scholarly journals Diversity of alien roadside herbs along an elevational gradient in western Mexico

NeoBiota ◽  
2021 ◽  
Vol 65 ◽  
pp. 71-91
Author(s):  
Isabel Pérez-Postigo ◽  
Jörg Bendix ◽  
Heike Vibrans ◽  
Ramón Cuevas-Guzmán
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Linear Models ◽  
Early Stage ◽  
Vegetation Type ◽  
Elevational Gradient ◽  
Clear Correlation ◽  
Natural Ecosystems ◽  
Alien Plant ◽  
Western Mexico

Growing numbers of alien plant species threaten natural ecosystems worldwide. Mexico, as a megadiverse country, has lower numbers of alien species than other regions in America. However, there is a lack of information on the factors that determine the diversity patterns of alien species and their relative importance in the vegetation. The diversity of alien roadside herbs was analysed along an elevational gradient in western Mexico, including their relationship with environmental factors. Three hundred and seventeen herbaceous species were found in 37 sampling sites; 10% were aliens. The proportion of alien species in the ruderal herbaceous communities was lower than the average for this vegetation type in the country. Absolute species richness of natives was significantly and positively correlated with elevation. Absolute species richness of aliens was not significantly correlated with elevation, still; higher values were found at lower elevations. Generalised linear models for relative species richness and relative abundance of aliens with elevation had positive estimates near 0, which, though statistically significant, indicated a weak relationship. Other environmental co-factors, such as the distance to roads and highways, climatic variables, and disturbance indicators, were included in a random forest model. No clear correlation patterns were found. This seemingly random distribution of alien herbaceous plants in the region might be caused by the relatively recent introduction of most of the species. They have not yet had time to expand their distribution to their potential maximum. The early stage of the naturalisation process allows us to minimise the further spread of some species with targeted management and prevent them from becoming invasive.

scholarly journals Floristic composition and potential invasiveness of alien herbaceous plant in Western Mexico

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Isabel Pérez-Postigo ◽  
Heike Vibrans ◽  
Jörg Bendix ◽  
Ramón Cuevas-Guzmán
Keyword(s):  
Invasive Species ◽  
Alien Species ◽  
Floristic Composition ◽  
Tree Cover ◽  
Herbaceous Plant ◽  
World Knowledge ◽  
Importance Value Index ◽  
Alien Plant ◽  
Western Mexico ◽  
Roadside Vegetation

Introduction: Numbers of alien plant species are rising around the globe, but not all of them become invasive. Whereas introductions have been documented for several decades in some regions of the world, knowledge on alien species in Western Mexico is limited. Here, we study roadside vegetation along an elevational gradient, which includes a protected area. Objective: We analysed the floristic composition of herbaceous alien species, their distribution patterns, and their relationship with various environmental factors. A relative importance value index (IVI) identified the most important and, therefore, probably invasive taxa. Methods: During 2017 and 2018, roadside vegetation was documented with 4-6 transects every 300 altitudinal meters, from 0 to 2 100 m, for a total of 37 transects. Each transect consisted of five 1 m² plots. All herbaceous species were registered and alien taxa identified. A cluster analysis distinguished grouping of species based on elevation. The potentially invasive species were identified by their IVI, based on the sum of relative frequency and density values. The influence of environmental variables was analysed with a canonical correspondence analysis. Results: Most alien species were grasses; other families were represented by one or two species. The species were grouped into three main clusters. The first group included rare species, the second consisted of species restricted to higher altitudes, and the third group were tropical taxa with a distribution from sea level to medium altitudes. The most important potentially invasive species were: Urochloa maxima, Melinis repens, Eragrostis ciliaris and Cynodon dactylon, all African grasses introduced for grazing. The IVI of the species was related to tree cover, leaf litter depth and surface stone cover for some species and, for others, to soil compaction, distance to major roads and elevation. Conclusions: The alien ruderal species clustered according to the general climate (temperate vs. tropical). Grasses of African origin are of highest concern as invasive species. Although most introductions are related to human disturbance, each species becomes dominant under certain environmental conditions. Thus, management programs must be specifically adjusted to each individual invasive alien.

