Using a spatially explicit population model to evaluate management scenarios for an invasive deer population

A predictive model for seagrass bed coverage (presence/absence at 1-m resolution) and ecological attributes of the bed, such as biomass and shoot density, would be a valuable management tool. But forming such a predictive model is complicated by a number of factors that strongly influence seagrass bed structure and our interpretation of its ecological function. The factors include the effects of waves and water depth (hydrodynamic setting) and the spatial and temporal scales of the sampling technique itself. In this study, we examined the coherence of predictions of seagrass cover and ecological attributes of temperate, mixed-species seagrass derived from two common sampling techniques, (video) line transect (commonly used by biologists) and grid-sampled surveys (often used in remote sensing). Mapping resolution was held constant at 1 m, and the two techniques applied across seagrass beds of varying coverage that reflected the effect of a hydrodynamic gradient ranging from patchy, high-energy beds to continuous cover, low-energy beds. We found that the prediction of seagrass coverage as a function of hydrodynamic setting can be improved not only by increasing the spatial extent of sampling at a fixed resolution (1 m), but also by ensuring that data for both dependent (e.g., percent cover) and independent (e.g., wave exposure) variables are averaged over similar scales (spatial extent and resolution). Large-scale features of the landscape, such as patches several meters in width, appeared to be best quantified by sampling over a large spatial extent, as with the video transects. Therefore, contiguous sampling over a broad spatial extent, as opposed to our numerous, somewhat smaller sampling (grid-sampled, 50 × 50 m areas) is the more appropriate strategy for predicting the probability of seagrass bed cover. Conversely, we found that ecological attributes of the seagrass bed (biomass, shoot density, and sediment composition) were best characterized by sampling over a shorter spatial extent (i.e., <50 m), indicating that very localized conditions may have influenced patterns of seagrass community attributes. Generalizing information about seagrass bed ecological attributes obtained from high-resolution samples (fine scale) taken over a broad spatial extent (coarse or landscape scale), as may occur with resource surveys and impact assessments, has the potential to be highly misleading, especially in patchy environments. The influence of sampling scale and survey method on the prediction of coverage and ecological attributes of seagrass beds reveals the need to carefully choose sampling designs to evaluate seagrass distribution and their associated ecological characteristics in the Beaufort, North Carolina (USA) area, and perhaps in other like habitats.

Inter-specific interactions around resources, such as nesting sites, are an important factor by which invasive species impact native communities. As resource availability varies across different environments, competition for resources and invasive species impacts around those resources change. In urban environments, changes in habitat structure and the addition of introduced species has led to significant changes in species composition and abundance, but the extent to which such changes have altered competition over resources is not well understood. Australia’s cities are relatively recent, many of them located in coastal and biodiversity-rich areas, where conservation efforts have the opportunity to benefit many species. Australia hosts a very large diversity of cavity-nesting species, across multiple families of birds and mammals. Of particular interest are cavity-breeding species that have been significantly impacted by the loss of available nesting resources in large, old, hollow-bearing trees. Cavity-breeding species have also been impacted by the addition of cavity-breeding invasive species, increasing the competition for the remaining nesting sites. The results of this additional competition have not been quantified in most cavity breeding communities in Australia. Our understanding of the importance of inter-specific interactions in shaping the outcomes of urbanization and invasion remains very limited across Australian communities. This has led to significant gaps in the understanding of the drivers of interspecific interactions and how such interactions shape resource use in highly modified environments. This knowledge deficit limits the effectiveness of conservation and management efforts to mitigate the loss of nest sites for native species and the effectiveness of ongoing management actions, such as the addition of artificial nesting boxes.To address these gaps, I examined the changes in native and invasive alien species use of resources across urban gradients and examined the factors shaping inter-specific interactions to provide a mechanistic framework for understanding competition at the community scale and invasive species impact on native cavity-nesting species. The research presented here provides the first community-level description of competitive interactions, describes a mechanism driving interaction intensity, and provides a method to predict where and when invasive species impacts on nesting are likely to occur. Additionally, I show that both habitat structure and predation are important processes for urban cavity-nesting birds. My work highlights that many birds make some use of urban habitats. While there remains much to learn about how urban environments can be improved to support long term persistence of individual species, conservation and management efforts can enhance the opportunity to help a large number of birds in Australian cities.This study established a large-scale field project that included eight field sites across southeast QLD and NSW. The study was designed along both regional-scale invasion gradients, with focus on the Common (Indian) myna (Acridotheres tristis), and local-scale urbanization gradients. I discovered that interaction webs around tree hollows in urban environments are dominated by a small number of highly aggressive species, including the invasive common myna and that interaction frequency between species was positively correlated with the overlap in preferred breeding sites (breeding niche; Chapter 2). To investigate how breeding niche overlap can be applied to a community with many unstudied invasive species, I examined the extent of niche overlap between species in the cavity-breeding birds of Tasmania detailing the potential interaction network for the island (Chapter 3). I discovered that niche overlap predicted important inters-specific interactions and that most native cavity-nesting species potentially face increased competition for nesting sites as a result of the addition of multiple invasive species.In Chapter 4, I examined how birds use supplementary nesting sites (i.e, nest boxes) varied across urban environments in different landscape contexts across New South Wales and Queensland), and across cities which have been invaded for different lengths of time. This was aimed at understanding the importance of artificial nest boxes as supplementary resources in areas with limited breeding cavities due to human impacts. There was high variation in the rates of nest box use both by invasive and native species such that the importance of nest boxes as supplemental nesting sites will differ across cities. I found that many nesting attempts in the nest boxes failed, highlighting the need to account for both competition and predation when designing and deploying nest boxes.Finally, in Chapter 5, I explored patterns in the community composition of urban bird communities. This allowed me to test the impacts of regional invasion dynamics and local variation in habitat on avian community richness and abundance. I discovered that increasing habitat structure and decreasing abundance of despotic species (i.e., species which influence community composition through aggressive interactions such as the noisy miner) predicted greater native species richness. More broadly the work presented in this thesis highlights that urban conservation efforts will be improved by a better including into management actions and future work the factors influencing breeding dynamics and resource use.

