Types of Data and the General Framework of Analysis

Author(s):  
Joseph A. Veech

For most habitat analyses, researchers typically collect and examine environmental data from the landscape scale (a few square kilometers to hundreds of square kilometers) all the way down to the scale of a microhabitat (tens of square meters). At the larger spatial extents, the data may be GIS-based such as spatially referenced land cover data. At smaller spatial scales, the data may be collected (variables measured) in the field at the study sites. Data for a habitat analysis are often based on randomly located and spatially delineated sampling or survey plots. The environmental data compose a set of a few to tens of predictor variables that are used in statistical tests for a relationship with the response variable that is typically species presence–absence, abundance (counts of individuals), or activity level. Depending on the spatial scale of analysis, predictor variables could represent different environmental variables such as vegetation structure, soil properties, and other characteristics of the substrate. Climate and weather variables are environmental, but they are not considered to be characteristics of the habitat. The formal habitat analysis consists of testing for a statistical relationship between the response variable and one or more environmental predictor variables so as to identify those variables that truly are habitat characteristics. A study of the habitat of the brown-throated sloth in Costa Rica is used to further explain the type of data used in characterizing the habitat of a species.

Author(s):  
Joseph A. Veech

Species vary tremendously in their life histories and behavior. The particular life history traits and behavior of the focal species must be considered when designing a study to examine habitat associations. For some species, individuals use different areas (of the landscape or territory) for breeding and foraging. As such, the important characteristics for the foraging and breeding habitats may be different. The dramatically different life stages of some organisms (e.g., amphibians and some insects) often correspond to equally dramatic differences in habitat use between juveniles and adults. For some species, habitat use differs among seasons. Species that are highly mobile and have individuals that move around substantially on a daily or weekly basis are particularly challenging for a habitat analysis. For these species, the most efficient and appropriate study design may be one that tracks individuals (through radio-telemetry or GPS) and analyzes the environmental or habitat characteristics at locations where the individual has stopped, rather than trying to survey for the species in pre-established and insufficiently small survey plots. In addition, individual movement and the issues mentioned above may necessitate that environmental variables are measured and analyzed at multiple spatial scales.


Author(s):  
Joseph A. Veech

A dataset for a hypothetical ground-dwelling beetle species is used to illustrate five methods of habitat analysis: (1) comparison of group means, (2) multiple linear regression, (3) multiple logistic regression, (4) classification and regression trees, and (5) principal components analysis. The dataset consists of abundance (counts of individuals) recorded in each of 100 small survey plots located throughout forested study sites. The following environmental predictor variables were measured in each plot: percentage canopy cover, depth of leaf litter, volume of woody debris, ratio of oak to non-oak trees, and soil type. Techniques for assessing normality of each variable and multicollinearity among variables are discussed and recommended prior to conducting the habitat analysis. Assumptions, strengths, and weaknesses of each method are discussed.


Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 418
Author(s):  
Cleber Santos ◽  
Rayonil Carneiro ◽  
Camilla Borges ◽  
Didier Gastmans ◽  
Laura Borma

The use of stable isotopes of hydrogen and oxygen is a tool widely used to trace water paths along the hydrological cycle, providing support for understanding climatic conditions in different spatial scales. One of the main synoptic scale events acting in southeastern Brazil is the South Atlantic Convergence Zone (SACZ), which causes a large amount of precipitation from southern Amazonia to southeastern Brazil during the southern summer. In order to determine the isotopic composition of precipitation during the action of SACZ in São Francisco Xavier in southeastern Brazil, information from the Weather Forecasting and Climate Studies Center of the National Institute for Space Research (CPTEC) was used regarding SACZ performance days, the retrograde trajectories of the HYSPLIT model, and images from the GOES-16 satellite, in addition to the non-parametric statistical tests by Spearman and Kruskal–Wallis. A high frequency of air mass trajectories from the Amazon to southeastern Brazil was observed when the SACZ was operating. During the SACZ events, the average isotopic composition of precipitation was more depleted, with a δ18O of −9.9‰ (±2.1‰), a δ2H of −69.3‰ (±17.9‰), and d-excess of 10.1‰ (±4.0‰). When disregarding the SACZ performance, the annual isotopic composition can present an enrichment of 1.0‰ for δ18O and 8.8‰ for the δ2H. The long-term monitoring of trends in the isotopic composition of precipitation during the SACZ events can assist in indicating the evapotranspiration contribution of the Amazon rainforest to the water supply of southeastern Brazil.


