Landscape Structural Complexity Research Articles

Геосистемы юга Средней Сибири: методика и результаты картографирования

The сlassification of geosystem used in mapping is based on a system-hierarchic approach to detecting the co-involvement of landscape taxons. At the same time, we took into account the positioning of individual territories in the system of physical- geographical regionalization. The complexity of the landscape structure of the studied territory is due to its location at the junction of high- and lowland regions belonging to four physical-geographical areas. In the area under study, we identified and described more than 200 groups of fairies, which were then typed into classes of facies, geomes, and groups of geomes. Geoinformation mapping is performed using vector topographic basis and Earth remote sensing data. The decryption of synthesized space images was carried out manually and was based on field landscape surveys data. Digitization and indexing of landscape contours, creation, design and layout of the map were carried out in GIS MapInfo Professional. The cartographical analysis revealed regional differences in the complexity of landscape horizontal structures of high- and lowland regions, as well as the composition and structure of typological spectra of regional geosystems. Lowland geosystems mostly have a fairly uniform horizontal structure and large areas of landscape patterns. At the same time, mountain areas are characterized by considerable complexity and contrast of landscape structure.

Benefits of wildflower areas as overwintering habitats for ground-dwelling arthropods depend on landscape structural complexity

Wildflower areas are a popular agri-environment scheme to counteract the biodiversity loss in agro-ecosystems. While benefits for flower-visiting and predatory insects during the vegetation period were frequently shown, few studies addressed the suitability of wildflower areas as overwintering habitats. Here, we studied the significance of wildflower areas as overwintering habitats and whether their benefits vary with landscape context, i.e. the proportions of permanent semi-natural habitats such as hedges. We selected ten landscapes that encompassed independent gradients of proportions of permanent semi-natural habitats (e.g. hedgerows, ditches) and transient wildflower areas. The centres of the landscapes were pairs of wildflower areas and arable fields on which we sampled overwintering ground-dwelling arthropods by emergence traps. In total, we recorded 2838 overwintering individuals from 115 species of rove and carabid beetles as well as spiders. Abundance of rove beetle larvae, as well as species richness of adult rove beetles and spiders was significantly higher in wildflower areas than in arable fields. With respect to landscape context, abundance and species richness of adult rove beetles showed a hump-shaped relationship with the proportion of permanent semi-natural habitats. The abundance of adult carabid beetles showed a hump-shaped relationship with the proportion of transient wildflower areas, while the abundance of carabid beetle larvae showed a hump-shaped pattern with permanent semi-natural habitats. For the first time we showed that, similar to the vegetation period, benefits of wildflower areas as overwintering habitats for ground-dwelling arthropods depend on both local habitat characteristics as well as landscape context. Benefits of wildflower areas for overwintering were highest in simple landscapes with an intermediate proportion of either permanent semi-natural habitats or transient wildflower areas. Our results suggest that in order to sustainably maintain the functional guild of ground-dwelling arthropods, agricultural landscapes should provide both sown wildflower areas and permanent semi-natural habitats. Our results also support the general claim that semi-natural habitats should at least contribute 10–15% to agricultural landscapes in order to maintain the characteristic biodiversity in modern agro-ecosystems.

Mapping of geosystems in the south of the Yenisei Siberia for environmental assessment

Landscape mapping of the southern regions of Middle Siberia within the territory of the planned complex investment project “Yenisei Siberia” on collateral economic development of 3 regions (Krasnoyarsk Territory, Republics of Khakassia and Tyva) is carried out. Works were performed with using uniform geosystem classification based on systemic hierarchical approach to identification of a taxonomy of landscape units. It considers positioning of concrete territories and typological ranges of regional geosystems in the system of physical geographycal regionalization. The technique of mapping was based on the V.B. Sochava’s doctrine about geosystems and the principles of creation of hierarchical structure of geomers by integration of structural and structural-dynamic indicators. Own ideas of authors of geosystems classification received from experience of landscape mapping of other regions in the South of Siberia by drawing up the map are used. As a result of research a big variety of geosystems is revealed on the map through display of spatial differentiation of areals of distribution of geomers of a rank of group of fatsias is revealed. The complexity of landscape structure is caused by position of the territory of researches of a joint of four landscape regions.