Owing to climate change-induced global warming, the frequency and duration of extremely hot events over the Iberian Peninsula (IP), such as heatwaves, are expected to continue to increase. This study shows the change of individual and monthly concurrent extremely hot events and burned area in the IP in the recent period of 1998–2015, compared with the reference period 1980–1997. Results show a dichotomic behaviour, with June and August showing an increase in extremely hot events and July and September showing many regions with a decrease, both in individual and concurrent events (most prominently in September). Furthermore, regions with such increases also show a change in spatial extent, with a greater area simultaneously affected by the two extremes (particularly in June). Also, even though the incidence of large burned areas decreased in north-western Spain in July and August, these increased in June. Indeed, together with more extreme heat events observed in the region, an increase in burned area was also found in June. This work paves the way for future studies to delve into the causes and effects of extreme heat events over the IP, to raise awareness of the need by forest authorities of developing early warning systems.

Sediment echo sounder data are routinely collected during research cruises with a geophysical or geological programme. This has resulted in the accumulation of huge amounts of sub-bottom data over the last decades (more than 30,000 survey lines of variable length in the Baltic Sea for the IOW alone), which are often not further interpreted. On the other hand, the value of these datasets for research and industry is increasing, as new regulations (e.g. related to the establishment of marine protected areas) and offshore infrastructure (e.g. wind farms) often prohibit the collection of new survey data. Current topics of interest in the Baltic Sea include the reconstruction of the Late Pleistocene to Holocene palaeogeography of the Baltic Sea and the identification of fluid flow and free methane in the subsurface. The latter can be used to assess the potential release of methane from carbon-rich sediments accumulating in the Baltic Sea basins by identifying the extent, depth and temporal variation of free gas surfaces (e.g. due to seasonal effects and changing wind conditions) in sediment echosounder data. Free gas in the subsurface and water column is readily identified in sediment echosounder and low-frequency multibeam echosounder data due to the increase in acoustic impedance between water-saturated sediments and gas. &amp;#160;Information on methane release is needed to assess the suitability of natural sediments in the Baltic Sea basins as a long-term carbon sink. The methane reservoirs in the southern Baltic Sea are related to various sedimentary and tectonic situations. The frequent generation of methane due to organic carbon accumulation, which is released into the water column and potentially the atmosphere, would have an antagonistic effect on carbon burial. Due to the large amount of data available, a deep learning model (U-Net) is trained on sediment echo sounder data from the Arkona Basin in the southern Baltic Sea to identify free gas surfaces and their depth below the surface. The parameters of the free gas surfaces are related to the thickness of the Late Pleistocene and Holocene sedimentary units (Baltic Ice Lake, Ancylus Lake and Littorina Sea). Repeated lines of sediment echo sounder data allow assessment of changes in spatial extent and depth of free gas through time.