scholarly journals Environmental filters determine the distribution of tree species in a threatened biodiversity hotspot in western Mexico

2020 ◽  
Vol 98 (2) ◽  
pp. 219-237 ◽  
Author(s):  
Maribel Arenas-Navarro ◽  
Felipe García-Oliva ◽  
Andrés Torres-Miranda ◽  
Oswaldo Téllez-Valdés ◽  
Ken Oyama
Keyword(s):  
Species Richness ◽  
Species Distribution ◽  
Tree Species ◽  
Elevational Gradient ◽  
Biodiversity Hotspot ◽  
Environmental Filters ◽  
Ecological Diversification ◽  
Western Mexico ◽  
Tree Species Richness ◽  
Quercus Species

Background: Analyzing interactions between vegetation and environmental factors at regional scales provide information for the understanding of species assemblages. Hypotheses: Environmental restrictions at higher elevations produce a decreasing species richness pattern along an elevational gradient and the climatic variables related to temperature and precipitation are the main filters of species distribution. Objectives: (1) To identify the different assemblages of tree species occurring in a biodiversity hotspot; (2) to analyze the pattern of tree species richness along an elevational gradient; and (3) to analyze the environmental filters that determine the species distribution. Study site: Serranías Meridionales of Jalisco in western Mexico. Period of study: 2016-2018. Methods: Thirty-three rectangular 0.1 ha plots were established for vegetation and environmental characterization. Cluster and canonical correspondence analyses were conducted to analyze tree species composition. We defined three groups of variables (climatic, relief and soil) to evaluate the influence of environmental filters. We used generalized linear models to assess the contribution of each group to the spatial variation in species richness. Results: A total of 63 tree species were recorded. The cluster analysis defined eight groups within three forest types. The species richness showed a hump-shaped pattern along the elevational gradient and the climatic and soil variables explained a considerable amount of variation in the species richness. Conclusions: The tree species richness in the Serranías Meridionales de Jalisco is dominated by a striking number of Pinus and Quercus species. This biodiversity hotspot is an important site for the understanding of tree ecological diversification in Mexico.

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.

scholarly journals Impacts of alien plant invasions on species richness in Mediterranean-type ecosystems: a meta-analysis

2009 ◽  
Vol 33 (3) ◽  
pp. 319-338 ◽  
Author(s):  
Mirijam Gaertner ◽  
Alana Den Breeyen ◽  
Cang Hui ◽  
David M. Richardson
Keyword(s):  
South Africa ◽  
Species Richness ◽  
Alien Species ◽  
Plant Species ◽  
Native Species ◽  
Meta Analysis ◽  
Growth Forms ◽  
Alien Plant ◽  
Native Species Richness ◽  
Mediterranean Type Ecosystems

Besides a general consensus regarding the negative impact of invasive alien species in the literature, only recently has the decline of native species attributable to biological invasions begun to be quantified in many parts of the world. The cause-effect relationship between the establishment and proliferation of alien species and the extinction of native species is, however, seldom demonstrated. We conducted a meta-analysis of studies in Mediterranean-type ecosystems (MTEs) to examine: (1) whether invasion of alien plant species indeed causes a reduction in the number of native plant species at different spatial and temporal scales; (2) which growth forms, habitat types and areas are most affected by invasions; and (3) which taxa are most responsible for native species richness declines. Our results confirm a significant decline in native species richness attributable to alien invasions. Studies conducted at small scales or sampled over long periods reveal stronger impacts of alien invasion than those at large spatial scales and over short periods. Alien species from regions with similar climates have much stronger impacts, with the native species richness in South Africa and Australia declining significantly more post-invasion than for European sites. Australian Acacia species in South Africa accounted for the most significant declines in native species richness. Among the different growth forms of alien plants, annual herbs, trees and creepers had the greatest impact, whereas graminoids generally caused insignificant changes to the native community. Native species richness of shrublands, old fields and dune vegetation showed significant declines, in contrast to insignificant declines for forest habitats.