Density of white-tailed deer in relation to vegetation in a landscape of northern Veracruz

The white-tailed deer, Odocoileus virginianus, is poorly known in the state of Veracruz, Mexico. In this paper we report the relationships between deer population density and vegetation variables in a landscape in Tantoyuca, northern Veracruz. Pellet groups and vegetation were sampled across 40 strip transects (500 x 2 m) in five locations from April to June 2014. The relationships between deer density and vegetation variables were evaluated with hierarchical agglomerative clustering methods to group tree species per transect, as well as generalized linear models. Density (number of deers/km2) was estimated using the semi-automated process PELLET, and was compared between locations, major vegetation types, and transect clusters. Deers were present in 98 % of the transects sampled, with a mean density of 4.2 ± 2.8 deers/km2. Higher densities were estimated in secondary vegetation and pasture-cropping sites. The 40 transects were grouped into four clusters according to the abundance of tree species. In addition, deer density varied between clusters. The density of the white-tailed deer was positively correlated with understory cover and negatively correlated with basal area. Deer density in Tantoyuca is within the range reported in other regions of the state of Veracruz. The use of generalized linear models enabled to predict the density of the white-tailed deer based on some vegetation variables. The localities studied differ in plant composition and structure, and the highest deer density was located in sites with a more diverse and dense plant composition and structure. It is suggested to undertake an in-depth investigation about the effect of landscape structural complexity and connectivity on this and other wildlife species.

Landscape complexity has limited effects on the genetic structure of two arable plant species, Adonis aestivalis and Consolida regalis

SummaryThe agricultural landscape of central Europe has changed dramatically in recent decades due to intensified cultivation, bringing many of its characteristic species to the brink of extinction. We investigated whether landscape structure affects the genetic structure and diversity of remnant populations of the two arable plant species Adonis aestivalis and Consolida regalis. We used dominant amplified fragment length polymorphism markers (AFLPs) and compared populations from six regions of 5 km² in central Germany. These regions represent two different classes of landscape structural complexity: intensively used, homogeneous landscapes (>95% of area covered by arable land with low extent of field margins) or heterogeneous regions (<60% of area covered by arable land with large extent of field margins). Contrary to expectations, within‐population diversity levels did not significantly differ between homogeneous and heterogeneous landscapes. No significant isolation‐by‐distance was found for either species, regardless of landscape structure, and genetic structures may still mirror more continuous conditions before large‐scale restructuring commenced in Germany's arable landscapes from the 1950s onwards. These results suggest that current landscape complexity, as such, is not as important for local‐level genetic structure for the species studied. Thus, homogenised and intensively used landscapes may also be important for the conservation of arable plant diversity and should not be neglected.

A new arc–chord ratio (ACR) rugosity index for quantifying three-dimensional landscape structural complexity

Rugosity is an index of surface roughness that is widely used as a measure of landscape structural complexity in studies investigating spatially explicit ecological patterns and processes. This paper identifies and demonstrates significant issues with how we presently measure rugosity and, by building on recent advances, proposes a novel rugosity index that overcomes these issues. The new arc-chord ratio (ACR) rugosity index is defined as the contoured area of the surface divided by the area of the surface orthogonally projected onto a plane of best fit (POBF), where the POBF is a function (interpolation) of the boundary data only. The ACR method is described in general, so that it may be applied to a range of rugosity analyses, and its application is detailed for three common analyses: (a) measuring the rugosity of a two-dimensional profile, (b) generating a rugosity raster from an elevation raster (a three-dimensional analysis), and (c) measuring the rugosity of a three-dimensional surface. Two case studies are used to compare the ACR rugosity index with the rugosity index most commonly used (i.e. surface ratio rugosity), demonstrating the advantages of the ACR index. The ACR method for quantifying rugosity is simple, accurate, extremely versatile, and consistent in its principles independent of data dimensionality (2-D or 3-D), scale and analysis software used. It overcomes significant issues presented by traditional rugosity indices (e.g. decouples rugosity from slope) and is a promising new landscape metric. To further increase ease of use I provide multiple ArcGIS® resources in the electronic supplementary materials (e.g. Online Appendix 1: a downloadable ArcToolbox containing two ACR rugosity geoprocessing model tools).

