Landscape moderation of biodiversity patterns and processes ‐ eight hypotheses

Bumblebees (Bombus spp.) are declining in most parts of Western Europe. Many studies have highlighted the role of agricultural intensification and urbanisation in this decline, and some have also shown the influence of landscape composition on bumblebee populations. However, very few studies have explored bumblebee communities prior to the onset of these major land use changes, and those studies that do are mostly based on low-resolution spatial data. Here, we perform a comparative analysis based on detailed landscape composition and bumblebee occurrence records between the early twentieth century (1910–1930) and the contemporary period (2013–2015) in four localities representative of Belgium. We show that bumblebee assemblages changed drastically over this period, and that the decline in richness was strongest in areas with the greatest increase in urbanization and agricultural intensification. The one locality still retaining a high proportion of grasslands, orchards and woodlands with the smallest overall change in landscape composition still hosts a rich bumblebee fauna, very similar than in the past. We provide recommendations for land use management based on these findings. We also warn about the importance of other factors such as land use intensity, climatic conditions and altitude, which should be included in any future study addressing changes in bumblebee populations related to land use changes.

Distinguishing the relative contributions of landscape composition and configuration change on ecosystem health from a geospatial perspective

In recent years, several vector-borne, parasitic or zoonotic diseases have (re)-emerged and spread in Europe and elsewhere with major health, ecological, socio-economical and political consequences. One of these diseases is leishmaniasis. In southwestern France, it is transmitted by two sandfly vectors (Phlebotomus ariasi and Phlebotomus perniciosus). The objective of this research was to assess the effects of land cover and land cover change and fragmentation on the spatial distribution of Phlebotomus ariasi in southwestern France. Using GIS and remote sensing techniques we analysed the relationships between vectors and landscape-level environmental variables based on time series of fine resolution satellite data over the last two decades. Environmental variables were extracted from Landsat TM images and included both landscape composition and configuration. Changes in landscape composition and configuration were analysed and a logistic regression was used to test the association between sandfly presence/absence and these variables. The study suggested that, although relevant changes in landscape composition and structure were not found between 1984 and 2003, there is a significant association with some environmental variables describing sandfly habitat.

Changes in landscape composition and configuration patterns of Sancaktepe Municipal District in the Asian side of Istanbul Metropolitan City of Turkey were analysed using landscape metrics. Class-level and landscape-level metrics were calculated from the land cover/land use data using Patch Analyst, an extension in the Arc View GIS. The land cover/land use data were derived from classified satellite images of Landsat Thematic Mapper of 2002 and 2009 for Sancaktepe District. There was evidence of increase in agglomeration process of built-up patches as indicated by the increases in mean patch size, decrease in total edge and number of patches between 2002 and 2009. The urban expansion pattern experienced overall was not fragmented but concentrated due to infilling around existing patches. Changes in Area-Weighted Mean Shape Index and Area-Weighted Patch Fractal Dimension Index indicated that the physical shapes within built-up, forest and bareland areas were relatively complex and irregular. A conclusion is made in this study that spatial metrics are useful tools to describe the urban landscape composition and configuration in its various aspects and certain decisions whether to approve a specific development in urban planning could, for example, be based on some measures of urban growth form or pattern in terms of uniformity and irregularity, attributable to the dynamic processes of agglomeration and fragmentation of land cover/land use patches caused by urban expansion.

The relative importance of deterministic and neutral processes in shaping assembly of communities remains controversial, partly due to inconsistencies between theoretical, empirical, and experimental studies. We investigate the interplay between local (productivity) and regional (size of species pool) assembly mechanisms in communities of phytoplankton and zooplankton in 72 experimental microcosms. Local environmental conditions were manipulated by varying the level of nutrients in the water (ambient, low, high). The size of regional species pool colonizing each microcosm was manipulated by mixing phytoplankton and zooplankton species from different numbers of source ponds (n = 2, 4, 8 and 16). Our results show that local communities assembled differently depending on the numbers of sources available for colonization. Microcosms with larger species pools supported greater numbers of species. In contrast, the effects of productivity led to different results across trophic groups. Phytoplankton communities were, on average, more diverse on more productive treatments, while zooplankton communities were more diverse under less productive treatments. Phytoplankton and zooplankton communities responded to both sources of variation, although the size of species pool was a better predictor of communities’ composition than the local effects of productivity. These results reinforce the view that community assembly is influenced by the interplay of both local and regional drivers but that the relative importance of these factors varies with trophic groups.