scholarly journals Models of alien species richness show moderate predictive accuracy and poor transferability

NeoBiota ◽  
2018 ◽  
Vol 38 ◽  
pp. 77-96 ◽  
Author(s):  
César Capinha ◽  
Franz Essl ◽  
Hanno Seebens ◽  
Henrique Miguel Pereira ◽  
Ingolf Kühn
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Linear Models ◽  
Negative Binomial ◽  
Predictive Accuracy ◽  
Multivariate Adaptive Regression Splines ◽  
Boosted Regression Trees ◽  
Data Sets ◽  
Explanatory Variables ◽  
Taxonomic Groups

Robust predictions of alien species richness are useful to assess global biodiversity change. Nevertheless, the capacity to predict spatial patterns of alien species richness remains largely unassessed. Using 22 data sets of alien species richness from diverse taxonomic groups and covering various parts of the world, we evaluated whether different statistical models were able to provide useful predictions of absolute and relative alien species richness, as a function of explanatory variables representing geographical, environmental and socio-economic factors. Five state-of-the-art count data modelling techniques were used and compared: Poisson and negative binomial generalised linear models (GLMs), multivariate adaptive regression splines (MARS), random forests (RF) and boosted regression trees (BRT). We found that predictions of absolute alien species richness had a low to moderate accuracy in the region where the models were developed and a consistently poor accuracy in new regions. Predictions of relative richness performed in a superior manner in both geographical settings, but still were not good. Flexible tree ensembles-type techniques (RF and BRT) were shown to be significantly better in modelling alien species richness than parametric linear models (such as GLM), despite the latter being more commonly applied for this purpose. Importantly, the poor spatial transferability of models also warrants caution in assuming the generality of the relationships they identify, e.g. by applying projections under future scenario conditions. Ultimately, our results strongly suggest that predictability of spatial variation in richness of alien species richness is limited. The somewhat more robust ability to rank regions according to the number of aliens they have (i.e. relative richness), suggests that models of aliens species richness may be useful for prioritising and comparing regions, but not for predicting exact species numbers.

scholarly journals Plant communities and their environmental drivers on an arid mountain, Gebel Elba, Egypt

2020 ◽  
Vol 1 ◽  
pp. 21-36 ◽  
Author(s):  
Maged M. Abutaha ◽  
Ahmed A. El-Khouly ◽  
Norbert Jürgens ◽  
Jens Oldeland
Keyword(s):  
Species Richness ◽  
Environmental Factors ◽  
Soil Quality ◽  
Vegetation Structure ◽  
Biological Diversity ◽  
Vegetation Type ◽  
Elevational Gradient ◽  
Environmental Drivers ◽  
Mountain Range ◽  
Perennial Vegetation

Aims: Gebel Elba is an arid mountain range supporting biological diversity that is incomparable to any other region of Egypt. This mountain has a vegetation structure and floristic community similar to the highlands of East Africa and the southwestern Arabian Peninsula. We aimed to provide the first classification of the vegetation units on Gebel Elba and identify the environmental factors controlling their distribution. Study area: Wadi Yahmib and its tributaries, which drain the north-western slopes of Gebel Elba, south-eastern Egypt. Methods: On the basis of 169 relevés, we used TWINSPAN to classify the perennial vegetation. We calculated separate GAMs for the deciduous and evergreen species to describe the patterns for each leaf strategy type with elevation. We used CCA to quantify the relationship between the perennial vegetation and the studied environmental factors. To estimate diversity and our sampling strategy, we used rarefaction curves for species richness. Results: We identified seven communities along the elevational gradient of Wadi Yahmib and its tributaries. We found that each community was restricted to a confined habitat depending on its drought resistance ability. Deciduous Vachellia woodland was the main vegetation type on Gebel Elba, while evergreen Olea woodland appeared in small fragments at higher elevations. We analysed the distribution patterns of deciduous and evergreen trees along the elevational gradient. We found a turnover at 500 m, indicating a potential ecotone between the Vachellia and Olea woodlands that was occupied by a Ficus community. CCA revealed the importance of altitude and soil quality in determining the vegetation structure of Gebel Elba. The species richness increased with elevation as a result of reduced stress and increased water availability at the upper wadis. Conclusions: This study identified seven vegetation units in the study area and showed the importance of orographic precipitation, soil quality and the complex topography in determining the habitats. Taxonomic reference: Boulos (2009); names updated according to POWO (2019). Abbreviations: CCA = Canonical Correspondence Analysis; GAM = Generalized Additive Model; TWINSPANTWINSPAN = Two Way Indicator Species Analysis.

