scholarly journals Can the metacommunity data matrix predict changes in species incidence and abundance?

2016 ◽  
Author(s):  
Donald M. Waller ◽  
Erika L. Mudrak ◽  
David A. Rogers
Keyword(s):  
Vascular Plant ◽  
Local Population ◽  
Null Model ◽  
Data Matrix ◽  
Site Conditions ◽  
Population Declines ◽  
Local Site ◽  
Species Incidence ◽  
Complex Models ◽  
Species Characteristics

AbstractMetacommunity matrices contain data on species incidence or abundance across sites, compactly portraying community composition and how it varies over sites. We constructed models based on an initial metacommunity matrix of either species incidence or abundance to test whether such data suffice to predict subsequent changes in incidence or abundance at each site. We then tested these models against extensive empirical data on vascular plant incidence and abundance collected from 156 forested sites in both the 1950s and 2000s. Predictions from these models parallel observed changes in species incidence and abundance in two distinctly different forest metacommunities and differ greatly from null model predictions. The abundance model shows greater power than the incidence model reflecting its higher information content. Predictions were more accurate for the more diverse forests of southern Wisconsin which are changing faster in response to succession and fragmentation. Simulations demonstrate that these results are fairly robust to variation in sampling intensity. These models, based only on the metacommunity matrix, do not require data on site conditions or species' characteristics. They thus provide a useful baseline for assessing more complex models incorporating data on species' functional traits, local site conditions, or landscape context. They may also prove useful to conservation biologists seeking to predict local population declines and extinction risks.

Stranding cases of endangered Ganges river dolphins in the Ghaghara–Sharada irrigation canals, Ganges river basin, India: conservation implications

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Shakti Prajapati
Keyword(s):  
River Basin ◽  
Local Population ◽  
Uttar Pradesh ◽  
Ganges River ◽  
Population Declines ◽  
Irrigation Canals ◽  
Indus River ◽  
River Dolphin ◽  
Conservation Implications ◽  
Media Reports

AbstractPopulations of endangered Ganges and Indus river dolphins have been under severe threat from diversion of river water by dams, barrages, and canal networks across the Indus and Ganges–Brahmaputra river basins. River dolphins prefer deep water and might enter irrigation canals in the dry-season, getting stranded there. Stranding can cause mortality and local population declines, and poses an emerging challenge to river dolphin conservation efforts. In Pakistan’s Indus river basin, stranding rates of Indus dolphins in irrigation canals are high, and well-coordinated rescue-release operations are undertaken. Despite commendable river dolphin rescue efforts in some parts of India, stranding cases are not always reported. From open-access media reports (2007–08 to 2017–18), I found 26 stranding cases of Ganges river dolphins from the Ghaghara–Sharada canal network across seven districts of Uttar Pradesh, India. Of these, 62% reports were from 2015 to 2016. Most cases occurred in secondary and tertiary canal branches. Interviews with fishers, farmers, and government officials revealed low awareness of stranding cases. Stranded dolphins might have no chance of returning to their source habitat, unless rescued. From my results, I discuss how current barrage-canal operations could influence dolphin stranding risk, and their implications for flow management in the Ghaghara–Sharada river basin.

scholarly journals Seasonal changes in distribution and abundance of a local Corncrake population

2020 ◽  
Author(s):  
Michał Budka ◽  
Patryk Kokociński ◽  
Paweł Bogawski ◽  
Maciej Nowak ◽  
Joanna Teresa Białas ◽  
...  
Keyword(s):  
Population Size ◽  
Breeding Season ◽  
Site Fidelity ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Local Population ◽  
Bird Species ◽  
Adult Males ◽  
Habitat Conditions ◽  
Population Declines

Abstract Many bird species have experienced short- or long-term population declines. However, the mechanisms and reasons underlying such negative changes are often not fully understood, making it difficult to identify effective conservation measures to recover populations. In this study, we focused on local changes in the abundance and distribution of calling male Corncrakes Crex crex in relation to: (1) within- and between-season site fidelity of adult males, (2) spatial distribution of territories in consecutive years and (3) the effect of habitat conditions on population size. We counted the number of calling males at ten randomly selected study plots (1 km2) in 2014–2018. Additionally, males were caught and individually marked in years 2015–2017. We found significant between-year changes in Corncrake abundance, from a 34% decrease to a 21% increase. On average, 32% of males established territories in the same locations as males recorded in the previous year. Breeding site fidelity was very low, with only 2–5% of males recaptured in the following year. Males selected areas characterized by higher values of NDVI (Normalized Difference Vegetation Index–higher values indicate more biomass) than on average within the study area. Population size in a particular year was significantly affected by the NDVI of the previous year but not by the NDVI in the current breeding season. We suppose that Corncrakes may exhibit a nomadic breeding behavior, and settle at territories when they encounter optimal habitat conditions. Moreover, as population size was negatively correlated with habitat conditions at the beginning of the previous breeding season, we suppose that local population changes may reflect more general trends in a whole population rather than local breeding success. Therefore, we highlight the need for better knowledge of Corncrake dispersal within the main European population and for the coordination of monitoring and conservation efforts, especially in those regions where most Corncrakes breed.

