Maurizia Sigura

Conservation tillage mitigates the negative effect of landscape simplification on biological control

Summary Biological pest control is a key ecosystem service, and it depends on multiple factors acting from the local to the landscape scale. However, the effects of soil management on biological control and its potential interaction with landscape are still poorly understood. In a field exclusion experiment, we explored the relative effect of tillage system (conservation vs. conventional tillage) on aphid biological control in 15 pairs of winter cereal fields (barley and wheat) selected along a gradient of landscape complexity. We sampled the abundance of the main natural enemy guilds, and we evaluated their relative contribution to aphid predation and parasitism. Conservation tillage was found to support more abundant predator communities and higher aphid predation (16% higher than in the fields managed under conventional tillage). In particular, both the abundance and the aphid predation of vegetation- and ground-dwelling arthropods were increased under conservation tillage conditions. Conservation tillage also increased the parasitism rate of aphids. A high proportion of semi-natural habitats in the landscape enhanced both aphid parasitism and predation by vegetation-dwelling organisms but only in the fields managed under conventional tillage. The better local habitat quality provided by conservation tillage may compensate for a low-quality landscape. Synthesis and applications. Our study stresses the importance of considering both soil management and landscape composition when planning strategies to maximize biological control services in agro-ecosystems, highlighting the role played by conservation tillage in supporting natural enemy communities. In simple landscapes, the adoption of conservation tillage will locally improve biological control provided by both predators and parasitoids mitigating the negative effects of landscape simplification. Moreover, considering the small scale at which both predation and parasitism responded to landscape composition, a successful strategy to improve biological control would be to establish a fine mosaic of crop and non-crop areas such as hedgerows, tree lines and small semi-natural habitat patches.

High cover of hedgerows in the landscape supports multiple ecosystem services in Mediterranean cereal fields

Summary Field-margin diversification through conservation and restoration of hedgerows is becoming a prominent intervention for promoting biodiversity and associated ecosystem services in intensive agricultural landscapes. However, how increasing cover of hedgerows in the landscape can affect ecosystem services has rarely been considered. Here, we assessed the effect of increased field-margin complexity at the local scale and increasing cover of hedgerows in the landscape on the provision of pest control, weed control and potential pollination. Locally, three types of field margin were compared as follows: (i) standard grass margin, (ii) simple hedgerow and (iii) complex hedgerow, along two independent gradients of hedgerow cover and arable land cover in the landscape. We performed an exclusion experiment to measure biological control of cereal aphids and assessed natural enemy and pest abundance in the field. We sampled plant weed communities and performed a phytometer experiment to test the effects of pollinators on plant reproductive success. At the local scale, planting a new hedgerow or improving its structural complexity and vegetation diversity did not enhance the delivery of ecosystem services in the neighbouring field. However, high cover of hedgerows in the landscape enhanced aphid parasitism (from 12 to 18%) and potential pollination (visitation rate and seed set increased up to 70%) irrespective of local margin quality. The cover of arable land in the landscape reduced the abundance of plant-dwelling predators and weed diversity, but did not affect the delivery of the investigated ecosystem services. Synthesis and applications. Our results highlight the key importance of the surrounding landscape context, rather than local factors, to the delivery of ecosystem services. This suggests a need for new policies that pay particular attention to the conservation of hedgerows at large scales for promoting multiple ecosystem services in agroecosystems. Specifically, hedgerows can serve to develop a network of ecological corridors that can facilitate the movement of beneficial organisms, such as pollinators and natural enemies in the agricultural matrix. Such interventions may be a ‘low cost–high benefit solution’, since farmers can create or conserve high-quality habitats taking little or no land from crop production and without the need to change their crop management.

Conservation tillage affects species composition but not species diversity: a comparative study in Northern Italy.

Conservation tillage (CT) is widely considered to be a practice aimed at preserving several ecosystem functions. In the literature, however, there seems to be no clear pattern with regard to its benefits on species diversity and species composition. In Northern Italy, we compared species composition and diversity of both vascular plants and Carabids under two contrasting tillage systems, i.e., CT and conventional tillage, respectively. We hypothesized a significant positive impact of CT on both species diversity and composition. We also considered the potential influence of crop type. The tillage systems were studied under open field conditions with three types of annual crops (i.e., maize, soybean, and winter cereals), using a split-plot design on pairs of adjacent fields. Linear mixed models were applied to test tillage system, crop, and interaction effects on diversity indices. Plant and Carabids communities were analyzed by multivariate methods (CCA). On the whole, 136 plant and 51 carabid taxa were recorded. The two tillage systems studied did not differ in floristic or carabid diversity. Species composition, by contrast, proved to be characteristic for each combination of tillage system and crop type. In particular, CT fields were characterized by nutrient demanding weeds and the associated Carabids. The differences were especially pronounced in fields with winter cereals. The same was true for the flora and Carabids along the field boundaries. For studying the effects of CT practices on the sustainability of agro-ecosystems, therefore, the focus should be on species composition rather than on diversity measures.

Soil management shapes ecosystem service provision and trade-offs in agricultural landscapes

Agroecosystems are principally managed to maximize food provisioning even if they receive a large array of supporting and regulating ecosystem services (ESs). Hence, comprehensive studies investigating the effects of local management and landscape composition on the provision of and trade-offs between multiple ESs are urgently needed. We explored the effects of conservation tillage, nitrogen fertilization and landscape composition on six ESs (crop production, disease control, soil fertility, water quality regulation, weed and pest control) in winter cereals. Conservation tillage enhanced soil fertility and pest control, decreased water quality regulation and weed control, without affecting crop production and disease control. Fertilization only influenced crop production by increasing grain yield. Landscape intensification reduced the provision of disease and pest control. We also found tillage and landscape composition to interactively affect water quality regulation and weed control. Under N fertilization, conventional tillage resulted in more trade-offs between ESs than conservation tillage. Our results demonstrate that soil management and landscape composition affect the provision of several ESs and that soil management potentially shapes the trade-offs between them.