1 Species-rich semi-natural grasslands in Europe developed during prehistoric times and have endured due to human activity. At the same time, intensive grassland management or changes in land use may result in species extinction. As a consequence, plant diversity in semi-natural calcareous grasslands may be related to both historical and current human population density. 2 We hypothesize that current vascular plant diversity in semi-natural calcareous grasslands is positively correlated with the Late Iron Age (c. 800-1000 years ago) density of human settlements (indicated by Late Iron Age fortresses and villages) due to enhancement of grassland extent and species dispersal, and negatively correlated with current human population density due to habitat loss and deterioration. 3 We described the size of the community vascular plant species pool, species richness per 1 m(2) and the relative richness (richness divided by the size of the species pool) in 45 thin soil, calcareous (alvar) grasslands in Estonia. In addition to historical and current human population density we considered simultaneously the effects of grassland area, connectivity to other alvar grasslands, elevation above sea level (indicating grassland age), soil pH, soil N, soil P, soil depth, soil depth heterogeneity, geographical east-west gradient, precipitation and spatial autocorrelation. 4 Both the size of the community species pool and the species richness are significantly correlated with the Late Iron Age human population density. In addition, species richness was unimodally related to the current human population density. The relative richness (species 'packing density') was highest in the intermediate current human population densities, indicative of moderate land-use intensity. 5 Community species pool size decreased non-linearly with increasing soil N, and was highest at intermediate elevation. Small-scale richness was greater when sites were well connected and when the elevation was intermediate. Spatial autocorrelation was also significant for both species pool size and small-scale richness. 6 In summary, human land-use legacy from prehistoric times is an important aspect in plant ecology, which could be an important contributor to the current variation in biodiversity. (Less)

The causes of linear relationships between local species richness and the size of the actual species pool in closed subalpine meadow communities and open plant communities of the alpine stony substrate (the Greater Caucasus Mountains) were analyzed using a computer simulation model. The results demonstrated that this relationship is insufficient evidence for the variation of local species richness among communities is wholly or partly determined by regional processes (the species-pool hypothesis). A relatively proportional ratio between these variables can also arise where local species richness and the size of the species pool both depend on local processes, or where local species richness is determined by local factors alone while the size of the species pool is determined by both local and regional factors.

Intermediate human activities maximize dryland ecosystem services in the long-term land-use change: Evidence from the Sangong River watershed, northwest China

Change detection approaches based on historical maps are frequently used in fluvial geomorphology to reconstruct long‐term river trajectories and evaluate the level of functional degradation. On this basis, achievable rehabilitation goals may also be addressed. However, most of these studies explore the changes of land cover over time only through changes in the landscape composition, which is nevertheless not sufficient to assess accurately the river responses to natural and/or man‐made disturbances. In this study, we present that transition matrices and new metrics derived from this approach can be used to evaluate the land cover and ecotone area changes at multispatial scales on a 6 km long reach of the Upper Rhine. This study was based on the historical maps of 1828, 1838 and 1872 and using Open Street Map (OSM) for 2021. Our approach was targeting to assess (i) the composition and configuration of a fluvial landscape over time from pixel to landscape scale, (ii) the accurate location of land cover changes, their nature and their intensities, and (iii) the location, nature and diversity of the ecotone areas and their spatial complexities over time. The results showed that (i) the absence of changes in landscape composition over time cannot be interpreted as stability in the fluvial landscape in all cases, (ii) transition matrices are robust tools to face interpretation biases caused by conventional approaches based on landscape composition, because they allow us to trace the changes of each element of the transformed landscape elements. From this study, we indicate that the Rhine regulation induced a habitat and ecotone homogenization following the river correction works, which was exacerbated by the Rhine by‐passing, mainly due to the degradation of lateral connectivity between the main channel and the floodplain and global loss of the hydrosystem functionality.