scholarly journals Distribution and diversity of Papilionidae and Pieridae (Lepidoptera: Papilionoidea) in Loxicha Region, Oaxaca, Mexico

2020 ◽  
Vol 68 (1) ◽  
Author(s):  
Armando Luis-Martínez ◽  
Alejandra Sánchez García ◽  
Omar Ávalos-Hernández ◽  
José Luis Salinas-Gutiérrez ◽  
Marysol Trujano-Ortega ◽  
...  
Keyword(s):  
Species Richness ◽  
Deciduous Forest ◽  
Vegetation Type ◽  
Cloud Forest ◽  
Alpha Diversity ◽  
Elevational Gradient ◽  
Tropical Deciduous Forest ◽  
Sampling Effort ◽  
Vegetation Types ◽  
Species Richness And Diversity

Introduction: A reliable list of species and the analysis of diversity patterns of hyperdiverse taxa, like butterflies, are fundamental for monitoring and managing biological resources. Oaxaca is one of the most diverse states in Mexico for many groups including Lepidoptera and most of its diversity is unknown. Objective: to estimate and describe the species richness and diversity of Papilionidae and Pieridae along an altitudinal gradient and five vegetation types in the Loxicha Region, Oaxaca, Sierra Madre del Sur. Methods: Sampling effort comprised 222 collecting days during a period of seven years. We estimated the alpha diversity for 17 sites within an elevational gradient from 80 to 2 850 m, with five vegetation types: tropical deciduous forest (TDF), tropical sub-deciduous forest (TSDF), cloud forest (low and middle levels) (CF), oak-pine and cloud forest (high level) (OPCF) and oak-pine forest (OPF). Results: We obtained a list of 69 species (27 Papilionidae and 42 Pieridae), of 34 genera and five subfamilies, from literature records and fieldwork. These species are 60 % of the Pieridae and 48 % of the Papilionidae recorded for the state. The Loxicha Region has 36 % of the Pieridae and 30 % of the Papilionidae of Mexico. Both families present different species richness patterns by vegetation type. Papilionidae is richer in the TDF with 23 estimated species and most of the species of this family (84 %) occur below 500 m. Meanwhile, species richness of Pieridae has non-significant differences among vegetations types, except for OPF which has fewer species than the other types. The elevational gradient was divided into three levels (0-750, 750-1 800, 1 800-2 850 m) showing a reduction of species richness and diversity for both families at higher altitudes. Conclusions: Papilionidae species are more restricted to a vegetation type or elevational level than Pieridae species. Likely reasons are higher vagility (including migrations) and wider ecological tolerance of most Pieridae.

scholarly journals Emerging Urban Forests: Opportunities for Promoting the Wild Side of the Urban Green Infrastructure

2019 ◽  
Vol 11 (22) ◽  
pp. 6318 ◽  
Author(s):  
Ingo Kowarik ◽  
Anne Hiller ◽  
Greg Planchuelo ◽  
Birgit Seitz ◽  
Moritz von der Lippe ◽  
...  
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Green Infrastructure ◽  
Urban Forest ◽  
Urban Forests ◽  
Tree Regeneration ◽  
Carabid Beetles ◽  
Alien Plant ◽  
Urban Green ◽  
Urban Green Infrastructure