scholarly journals Predicting how populations decline to extinction

2011 ◽  
Vol 366 (1577) ◽  
pp. 2577-2586 ◽  
Author(s):  
Ben Collen ◽  
Louise McRae ◽  
Stefanie Deinet ◽  
Adriana De Palma ◽  
Tharsila Carranza ◽  
...  
Keyword(s):  
At Risk ◽  
Extinction Risk ◽  
Mammalian Species ◽  
Local Population ◽  
Population Decline ◽  
Scale Up ◽  
Population Level ◽  
Biological Traits ◽  
Population Declines ◽  
Trend Data

Global species extinction typically represents the endpoint in a long sequence of population declines and local extinctions. In comparative studies of extinction risk of contemporary mammalian species, there appear to be some universal traits that may predispose taxa to an elevated risk of extinction. In local population-level studies, there are limited insights into the process of population decline and extinction. Moreover, there is still little appreciation of how local processes scale up to global patterns. Advancing the understanding of factors which predispose populations to rapid declines will benefit proactive conservation and may allow us to target at-risk populations as well as at-risk species. Here, we take mammalian population trend data from the largest repository of population abundance trends, and combine it with the PanTHERIA database on mammal traits to answer the question: what factors can be used to predict decline in mammalian abundance? We find in general that environmental variables are better determinants of cross-species population-level decline than intrinsic biological traits. For effective conservation, we must not only describe which species are at risk and why, but also prescribe ways to counteract this.

Effects of human presence on the long-term trends of migrant and resident shorebirds: evidence of local population declines

2014 ◽  
Vol 18 (1) ◽  
pp. 73-81 ◽  
Author(s):  
B. Martín ◽  
S. Delgado ◽  
A. de la Cruz ◽  
S. Tirado ◽  
M. Ferrer
Keyword(s):  
Local Population ◽  
Population Declines ◽  
Human Presence ◽  
Long Term Trends

scholarly journals Storm Water Management

2021 ◽  
Vol 9 (VIII) ◽  
pp. 45-46
Author(s):  
Saurabh Ravikiran Dake
Keyword(s):  
Hydrological Cycle ◽  
Site Conditions ◽  
Urban Flooding ◽  
Land Use Patterns ◽  
Use Patterns ◽  
The Past ◽  
Local Site ◽  
Management Techniques ◽  
Sustainable Stormwater Management ◽  
Impervious Areas

Over the past years, rapid growth due to urbanization and industrialization, the changes in Land over and land use patterns have resulted in permanent environmental pollution to the hydrological processes. The hydrological cycle in cities is seriously affected due to increasing impervious areas as a result of urban development which has enhanced the risk of urban flooding. The increase in the impermeable area decreases infiltration, increases the runoff and reduces the time of concentration. Hence, for a given amount of rainfall, greater flooding is generated. Understanding the scope and limitation of sustainable stormwater management techniques detailed literature review is carried out. Site suitability is based on spatial analysis of data like geomorphology, slope, recharge condition, landuse and Landover map. Then analyzing local site conditions possible techniques that could be used to manage stormwater runoff are recommended and conclusions are drawn on the same.

New GMPEs for the Sagami Bay Region in Japan for Moderate Magnitude Events with Emphasis on Differences on Site Amplifications at the Seafloor and Land Seismic Stations of K-NET

2020 ◽  
Vol 110 (5) ◽  
pp. 2577-2597 ◽  
Author(s):  
Jinjun Hu ◽  
Jingyang Tan ◽  
John X. Zhao
Keyword(s):  
Water Layer ◽  
Soil Condition ◽  
Site Amplification ◽  
Site Conditions ◽  
Sagami Bay ◽  
Site Class ◽  
Offshore Area ◽  
Local Site ◽  
Individual Site ◽  
Kanto Basin

ABSTRACT Ground-motion prediction equations (GMPEs) for the horizontal and vertical spectral accelerations (SAs) from the offshore area off the Sagami Bay is presented in this article. To compare the ground motions on the seafloor with those at onshore sites, an onshore GMPE was derived for the onshore stations adjacent to the offshore sites and including those in the Kanto basin sites. The offshore dataset includes 738 three-component records, and the onshore dataset includes 3775 records; both datasets are derived from the same set of 233 earthquakes selected for this study. The local site conditions of the offshore sites are investigated by implementing the mean horizontal-to-vertical response spectral ratios because soil condition data are unavailable. Individual site correction terms are used for the offshore sites due to differences among the site conditions, whereas site-class terms are used for the onshore sites based on the travel-time-averaged shear-wave velocity to 30 m (VS30). A comparison between the offshore and onshore models shows that the horizontal SAs for the whole periods and vertical SAs for moderate and long periods of the offshore motions are considerably larger than those of the onshore motions due to the deep deposition layer comprising soft sediment blanketing the seafloor; the vertical SAs of the offshore motions are slightly smaller than those of the onshore motions at short spectral periods. The inconsistency of the vertical motions at short periods may be due to the combined effect of the deposition layer and water layer. However, the vertical site amplification for short periods is independent of the water depth, and the reason of high-frequency deficiency in vertical components need further investigation.

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