scholarly journals Factores biogeográficos y cambios de uso del suelo (2009-2013) en el nicho de "Trogon elegans ambiguus" y "Euptilotis neoxenus" en Chihuahua, México

2018 ◽  
Vol 44 (2) ◽  
pp. 763
Author(s):  
M.E. Torres-Olave ◽  
L.C. Bravo-Peña ◽  
L.C. Alatorre-Cejudo ◽  
M.I. Uc-Campos ◽  
M.O. González-León
Keyword(s):  
Land Use ◽  
Vegetation Dynamics ◽  
Ecological Niche ◽  
Potential Distribution ◽  
Plant Cover ◽  
Land Use Changes ◽  
Hardwood Forests ◽  
Ecological Niches ◽  
Niche Modelling ◽  
Current State

Few studies have addressed the current state of the Trogon elegans ambiguus and Euptilotis neoxenus ecological niches, as well as the vegetation dynamics and land use changes where these birds live. This work estimates the potential distribution of Trogon elegans ambiguus and Euptilotis neoxenus in Chihuahua and studies the land use changes in two time periods (2009 and 2015). The MaxEnt software was used to model the ecological niches in Chihuahua, Mexico. The maps of changes in land use and plant cover were reclassified and the classes were homogenized. A crosstab analysis was used to compare correspondence matrices. The results indicate that Trogon elegans ambiguus and Euptilotis neoxenus underwent a niche loss in conifer and hardwood forests, which became farmland or pasture-bushes. Ecological niche modelling is a useful tool to identify suitable areas for species with NOM-059-SEMARNAT-2010 status. In the case of Trogon elegans ambiguus, land use changes mainly affect the municipalities of Temosachi and Madera.

scholarly journals A Model-Based Tool for Assessing the Impact of Land Use Change Scenarios on Flood Risk in Small-Scale River Systems—Part 1: Pre-Processing of Scenario Based Flood Characteristics for the Current State of Land Use

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 102
Author(s):  
Frauke Kachholz ◽  
Jens Tränckner
Keyword(s):  
Land Use ◽  
River Flow ◽  
Land Use Changes ◽  
Small Rivers ◽  
Small Scale ◽  
Model Parameters ◽  
Ungauged Catchments ◽  
Model Based ◽  
Current State ◽  
The Impact

Land use changes influence the water balance and often increase surface runoff. The resulting impacts on river flow, water level, and flood should be identified beforehand in the phase of spatial planning. In two consecutive papers, we develop a model-based decision support system for quantifying the hydrological and stream hydraulic impacts of land use changes. Part 1 presents the semi-automatic set-up of physically based hydrological and hydraulic models on the basis of geodata analysis for the current state. Appropriate hydrological model parameters for ungauged catchments are derived by a transfer from a calibrated model. In the regarded lowland river basins, parameters of surface and groundwater inflow turned out to be particularly important. While the calibration delivers very good to good model results for flow (Evol =2.4%, R = 0.84, NSE = 0.84), the model performance is good to satisfactory (Evol = −9.6%, R = 0.88, NSE = 0.59) in a different river system parametrized with the transfer procedure. After transferring the concept to a larger area with various small rivers, the current state is analyzed by running simulations based on statistical rainfall scenarios. Results include watercourse section-specific capacities and excess volumes in case of flooding. The developed approach can relatively quickly generate physically reliable and spatially high-resolution results. Part 2 builds on the data generated in part 1 and presents the subsequent approach to assess hydrologic/hydrodynamic impacts of potential land use changes.

scholarly journals Effects of Climate and Land Use changes on Vegetation Dynamics in the Yangtze River Delta, China Based on Abrupt Change Analysis

2020 ◽  
Vol 12 (5) ◽  
pp. 1955
Author(s):  
Lei Wan ◽  
Huiyu Liu ◽  
Haibo Gong ◽  
Yujia Ren
Keyword(s):  
Land Use ◽  
Vegetation Dynamics ◽  
Abrupt Change ◽  
Land Use Changes ◽  
Yangtze River Delta ◽  
Change Analysis ◽  
Land Use Types ◽  
Natural Land ◽  
Abrupt Change Analysis ◽  
Relationship Of