Landscape Structural Complexity of High‐Mountain Polylepis australis Forests: A New Aspect of Restoration Goals

Forest restoration efforts should aim at creating landscapes with a balanced array of forest stands at varying successional stages, thus providing habitat for a wealth of species and multiple ecosystem services. In most high‐mountain ecosystems of South America, long‐term livestock rearing activities that include fires, browsing, and trampling have delayed or stopped forest succession resulting in simplified landscapes. To determine appropriate restoration goals for Polylepis australis mountain forests of Central Argentina, we established 146 plots of 900 m2 plots throughout five river basins with different historic livestock stocking rates. In each plot, we measured tree heights, canopy cover, estimated age of oldest tree, volume of standing and fallen dead wood, fern cover, and abundance of shade tolerant Maytenus boaria trees. K‐means cluster analysis using tree heights and canopy cover as classificatory variables yielded four biologically meaningful clusters. Clusters 1, 2, 3, and 4 comprising 68, 10, 13, and 9% of the plots, respectively, showed increasing amounts of standing and fallen dead wood, fern cover, and abundance of shade tolerant M. boaria trees. Plots in clusters 1 and 2 were proportionally more abundant in basins with high human impact and at the altitudinal extremes of P. australis distribution, whereas plots in clusters 3 and 4 were relatively more abundant in well‐preserved basins and at the optimum of their altitudinal distribution. We interpret clusters 1, 2, 3, and 4 as degraded, regenerating, young, and mature forests, respectively. Restoration goals should focus on attaining an even distribution of forest types similar to that found in our best‐preserved basins.

Mixed effects of landscape structure and farming practice on bird diversity

Bird abundance, species richness and diversity of bird communities were analysed on 59 plots during breeding season and 61 plots during winter (500 m × 500 m around winter wheat fields) in two contrasting regions of Germany differing in land-use history (West vs. East), landscape structural complexity (40–100% arable land) and farming practice (organic vs. conventional). Abundance, species richness and diversity were higher in West Germany, presumably due to the higher overall habitat-type diversity, and decreased with decreasing landscape complexity, this being marked for farmland and forest birds. In contrast, abundances of openland bird species were higher in East Germany during both seasons and increased with decreasing landscape complexity. During breeding season (but not in winter) organic farming enhanced the species richness of all bird groups, presumably due to more and diverse food resources. Farmland and forest bird species in agricultural landscapes therefore appear to be mainly enhanced by landscape complexity owing to the availability of nesting and sheltering places in non-crop habitats, while openland bird species require high proportions of arable land.

Small mammals in agricultural landscapes: Opposing responses to farming practices and landscape complexity

Organic farming often counteracts the decline of various taxa owing to agricultural intensification, but little is known about the relative importance of local management and landscape context for small mammals. We examined the abundance, species richness and diversity of small mammal communities in 22 organically and conventionally managed winter wheat fields pairwise located along a gradient of landscape structural complexity (41–94% arable land). Complex landscapes significantly increased small mammal abundance and (with marginal significance) species richness and diversity, but only in conventional fields, whereas organic farming increased small mammals in simple landscapes. These results indicate the importance of landscape complexity for small mammal populations in an intensified agriculture. Analyses at multiple spatial scales (100 m, 250 m, 500 m radii around focal fields), showed opposing responses of the three most abundant species to landscape complexity. Apodemus agrarius PALLAS abundance increased with increasing landscape complexity at a spatial scale of 100 m, whereas Microtus arvalis PALLAS and Sorex araneus L. abundances decreased with increasing landscape complexity at spatial scales of 100 m and 500 m, respectively, suggesting species-specific ecological needs as well as functional spatial scales for conservation management. In conclusion, agri-environmental measures for small mammals such as organic farming are most effective in simple landscapes, while complex landscapes presumably function as source habitats and can compensate for local agricultural intensification in conventional fields.

