Wildlife has existed in urban areas since records began. However, the discipline of urban ecology is relatively new and one that is undergoing rapid growth. All wildlife in urban areas will interact with humans to some degree. With rates of urbanisation increasing globally, there is a pressing need to understand the type and nature of human–wildlife interactions within urban environments, to help manage, mitigate or even promote these interactions. Much research attention has focussed on the core topic of human–wildlife conflict. This inherent bias in the literature is probably driven by the ease with which it can be quantified and assessed. Human–wildlife conflicts in terms of disease transmission, physical attack and property damage are important topics to understand. Equally, the benefits of human–wildlife interactions are becoming increasingly recognised, despite being harder to quantify and generalise. Wildlife may contribute to the provision of ecosystem services in urban areas, and some recent work has shown how interactions with wildlife can provide a range of benefits to health and wellbeing. More research is needed to improve understanding in this area, requiring wildlife biologists to work with other disciplines including economics, public health, sociology, ethics, psychology and planning. There will always be a need to control wildlife populations in certain urban situations to reduce human–wildlife conflict. However, in an increasingly urbanised and resource-constrained world, we need to learn how to manage the risks from wildlife in new ways, and to understand how to maximise the diverse benefits that living with wildlife can bring.

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Human–wildlife interactions in urban areas: a review of conflicts, benefits and opportunities

Plant specimens stored in herbaria are being used as never before to document the impacts of global change on humans and nature. However, published statistics on the use of biological collections are rare, and ecologists lack quantitative data demonstrating the relevance to science of herbarium specimens. I found 382 studies with original data that used herbarium specimens to document biogeographical patterns or environmental changes. Most studies are less than 10 years old, and only 1.4% of the herbarium specimens worldwide have been used to answer biogeographical or environmental questions. The vast majority (82%) of papers dealt with vascular plants, but some studies also used bryophytes, lichens, seaweeds and fungi. The herbarium specimens were collected from all continents, but most of the studies used specimens from North America (40% of studies) or Europe (28%). Many types of researches (conservation, plant disease, plant invasion, pollution, etc.) can be conducted using herbarium specimens. Climate change, and especially phenological reconstructions, are clearly emerging research topics. By group, small herbaria ( 1,000,000 specimens) for biogeographical and environmental research, but in most cases, only large facilities provide specimens collected worldwide. The median number of specimens per study in papers using computerized collections (15,295) was much higher than for papers that did not include electronic data (226). The use of molecular analyses to investigate herbarium specimens is still relatively unexplored, at least from biogeographical and environmental points of view. Combined with recently developed procedures to correct biases, herbarium specimens might provide in the near future exciting additional spatio-temporal insights that are currently unimaginable.

Biological collections in an ever changing world: Herbaria as tools for biogeographical and environmental studies

Given the increasing prevalence of cities, a better mechanistic and functional understanding of plant responses to urbanisation will assist biodiversity conservation and the provision of ecosystem services. Plant functional traits offer an opportunity to do this. To explore the relationship between plant traits and the urban environment, we synthesised the results of 29 studies that specifically examined plant traits or niche indicators (e.g. Ellenberg numbers) of urban floras. Niche indicators for nutrients, temperature and alkalinity were found to consistently increase across many studies. Some plant traits (e.g. woodiness, seed mass and height) tended to increase in response to urbanisation, while other traits have mixed responses and many other traits are understudied. We propose that variability in the observed responses is linked to the consistency and strength of urban stressors acting on those traits, and the importance of local factors. Our synthesis highlights the complexity of urban plant–environment interactions with many traits influenced by multiple abiotic, biotic and disturbance effects of urbanisation. Multiple stressors make it difficult to detect trends in urban plant trait signatures unless one urban stressor drives a particularly strong response or multiple stressors act on the response in the same direction. While our review has developed a better understanding of how urbanisation may assemble urban floras, further advances can be gained through studies that focus on specific urbanisation processes, measurable morphological traits and data curation and analyses that facilitate meta-analysis.