Vegetation dynamics is thought to be affected by climate and land use changes. However, how the effects vary after abrupt vegetation changes remains unclear. Based on the Mann-Kendall trend and abrupt change analysis, we monitored vegetation dynamics and its abrupt change in the Yangtze River delta during 1982–2016. With the correlation analysis, we revealed the relationship of vegetation dynamics with climate changes (temperature and precipitation) pixel-by-pixel and then with land use changes analysis we studied the effects of land use changes (unchanged or changed land use) on their relationship. Results showed that: (1) the Normalized Vegetation Index (NDVI) during growing season that is represented as GSN (growing season NDVI) showed an overall increasing trend and had an abrupt change in 2000. After then, the area percentages with decreasing GSN trend increased in cropland and built-up land, mainly located in the eastern, while those with increasing GSN trend increased in woodland and grassland, mainly located in the southern. Changed land use, except the land conversions from/to built-up land, is more favor for vegetation greening than unchanged land use (2) after abrupt change, the significant positive correlation between precipitation and GSN increased in all unchanged land use types, especially for woodland and grassland (natural land use) and changed land use except built-up land conversion. Meanwhile, the insignificant positive correlation between temperature and GSN increased in woodland, while decreased in the cropland and built-up land in the northwest (3) after abrupt change, precipitation became more important and favor, especially for natural land use. However, temperature became less important and favor for all land use types, especially for built-up land. This research indicates that abrupt change analysis will help to effectively monitor vegetation trend and to accurately assess the relationship of vegetation dynamics with climate and land use changes.

scholarly journals Ecological niche overlap among species of the genus Zaluzania (Asteraceae) from the dry regions of Mexico

2020 ◽  
Vol 153 (3) ◽  
pp. 337-347
Author(s):  
Mario Ernesto Suárez-Mota ◽  
José Luis Villaseñor
Keyword(s):  
Ecological Niche ◽  
Potential Distribution ◽  
Area Under The Curve ◽  
Niche Overlap ◽  
Ecological Niches ◽  
Niche Conservatism ◽  
Distribution Models ◽  
Closely Related Species ◽  
Environmental Pressures ◽  
Fundamental Niche

Background and aims – The hypothesis of ecological niche conservatism postulates that closely related species share ecologically similar environments; that is, they tend to maintain the characteristics of their fundamental niche over time. The objective of this study is to evaluate the similarity and equivalence of the ecological niches among species of the genus Zaluzania (Asteraceae), characteristic of the Mexican arid and semi-arid regions, to infer their potential niche conservatism. Methods – Based on critically reviewed herbarium occurrence data, potential distribution models for eight species of Zaluzania were generated using the Maxent algorithm. The overlap between potential distribution areas was then evaluated using equivalence and ecological niche parameters implemented in the ENMTools software; for this we quantified the degree of overlap and similarity between the niches using the equivalence (D) and similarity (I) parameters.Key results – The resulting models show that species display areas of high suitability along the Mexican dry regions, as well as overlapping heterogeneous values. All models showed high AUC (Area Under the Curve) values (> 0.8). The D and I values between each pair of species showed low values of overlap.Conclusions – Each species of the genus shows a fundamental niche distinct from their sister species. The genus thus offers an example of niche divergence among species, with each one adapting to different environmental pressures. Our results do not support the hypothesis of niche conservatism in the genus, suggesting that the species evolved in divergent environments.

scholarly journals Progressively approaching the distribution of Passiflora ischnoclada (Passifloraceae) from a single occurrence record

Check List ◽  
2015 ◽  
Vol 11 (4) ◽  
pp. 1717
Author(s):  
Renato De Giovanni ◽  
Luís Carlos Bernacci
Keyword(s):  
Ecological Niche ◽  
Potential Distribution ◽  
New Records ◽  
Field Work ◽  
Model Ensemble ◽  
Niche Modelling ◽  
Distribution Models ◽  
Guide Field ◽  
Real Distribution ◽  
Modelling Techniques

Until recently, Passiflora ischnoclada was only known from a single occurrence record. In this paper we describe how different ecological niche modelling techniques were successively used to generate better potential distribution models for the species and guide field work. At each step, new records were found until the species’ real distribution was approximated based on a model ensemble created with five different algorithms. The estimated distribution is concentrated on a single area of 84 km2 where the species is considered endangered.

