Context matters: the landscape matrix determines the population genetic structure of temperate forest herbs across Europe

Context Plant populations in agricultural landscapes are mostly fragmented and their functional connectivity often depends on seed and pollen dispersal by animals. However, little is known about how the interactions of seed and pollen dispersers with the agricultural matrix translate into gene flow among plant populations. Objectives We aimed to identify effects of the landscape structure on the genetic diversity within, and the genetic differentiation among, spatially isolated populations of three temperate forest herbs. We asked, whether different arable crops have different effects, and whether the orientation of linear landscape elements relative to the gene dispersal direction matters. Methods We analysed the species’ population genetic structures in seven agricultural landscapes across temperate Europe using microsatellite markers. These were modelled as a function of landscape composition and configuration, which we quantified in buffer zones around, and in rectangular landscape strips between, plant populations. Results Landscape effects were diverse and often contrasting between species, reflecting their association with different pollen- or seed dispersal vectors. Differentiating crop types rather than lumping them together yielded higher proportions of explained variation. Some linear landscape elements had both a channelling and hampering effect on gene flow, depending on their orientation. Conclusions Landscape structure is a more important determinant of the species’ population genetic structure than habitat loss and fragmentation per se. Landscape planning with the aim to enhance the functional connectivity among spatially isolated plant populations should consider that even species of the same ecological guild might show distinct responses to the landscape structure.

Getting Lost in the Matrix? On How the Characteristics and Arrangement of Linear Landscape Elements Influence Ecological Connectivity

ContextLinear landscape elements (LLEs) such as ditches and hedgerows can increase the ecological connectivity of habitat embedded within agricultural areas by acting as corridors for animal movement. However, we lack knowledge on how the spatial arrangement of LLEs influence dispersal, impeding our ability to offer robust advice on how best to add new LLEs to improve connectivity.ObjectivesTo examine how the width and spatial orientations of LLEs composing an intersecting network might influence connectivity across landscapes.MethodsWe used an individual-based dispersal model to simulate the stochastic movement of small organisms through stylised LLEs of different characteristics. Landscapes were composed of two habitat patches separated by a grid-like network of LLEs composed of two types: 1.) connecting-edges (touching patches on either end) and 2.) transecting-edges (running perpendicular to connecting-edges). By altering the numbers and widths of each LLE type we sought to understand the effect of these variables on inter-patch dispersal rates.ResultsIncreasing the number or width of connecting-edges improved connectivity but, conversely, increasing the number or width of transecting-edges reduced it. The greater freedom of movement offered by increasing numbers of transecting-edges may have inhibited connectivity, as individuals with limited perceptual-range were more likely to become trapped in complex networks and thus fail to navigate to suitable habitat patches.ConclusionsThe orientation of LLEs with respect to landscape resources greatly affects their impact on connectivity. The addition of LLEs to landscapes may decrease their connectivity for small, flightless species if they do not directly channel dispersers toward landscape resources.

The loss of woody linear landscape elements in agriculture landscape in Wielkopolska region (Poland) in 21th century

With the loss of natural and semi-natural habitats, the diversity and the amount of ecosystem services that can be provided in the agricultural landscape are diminishing, and self-regulatory abilities decrease. The aim of the research (72 sample plots – 1 x 1 km squares, mean time span equal to 8 years) was to recognise the changes in the number and length of woody (tree or shrub) linear landscape elements, and the number of solitary trees in the Wielkopolska region to verify how rapid development of agriculture in Poland in the 21st century affects the landscape structure. The analyses show a decline by 9.3% (from 2.17 to 1.97 km/km2) in length of woody linear elements, 7.4% (from 16.5 to 15.0 per km2) in number of woody linear elements, and 14.6% (from 28.8 to 24.4 per km2) in solitary trees. The loss was significantly faster in the period (2017-2018) of liberalisation of the regulations on tree and shrub removal, mainly due to a high rate of removal in plots located in an urbanized landscape. The decrease in length of woody linear elements occurred in all the categories of their location distinguished in the study (by 9-41% in a category). The highest loss occurred in the woody linear elements located along melioration ditches and water courses, along roads, and in the outskirt of towns. These changes are similar to those occurring in the 20th century in western Europe. The decrease in the number of woody linear landscape elements and solitary trees can be considered an indicator of the unsustainable agriculture management.

Structure Analysis of Hedgerows With Respect to Perennial Landscape Lines in Two Contrasting French Agricultural Landscapes

Characterizing the spatial distribution of hedgerows over landscapes is important for understanding the effects of this distribution on the dynamics of plant and animal populations. Because hedgerows are planted or managed, the authors hypothesized that their distribution depends on the presence of other linear landscape elements, namely, roads and channels. Using proximity analyses, the authors thus assessed how the spatial distribution of hedgerows was impacted by the position of these linear landscape elements and the spatial extent of this impact for two contrasting agricultural landscapes. The results indicate that hedgerows were generally associated at short distances with other elements (100-150 m). Hedgerows had different association patterns depending on their orientation in one of the two landscapes. In that same landscape, within-landscape heterogeneity was related to different association patterns. These results indicate that models of the spatial distribution of hedgerows would gain from being based on the location of roads and channels in the studied landscape.

