scholarly journals Tropical rainforest fragmentation affects plant species richness, composition and abundance depending on plant-size class and life history

2020 ◽  
Vol 99 (1) ◽  
pp. 92-103
Author(s):  
Armando Aguirre-Jaimes ◽  
Juan Carlos López-Acosta ◽  
Rodolfo Dirzo
Keyword(s):  
Life History ◽  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Fragment Size ◽  
Plant Size ◽  
Size Category ◽  
Floristic Similarity ◽  
Mature Forest ◽  
Continuous Forest

Background: Tropical rain forests have been impacted by land use change, leading to major deforestation and fragmentation. Understanding how fragmentation impacts plant communities is central for tropical conservation. Questions: i) How does species richness vary across a range of fragment sizes, and does it vary with plant size-structure? ii) how are species composition and floristic similarity affected by forest fragmentation? iii) does habitat fragmentation affect the representation of species with different life-history and regeneration patterns? Studied species: We sampled overall plant communities and calculated diversity metrics of mature-forest and light-demanding species, considering plants of different size-categories (defined by diameter at breast height, DBH). Study site: This study was carried out at Los Tuxtlas, Veracruz, Mexico. An area originally dominated extensive evergreen tropical forest, but currently highly fragmented Methods: We sampled plants in five forest fragments representing (2 - 36 ha), and a large patch of continuous forest (700 ha). Within each site we established ten-50 × 2 m transects and registered all woody plants with DBH > 1 cm. Results: Species richness declined as fragment size became smaller. Such decline was significant considering all plants (DBH > 1.0 cm) but became non-significant as plant size-category increased (DBH > 2.5, or > 10 cm.). Small fragments had distinguishable assemblages compared to continuous forest and also a reduction in the representation of mature-forest species compared to light-demanding species. Conclusions: Our findings confirm that fragmentation affects tropical plant species diversity, but the effect is differential, depending on plant size-category and life history.

Species Richness of Sclerophyll (Heathy) Plant Communities in Australia ̵2 the Influence of Overstorey Cover

1989 ◽  
Vol 37 (4) ◽  
pp. 337 ◽  
Author(s):  
RL Specht ◽  
A Specht
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Unit Area ◽  
Vascular Plant ◽  
Biotic Factor ◽  
Rate Of Development ◽  
South West ◽  
Open Forest ◽  
Simultaneous Decrease

The species richness (number of vascular-plant species per unit area) of sclerophyll (heathy) plant communities is examined from south-east Queensland to south-west Western Australia. The species richness of communities of heathy open forest, heathy open scrub, dry heathland and wet heathland is consist- ently similar throughout southern Australia and decreases from dry heathland (on laterite, coastal and inland localities) to heathy open forest, heathy open scrub and wet heathland. Investigation of related microcommunities at Cooloola, Stradbroke Island, Ku-ring-gai Chase and Wilsons Promontory indicates that species richness decreases linearly as overstorey cover increases. In post-fire succession on Stradbroke Island heathy woodland and Dark Island heathland, species richness declines linearly as overstorey cover increases during the regeneration of the community. The appli- cation of limiting fertiliser to Stradbroke Island heathy woodland and Dark Island heathland increases the rate of development of overstorey cover, with a simultaneous decrease in species richness. Species richness of the understorey strata of plant communities appears to be inversely related to the rate of development of foliage projective cover in the overstorey. If an environmental or biotic factor inhibits or retards the development of overstorey cover, the understorey increases in species richness. Conversely, if any environmental or biotic factor accelerates the development of overstorey cover, the understorey species show a reduction in species richness.

scholarly journals The invasive herb Lupinus polyphyllus can reduce plant species richness independently of local invasion age

2021 ◽  
Author(s):  
Marju Prass ◽  
Satu Ramula ◽  
Miia Jauni ◽  
Heikki Setälä ◽  
D. Johan Kotze
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Community ◽  
Plant Communities ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Ecological Impacts ◽  
Plant Community Composition ◽  
Lupinus Polyphyllus ◽  
Local Invasion

AbstractThe ecological impacts of invasive species may change or accumulate with time since local invasion, potentially inducing further changes in communities and the abiotic environment. Yet, time since invasion is rarely considered when investigating the ecological impacts of invasive non-native species. To examine the effect of time since invasion on the ecological impacts of Lupinus polyphyllus, a perennial nitrogen-fixing herb, we surveyed vascular plant communities in the presence and absence of L. polyphyllus in young, intermediate, and old semi-natural grassland sites (ca. 5, 10, 15 years representing both time since lupine invasion and plant community age). We analyzed vascular plant community composition, vascular plant species richness, and the cover of various ecological plant groups and L. polyphyllus. In contrast to our hypotheses, we found no change in the mean cover of L. polyphyllus (about 35%) with time since local invasion, and an ordination did not suggest marked changes in plant community composition. L. polyphyllus was associated with lower species richness in invaded plant communities but this effect did not change with time since invasion. Invaded plant communities were also associated with lower occurrence of generalist, oligotrophic (low-nutrient-adapted) and copiotrophic (nutrient-demanding) species but no temporal dynamics were detected. We conclude that even the intermediate cover of L. polyphyllus can reduce plant species richness, but the ecological impact caused by this invader might not dramatically change or accumulate with time since invasion.