2010 ◽  
Vol 61 (11) ◽  
pp. 1227 ◽  
Author(s):  
Elisabeth M. A. Strain ◽  
Craig R. Johnson

Habitat characteristics can influence marine herbivore densities at a range of spatial scales. We examined the relationship between benthic habitat characteristics and adult blacklip abalone (Haliotis rubra) densities across local scales (0.0625–16 m2), at 2 depths, 4 sites and 2 locations, in Tasmania, Australia. Biotic characteristics that were highly correlated with abalone densities included cover of non-calcareous encrusting red algae (NERA), non-geniculate coralline algae (NCA), a matrix of filamentous algae and sediment, sessile invertebrates, and foliose red algae. The precision of relationships varied with spatial scale. At smaller scales (0.0625–0.25 m2), there was a positive relationship between NERA and ERA, and negative relationships between sediment matrix, sessile invertebrates and abalone densities. At the largest scale (16 m2), there was a positive relationship between NERA and abalone densities. Thus, for some biotic characteristics, the relationship between NERA and abalone densities may be scalable. There was very little variability between depths and sites; however, the optimal spatial scale differed between locations. Our results suggest a dynamic interplay between the behavioural responses of H. rubra to microhabitat and/or to abalone maintaining NERA free of algae, sediment, and sessile invertebrates. This approach could be used to describe the relationship between habitat characteristics and species densities at the optimal spatial scales.


2016 ◽  
Vol 5 (1) ◽  
pp. 126
Author(s):  
Jennifer Woodward ◽  
Jenny Sika ◽  
Carl Wambolt ◽  
Jay Newell ◽  
Sean Schroff ◽  
...  

<p class="emsd"><span lang="EN-GB">Greater sage-grouse (Centrocercus urophasianus) habitat characteristics were studied in central Montana primarily on Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle &amp; Young) dominated rangeland. The primary objective was to compare shrub and herbaceous parameters within (use, random or non-use) and between seasonal habitats (nest, brood, winter). Two study sites (Musselshell and Golden Valley counties), and 2 years (2004 and 2005) were compared. Nest, brood, and random sites were compared for herbaceous cover, and grass height (n = 648). Nest, brood, random, winter use and winter non-use sites were evaluated for shrub cover, density, and height. All differences were considered significant at P ≤ 0.05. Sage-grouse nested in areas with greater total shrub cover and height, and taller live and residual grass than was randomly available. No differences were found between brood and paired random sites for any of the herbaceous or shrub parameters measured. Shrub cover and density were greater at winter use sites than non-use sites. Winter use sites had less shrub cover than nest sites. The nest and brood habitat had similar shrub cover, density, and height on the study area. Sage-grouse habitats should be managed to include sagebrush, forbs, and grass. Herbaceous vegetation was more important during nesting and brood rearing than during the winter. Therefore, some portions of <span>sage-</span>grouse habitat may benefit from management for greater herbaceous cover, but not at the expense of removing sagebrush. Sagebrush cover from 10 to 15 percent was the most consistent component of sage-grouse habitat.</span></p>


2017 ◽  
Vol 130 (4) ◽  
pp. 281 ◽  
Author(s):  
David Hamer

Bears (Ursus spp.) in North America eat the seeds of several pines (Pinus spp.), including Limber Pine (P. flexilis E. James). Information on use of Limber Pine in Canada is limited to a report of three bear scats containing pine seeds found in Limber Pine stands of southwestern Alberta. After my preliminary fieldwork in Banff National Park revealed that bears were eating seeds of Limber Pine there, I conducted a field study in 2014–2015 to assess this use. Because bears typically obtain pine seeds from cone caches (middens) made by Red Squirrels (Tamiasciurus hudsonicus), I described the abundance, habitat characteristics, and use by bears of Red Squirrel middens in and adjacent to Limber Pine stands at six study sites. On Bow River escarpments, I found abundant Limber Pines (basal area 1–9 m2/ha) and middens (0.8 middens/ha, standard deviation [SD] 0.2). Of 24 middens, 13 (54%) had been excavated by bears, and three bear scats composed of pine seeds were found beside middens. Although Limber Pines occurred on steep, xeric, windswept slopes (mean 28°, SD 3), middens occurred on moderate slopes (mean 12°, SD 3) in escarpment gullies and at the toe of slopes in forests of other species, particularly Douglas-fir (Pseudotsuga menziesii). At the five other study sites, I found little or no use of Limber Pine seeds by bears, suggesting that Limber Pine habitat may be little used by bears unless the pines are interspersed with (non-Limber Pine) habitat with greater forest cover and less-steep slopes where squirrels establish middens. These observations provide managers with an additional piece of information regarding potential drivers of bear activity in the human-dominated landscape of Banff National Park’s lower Bow Valley.


