The effects of local filtering processes on the structure and functioning of native plant communities in experimental urban habitats

Despite a growing literature-base devoted to documenting biodiversity patterns in cities, little is known about the processes that influence these patterns, and whether they are consistent over time. In particular, numerous studies have identified the capacity of cities to host a rich diversity of plant species. This trend, however, is driven primarily by introduced species, which comprise a large proportion of the urban species pool relative to natives. Using an experimental common garden study, we assessed the relative influence of local assembly processes (i.e., soil environmental filtering and competition from spontaneous urban species) on the taxonomic and functional diversity of native plant communities sampled over four seasons in 2016-2018. Taxonomic and functional diversity exhibited different responses to local processes, supporting the general conclusion that species- and trait-based measures of biodiversity offer distinct insights into community assembly dynamics. Additionally, we found that neither soil nor competition from spontaneous urban species influenced taxonomic or functional composition of native species. Functional composition, however, did shift strongly over time and was driven by community-weighted mean differences in both measured traits (maximum height, Hmax; specific leaf area, SLA; leaf chlorophyll a fluorescence, chl a) and the relative proportions of different functional groups (legumes, annual and biennial-perennial species, C4 grasses, and forbs). In contrast, taxonomic composition only diverged between early and late seasons. Overall, our results indicate that native species are not only capable of establishing and persisting in vacant urban habitats, they can functionally respond to local filtering pressures over time. This suggests that regional dispersal limitation may be a primary factor limiting native species in urban environments. Thus, future regreening and management plans should focus on enhancing the dispersal potential of native plant species in urban environments, in order to achieve set goals for increasing native species diversity and associated ecosystem services in cities.

Conservation of endemic lizards in New Zealand cities

<p>Globally, biodiversity is in crisis. One contributing factor is the rapid urbanisation of the world’s population. Land cover change associated with urbanisation radically alters ecosystems, making them uninhabitable for many species. Additionally, people who live in cities often have reduced contact with nature and there are fears that a lack of nature experience may diminish concern for the environment and biodiversity among urbanites. For these reasons, people in cities are increasingly being encouraged and empowered to reduce environmental impacts and connect with nature through urban restoration and backyard conservation. Internationally, lizards are a common feature of urban biodiversity but in New Zealand, where many species are threatened, little is known about populations of endemic skinks and geckos in cities. In order to effectively manage urban lizard populations, greater knowledge is needed about where and how lizards are surviving in cities, and what potential exists for their restoration. I investigated species diversity and abundance of lizards in New Zealand cities, making comparisons with historical species distributions to inform urban restoration and investigating the potential role that participatory conservation might play in their protection. To collate current knowledge about past and present distributions of urban-dwelling lizards, I reviewed records for six New Zealand cities from published and unpublished literature and databases. Little research was identified from cities and the majority of lizard records were of one-off sightings, or surveys related to salvage or biosecurity operations. Comparing current species records with historical species distributions, it found that the diversity of lizards in all of the cities has declined dramatically since human colonisation. To begin to fill the identified knowledge gap and to provide baselines for future monitoring, I carried out skink surveys in four cities and trialled a citizen science project that collected public sighting records from residential backyards. Surveys undertaken in urban habitats captured four species of endemic skink: Oligosoma aeneum in Hamilton, O. polychroma, O. aeneum and O. ornatum in Wellington, O. polychroma in Nelson, and O. aff. polychroma Clade 5 in Dunedin. Site occupancy and number of captures were highly variable among the species and cities, with a very high proportion of sites occupied by skinks in Nelson and Wellington compared with Hamilton and Dunedin. Modelling showed O. polychroma catch per unit effort was positively related to rat tracking rates when grass cover was low but showed a negative relationship when grass cover was high. Higher proportions of urban land cover within 500 m were negatively associated with body condition. The public sightings website gathered more than 100 records from around the Wellington region over one summer, suggesting citizen science may be a cost-effective solution for building knowledge about lizards in residential gardens that are otherwise difficult to survey. While skink sightings were reported from all over the city, gecko sightings appeared in clusters. Compared with a random sample of street addresses, both skink and gecko sightings were more common closer to forest land cover, but only skink sightings were more common in backyards that were north facing. Finally, I administered a questionnaire survey to understand how socio- demographic characteristics relate to willingness to engage in three different pro-conservation activities that might benefit lizards: pest mammal trapping, biodiversity monitoring and pest mammal monitoring. Public willingness to engage in all three activities was positively related to respondents’ nature relatedness and nature dosage, while only the two monitoring activities were positively related to education. The relationship between willingness and nature relatedness was weaker for pest trapping than it was for the two monitoring activities, suggesting that willingness to trap may be determined by factors other than environmental concern. Native lizards are an important component of New Zealand’s urban biodiversity. Despite cities having lost significant proportions of their original lizard fauna, a wide variety of habitats in cities still support numerous species. Some of these species seem well adapted to cope with the challenges of urban living, while further research is required to understand whether populations of other species are stable or in decline. To ensure the persistence of lizards in cities, further surveys using a variety of methods should be undertaken to assess lizard diversity and abundance in urban habitats and understand population trends of rare and sparsely distributed species. Public sightings may provide a useful starting point for assessing distribution patterns and allowing the targeting of surveys. In the future, through urban restoration, cities may offer opportunities to conserve a larger proportion of endemic species by reintroducing species that have become regionally extinct.</p>