The Tonle Sap or Great Lake of Cambodia is the largest freshwater lake in Southeast Asia, exhibiting large changes in spatial extent between the wet and dry seasons. The extensive wetlands around the Tonle Sap support a high level of biodiversity of great importance not only to the Tonle Sap but to the entire Mekong river system. Time-series of MODIS 500 m 8 day surface reflectance product imagery covering the period 2000-2005 were used to establish seasonal flooding cycles and flooding extents, and ASTER surface reflectance product was used to map vegetation distributions. Water resource use on the Mekong upstream of the Tonle Sap is reducing and moderating the monsoonal flood pulse which sustains the lake and floodplain system. This can be linked to the timing of large dam construction within the Mekong River basin. There is an urgent need to develop more effective cross-border management plans and cooperation for the water resources of the Mekong system before the unique and economically important Tonle Sap region slips into further decline.

1. Faced with the prospect of dealing with several hundred or even thousands of habitat sites, environmental managers in dense pond landscapes often have insufficient information. 2. In addition, there is a need to treat pond habitats as a totality, in that the intervening terrestrial matrix is relevant to the distribution and persistence of certain species. 3. Part of the terrestrial matrix is concerned with the spatial distribution of ponds and their ‘connectedness’, termed here ‘pondscape’. 4. An initial approach to delineating ‘pondscape’ is demonstrated. Such delineation enables environmental managers not only to conceptualize core areas of pond habitat, but also to trace changes in spatial extent and form, and to predict (and where necessary mitigate) changes arising from proposed development. 5. Though the approach is in part an abstraction, it also provides the advantages of synoptic description, monitoring and planning evaluation. © 1997 John Wiley & Sons, Ltd.

Invasive species have substantial impacts across the globe. While management efforts should aim to minimize undesirable impacts, we have a poor understanding of how impacts of a given invasive species vary spatially. Here, we develop a framework for considering heterogeneity of invasive species impacts that allows us to explore the range of possible spatial patterns of impact. This framework incorporates two factors—how invasive species abundance varies among sites (i.e., abundance distributions) and how invasive species impact varies as a function of abundance (i.e., abundance–impact curves). Combining these two factors allows for the creation of probability distributions that represent how invasive species impacts may vary spatially among sites. We used published abundance distributions and inferred abundance–impact curves to generate impact distributions for two problematic invasive species—zebra mussel and Eurasian watermilfoil—across lakes in Wisconsin, USA. Impact distributions of these species tended to be right‐skewed (i.e., the majority of sites had low impacts), although the tail thickness varied. We also simulated how a broader range of combinations of invasive species abundance distributions and abundance–impact curves produce different patterns of invasive species impact. These simulations illustrate a remarkable diversity of invasive species spatial impact patterns—probability distributions of impact were left‐skewed, right‐skewed, bimodal, and normal. Total landscape‐level impacts, estimated by summing site‐level impacts, were similarly variable depending on the distribution of site‐level impacts. Our results indicate that invasive species abundance and abundance–impact curves ultimately affect how invasive species impacts are distributed across the landscape, which has important implications for invasive species management.

Environmental managers struggle with communicating accurate and relevant information and with gaining trust from the communities they serve, problems that are especially pronounced in minority and colonized communities. An important step in developing successful management strategies is partnering directly with the communities involved, but community perceptions are rarely surveyed thoroughly when developing these strategies. We held discussions with 73 people across 22 small groups about their perceptions of environmental issues, with a focus on invasive species, on the island of Guåhan (Guam), a US island territory with a long and continued history of colonization by Western countries. We conducted these small group discussions with long‐time residents to learn about their environmental concerns and perceptions of invasive species and management efforts. Using grounded theory, we identified themes concerning apathy, proenvironmental behaviors, frustrations with efficacy, and disconnectedness from environmental decision‐making among residents of Guåhan. Residents expressed feeling disconnected from management decisions, which they critiqued as ineffective, but largely felt helpless to affect. Still, residents related to us their proenvironmental behaviors (e.g., picking up litter and controlling invasive species) and expressed a desire to learn more about management efforts. Our results highlight a clear need for improvement and expansion of engagement with Guåhan residents about environmental management, as well as opportunities to engage with a concerned and potentially proactive community.

