Destruction of habitat is the major cause for loss of biodiversity. This volume presents the population ecology of Atlantic salmon and brown trout and how it is influenced by the environment in terms ...of growth, migration, spawning and recruitment.
•Habitat degradation influenced extinction in a wide range of landscapes.•Habitat composition outweighed configuration effects for all species.•Landscape quality shifted amount-fragmentation ...extinction thresholds.•Quality-induced extinction thresholds emerged in moderate and high degradation.•Degradation effects should be considered alongside habitat loss and fragmentation.
Habitat quality is a fundamental driver of species distributions and population outcomes but is often difficult to measure and compare alongside measures of habitat amount and fragmentation. Consequently, habitat quality is often omitted from many landscape-level habitat analyses or more indirectly or subjectively represented in resulting habitat management or conservation planning. Yet, the implications of this conceptual and planning omission are poorly understood. We lack general theory that identifies the conditions under which habitat quality is expected to play a vital role in characterizing local and regional population responses. Using a factorial simulation design, we examined the independent contributions of habitat quality, amount, and fragmentation to population persistence to identify the conditions under which habitat quality might be expected to play a more important role than those of habitat amount or fragmentation. We generated a wide range of fractal landscapes, independently varying in habitat amount, fragmentation, and quality in QRule. We simulated interactive animal movement, habitat selection, and persistence for r and K strategist species with short and long dispersal abilities using spatially explicit individual-based models developed in HexSim. Population abundance and extinction risk were recorded through time for each landscape-species combination and used to quantify the relative influence of habitat amount, fragmentation, and landscape quality on population outcomes. We found that habitat degradation influenced extinction risk through a wide range of landscape conditions and species attributes. The most severe extinction responses were observed in scenarios of combined habitat loss and degradation, suggesting that the interactive effects of these variables may greatly affect persistence. Landscape quality modified extinction risks associated with habitat amount-fragmentation thresholds, and we found evidence for quality-based extinction thresholds as habitat was degraded. The strength of landscape-level quality on extinction risk outcomes suggests that habitat degradation should be further investigated as a major driver of population responses to landscape change. A more inclusive paradigm may be required to elucidate the general influences landscape change on population extinction. Habitat degradation, along with habitat loss and fragmentation, should be explicitly considered when assessing the implications of landscape change on population extinction.
In this paper, we tested whether the spatial distribution of a given species in more or less fragmented and disturbed landscapes depends on the species habitat specialization. We studied 891 spatial ...replicates from the French Breeding Bird Survey (FBBS) monitored at least two years during 2001-2005, and two independent landscape databases measuring respectively landscape fragmentation and recent landscape disturbance on each FBBS replicate. We used a continuous habitat specialization index for the 105 most common bird species monitored by the FBBS. We further modelled the spatial variation in abundance of each species according to fragmentation and disturbance across FBBS replicates, accounting for habitat differences and spatial trends. We then tested whether more or less specialized species responded to landscape fragmentation and disturbance. We found that the more specialist a species, the more negative its spatial response to landscape fragmentation and disturbance. Although there was a very high variation around these tendencies indicating that there are many other drivers of species distribution, our results suggest that measuring specialization may be helpful in predicting which species are likely to thrive in human degraded landscapes. We also emphasize the need to consider both positive and negative species responses when assessing consequences of habitat change in communities.
A Clouded Leopard in the Middle of the Road is an eye-opening introduction to the ecological impacts of roads. Drawing on over ten years of active engagement in the field of road ecology, Darryl ...Jones sheds light on the challenges roads pose to wildlife—and the solutions taken to address them. One of the most ubiquitous indicators of human activity, roads typically promise development and prosperity. Yet they carry with them the threat of disruption to both human and animal lives. Jones surveys the myriad, innovative ways stakeholders across the world have sought to reduce animal- vehicle collisions and minimize road-crossing risks for wildlife, including efforts undertaken at the famed fauna overpasses of Banff National Park, the Singapore Eco-Link, "tunnels of love" in the Australian Alps, and others. Along the way, he acquaints readers with concepts and research in road ecology, describing the field's origins and future directions. Engaging and accessible, A Clouded Leopard in the Middle of the Road brings to the foreground an often-overlooked facet of humanity's footprint on earth.
Sage-grouse (Centrocercus spp.) are influencing rapidly evolving land management policy in the western United States. Management objectives for fine-scale vegetation characteristics (e.g., grass ...height >18 cm) have been adopted by land management agencies based on resource selection or relationships with fitness proxies reported among numerous habitat studies. Some managers, however, have questioned the appropriateness of these objectives. Moreover, it remains untested whether habitat–fitness relationships documented at fine scales (i.e., among individual nests within a study area) also apply at scales of management units (e.g., pastures or grazing allotments), which are many orders of magnitude larger. We employed meta-analyses of studies published from 1991 to 2019 to help resolve the role of fine-scale vegetation structure in nest site selection and nest success across the geographic range of greater sage-grouse (C. urophasianus) and evaluate the validity of established habitat management objectives. Specifically, we incorporated effects of study design and functional responses to resource availability in meta-regression models linking vegetation structure to nest site selection, and used a novel meta-analytic approach to simultaneously model vegetation structure and its relationship to nest success. Our approach tested habitat relationships at a range-wide extent and a grain size closely matching scales at which agencies make management decisions. We found moderate, but context-dependent, effects of shrub characteristics and weak effects of herbaceous vegetation on nest site selection. None of the tested vegetation characteristics were related to variation in nest success, suggesting nesting habitat–fitness relationships have been inappropriately extrapolated in developing range-wide habitat management objectives. Our findings reveal surprising flexibility in habitat use for a species often depicted as having very particular fine-scale habitat requirements, and cast doubt on the practice of adopting precise management objectives for vegetation structure based on findings of individual small-scale field studies.