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.

Changes of alpine meadow and heath phytocoenoses in the Lagonaki upland (West Caucasus) during the last 15–20 years

2012 ◽  
pp. 3-12 ◽  
Author(s):  
V. V. Akatov ◽  
T. V. Akatova
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Alpine Meadow ◽  
Sharp Decrease ◽  
Livestock Grazing ◽  
Climatic Warming ◽  
The West ◽  
Total Coverage ◽  
Made In

Six sites representing the alpine heaths (ass. Pediculari comosae–Eritrichietum caucasici Minaeva et Onipchenko 2002) and four sites of subalpine meadows (ass. Betonici macranthae–Calamagrostietum arundinaceae Onipchenko 2002) located on the Lagonaki upland (West Caucasus) were described in 1989–1992 and 1994, 1995 correspondingly. Altogether 250 relevés were made. In 2010 all sites were re-described. Some changes in total coverage, frequency of plant species and species richness of plant communities were analyzed. Two possible reasons of the changes are discussed: climatic warming on the West Caucasus and a sharp decrease in the intensity of livestock grazing.

Plant species richness is not consistently associated with productivity in experimental subalpine meadow plant communities

2015 ◽  
Vol 50 (3) ◽  
pp. 207-217 ◽  
Author(s):  
Ziqiang Yuan ◽  
Kailiang Yu ◽  
Howard Epstein ◽  
Katia Stefanova ◽  
Rong Zhang
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Communities ◽  
Plant Species Richness ◽  
Subalpine Meadow

scholarly journals Effects of plant species diversity on nematode community composition and diversity in a long-term biodiversity experiment

Oecologia ◽  
2021 ◽  
Author(s):  
Peter Dietrich ◽  
Simone Cesarz ◽  
Tao Liu ◽  
Christiane Roscher ◽  
Nico Eisenhauer
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Plant Species ◽  
Plant Communities ◽  
Plant Diversity ◽  
Plant Species Richness ◽  
Resource Quality ◽  
Plant Feeding ◽  
Shoot Mass

AbstractDiversity loss has been shown to change the soil community; however, little is known about long-term consequences and underlying mechanisms. Here, we investigated how nematode communities are affected by plant species richness and whether this is driven by resource quantity or quality in 15-year-old plant communities of a long-term grassland biodiversity experiment. We extracted nematodes from 93 experimental plots differing in plant species richness, and measured above- and belowground plant biomass production and soil organic carbon concentrations (Corg) as proxies for resource quantity, as well as C/Nleaf ratio and specific root length (SRL) as proxies for resource quality. We found that nematode community composition and diversity significantly differed among plant species richness levels. This was mostly due to positive plant diversity effects on the abundance and genus richness of bacterial-feeding, omnivorous, and predatory nematodes, which benefited from higher shoot mass and soil Corg in species-rich plant communities, suggesting control via resource quantity. In contrast, plant-feeding nematodes were negatively influenced by shoot mass, probably due to higher top–down control by predators, and were positively related to SRL and C/Nleaf, indicating control via resource quality. The decrease of the grazing pressure ratio (plant feeders per root mass) with plant species richness indicated a higher accumulation of plant-feeding nematodes in species-poor plant communities. Our results, therefore, support the hypothesis that soil-borne pathogens accumulate in low-diversity communities over time, while soil mutualists (bacterial-feeding, omnivorous, predatory nematodes) increase in abundance and richness in high-diversity plant communities, which may contribute to the widely-observed positive plant diversity–productivity relationship.

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.

Eucalyptus plantations in temperate grasslands: responses of taxonomic and functional diversity of plant communities to environmental changes

2020 ◽  
Author(s):  
Pamela E. Pairo ◽  
Estela E. Rodriguez ◽  
M. Isabel Bellocq ◽  
Pablo G. Aceñolaza
Keyword(s):  
Species Richness ◽  
Leaf Litter ◽  
Plant Species ◽  
Functional Diversity ◽  
Plant Communities ◽  
Environmental Variables ◽  
Canopy Cover ◽  
Land Uses ◽  
Eucalypt Plantations ◽  
Plantation Age

