonical Correspondence Analysis (CCA) revealed no significant relationship between soil parameters and the abundance of C. odorata suggesting eurytopy to edaphic conditions. Peak abundance of C. odorata was associated with coconut, banana, mango, gemelina and mahogany plantation environments, and reduced abundance of native plant species. This study shows that C. odorata is highly adaptive and a potential threat to native plant biodiversity and agro-ecosystem sustainability, and that its distribution seems to be supported by plant monoculture system.

Effects of introduced Canada geese (Branta canadensis) on native plant communities of the Southern Gulf Islands, British Columbia

Recent experiments suggest that introduced, non-migratory Canada geese (Branta canadensis) may be facilitating the spread of exotic grasses and decline of native plant species abundance on small islets in the Georgia Basin, British Columbia, which otherwise harbour outstanding examples of threatened maritime meadow ecosystems. We examined this idea by testing if the presence of geese predicted the abundance of exotic grasses and native competitors at 2 spatial scales on 39 islands distributed throughout the Southern Gulf and San Juan Islands of Canada and the United States, respectively. At the plot level, we found significant positive relationships between the percent cover of goose feces and exotic annual grasses. However, this trend was absent at the scale of whole islands. Because rapid population expansion of introduced geese in the region only began in the 1980s, our results are consistent with the hypothesis that the deleterious effects of geese on the cover of exotic annual grasses have yet to proceed beyond the local scale, and that a window of opportunity now exists in which to implement management strategies to curtail this emerging threat to native ecosystems. Research is now needed to test if the removal of geese results in the decline of exotic annual grasses.

Linking field based studies with greenhouse experiments: the impact of Centaurea stoebe (=C. maculosa) in British Columbia grasslands

The grassland community of Lac du Bois Provincial Park in the interior of British Columbia has become increasingly invaded by Centaurea stoebe (=Centaurea maculosa; spotted knapweed). Allelopathy, through the production of the phytotoxin (±)-catechin by C. stoebe roots is believed to be partly responsible for knapweed’s invasive success. We used field sampling and greenhouse experiments to examine two questions: (1) Is increasing abundance of C. stoebe negatively associated with the abundance of specific native grassland species? (2) Do species that exhibit a negative correlation with C. stoebe abundance in the field demonstrate increased levels of susceptibility to application of (±)-catechin during germination? Thirty-eight plots were sampled in the grassland, encompassing areas of low—high knapweed abundance. Seeds from eight native species, exhibiting positive, neutral or negative correlation with knapweed abundance, were treated with three concentrations (0, 0.5, 2.0 mg/mL) of (±)-catechin. Root growth and percent germination were measured over a 6-week period. The results indicate that C. stoebe abundance is negatively correlated with native plant species abundance and may alter plant community composition. Moreover root radical growth was significantly negatively affected by treatment with (±)-catechin in all four native plant species that exhibited a negative correlation with knapweed abundance in the field. Past studies have failed to conclusively link greenhouse results with plant community patterns. Here, we provide a correlative link between plant community composition and tolerance to a phytotoxin.

Public preferences and values for management of aquatic invasive plants in state parks

Alien invasive plants (AIP) significantly impact the ecology of natural areas and nature-based recreation, yet control programs are chronically underfunded. This study examined Florida residents' willingness-to-pay (WTP) to control aquatic AIP in river and lake state parks through entrance fees. We used a method commonly applied in the nonmarket valuation literature, but not previously applied to AIP, and found that residents have a high WTP to control AIP and are willing to support control programs through entrance fees. In 2007, we surveyed 1299 Florida residents to estimate the impact of AIP on state park recreation. The survey included conjoint choice questions to establish the impact of several park attributes on respondents' economic utility or welfare: abundance of AIP, entrance fees, park facilities, abundance of native plant species, and abundance of native animal species. Using entrance fees as a payment vehicle, we estimated that the typical Florida resident has a per-visit WTP of $6.15 to reduce AIP coverage, $4.41 to improve park facilities, $3.81 to increase the abundance of native plants, and $4.99 to increase the abundance for native animals. We used annual attendance data from 63 river and lake state parks to calculate statewide WTP to control AIP and found that local residents are willing to spend $12.26 million/yr, and all users are willing to spend $35.01 million/yr to keep AIP from becoming “numerous and dense” in the 63 parks. This far outweighs the $26 million/yr that the state is currently spending in all natural areas, including state parks.

