Effects of Aminopyralid on California Annual Grassland Plant Communities

2015 ◽  
Vol 8 (1) ◽  
pp. 98-109 ◽  
Author(s):  
Joseph M. DiTomaso ◽  
Guy B. Kyser
Keyword(s):  
Species Richness ◽  
Plant Communities ◽  
Individual Species ◽  
Block Designs ◽  
Native Plant ◽  
Yellow Starthistle ◽  
Growing Seasons ◽  
Annual Grasslands ◽  
Annual Grassland ◽  
California Annual Grassland

AbstractAminopyralid is the most commonly used herbicide for the control of yellow starthistle and other invasive thistles in annual grasslands of California. Although the effects of aminopyralid on native plant communities over a 2-yr period have been evaluated in prairies dominated by perennial species in the northern central states, similar evaluations have not been conducted in grassland communities of California, which are generally composed of a high diversity of native and nonnative annual species. In this study we monitored the effects of 53 and 123 g ae aminopyralid ha−1on individual species cover and species richness over three growing seasons in two locations on California annual grassland. Treated plots were compared to untreated plots in randomized complete-block designs. Results were largely consistent between the two trials. In the first season after treatment, both rates of aminopyralid reduced dicot cover significantly, particularly members of the Asteraceae and Fabaceae. Treated plots also showed reduced species richness. However, these differences were less pronounced in the second season after treatment, particularly at the low rate. By the third season after treatment in both sites, there were no longer any significant effects on cover or species richness at the low herbicide rate. On California annual grasslands, winter applications of low rates of aminopyralid have been shown to give excellent control of yellow starthistle, providing long-term benefits to grassland ecosystems. Results of the current study suggest that negative impacts of aminopyralid on the desirable native forb community are transitory.

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2208 ◽  
Author(s):  
Thomas K. Lameris ◽  
Joseph R. Bennett ◽  
Louise K. Blight ◽  
Marissa Giesen ◽  
Michael H. Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies.

scholarly journals Antigonon leptopus invasion is associated with plant community disassembly in a Caribbean island ecosystem

2021 ◽  
Author(s):  
Maarten B. Eppinga ◽  
Elizabeth A. Haber ◽  
Luke Sweeney ◽  
Maria J. Santos ◽  
Max Rietkerk ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Plant Community ◽  
Plant Communities ◽  
Biodiversity Loss ◽  
Native Plant ◽  
Tropical Islands ◽  
Caribbean Island ◽  
Occurrence Patterns ◽  
The Impact

AbstractInvasions by non-native plant species are widely recognized as a major driver of biodiversity loss. Globally, (sub-)tropical islands form important components of biodiversity hotspots, while being particularly susceptible to invasions by plants in general and vines in particular. We studied the impact of the invasive vine A. leptopus on the diversity and structure of recipient plant communities on the northern Caribbean island St. Eustatius. We used a paired-plot design to study differences in species richness, evenness and community structure under A. leptopus-invaded and uninvaded conditions. Community structure was studied through species co-occurrence patterns. We found that in plots invaded by A. leptopus, species richness was 40–50% lower, and these plots also exhibited lower evenness. The magnitude of these negative impacts increased with increasing cover of A. leptopus. Invaded plots also showed higher degrees of homogeneity in species composition. Species co-occurrence patterns indicated that plant communities in uninvaded plots were characterized by segregation, whereas recipient plant communities in invaded plots exhibited random co-occurrence patterns. These observations suggest that invasion of A. leptopus is not only associated with reduced species richness and evenness of recipient communities in invaded sites, but also with a community disassembly process that may reduce diversity between sites. Given that A. leptopus is a successful invader of (sub-)tropical islands around the globe, these impacts on plant community structure highlight that this invasive species could be a particular conservation concern for these systems.

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

2016 ◽  
Author(s):  
Thomas K Lameris ◽  
Joseph R Bennett ◽  
Louise K Blight ◽  
Marissa Giesen ◽  
Michael H Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116-years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we also tested predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted we would observe high nutrient loading and exotic plant species richness and cover on nearby islands with versus without gull colonies as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results suggest that gulls have the potential to drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation. Because human activities have contributed to long-term change in gull populations, our results further suggest compelling, indirect links between human management decisions and plant community composition on islands of the Georgia Basin.

scholarly journals Effects of the invasive plant Xanthium strumarium on diversity of native plant species: A competitive analysis approach in North and Northeast China

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0228476
Author(s):  
Mazher Farid Iqbal ◽  
Ming-Chao Liu ◽  
Aafia Iram ◽  
Yu-Long Feng
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Northeast China ◽  
Invasive Plant ◽  
Diversity Index ◽  
Diversity Indices ◽  
Xanthium Strumarium ◽  
Native Plant ◽  
Native Plant Species

Xanthium strumarium is native to North America and now has become one of the invasive alien species (IAS) in China. In order to detect the effects of the invader on biodiversity and evaluate its suitable habitats and ecological distribution, we investigated the abundance, relative abundance, diversity indices, and the number of the invasive and native plants in paired invaded and non-invaded quadrats in four locations in North and Northeast China. We also analyzed the effects of monthly mean maximum and minimum temperatures, relative humidity (%), and precipitations (mm). Strong positive significant (P < 0.01) correlation and maximum interspecific competition (41%) were found in Huailai between invaded and non-invaded quadrats. Shannon’s Diversity Index showed that non-invaded plots had significantly (P < 0.05) more diversified species than invaded ones. The significant (P < 0.05) Margalef’s Richness Index was found in Huailai and Zhangjiakou in non-invaded recorded heterogeneous nature of plant communities. Similarly, significant (P < 0.05) species richness found in Huailai and Zhangjiakou in non-invaded quadrats compared to invaded ones. Maximum evenness of Setaria feberi (0.47, 0.37), Seteria viridis (0.43) found in Fushun and Zhangjiakou recorded more stable in a community compared to other localities. Evenness showed positive relationship of Shannon Entropy within different plant species. The higher dissimilarity in plant communities found in Huailai (87.06%) followed by Yangyuan (44.43%), Zhangjiakou (40.13%) and Fushun (29.02%). The significant (P < 0.01) value of global statistics R (0.943/94.3%) showed high species diversity recorded in Huailai followed by Zhangjiakou recorded by non-metric multidimensional scaling and analysis of similarity between invaded and non-invaded plots. At the end it was concluded that the diversity indices reduced significantly (P < 0.05) in invaded quadrats indicated that native plant species become less diverse due to X. strumarium invasion. The degrees of X. strumarium invasion affected on species richness resulted to reduce diversity indices significantly in invaded quadrats.