Large animals provide crucial seed dispersal services, yet face continued threats and are susceptible to changes in landscape composition and configuration. Thus, there is a growing imperative to improve understanding of animal‐generated seed dispersal using models that incorporate spatial complexity in a realistic, yet tractable, way.We developed a spatially explicit agent‐based seed dispersal model, with disperser movements informed by biotelemetry data, to evaluate how landscape composition and configuration affect seed dispersal patterns. We illustrated this approach for the world's second largest ratite, the emu (Dromaius novaehollandiae), a highly mobile generalist frugivore considered an important long‐distance disperser for many plant species across Australia.When animal movement is unrestricted, model parameters related to seed gut passage largely determine seed dispersal kernels. However, as habitat loss and fragmentation increase, the extent of long‐distance dispersal events is reduced and seed shadows became progressively more aggregated. This effect is due to the emu not being able to move between disconnected parts of the landscape, with small changes in habitat structure causing decreased long‐distance dispersal.We simulated seed dispersal patterns generated by three commonly used generic models of animal movement – unbiased and biased correlated random walks and Lévy walks – to evaluate how different representations of movement affect estimations of animal movements and emergent seed dispersal patterns. Simulated movements informed by the emu biotelemetry data resulted in longer median seed dispersal distances than do the three generic models.Synthesis.Changes in landscape composition and configuration can dramatically alter patterns of zoochorous seed dispersal as they influence animal movement. However, when models are used to simulate the patterns of seed dispersal, decisions about how animal movement is represented also affect estimates of seed dispersal.

Most homeotherms in seasonal environments are faced with food shortage in winter or other unfavourable periods. A hypothesis is advanced that such animals make use of disturbances in climax ecosystems to survive and to exploit the more food-productive seasons. Then landscape composition will greatly influence the densities of breeding populations in their normal habitats. Evidence is given that food increases drastically in spring in climax or normal habitats, e.g. from increases in herbage biomass and its nutrient composition, indirectly from regional differences in litter size and from the unsaturated state of northern bird communities. Secondary successions and human cultivation are shown to bring new or increased food supply in winter. The landscape effect on breeding populations is related to seasonality, animal movements and distribution, predictability and successional states of disturbances. Landscape effects are traced for a series of Scandinavian homeotherms, ranging from cervids to migrant birds via some more or less synanthropic species. Recent changes in landscape composition are shown to have profoundly affected their breeding populations. However, in the long run certain predictable disturbances may be of no use for animals from other habitats due to competition from settled conspecifics. Some animals may have become adapted to exploit disturbances in climax ecosystems. Such adaptations may be as important as migration or hibernation in other species. Better knowledge of these adaptations or similar general characteristics and of recent changes in landscape composition may enable us to interpret many changes in abundance which are now obscure.