Conservation of endemic lizards in New Zealand cities

<p>Globally, biodiversity is in crisis. One contributing factor is the rapid urbanisation of the world’s population. Land cover change associated with urbanisation radically alters ecosystems, making them uninhabitable for many species. Additionally, people who live in cities often have reduced contact with nature and there are fears that a lack of nature experience may diminish concern for the environment and biodiversity among urbanites. For these reasons, people in cities are increasingly being encouraged and empowered to reduce environmental impacts and connect with nature through urban restoration and backyard conservation. Internationally, lizards are a common feature of urban biodiversity but in New Zealand, where many species are threatened, little is known about populations of endemic skinks and geckos in cities. In order to effectively manage urban lizard populations, greater knowledge is needed about where and how lizards are surviving in cities, and what potential exists for their restoration. I investigated species diversity and abundance of lizards in New Zealand cities, making comparisons with historical species distributions to inform urban restoration and investigating the potential role that participatory conservation might play in their protection. To collate current knowledge about past and present distributions of urban-dwelling lizards, I reviewed records for six New Zealand cities from published and unpublished literature and databases. Little research was identified from cities and the majority of lizard records were of one-off sightings, or surveys related to salvage or biosecurity operations. Comparing current species records with historical species distributions, it found that the diversity of lizards in all of the cities has declined dramatically since human colonisation. To begin to fill the identified knowledge gap and to provide baselines for future monitoring, I carried out skink surveys in four cities and trialled a citizen science project that collected public sighting records from residential backyards. Surveys undertaken in urban habitats captured four species of endemic skink: Oligosoma aeneum in Hamilton, O. polychroma, O. aeneum and O. ornatum in Wellington, O. polychroma in Nelson, and O. aff. polychroma Clade 5 in Dunedin. Site occupancy and number of captures were highly variable among the species and cities, with a very high proportion of sites occupied by skinks in Nelson and Wellington compared with Hamilton and Dunedin. Modelling showed O. polychroma catch per unit effort was positively related to rat tracking rates when grass cover was low but showed a negative relationship when grass cover was high. Higher proportions of urban land cover within 500 m were negatively associated with body condition. The public sightings website gathered more than 100 records from around the Wellington region over one summer, suggesting citizen science may be a cost-effective solution for building knowledge about lizards in residential gardens that are otherwise difficult to survey. While skink sightings were reported from all over the city, gecko sightings appeared in clusters. Compared with a random sample of street addresses, both skink and gecko sightings were more common closer to forest land cover, but only skink sightings were more common in backyards that were north facing. Finally, I administered a questionnaire survey to understand how socio- demographic characteristics relate to willingness to engage in three different pro-conservation activities that might benefit lizards: pest mammal trapping, biodiversity monitoring and pest mammal monitoring. Public willingness to engage in all three activities was positively related to respondents’ nature relatedness and nature dosage, while only the two monitoring activities were positively related to education. The relationship between willingness and nature relatedness was weaker for pest trapping than it was for the two monitoring activities, suggesting that willingness to trap may be determined by factors other than environmental concern. Native lizards are an important component of New Zealand’s urban biodiversity. Despite cities having lost significant proportions of their original lizard fauna, a wide variety of habitats in cities still support numerous species. Some of these species seem well adapted to cope with the challenges of urban living, while further research is required to understand whether populations of other species are stable or in decline. To ensure the persistence of lizards in cities, further surveys using a variety of methods should be undertaken to assess lizard diversity and abundance in urban habitats and understand population trends of rare and sparsely distributed species. Public sightings may provide a useful starting point for assessing distribution patterns and allowing the targeting of surveys. In the future, through urban restoration, cities may offer opportunities to conserve a larger proportion of endemic species by reintroducing species that have become regionally extinct.</p>