There is considerable debate about the role of competition in shaping species distributions over broad spatial extents. This debate has practical implications because predicting changes in species' geographic ranges in response to ongoing environmental change would be simpler if competition could be ignored. While this debate has been the subject of many reviews, recent literature has not addressed the rates of relevant processes. This omission is surprising in that ecologists hypothesized decades ago that regional competitive exclusion is a slow process. The goal of this review is to reassess the debate under the hypothesis that competitive exclusion over broad spatial extents is a slow process. Available evidence, including simulations presented for the first time here, suggests that competitive exclusion over broad spatial extents occurs slowly over temporal extents of many decades to millennia. Ecologists arguing against an important role for competition frequently study modern patterns and/or range dynamics over periods of decades, while much of the evidence for competition shaping geographic ranges at broad spatial extents comes from paleoecological studies over time scales of centuries or longer. If competition is slow, as evidence suggests, the geographic distributions of some, perhaps many species, would continue to change over time scales of decades to millennia, even if environmental conditions did not continue to change. If the distributions of competing species are at equilibrium it is possible to predict species distributions based on observed species–environment relationships. However, disequilibrium is widespread as a result of competition and many other processes. Studies whose goal is accurate predictions over intermediate time scales (decades to centuries) should focus on factors associated with range expansion (colonization) and loss (local extinction), as opposed to current patterns. In general, understanding of modern range dynamics would be enhanced by considering the rates of relevant processes.

A significant environmental change took place in the middle course of the Obra River (western Poland). The natural river bed pattern was replaced here by three artificial canals in the beginning of the 19 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century. Before that time the Obra River bed had been characterized by various river patterns (multi-channel, meandering and disappearing in wetlands). GPR (ground-penetrating radar) surveys and the analysis of historical maps and satellite and aerial images were conducted to retrace the natural river course and changes of spatial extent of Obrzańskie Lake. Two types of the Obra river patterns, which had been functioning here before the period of the hydrotechnical works, were retraced: a large scale meandering pattern and a relatively smaller scale multi-channel pattern indicating features of anastomosing river. The transformation from the meandering to multi-channel pattern might have been caused by climatic changes and/or forming a bifurcation to the Odra River. Historical maps indicated that the multi-channel pattern was active in the second half of the 18 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century. Next, the multichannel pattern was artificially transformed into the North Obra Canal. Furthermore, the shorelines of Obrzańskie Lake from the period preceding the hydrotechnical works and from the 19 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century were delineated on the basis of the geophysical and remote sensing surveys. Before the anthropogenic intervention, the lake had been directly connected with a network of the Obra channels. Construction of the North Obra Canal resulted in significant decrease of the lake's surface. The presented results may be used in a restoration project aiming to reconstruct the natural river course. Such intervention would increase natural values of the middle Obra valley and influence development of tourism in this area.

Invasive alien species are major driver of socio-ecological changes, and pose threats to protected areas (PAs) and native biodiversity globally. To reduce their impacts, management effort should be timely, and guided through stakeholder engagement. This study investigated the level of community awareness, and documented perceptions and stakeholder participation in management of invasive alien plant species (IAPS) in ten of Nepal's twenty PAs (five from each Tarai-Siwalik and Mountain regions). It draws on focus group discussions (n = 60) and key informant interviews (n = 47). We found that people had substantial local knowledge of IAPS and had been substantially impacted by them without having knowledge of their exotic nature. Reported impacts included native species loss, increased weeding time, crop loss, reduced forage availability, and reduced forest regeneration. Lantana camara, Mikania micrantha, Ageratina adenophora and Ageratum houstonianum were the most problematic IAPS causing both ecological and socio-economic impacts. Management efforts were sporadic, inadequate and rarely guided by formal plans or programs. Regional analysis showed that the PAs located in the Tarai-Siwalik regions (southern lowland) experienced greater invasion impacts but received marginally more management than the mountain PAs. While efforts have been made to control IAPS both by local communities and PA authorities at few locations in the Tarai-Siwalik region, the lack of such efforts despite growing problems in the mountain PAs with unique biodiversity is a matter of great conservation concern. Overall, limited participation among stakeholders, along with very low resource mobilization are the key barriers to effective management of IAPS in Nepal's PAs.