Author(s):  
Barbara Thiers ◽  
Paula Mabee ◽  
Anna Monfils

The U.S. national heritage of approximately one billion biodiversity specimens, once digitized, can be linked to emerging digital data sources to form an information-rich network for exploring earth’s biota across taxonomic, temporal and spatial scales. A workshop held 30 October - 1 November 2018 at Oak Spring Garden in Upperville, VA under the leadership of the Biodiversity Collections Network (BCoN) developed a plan for maximizing the value of our collections resource for research and education. In their deliberations, participants drew heavily on recent literature as well as surveys, and meetings and workshops held over the past year with the primary stakeholder community of collections professionals, researchers, and educators. We propose to focus future biodiversity infrastructure and digital resources on building a network of extended specimen data that encompasses the depth and breadth of biodiversity specimens and data held in U.S. collections institutions (BCoN 2019). The extended specimen network (ESN) includes the physical voucher specimen curated and housed in a collection and its associated genetic, phenotypic and environmental data. These core data types, selected because they are key to answering driving research questions, include physical preparations such as tissue samples and their derivative products such as gene sequences or metagenomes, digitized media and annotations, and taxon- or locality-specific data such as occurrence observations, phylogenies and species distributions. Existing voucher specimens will be extended both manually and through new automated methods, and data will be linked through unique identifiers, taxon name and location across collections, across disciplines and to outside sources of data. As we continue our documentation of earth’s biota, new collections will be enhanced from the outset, i.e., accessioned with a full suite of data. We envision the ESN proposed here will be the gold standard for the structured cloud of integrated data associated with all vouchered specimens. Collectively, data linked through the ESN will enhance the capacity to explore research questions across taxonomic, temporal and spatial scales. The ESN will allow researchers to explore the rules that govern how organisms, grow, diversify and interact, and enable scientists to ask more nuanced research questions specific to how environmental change and human activities may affect those rules. The specimen, coupled with the open access ESN, and immediate and relevant science resulting from the ESN, can play a unique role in promoting STEM education, involving citizen scientists, and empowering a scientifically literate society. The specimen and the associated data provide a relatable and engaging entry point to participate in iterative data driven science, learn core data literacy skills, and build open, transdisciplinary collaboration. Creating the ESN requires new infrastructure to provide the linkages between the specimen and data derived from it. On the established foundation of existing digital data from collections it will require the development of new standards, connections, and resources such as ontologies to facilitate discovery, and implementation of a robust identifier tracking system. Finally, continued digitization of established, as well as new collections, is necessary to ensure the grounding of extended specimen data in the framework of when and where it was collected. The ESN will also require new approaches to data sharing and collaboration, partnerships with national and international data providers, computer and data scientists, educators and industry. The ESN will benefit from research-driven episodic funding for the collection of new specimens, which in turn will require digitization and curation. For the ESN to function as envisaged above, it will require long-term support for a central organizing unit with responsibility for community coordination, education and outreach, data mobilization, and maintenance of the central data repository and the network infrastructure.


Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2779
Author(s):  
Tatenda Dalu ◽  
Rolindela Tshivhase ◽  
Ross N. Cuthbert ◽  
Florence M. Murungweni ◽  
Ryan J. Wasserman

The study of wetlands is particularly important as these systems act as natural water purifiers and thus can act as sinks for contaminated particles. Wetland sediments are important as they provide an indication of potential contamination across temporal and spatial scales. The current study aimed to investigate the distributions of selected metals and nutrients in different sites in relation to sediment depth, and identify relationships among sediment metals. Significant differences in nutrient (i.e., N, P) and metal (i.e., K, Mg, Na, Fe, Cu, B) concentrations were found across study sites, whereas nutrients (i.e., N, P) and metals (i.e., Ca, Mg, Fe, Cu, Zn) were significantly different with sediment depths. When compared against Canadian sediment standards, most of the assessed metals were within the “no effect” level across the different sites and depths. The K, Ca, and Mg concentration showed extreme contamination across all sites and depths. The enrichment factor values for K, Ca, and Mg showed extremely high enrichment levels for all sites and sediment depths. The Na, Mn, Fe, Cu, Zn, and B concentration showed mostly background enrichment levels. All sediments across the different sites and sediment depths indicated deterioration of sediment quality. Pearson correlations suggest that most metals might have originated in a similar source as that of Mn and B, owing to a lack of significant differences. These results provide baseline information for the general management of the Nylsvley Wetland in relation to sediment metal pollution. The specific sources of metal contaminants also require further elucidation to further inform management efforts.


2014 ◽  
Vol 83 (4) ◽  
pp. 217-225 ◽  
Author(s):  
Eva Johanna Rode-Margono ◽  
K. Anne-Isola Nekaris

Predation pressure, food availability, and activity may be affected by level of moonlight and climatic conditions. While many nocturnal mammals reduce activity at high lunar illumination to avoid predators (lunarphobia), most visually-oriented nocturnal primates and birds increase activity in bright nights (lunarphilia) to improve foraging efficiency. Similarly, weather conditions may influence activity level and foraging ability. We examined the response of Javan slow lorises (Nycticebus javanicus Geoffroy, 1812) to moonlight and temperature. We radio-tracked 12 animals in West Java, Indonesia, over 1.5 years, resulting in over 600 hours direct observations. We collected behavioural and environmental data including lunar illumination, number of human observers, and climatic factors, and 185 camera trap nights on potential predators. Nycticebus javanicus reduced active behaviours in bright nights. Although this might be interpreted as a predator avoidance strategy, animals remained active when more observers were present. We did not find the same effect of lunar illumination on two potential predators. We detected an interactive effect of minimum temperature and moonlight, e.g. in bright nights slow lorises only reduce activity when it is cold. Slow lorises also were more active in higher humidity and when it was cloudy, whereas potential predators were equally active across conditions. As slow lorises are well-adapted to avoid/defend predators by crypsis, mimicry and the possession of venom, we argue that lunarphobia may be due to prey availability. In bright nights that are cold, the combined effects of high luminosity and low temperature favour reduced activity and even torpor. We conclude that Javan slow lorises are lunarphobic – just as the majority of mammals.


Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 422
Author(s):  
Ramon Felipe Bicudo da Silva ◽  
Mateus Batistella ◽  
James D. A. Millington ◽  
Emilio Moran ◽  
Luiz A. Martinelli ◽  
...  

Agricultural systems are heterogeneous across temporal and spatial scales. Although much research has investigated farm size and economic output, the synergies and trade-offs across various agricultural and socioeconomic variables are unclear. This study applies a GIS-based approach to official Brazilian census data (Agricultural Censuses of 1995, 2006, and 2017) and surveys at the municipality level to (i) evaluate changes in the average soybean farm size across the country and (ii) compare agricultural and socioeconomic outcomes (i.e., soybean yield, agricultural production value, crop production diversity, and rural labor employment) relative to the average soybean farm size. Statistical tests (e.g., Kruskal–Wallis tests and Spearman’s correlation) were used to analyze variable outcomes in different classes of farm sizes and respective Agricultural Censuses. We found that agricultural and socioeconomic outcomes are spatially correlated with soybean farm size class. Therefore, based on the concepts of trade-offs and synergies, we show that municipalities with large soybean farm sizes had larger trade-offs (e.g., larger farm size was associated with lower crop diversity), while small and medium ones manifest greater synergies. These patterns are particularly strong for analysis using the Agricultural Census of 2017. Trade-off/synergy analysis across space and time is key for supporting long-term strategies aiming at alleviating unemployment and providing sustainable food production, essential to achieve the UN Sustainable Development Goals.


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