Many cities aim to increase urban forest cover to benefit residents through the provision of ecosystem services and to promote biodiversity. As a complement to traditional forest plantings, we address opportunities associated with “emerging urban forests” (i.e., spontaneously developing forests in cities) for urban biodiversity conservation. We quantified the area of successional forests and analyzed the species richness of native and alien plants and of invertebrates (carabid beetles, spiders) in emerging forests dominated by alien or native trees, including Robinia pseudoacacia, Acer platanoides, and Betula pendula. Emerging urban forests were revealed as shared habitats of native and alien species. Native species richness was not profoundly affected by the alien (co-)dominance of the canopy. Instead, native and alien plant species richnesses were positively related. Numbers of endangered plants and invertebrates did not differ between native- and alien-dominated forest patches. Patterns of tree regeneration indicate different successional trajectories for novel forest types. We conclude that these forests (i) provide habitats for native and alien species, including some endangered species, (ii) allow city dwellers to experience wild urban nature, and (iii) support arguments for adapting forests to dynamic urban environments. Integrating emerging urban forests into the urban green infrastructure is a promising pathway to sustainable cities and can complement traditional restoration or greening approaches.

Endangered anurans in a novel forest in the highlands of Sri Lanka

2012 ◽  
Vol 39 (7) ◽  
pp. 641 ◽  
Author(s):  
Rohan S. Pethiyagoda Jr ◽  
Kelum Manamendra-Arachchi
Keyword(s):  
Species Richness ◽  
Sri Lanka ◽  
Alien Species ◽  
Life Cycles ◽  
Primary Forest ◽  
Novel Ecosystems ◽  
Alien Plant ◽  
Novel Ecosystem ◽  
Extant Species ◽  
Species Richness And Abundance

Context Lands without agricultural or urban use embedded within agricultural and urban regions now account for ~35% of Earth’s terrestrial extent. Although created by human disturbances, these ‘novel ecosystems’, usually poor in native flora and often dominated by alien species, do not require human intervention for their maintenance. Given their large and increasing area, however, their ability to support native – and especially threatened – faunas warrants investigation. With 20 species already extinct and 47 of its 91 extant species assessed as Endangered or Critically Endangered, Sri Lanka’s amphibian fauna is in trouble. The 18 anurans (12 of these Endangered) occurring above 1500 m in the island’s central mountains are at particular risk from drastic declines in the extent and quality of habitat. Habitat restoration, however, is retarded by successional vegetation being arrested at least in the decadal time-frame by alien invasive species, creating a ‘novel ecosystem’. Aim To investigate whether such an ecosystem is able to support native anurans with a species richness and abundance comparable to that of neighbouring tropical montane cloud forest. Methods We surveyed 110 transects (each 20 m × 2 m) across three neighbouring locations covering three microhabitat-types, and recorded 552 specimens. One-way analyses of variance and post hoc, pair-wise Tukey’s tests were performed to test for differences in species richness and abundance among the three microhabitat types. Key result Of the 15 anuran species occurring in the neighbouring primary forest, 12 (eight of them Endangered) had established populations in the novel ecosystem (a former tea plantation), with abundances comparable to (or in some cases exceeding) those in primary forest. Conclusion Even young secondary forest dominated by alien plant species, in which native vegetation is almost wholly absent, can provide adequate habitat for most threatened highland anurans in Sri Lanka. Implications (1) Even if florally poor and dominated by alien species, novel ecosystems may present potential conservation opportunities for previously threatened faunas. (2) Threatened anurans exclusively dependent on primary forest and unable to utilise secondary-growth forest should receive greater conservation attention and be prioritised for in situ conservation measures. (3) Given their large and increasing extent globally, novel ecosystems should be considered as part of the area of occupancy of species able to complete their life cycles in them when assessed for conservation purposes, rather than being arbitrarily discarded as ‘degraded’.

Sign in / Sign up

Export Citation Format

Share Document