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

2016 ◽  
Author(s):  
Thomas K Lameris ◽  
Joseph R Bennett ◽  
Louise K Blight ◽  
Marissa Giesen ◽  
Michael H Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116-years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we also tested predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted we would observe high nutrient loading and exotic plant species richness and cover on nearby islands with versus without gull colonies as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results suggest that gulls have the potential to drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation. Because human activities have contributed to long-term change in gull populations, our results further suggest compelling, indirect links between human management decisions and plant community composition on islands of the Georgia Basin.

scholarly journals Soil Microbes Alter the Diversity-Invasibility Relationship by Promoting a Complementarity Effect on Community Invasion Resistance

2021 ◽  
Author(s):  
Xiao-Yan Wang ◽  
Song Gao ◽  
Tong Chen ◽  
Jiang Wang ◽  
Fei-Hai Yu
Keyword(s):  
Invasive Species ◽  
Species Richness ◽  
Exotic Species ◽  
Plant Communities ◽  
Soil Microbes ◽  
Exotic Plants ◽  
Invasion Resistance ◽  
Native Plant ◽  
Complementarity Effect ◽  
Negative Effect

Abstract Background Soil microbes can affect both the invasiveness of exotic plants and the invasibility of native plant communities, but it still remains unclear whether soil microbes can influence the relationship between native plant diversity and community invasibility.Methods We constructed native plant communities with three levels of species richness (one, three, or six species) in unsterilized or sterilized soil (i.e., with or without soil microbes) and either prevented their invasion by exotic plants or allowed them to be invaded by each of three exotic species (Solidago canadensis, Erigeron canadensis or Symphyotrichum subulatum), which are highly invasive in China. The soils conditioned by the native plant communities that were not invaded by the exotic species were used as soil microbe inocula to test whether species richness-induced differences in soil microbes affected the growth of each of the three invasive species.Results Compared with soils containing microbes, the absence of soil microbes weakened the negative species richness-invasibility relationship, indicating that soil microbes can contribute to higher invasion resistance in more diverse native plant communities. In the presence of soil microbes, the higher invasion resistance of more diverse communities was mainly ascribed to the complementarity effect. However, soil microbes from communities with a higher species richness did not have a stronger negative effect on the growth of any of the three invasive species. Conclusion Soil microbes can alter the diversity-invasibility relationship by promoting the complementarity effect on community invasion resistance. Our results highlight the importance of integrating the role of soil microbes when testing the diversity-invasibility hypothesis.

scholarly journals Disentangling the Ecological Determinants of Species and Functional Trait Diversity in Herb-Layer Plant Communities in European Temperate Forests

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 552
Author(s):  
Janez Kermavnar ◽  
Lado Kutnar ◽  
Aleksander Marinšek
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Plant Communities ◽  
Functional Trait ◽  
Forest Stand ◽  
Relative Importance ◽  
Herb Layer ◽  
Bud Bank ◽  
Tree Species Composition ◽  
Stand Characteristics

Forest herb-layer vegetation responds sensitively to environmental conditions. This paper compares drivers of both taxonomic, i.e., species richness, cover and evenness, and functional herb-layer diversity, i.e., the diversity of clonal, bud bank and leaf-height-seed plant traits. We investigated the dependence of herb-layer diversity on ecological determinants related to soil properties, climatic parameters, forest stand characteristics, and topographic and abiotic and biotic factors associated with forest floor structure. The study was conducted in different forest types in Slovenia, using vegetation and environmental data from 50 monitoring plots (400 m2 each) belonging to the ICP Forests Level I and II network. The main objective was to first identify significant ecological predictors and then quantify their relative importance. Species richness was strongly determined by forest stand characteristics, such as richness of the shrub layer, tree layer shade-casting ability as a proxy for light availability and tree species composition. It showed a clear positive relation to soil pH. Variation in herb-layer cover was also best explained by forest stand characteristics and, to a lesser extent, by structural factors such as moss cover. Species evenness was associated with tree species composition, shrub layer cover and soil pH. Various ecological determinants were decisive for the diversity of below-ground traits, i.e., clonal and bud bank traits. For these two trait groups we observed a substantial climatic signal that was completely absent for taxonomy-based measures of diversity. In contrast, above-ground leaf-height-seed (LHS) traits were driven exclusively by soil reaction and nitrogen availability. In synthesis, local stand characteristics and soil properties acted as the main controlling factors for both species and trait diversity in herb-layer communities across Slovenia, confirming many previous studies. Our findings suggest that the taxonomic and functional facets of herb-layer vegetation are mainly influenced by a similar set of ecological determinants. However, their relative importance varies among individual taxonomy- and functional trait-based diversity measures. Integrating multi-faceted approaches can provide complementary information on patterns of herb-layer diversity in European forest plant communities.

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

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