Main macroinvertebrate community drivers and niche properties for characteristic species in urban/rural and lotic/lentic systems

The effect of urbanization is often reflected both in lotic and lentic habitats, through changes in diversity and structural and compositional changes in macroinvertebrate communities. In this study, we focused on macroinvertebrate assemblage in lotic and lentic ecosystems of the Krąpiel River catchment area (NW Poland) with the following aims: (1) to determine the main driver in structuring lotic and lentic macroinvertebrate communities and the factors that influence them in urban versus rural landscapes; (2) to test whether the diversity of macroinvertebrate assemblages in urban lotic/lentic ecosystems is lower than that in rural landscapes; (3) to identify characteristic macroinvertebrate species for urban and rural lotic/lentic ecosystems; to (4) determine species tolerance ranges and species optimums, with special emphasis on characteristic “urban” and “rural” species. Distance from study sites to built-up areas and conductivity were the main factors contributing to the separation of urban vs. rural habitats. For lotic sites, temperature, the percentage of built-up area, insolation, and oxygen concentration were the main factors significantly associated with changes in community composition. For lentic sites, insolation, temperature, and BOD5 were recognized as the main factors which are significantly associated with changes in community composition. The results for lentic habitats were as expected: average species richness was higher in rural than in urban habitats. The characteristic species for each of the four habitat groups included Mideopsis orbicularis for Lentic rural habitats; Hygrobates longipalpis for Lotic rural habitats; Piona sp. for Lentic urban habitats; Mideopsis crassipes for Lotic urban habitats. Hygrobates longipalpis and Piona sp. were at the opposite sides with respect to the degree of urbanization. Result of this investigation has shown that the impact of urbanization and consequently the implementation of conservation measures should be viewed separately within the lentic and lotic gradient.

Cross-Context Responses to Novelty in Rural and Urban Small Mammals

The Anthropocene is the era of urbanization. The accelerating expansion of cities occurs at the expense of natural reservoirs of biodiversity and presents animals with challenges for which their evolutionary past might not have prepared them. Cognitive and behavioral adjustments to novelty could promote animals’ persistence under these altered conditions. We investigated the structure of, and covariance between, different aspects of responses to novelty in rural and urban small mammals of two non-commensal rodent species. We ran replicated experiments testing responses to three novelty types (object, food, or space) of 47 individual common voles (Microtus arvalis) and 41 individual striped field mice (Apodemus agrarius). We found partial support for the hypothesis that responses to novelty are structured, clustering (i) speed of responses, (ii) intensity of responses, and (iii) responses to food into separate dimensions. Rural and urban small mammals did not differ in most responses to novelty, suggesting that urban habitats do not reduce neophobia in these species. Further studies investigating whether comparable response patters are found throughout different stages of colonization, and along synurbanization processes of different duration, will help illuminate the dynamics of animals’ cognitive adjustments to urban life.