ABSTRACTUnderstanding how human land-uses impact on local communities is required to implement management and conservational policies and practices. Tree plantations have become one of the fastest-growing land uses in recent decades and their impact on biodiversity was evaluated mainly at the taxonomic level. Our aim was to analyze the effects of changes in environmental drivers along the 12 years eucalypt plantations chronosequence on alfa, beta, taxonomic and functional diversity of understory plant communities. We selected nine plantation ages with three replicates per age and three protected grasslands as reference habitat. At each replicate, we established three plots to measure plant species cover and environmental variables, which are expected to change with plantation age. Results showed that species richness and all diversity indices significantly declined with increasing plantation age. Canopy cover, soil pH, and leaf litter were the most important drivers that explained the decline in taxonomic and functional diversity of plants through the forest plantation. Based on the Path analyses results, canopy cover had an indirect relationship with plant functional diversity mediated by leaf litter, soil pH and plant species richness. The results of the association between functional traits and environmental variables have revealed that high dispersal potential, annual, barochorous, and zoochorous plant species were the functional traits more affected by the eucalypt plantations. Given that leaf litter was negatively associated with all diversity facets, we recommend reducing their accumulation within eucalypt plantation to enhance biodiversity conservation and the provision of pampean grassland ecosystem functions.

scholarly journals Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

2016 ◽  
Vol 13 (4) ◽  
pp. 1237-1253 ◽  
Author(s):  
Naïm Perreault ◽  
Esther Lévesque ◽  
Daniel Fortier ◽  
Laurent J. Lamarque
Keyword(s):  
Species Richness ◽  
Soil Moisture ◽  
Plant Species ◽  
Plant Communities ◽  
Stable State ◽  
Plant Species Richness ◽  
Arctic Ecosystems ◽  
Erosion Processes ◽  
Short Period ◽  
Ice Wedge

Abstract. Continuous permafrost zones with well-developed polygonal ice-wedge networks are particularly vulnerable to climate change. Thermo-mechanical erosion can initiate the development of gullies that lead to substantial drainage of adjacent wet habitats. How vegetation responds to this particular disturbance is currently unknown but has the potential to significantly disrupt function and structure of Arctic ecosystems. Focusing on three major gullies of Bylot Island, Nunavut, we estimated the impacts of thermo-erosion processes on plant community changes. We explored over 2 years the influence of environmental factors on plant species richness, abundance and biomass in 62 low-centered wet polygons, 87 low-centered disturbed polygons and 48 mesic environment sites. Gullying decreased soil moisture by 40 % and thaw-front depth by 10 cm in the center of breached polygons within less than 5 years after the inception of ice wedge degradation, entailing a gradual yet marked vegetation shift from wet to mesic plant communities within 5 to 10 years. This transition was accompanied by a five times decrease in graminoid above-ground biomass. Soil moisture and thaw-front depth changed almost immediately following gullying initiation as they were of similar magnitude between older (> 5 years) and recently (< 5 years) disturbed polygons. In contrast, there was a lag-time in vegetation response to the altered physical environment with plant species richness and biomass differing between the two types of disturbed polygons. To date (10 years after disturbance), the stable state of the mesic environment cover has not been fully reached yet. Our results illustrate that wetlands are highly vulnerable to thermo-erosion processes, which drive landscape transformation on a relative short period of time for High Arctic perennial plant communities (5 to 10 years). Such succession towards mesic plant communities can have substantial consequences on the food availability for herbivores and carbon emissions of Arctic ecosystems.

Effects of size, shape, and edge on vegetation in remnants of the upland boreal mixed-wood forest in agro-environments of Alberta, Canada

2007 ◽  
Vol 85 (3) ◽  
pp. 273-284 ◽  
Author(s):  
L. Dennis Gignac ◽  
Mark R.T. Dale
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Plant Species ◽  
Fragment Size ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Percent Cover ◽  
Shrub Species ◽  
Alien Plant ◽  
Species Richness And Abundance

Forty-one remnants of the aspen-dominated upland forest in three subregions of the dry boreal mixed-wood in Alberta were studied to determine effects of fragment size and shape on native and alien plant species richness and abundance in agro-environments. The percent cover of all vascular plant species was visually estimated in 5 m diameter circular plots along transects that covered the length and the width of each fragment. A subset of 12 of the largest fragments (>900 m2) that had distinct interiors (portions of the fragment >15 m from any edge) was used to measure edge effects on the vegetation. Regression analyses revealed significant positive relationships between species richness and area regardless of the subregion. Species richness stabilized in fragments that were larger than 11 ha. Edges did not affect shrub species richness and only affected herbaceous species richness on west- and south-facing aspects. Shrub abundance decreased and herb abundance increased up to 20 m from the edges regardless of orientation. Edges did not support a different suite of species than interiors, although several species occurred more frequently in the interior than along the edges. Alien species richness and abundance reached their highest values between 5 and 15 m from the edge, and some of those species could be found up to 40 m from the edge. Although larger fragments generally supported more alien species than smaller fragments, the smallest fragments had the greatest number of species per metre squared. Results from this study indicated that it would be preferable to conserve larger woodlots rather then several smaller woodlots on the landscape.

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