Ecosystem Services Along the Urban–Rural–Natural Gradient: An Approach for a Wide Area Assessment and Mapping

Landscapes can be viewed as a continuum and studied using spatial gradients along which environmental modifications determine the structural and functional components of ecosystems. The analysis and quantification of Ecosystem Services, intended as the benefits people obtain from ecosystems, play a crucial role in sustainable landscape planning. In this framework we developed a novel method for the identification and characterization of the landscapes nested along the urban-rural-natural gradient and the analysis of potential ES supply and demand within said landscapes. The Kernel Density Estimation technique was applied to calculate continuous intensity indicators associated with urbanization, agriculture, and natural elements, considered as key components of the gradient. The potential ES demand and supply within each landscape area were assessed using expert–knowledge based indices associated to the LULC CORINE classes. Results showed a complex organization of “pillar” and transitional landscapes along the gradient, which match different bundles of ES demand and supply.

Conservation tillage reduces the negative impact of urbanisation on carabid communities

Urban sprawl has been widely recognised as major cause of biodiversity decline across multiple taxonomic levels. Nevertheless, comprehensive studies investigating the effects of landscape urbanisation and farming practices on arthropod biodiversity in agroecosystems are still scarce. We explored the combined effect of urbanisation in the landscape and tillage management (conservation vs. conventional tillage) on predatory carabid beetle communities (Coleoptera: Carabidae) in 10 pairs of winter cereal fields in the agricultural landscape of Udine province (north‐east Italy). Urbanisation (at 750 m scale) strongly decreased carabid activity density, species richness, functional richness and increased functional divergence. We, however, found an interaction between tillage system and the proportion of urban areas in the landscape, i.e., the negative effects of urbanisation on carabid communities were more evident in the fields managed under conventional tillage, while conservation tillage supported more diverse (both taxonomically and ecologically) and abundant beetle communities also in highly urbanised landscapes. We also found that different functional groups differently responded to tillage management. The better local habitat quality provided by conservation tillage may mitigate the negative effects of urbanisation on carabid communities. Our study stresses the importance of considering both local management and landscape composition when planning strategies to support farmland biodiversity.

Exotic plant invasion in agricultural landscapes: a matter of dispersal mode and disturbance intensity

Question Does dispersal mode and/or disturbance intensity affect the spread of exotic species across agricultural landscapes? Location Friuli Venezia Giulia, NE Italy. Methods We analyzed alpha- and beta-diversity of native and exotic plants in 128 plots distributed in four habitats (viz. woods, hedgerows, field boundaries and meadows), in four agricultural areas in North-East Italy, along a gradient of increasing cover of arable land in the landscape. We used a multi-model inference approach to explore the relationships between species diversity and landscape variables (i.e. agricultural disturbance) testing the role of dispersal mode (i.e. biotic, abiotic) for both native and exotic plants. For each habitat and plant trait combination, distance decay of similarity was assessed by regression on distance matrices. Results Species diversity of exotic and native plants were related to the degree of disturbance (cover of crop) and proximity to disturbance (distance to crop) with different responses according to dispersal mode and habitat type. In most of the habitats, the number of species dispersed by biotic vectors decreased when disturbance was higher. We further found that in woods and hedgerows the interaction between disturbance and dispersal mode drove the exotic richness. Exotic species were less dispersal limited than native showing a weaker distance-decay of similarity. Conclusions The spread of exotic species in semi-natural habitats was driven by agricultural disturbance at the landscape scale. The effect of disturbance on exotic species richness was further shaped by species dispersal mode. Most initiatives related to preventing and controlling invasions are conducted at the local scale, whereas the influence of the land-use dynamics in the landscape is seldom explored. Our contribution provides useful information to identify the most susceptible semi-natural-habitats to exotic plant invasions according to intrinsic local resistance and large-scale processes such as invasiveness from the surrounding landscape. This article is protected by copyright. All rights reserved.

Patterns of biodiversity and habitat sensitivity in agricultural landscapes

Design of landscape is the process of the arrangement of spatial features with the objective of sustaining ecosystem services, and maintaining ecological functionality to meet societal needs. Along a gradient of cultivation intensity, the functional quality of agricultural landscape was explored and the relationships between landscape metrics and functional quality were analyzed, in order to make effective recommendations for landscape design aimed at sustainable land use schemes. The functional quality of landscape was calculated using the InVest model for 20 farm landscapes (North-Eastern Italy) where biodiversity (plant taxa) and sensitivity to disturbance (hemeroby) were used as model inputs. Results highlighted the importance of specific habitat types such as meadows and woodlands rather than other habitats for improving the biodiversity of agricultural landscapes. A high proportion of these habitats enhanced the functional quality of the landscape when the habitats were organized in large and not isolated patches in heterogeneous landscapes.

High Nature Value Farmland (HNVF) and Ecological Networks: Their Role in the Sustainability of Trans-Border Regions

Abstract European policies have shown that the integration of environmental instances in the planning process and the sustainable land development are major objectives. The aim of this paper is to discuss the chronological evolution of the ecological network concept, some of the experiences at the European level and in the Alpine-Adriatic region and the role of agricultural areas in ecological connectivity. A case study on mapping High Nature Value Farmland (HNVF) in the Friuli-Venezia Giulia region (Italy) shows the importance of HNVF in the creation of a regional ecological infrastructure, as well as some problems associated with their identification and mapping at regional and trans-boundary levels.