Forest corridors are often considered the main instrument with which to offset the effects of habitat loss and fragmentation. Brazilian forestry legislation requires that all riparian zones on ...private landholdings be maintained as permanent reserves and sets fixed minimum widths of riparian forest buffers to be retained alongside rivers and perennial streams. We investigated the effects of corridor width and degradation status of 37 riparian forest sites (including 24 corridors connected to large source-forest patches, 8 unconnected forest corridors, and 5 control riparian zones embedded within continuous forest patches) on bird and mammal species richness in a hyper-fragmented forest landscape surrounding Alta Floresta, Mato Grosso, Brazil. We used point-count and track-sampling methodology, coupled with an intensive forest-quality assessment that combined satellite imagery and ground truthed data. Vertebrate use of corridors was highly species-specific, but broad trends emerged depending on species life histories and their sensitivity to disturbance. Narrow and/or highly disturbed riparian corridors retained only a depauperate vertebrate assemblage that was typical of deforested habitats, whereas wide, well-preserved corridors retained a nearly complete species assemblage. Restriction of livestock movement along riparian buffers and their exclusion from key areas alongside deforested streams would permit corridor regeneration and facilitate restoration of connectivity /// Los corredores forestales a menudo son considerados el principal instrumento mediante el cual se atenúan los efectos de la pérdida y fragmentación del hábitat. La legislación silvícola brasileña requiere que todas las zonas riparias en terrenos privados sean mantenidas como reservas permanentes y define anchura mínima de los bosques riparios amortiguadores que deben ser retenidos a lo largo de ríos y arroyos permanentes. Investigamos los efectos de la anchura y del estatus degradación del corredor en 37 sitios forestales riparios (incluyendo 24 corredores conectados a parches forestales extensos, 8 corredores forestales no conectados y 5 zonas riparias control embebidas en parches de bosque continuos) sobre la riqueza de aves y de mamíferos en un paisaje forestal hiperfragmentado en Alta Floresta, Mato Grosso, Brasil. Utilizamos métodos de conteo por puntos y muestreo de huellas, además de una evaluación intensiva de la calidad del bosque que combinó imágenes de satélite y datos de verificación en campo. El uso de corredores por vertebrados fue altamente específico, pero emergieron patrones generales dependiendo de las historias de vida de las especies y de su sensibilidad a la perturbación. Los corredores riparios angostos y/o muy perturbados retuvieron un ensamble de vertebrados muy pobre que fue típico de hábitats deforestados, mientras que los corredores amplios, bien preservados retuvieron un ensamble de especies casi completo. La restricción del movimiento de ganado a lo de los corredores y su exclusión de áreas clave a lo largo de arroyos deforestados permitiría la regeneración de corredores y facilitaría la restauración de la conectividad.
Aim
The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their ...unequivocal identification. Our goal was to develop a tool for assigning vegetation‐plot records to the habitats of the EUNIS system, use it to classify a European vegetation‐plot database, and compile statistically‐derived characteristic species combinations and distribution maps for these habitats.
Location
Europe.
Methods
We developed the classification expert system EUNIS‐ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set‐theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species‐to‐habitat fidelity and constancy (occurrence frequency) in the classified data set. Finally, we mapped the plot locations for each habitat.
Results
Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man‐made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination.
Conclusions
EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS‐ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment.
EUNIS Habitat Classification is a standard classification of European habitats. We developed the classification expert system EUNIS‐ESy, which assigns vegetation plots to EUNIS habitats based on their species composition and geographic location. We classified 1,261,373 vegetation plots from the European Vegetation Archive and determined characteristic species combinations and prepared distribution maps for 199 habitats at Level 3 of EUNIS hierarchy.
Identification of critical habitat is central to major conservation laws protecting endangered species in North America and around the world. Yet the actual ecological research that is required to ...identify which habitats are critical to the survival or recovery of species is rarely discussed and poorly documented. Here we quantitatively assess the information and methods used to identify critical habitat in the recovery strategies of 53 vertebrates at risk in Canada. Of the critical habitat identifications assessed, 17% were based on habitat occupancy information, 28% on habitat characteristics and (or) functions, and 40% assessed habitat suitability by linking functional use and biophysical characteristics. However, only 15% of the recovery strategies we evaluated examined relationships between habitat and population viability, abundance, individual fitness, or survival. Furthermore, the breadth of evidence used to assess critical habitats was weaker among long-lived taxa and did not improve over time. Hence, although any approach used to identify critical habitat is likely to be a step in the right direction in minimally protecting and maintaining habitats supporting critical life-cycle processes, there is a persistent gap between the widely recognized importance of critical habitat and our ability to quantitatively link habitats to population trends and individual fitness.
PDF