The Importance of Linear Landscape Elements for Bats in a Farmland Area: The Influence of Height on Activity

In the past 50 years, widespread removal of hedges and hedgerows in many European regions, with a consequent reduction in biodiversity, has occurred as a result of farming intensification. Acknowledging the ecological importance of linear farmland landscape elements, many agro-environmental schemes provide financial support for the management, conservation and reconstruction of hedges and hedgerows. The efficacy of such initiatives, also aimed at bat conservation, could be enhanced by including the role of hedges and hedgerows correlated to the variability of their physical structure and to the surrounding landscape context. Linear landscape elements are in fact of great importance to bats, whose flight activity tends to increase in proximity to hedges and hedgerows, used both during foraging and as commuting routes. Nevertheless, information concerning the correlation between various physical structures of hedges and flight and foraging techniques in bats is still lacking. The present study analyses the activity of bats along two different hedge types, with and without trees, and in open spaces, in an area of the Padana plane (North-western Italy) as a function of different flight behaviours. Activity in bats appears higher along hedges than in open spaces but no significant differences are noted between the various hedge types under investigation. Foraging behaviour is primarily detected along hedges with trees but is lower along hedges without trees and in open spaces. This is particularly evident in bat species that have adapted to foraging in closed spaces surrounded by foliage (Myotis and Plecotus genera) or at the periphery of these environments (Pipistrellus genus), whereas it not seen species that forage in open spaces (Nyctalus genus). Hedge reconstruction aimed at bat conservation ought to, therefore, favour tall hedges with trees as opposed to low hedges without trees.

Hedgerows Have a Barrier Effect and Channel Pollinator Movement in the Agricultural Landscape

Agricultural intensification and the subsequent fragmentation of semi-natural habitats severely restrict pollinator and pollen movement threatening both pollinator and plant species. Linear landscape elements such as hedgerows are planted for agricultural and conservation purposes to increase the resource availability and habitat connectivity supporting populations of beneficial organisms such as pollinators. However, hedgerows may have unexpected effects on plant and pollinator persistence by not just channeling pollinators and pollen along, but also restricting movement across the strip of habitat. Here, we tested how hedgerows influence pollinator movement and pollen flow. We used fluorescent dye particles as pollen analogues to track pollinator movement between potted cornflowers Centaurea cyanus along and across a hedgerow separating two meadows. The deposition of fluorescent dye was significantly higher along the hedgerow than across the hedgerow and into the meadow, despite comparable pollinator abundances. The differences in pollen transfer suggest that hedgerows can affect pollinator and pollen dispersal by channeling their movement and acting as a permeable barrier. We conclude that hedgerows in agricultural landscapes can increase the connectivity between otherwise isolated plant and pollinator populations (corridor function), but can have additional, and so far unknown barrier effects on pollination services. Functioning as a barrier, linear landscape elements can impede pollinator movement and dispersal, even for highly mobile species such as bees. These results should be considered in future management plans aiming to enhance the persistence of threatened pollinator and plant populations by restoring functional connectivity and to ensure sufficient crop pollination in the agricultural landscape.

Deriving a per-field land use and land cover map in an agricultural mosaic catchment

Detailed data on land use and land cover constitute important information for Earth system models, environmental monitoring and ecosystem services research. Global land cover products are evolving rapidly; however, there is still a lack of information particularly for heterogeneous agricultural landscapes. We censused land use and land cover field by field in the agricultural mosaic catchment Haean in South Korea. We recorded the land cover types with additional information on agricultural practice. In this paper we introduce the data, their collection and the post-processing protocol. Furthermore, because it is important to quantitatively evaluate available land use and land cover products, we compared our data with the MODIS Land Cover Type product (MCD12Q1). During the studied period, a large portion of dry fields was converted to perennial crops. Compared to our data, the forested area was underrepresented and the agricultural area overrepresented in MCD12Q1. In addition, linear landscape elements such as waterbodies were missing in the MODIS product due to its coarse spatial resolution. The data presented here can be useful for earth science and ecosystem services research. The data are available at the public repository Pangaea (doi:110.1594/PANGAEA.823677).

Deriving a per-field land use and land cover map in an agricultural mosaic catchment

Detailed data on land use and land cover constitutes important information for Earth system models, environmental monitoring and ecosystem services research. Global land cover products are evolving rapidly, however, there is still a lack of information particularly for heterogeneous agricultural landscapes. We censused land use and land cover field by field in an agricultural mosaic catchment Haean, South Korea. We recorded the land cover types with additional information on agricultural practice and make this data available at the public repository Pangaea (doi:10.1594/PANGAEA.823677). In this paper we introduce the data, its collection and the post-processing protocol. During the studied period, a large portion of dry fields was converted to perennial crops. A comparison between our dataset and MODIS Land Cover Type (MCD12Q1) suggested that the MODIS product was restricted in this area since it does not distinguish irrigated fields from general croplands. In addition, linear landscape elements such as water bodies were not detected in the MODIS product due to its coarse spatial resolution. The data presented here can be useful for earth science and ecosystem services research.