Context Precise and accurate methods are essential to assess wildlife populations for sound management. We surveyed a managed population of fallow deer (Dama dama) in a Mediterranean environment in Italy, where this non-native ungulate has a negative impact on biodiversity. Aims We compare nocturnal distance-sampling (deer are detected by thermal imagery at night) population estimates with demographic projections of the same population. Methods We estimated natural survival in fawns (0.86), yearlings (0.83), adult males (0.70) and adult females (0.90) using capture–mark–recapture. By integrating survival estimates with population structure, reproductive traits and harvest data, we performed demographic projections. We performed nocturnal distance sampling on foot by using a thermal imagery once a year (in autumn) from 2001 to 2005. We walked 75–77 km (71 transects) per each survey. Key results We showed that our survey design met distance-sampling assumptions. Distance sampling and demographic projections yielded similar and precise (12.6% &amp;lt; CV &amp;lt;24.1%) population estimates, showing a decreasing (–164.64 deer year–1) population trend from 2755 deer in 2001 to 1877 in 2005. Conclusions We showed that nocturnal distance sampling is useful to monitor wild deer populations in forests effectively and that it represents a cost-effective tool to develop sounded management policy for this non-native species. We also provided, for the first time, a comprehensive stochastic population model for fallow deer in a Mediterranean environment. Using these population estimates, managers could reduce fallow deer population size to a level compatible with the conservation of the endangered Italian roe deer and improve forest regeneration. Implications Nocturnal distance sampling can be used to assess ungulate population living in dense forested habitats effectively and efficiently.

Current management in national and state forests has important but limited impacts on sustaining oaks in temperate forests of the eastern U.S

Identifying and understanding functional process domains (sensu Montgomery, 1999) in rivers is paramount for linking the physical habitat template to ecosystem structure and function. To date, efforts to do this have been rare, especially in large rivers, as they require appropriate tools for quantifying habitat heterogeneity with fine-scale resolution across broad spatial extents. In this study, we used side-scan sonar technology to map riverbed substrate at six sites in the Yellowstone and Missouri rivers. Substrate maps were then analyzed and visualized using geospatial analysis to relate fine-grained spatial substrate patterns to process domain structure. Our findings revealed two distinct nested domains of substrate patchiness, suggesting that different factors are responsible for shaping patterns of substrate at different scales. Although small-scale patchiness in substrate was likely driven by internal, or autogenic, physical processes, patterns at larger segment extents (>3 km) were often driven by abrupt transitions in habitat related to exogenous factors such as lateral erosion of talus, tributary inputs, and bank armoring. Additionally, we found that heterogeneity in benthic substrate increased with spatial extent at all of our study sites; however, this relationship was lower in the Missouri River, which is altered by impoundment. Our study represents one of the first efforts to relate benthic habitat heterogeneity to nested process domain structure in large riverscapes, and offers a unique perspective for linking landscape processes, geomorphological habitat heterogeneity, and biological structure and function in large rivers.

Species loss is occurring globally at unprecedented rates, and effective conservation planning requires an understanding of landscape characteristics that determine biodiversity patterns. Habitat heterogeneity is an important determinant of species diversity, but is difficult to measure across large areas using field-based methods that are costly and logistically challenging. Satellite image texture analysis offers a cost-effective alternative for quantifying habitat heterogeneity across broad spatial scales. We tested the ability of texture measures derived from 30-m resolution Enhanced Vegetation Index (EVI) data to capture habitat heterogeneity and predict bird species richness across the conterminous United States. We used Landsat 8 satellite imagery from 2013-2017 to derive a suite of texture measures characterizing vegetation heterogeneity. Individual texture measures explained up to 21% of the variance in bird richness patterns in North American Breeding Bird Survey (BBS) data during the same time period. Texture measures were positively related to total breeding bird richness, but this relationship varied among forest, grassland, and shrubland habitat specialists. Multiple texture measures combined with mean EVI explained up to 41% of the variance in total bird richness, and models including EVI-based texture measures explained up to 10% more variance than those that included only EVI. Models that also incorporated topographic and land cover metrics further improved predictive performance, explaining up to 51% of the variance in total bird richness. A texture measure contributed predictive power and characterized landscape features that EVI and forest cover alone could not, even though the latter two were overall more important variables. Our results highlight the potential of texture measures for mapping habitat heterogeneity and species richness patterns across broad spatial extents, especially when used in conjunction with vegetation indices or land cover data. By generating 30-m resolution texture maps and modeling bird richness at a near-continental scale, we expand on previous applications of image texture measures for modeling biodiversity that were either limited in spatial extent or based on coarse-resolution imagery. Incorporating texture measures into broad-scale biodiversity models may advance our understanding of mechanisms underlying species richness patterns and improve predictions of species responses to rapid global change.