Ecological impacts of feral pigs in the Hawaiian Islands

The foraging habits of exotic ungulate species can directly and indirectly affect native plant and animal distribution and abundance patterns. Most of the studies on feral pig interactions with other biota in the Hawaiian Islands have been published as difficult to access reports to governmental and nongovernmental organizations, graduate student theses, and a few in peer reviewed journals. In this paper we discuss the origins of pig introductions to Hawaii, their feralization process, population expansion, and interactions with native and non-native biota. We also consider the environmental effects triggered by pigs on local ecosystems and biotic communities. Feral pig activities can reduce the abundance of native plant species, enhance conditions for the establishment of invasive non-indigenous plants, and perhaps indirectly negatively impact native forest bird species. Pig foraging and traveling patterns may also lead to physical alteration of ecosystems by increasing soil erosion that may lead to watershed degradation. However, much remains to be learned about the strength and significance of aforementioned interactions and their long-term effects on Hawaiian biota and ecosystems due to some confounding events. Elucidating the dynamics and long-term ecological effects generated by pigs is a crucial step towards increasing our understanding of and more effectively managing biotic interactions.

Native and invasive plant interactions in wetlands and the minimal role of invasiveness

The effects of invasive plants on plants native to areas that are being invaded can be quite variable, depending on the species of the invasive plant involved as well as the physical characteristics of the location being invaded. My study focuses on the effects of Phragmites australis Linnaeus (common reed) and Lythrum salicaria L. (purple loosestrife) on the same native plant community. Uninvaded plots dominated by native plants Typha angustifolia L. (narrowleaf cattail) and Typha latifolia L. (broadleaf cattail) served as the control. I surveyed percent cover of species during early summer and midsummer for 3 years in six Hudson River freshwater tidal wetlands (sites). Differences in species richness, composition and abundance were small, but significant among invaded and uninvaded plots and among sites. However, these differences remained significant when data for dominant species (invasive and native) were removed. Differences in native plant species abundance were attributed to invasive plant species-specific characteristics and differences in species richness and composition were attributed to physical location (zonation) in these freshwater tidal marshes. “Invasive” status of a dominant plant species was less important in invasive plant–native plant interactions than species-specific characteristics and zonation. Further research into the effects of site and land-use on invasive plant impacts is recommended.

Effects of Prescribed Burning on Ground Cover in the New Jersey Pine Region

At least since the late 19th century foresters have been searching for an economically feasible method of returning the present forests of the New Jersey pine region to levels of higher production (Vermeule, Pinchot, Hollick, Smith, and Gifford 1900). Slow but continuous progress has been made since that time in fire control, public education, and the acquisition of knowledge of the silvicultural relationships of the forest trees. Now after nearly 15 years of experimentation by state and federal investigators, the application of prescribed burning has been suggested as a silvicultural practice for improving the upland forests of the region. As a result of its success in experimental areas, the practice shows promise of becoming wide-spread in the near future. Hence, it becomes more important that we understand as many as possible of the effects that will be created by the increased use of the practice. The foresters have and will continue to accumulate data on estimated timber yields and per acre costs of the management practice. Various other interested groups in and around the area are cooperating with the foresters in initiating studies of the broader aspects of the practice. At present there are several questions that warrant careful investigation. First, will the change in vegetation resulting from the practice make any significant alteration in the hydrologic relationships of the region? This study is already past the planning stage. Second, how will the management practice influence the wildlife in this very important game-producing area of the state? Third, how will the practice influence the productive potential of the forest soils of the region? Fourth, how will the practice influence agricultural industries, now flourishing in the region, through altering helpful and harmful insect populations and by increasing or decreasing the abundance of native plant species that harbor pathogens of cultivated species? These are some of the questions which should be investigated while such a management plan as prescribed burning is in the early stages of application. Several cooperating workers have already published on the methods used and the effectiveness of this practice in favoring the more valuable pine over the less valuable oak species (Little 1946, Little, Allen, and Somes 1948, Little, Allen, and Moore 1948, Somes and Moorhead 1950). For the most part, these studies have been focused on the arborescent species, data having been obtained on (1) growth, survival, and damage to individuals already present and (2) the effect of altered conditions on the reproduction of the various species. The present study is concerned with the influence of this management practice on the shrub, herb, and moss layers of the plant community. Prescribed burning is based on the principle that fire judiciously used favors a fire subclimax forest of high pine composition. Data obtained by the authors cited above indicate that these pine stands