Relationships between Danish organic farming and landscape composition

As human populations continue to grow, there is increasing demand to manage landscapes to increase the provisioning of multiple ecosystem services. However, this is challenging due to the negative (trade-off) and positive (synergistic) relationships that often exists among services. Understanding where and why these relationships occur should facilitate the implementation of better policies and strategies that can effectively manage multiple services simultaneously. However, our current understanding of what drives ecosystem service relationships, and the consequences for managing ecosystem services, remains limited. In this thesis, I address this by demonstrating the importance of understanding the drivers behind ecosystem service provision and the resulting trade-offs and synergies, and then apply this understanding to manage complex landscapes for multiple ecosystem services.In chapter 1, I discuss the conceptual theory behind ecosystem service relationships and how this information could be used to effectively manage multiple ecosystem services. I then outline the steps I undertake in this thesis to demonstrate this. I then conduct a literature review in chapter 2 to determine how the drivers of ecosystem service relationships, and the mechanisms linking these drivers to ecosystem service outcomes, are currently being investigated in assessments of ecosystem service synergies and trade-offs. I find that the majority of assessments of ecosystem service relationships do not explicitly identifying the drivers of these relationships. This is strongly related to the methods used to identify the trade-offs and synergies, with the less commonly used process-based approaches better equipped to explicitly identify the drivers underpinning ecosystem service relationships.I then develop models to identify the drivers underpinning the provisioning of multiple cultural ecosystem services in urban public greenspace, using the urban parks network of Brisbane, Australia, as a case study in chapter 3. Using data derived from a social survey and remotely sensed data, I demonstrate that the use of public parks for four cultural services (opportunities for physical exercise, nature interactions, relaxation and social interactions) are associated with spatial, environmental and facility characteristics of urban parks. However, physical exercise and social interactions are also driven by the socio-demographic characteristics of the people visiting the parks to receive these services. These results suggest that by introducing management actions that target specific variables within urban parks it may be possible to facilitate the provision of multiple cultural ecosystem services simultaneously.I then build upon the findings of chapter 3 to assess the implications of ecosystem service trade-offs and synergies on the management of multiple ecosystem services across the Brisbane parks network in chapters 4 and 5. In chapter 4, I conduct a scenario analysis to identify the trade-offs and synergies among the cultural ecosystem services identified in chapter 3 and carbon storage, and how these relationships vary under different revegetation management strategies commonly implemented in urban parks. I find that the relationships among the ecosystem services depend on the type of revegetation management strategy considered. This indicates that careful consideration of relationships among services could ensure the implementation of strategies that minimise trade-offs among services. In chapter 5 I use this underlying model to identify the optimal spatial allocation of multiple management actions to achieve targeted increases in the provision of carbon storage and the same set of cultural services across the Brisbane park network. I also consider the consequences of considering social equity in ecosystem service access and management and compare socially equitable and inequitable optimal solutions. I find that implementing strategies that consist of multiple management actions achieve greater increases in multiple ecosystem services. Furthermore, I find that accounting for social equity restricts the extent to which ecosystem service can be increased to, while also increasing management costs.Finally, in chapter 6 I synthesise the main findings of the previous chapters, and discuss the contributions of this thesis to the literature and future research directions. Currently, few studies explicitly identify the drivers of ecosystem service relationships, but this thesis demonstrates that considering drivers is vital to managing multiple ecosystem services effectively. Although this can be challenging, explicitly incorporating these drivers into assessments of ecosystem service relationships can ensure more effective management of multiple ecosystem services across landscapes. Ideally, to improve the management of multiple ecosystem services simultaneously, future research should focus on working towards more causally-explicit approaches to identify ecosystem service relationships, and on incorporating social equity into ecosystem service management strategies.

Intensification of land‐use in agricultural landscapes is responsible for a decline of biodiversity which provide important ecosystem services like pest‐control. Changes in landscape composition may also induce behavioural changes of predators in response to variation in the biotic or abiotic environment. By controlling for environmentally confounding factors, we here demonstrate that the orb web spider Araneus diadematus alters its web building behaviour in response to changes in the composition of agricultural landscapes. Thereby, the species increases its foraging efficiency (i.e. investments in silk and web asymmetry) with an increase of agricultural land‐use at intermediate spatial scales. This intensification is also related to a decrease in the abundance of larger prey. A negative effect of landscape properties at similar spatial scales on spider fitness was recorded when controlling for relative investments in capture thread length. This study consequently documents the web building flexibility in response to changes in landscape composition, possibly due to changes in prey availability.

Summary The regional species pool is a set of species available in a region and ecologically suitable for growing in the particular environment occupied by a local community. As species pools are largely influenced by evolutionary processes such as the conservation of ecological niches within lineages we hypothesize that the size of the regional species pool increases with the variety of distinct phylogenetic lineages represented in a local community. We contrast this with hypotheses invoking diversification of individual lineages within environments or stochastic present‐day assembly of local communities. We calculated phylogenetic distinctness for a local community as the number of nodes separating two species averaged over all pairwise comparisons across a phylogenetic topology of a regional flora. We calculated the size of the regional species pool for a local community as the number of species in the regional flora that share the ecological niche position of the species constituting the local community. Analysing field‐layer communities across a wide range of environments, we indeed found that local communities composed of phylogenetically highly distinct species recruit from larger species pools than communities of low phylogenetic distinctness. Accounting for the presence of two particularly diversifying lineages (Poaceae and Cyperaceae) confirmed these results. These results help us to understand how the species pool was assembled throughout evolution in different types of environments (immigration vs. in situ radiation of individual lineages). The phylogenetic approach is of large practical value to infer the size of the regional species pool because phylogenies have become available for many groups of species worldwide, while knowledge of the species’ ecological requirements or habitat affiliation (needed for the classical definition of species pools) is often still lacking. Synthesis. We show that the size of the regional species pool can be predicted by the average phylogenetic distinctness between the species present in a local community. This approach contributes to the understanding of the causes of species richness in regional species pools and local communities. The approach is also an important tool for determining the size of the regional species pool when parameters other than species phylogeny are not known.