/pdf/urbanisation-plant-traits-and-the-composition-of-urban-bep8gkmvf1.pdf

Urbanisation, plant traits and the composition of urban floras

Plant and fungal specimens in herbaria are becoming primary resources for investigating how plant phenology and geographic distributions shift with climate change, greatly expanding inferences across spatial, temporal, and phylogenetic dimensions. However, these specimens contain a wealth of additional data-including nutrients, defensive compounds, herbivore damage, disease lesions, and signatures of physiological processes-that capture ecological and evolutionary responses to the Anthropocene but which are less frequently utilized. Here, we outline the diversity of herbarium data, global change topics to which they have been applied, and new hypotheses they could inform. We find that herbarium data have been used extensively to study impacts of climate change and invasive species, but that such data are less commonly used to address other drivers of biodiversity loss, including habitat conversion, pollution, and overexploitation. In addition, we note that fungal specimens are under-explored relative to vascular plants. To facilitate broader application of plant and fungal specimens in global change research, we outline the limitations of these data and modern sampling and statistical tools that may be applied to surmount challenges they present. Using a case study of insect herbivory, we illustrate how novel herbarium data may be employed to test hypotheses for which few data exist, despite potentially large biases. With the goal of positioning herbaria as hubs for global change research, we suggest future research directions and curation priorities.

The unrealized potential of herbaria for global change biology

Human-dominated landscapes represent one of the most rapidly expanding and least-understood ecosystems on earth. Yet, we know little about which features in these landscapes promote sustainable wildlife populations. Historically, in urban areas, landowners have converted native plant communities into habitats dominated by nonnative species that are not susceptible to pest damage and require little maintenance. However, nonnative plants are also poor at supporting insects that are critical food resources for higher order consumers. Despite the logical connection, no study has examined the impact of nonnative plants on subsequent population responses of vertebrate consumers. Here, we demonstrate that residential yards dominated by nonnative plants have lower arthropod abundance, forcing resident Carolina chickadees (Poecile carolinensis) to switch diets to less preferred prey and produce fewer young, or forgo reproduction in nonnative sites altogether. This leads to lower reproductive success and unsustainable population growth in these yards compared with those with >70% native plant biomass. Our results reveal that properties landscaped with nonnative plants function as population sinks for insectivorous birds. To promote sustainable food webs, urban planners and private landowners should prioritize native plant species.

https://www.pnas.org/content/pnas/115/45/11549.full.pdf

Nonnative plants reduce population growth of an insectivorous bird

Summary


1 As human populations increasingly live in cities, urban floras and the ecosystem services they provide are under increasing threat Understanding the effects of urbanization on plants can help to predict future changes and identify ways to preserve biological diversity Relatively few studies document changes through time in the flora of a focal region and those that do primarily address European floras They often rely on contemporary spatial gradient studies as surrogates for changes with time



2 We compare historical species records (prior to 1940) with the current flora for Marion County, Indiana, USA, home to Indianapolis, the 13th largest city in the United States Specimens from the Friesner Herbarium of Butler University and other vouchered records for the county provided the basis for historical records Current records are derived from inventories of 16 sites conducted by Herbarium staff and other botanists over the past 15 years



3 Physiognomic group, wetland classification and nativity (native vs non-native) were determined for each species Fidelity to high-quality habitat was quantified using coefficients of conservatism (C-values)



4 The last 70 years have seen a significant turnover in species presence, most notably a decrease in native plant species number (24 per year) and quality, with an accompanying increase in non-native plants of 14 per year Loss of species has been non-random, with a disproportionate number of high-quality wetland plants lost The signature of past land use can be seen in physiognomic changes in the composition of the flora that reflect the shift from agriculture to urban/suburban land use



5 Many invasive non-native shrubs now present have escaped from cultivation, highlighting the combined threats of habitat conversion and human plant preference to native flora in cities These invasives likely present the greatest threat to remaining biodiversity



6 Synthesis This study demonstrates the value well-documented historical records, such as those housed in herbaria, can have in addressing current ecological issues

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Documenting effects of urbanization on flora using herbarium records.