Diversity of cereal aphid parasitoids in simple and complex landscapes

Structurally complex landscapes may enhance local species richness and interactions, which is possibly due to a higher species pool in complex landscapes. This hypothesis was tested using cereal aphid parasitoids (Hymenoptera, Aphidiidae) by comparing 12 winter wheat fields in structurally complex landscapes (>50% semi-natural habitats; n = 6) and structurally simple landscapes dominated by agricultural lands (>80% arable land; n = 6). Surprisingly, landscape structural complexity had no effect on aphid parasitoid species diversity. In complex landscapes 12 and in simple landscapes 11 species were found; 9 species occurred in both landscape types. Hence, arable fields in high-intensity agricultural landscapes with little non-crop area can support a similar diversity of cereal aphid parasitoids as structurally complex landscapes. This finding suggests that cereal aphid parasitoids may find necessary resources even in simple landscapes, making generalisations concerning the relationship between landscape composition and biodiversity in arable fields difficult.

Host density influences parasitism of the armyworm Pseudaletia unipuncta in agricultural landscapes

Summary Several studies have shown positive responses of parasitism to either host density or landscape complexity. However, no experiments have manipulated host density in landscapes of differing complexity. Here we report the results of a field experiment conducted to determine how host density and agricultural landscape structure jointly affect parasitism and parasitoid diversity of Pseudaletia unipuncta (Haworth) (Lepidoptera: Noctuidae). Parasitism was assessed by experimentally adding P. unipuncta sentinel larvae at low (1 larvae/plant) and high (3 larvae/plant) densities to detect parasitism in commercial cornfields located in a complex and a simple agricultural landscape. The braconid wasps Glyptapanteles militaris (Walsh) and Meteorus spp. accounted for 98.4% of the observed parasitism. Landscape structure did not influence parasitism (80.2% on average) and contrary to expectations, showed a trend towards increased parasitoid richness and diversity in the simple landscape. Increasing host density revealed a trend of increasing parasitoid richness and diversity, and differentially affected parasitism at the parasitoid specific level. G. militaris parasitized a significantly greater proportion of hosts at low host density, while the opposite occurred for Meteorus spp. (primarily M. communis ). These offsetting responses of parasitoids resulted in the lack of an overall host density effect on parasitism. The differential response of these parasitoids to host density is discussed in relation to differences in morphological and life history characteristics. Our results suggest that the specific composition of parasitoid assemblages could significantly alter parasitism at different host densities independently of landscape structural complexity.

Modelling indicators and indices of landscape complexity: an approach using G.I.S.

The study of complex environmental systems steadily gains momentum in the domain of environmental sciences. The complexity of landscapes, however, still lacks a proper definition, as well as a straightforward method for its calculation. The assessment of landscape complexity is indeed a difficult undertaking and research results hitherto published in the scientific literature demonstrate that several problems arise when the structural (quantitative) and the functional (qualitative) aspects of landscapes are considered to assess their complexity. With this paper, a straightforward method is proposed for deriving indicators of landscape complexity. This method relies on the identification of three key indicators which are necessary to describe landscape complexity: diversity, fractality and function. Three rules are given for applying these indicators to the study of landscape complexity. These three indicators are subsequently used to derive an index of structural and an index of functional landscape complexity (IS and IF, respectively). Example calculations of landscape complexity are given, based on a model landscape. Using a G.I.S., it is demonstrated that a distinction should be made between the concept “complexity of landscape change” and the concept “change in the landscape complexity”. The usefulness of G.I.S. for studying landscape structural complexity is significant for calculating IS and IF indices, albeit restricted by their limited topological capabilities for handling boundary calculations between adjacent land units.