Heat waves and droughts strongly impact productivity and ecosystem functioning in an abandoned subalpine grassland

2020 ◽  
Author(s):  
Ludovica Oddi ◽  
Marta Galvagno ◽  
Edoardo Cremonese ◽  
Gianluca Filippa ◽  
Mirco Migliavacca ◽  
...  
Keyword(s):  
Land Use ◽  
Biomass Production ◽  
Ecosystem Functioning ◽  
Vegetation Dynamics ◽  
Heat Waves ◽  
Land Use Changes ◽  
Nardus Stricta ◽  
Mountain Grasslands ◽  
Subalpine Grasslands ◽  
Relative Productivity

<p>Climate and land-use changes have major impacts on global biodiversity and carbon cycle of ecosystems. Severe heat waves and droughts, already experienced by the European Alps, e.g. in 2015 and 2018, are expected to further increase in the near future.</p><p>In the last decades, land-use changes have led to the abandonment of several mountain grasslands and pastures, so that in Europe a net conversion of grasslands to forest is currently occurring. However, the consequences of alpine grassland abandonment on the ecosystem responses to climate extremes are still largely unknown. Understanding climate change impacts and feedbacks of alpine and subalpine grasslands is essential, because they are ecologically sensitive ecosystems, and they constitute an important C sink and hotspots of biodiversity.</p><p>In this work we aim at understanding the effects of heat waves and drought on the relative productivity of grasses and forbs and consequently on ecosystem functioning in an abandoned subalpine grassland located in the Western Italian Alps (Aosta Valley) at 2100 m asl. We took advantage of a 10-years natural experiment in which we analysed biomass production, LAI and Net Ecosystem CO<sub>2</sub> Exchange. Vegetation of the study area is characterized by a dominance of the grass Nardus stricta, and by Arnica montana, Trifolium alpinum, Geum montanum and several other forb species typical of alpine and subalpine grasslands.</p><p>In the period 2009-2019, primary production as represented by biomass and leaf area index (LAI) gradually decreased with important drops in 2015 and 2018, which were characterised by extreme climatic conditions.</p><p>Considering the functional type response to extremes, the LAI peak of grasses, which appeared always the dominant portion of the total LAI, showed significantly lower values in 2015 and 2018 compared to long-term. On the other hand, LAI peak values of forbs showed higher variability among plots and years. The clear decrease of the LAI of grasses (mainly represented by Nardus stricta) contributed significantly to the decrease of the total biomass production and to the NEE reduction. The response of Nardus stricta to heat waves and drought is very clear and influences ecosystem functioning and consequently vegetation dynamics, modifying the relative productivity of grasses and forbs. As an example, in the years 2015 and 2018 an evident phenological response was observed in Arnica montana, with an exceptional number of inflorescences.</p><p>In conclusion, we found that heat waves and droughts have the potential to influence the natural vegetation dynamics following abandonment and contribute to the reduction of plant biomass production with consequences on the net ecosystem C exchange and species competition in mountain grasslands.</p>

scholarly journals Climatic affinities of Neotropical species of Capparaceae: an approach from ecological niche modelling and numerical ecology

2020 ◽  
Vol 193 (2) ◽  
pp. 263-275
Author(s):  
Jorge D Mercado Gómez ◽  
David A Prieto-Torres ◽  
Maylin Adriana Gonzalez ◽  
María Eugenia Morales Puentes ◽  
Tania Escalante ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Ecological Niche ◽  
Distribution Patterns ◽  
Ecological Niche Modelling ◽  
Dry Forest ◽  
Ecological Niches ◽  
Niche Modelling ◽  
Response Curves ◽  
Multivariate Statistical ◽  
Seasonally Dry

Abstract In the Neotropics, the distribution of Capparaceae has been historically associated with seasonally dry forest (NSDF), but recent taxonomic studies have questioned this assumption. Given the environmental co-occurrence of species and the need to understand their relationships with the ecosystem, we use ecological niche modelling and numerical ecology methods to better describe the distribution patterns of Capparaceae and their climatic affinities with NSDF. We used the Maxent algorithm to model the ecological niches of 104 species of Capparaceae, which gave maximum values of the response curves for climatic suitability. These values were used to carry out multivariate statistical analyses [principal components analysis (PCA), non-metric multidimensional scaling (NMDS) and discriminant analysis (DA)] to identify ecological associations based on climatic similitude among species. Both PCA and NMDS showed that annual precipitation, precipitation of the wettest quarter and precipitation of the driest quarter were the most important climatic variables shaping distributions of species and their associations with NSDF, moist tropical forest (MTF) and wet tropical forest (WTF). Although we found 72 species associated with NSDF as previously reported, DA revealed an overlapping pattern among the three ecological/climatic assemblages (NSDF, MTF and WTF). This confirms the existence of transition zones and species with wider niches. Our results provide an important biogeographical framework of ecological patterns for species associated with NSDF, opening new lines of research on the reconstruction of distribution in future climatic scenarios or palaeo-distributions.

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