Peri-urban natural areas, at the boundaries of cities and adjacent agricultural/ rural land, are subject to ecological threats endemic to both land use types. We used permanent plots to document changes in habitat quality by monitoring herbaceous-layer plant species presence and cover over a decade (1996/97 and 2007) in two peri-urban nature preserves in central Indiana, U.S.A. The preserves are comprised of different forest community types: wet-mesic depressional forest and mesic upland forest. Habitat characteristics, based on Floristic Quality Assessment parameters, showed only a single change for either preserve between survey years: wetness values were lower in the wet-mesic depressional site in 2007 than in 1996, indicating more plants with affinity for wet soil. No changes in community structure (total species richness, evenness, and diversity) were found. The number of nonnative species increased between survey years, especially in the wet-mesic depressional forest, where numbers went from zero to six, five of which are classified as invasive. There was considerable turnover in individual species presence, with perennial forb species the most likely species to be found in only 1 y or the other. Species did not rearrange themselves within plots, but completely appeared or disappeared from all plots within a preserve between the sample years, suggesting that species composition of the flora is dynamic. Management recommendations, including those related to evidence of heavy deer browse, are presented based on our findings. Repeat monitoring of our plots in future decades will allow quantification of any extinction debt that may now be in place due to the increased presence of nonnative species, especially invasive shrubs escaped from landscaping.

/pdf/changes-in-plant-species-composition-and-structure-in-two-2au1bxoxt3.pdf

Changes in Plant Species Composition and Structure in Two Peri-urban Nature Preserves over 10 Years

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship.

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Living More Than Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Indiana Plant Atlas

Urban forest fragments face challenges to habitat quality due to small size, isolation from larger natural areas, and close association with anthropogenic disturbance. Monitoring changes in vegetation can inform management practices targeted at preserving biodiversity in the face of these threats. Woollen’s Gardens is a high-quality mesic upland forest preserve in the city of Indianapolis, Indiana, USA, with a beechmaple older-growth forest and a significant display of showy spring wildflowers. The entire preserve was inventoried and quantitative vegetation analysis along seven 100 m transects was conducted in 2003 and again in 2016 to track changes. Data from both years document a high-quality flora with few non-native plants. Floristic Quality Index values for native species, derived from Floristic Quality Assessment, were 50.2 in 2003 and 47.3 in 2016. Native mean C-values of 4.5 and 4.3 for each year support that the site is comparable to the highest quality natural areas in central Indiana. Values declined little when non-natives were included, indicating non-natives are having little negative impact on the flora. Although non-natives comprised less than 10% of the flora, 11 of the 16 species are considered invasive in Indiana. In 2003, invasive Amur honeysuckle (Lonicera maackii) was among species in plots with the highest relative importance value. In 2016, invasive wintercreeper (Euonymus fortunei) was among these species. Limited public access to Woollen’s Gardens minimizes human disturbance, but invasive species are a threat to vegetation quality. Continuation of eradication efforts is strongly recommended before populations of these non-natives become more difficult to control.

/pdf/floristic-inventory-of-woollen-s-gardens-nature-preserve-wsqaurz3r7.pdf

Floristic Inventory of Woollen’s Gardens Nature Preserve, Indianapolis, Marion County, Indiana, USA, With Quantitative Vegetation Sampling of Permanent Plots in 2003 and 2016

Marcia E. Moore

Papers

Documenting effects of urbanization on flora using herbarium records.

Changes in Plant Species Composition and Structure in Two Peri-urban Nature Preserves over 10 Years

Living More Than Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Indiana Plant Atlas

Floristic Inventory of Woollen’s Gardens Nature Preserve, Indianapolis, Marion County, Indiana, USA, With Quantitative Vegetation Sampling of Permanent Plots in 2003 and 2016