Within and Among Patch Variability in Patterns of Insect Herbivory Across a Fragmented Forest Landscape.

Fragmentation changes the spatial patterns of landscapes in ways that can alter the flow of materials and species; however, our understanding of the consequences of this fragmentation and flow alteration for ecosystem processes and ecosystem services remains limited. As an ecological process that affects many ecosystem services and is sensitive to fragmentation, insect herbivory is a good model system for exploring the role of fragmentation, and the resulting spatial patterns of landscapes, in the provision of ecosystem services. To refine our knowledge of how changes in landscape pattern affect insect herbivory, we quantified the combined influence of among patch (patch area and patch connectivity) and within patch (location within patch; canopy, edge, interior) factors on amounts of insect herbivory in a fragmented forest landscape. We measured herbivory in 20 forest patches of differing size and connectivity in southern Quebec (Canada). Within each patch, herbivory was quantified at the interior, edge, and canopy of sugar maple trees during the spring and summer of 2011 and 2012. Results show that connectivity affects herbivory differently depending on the location within the patch (edge, interior, canopy), an effect that would have gone unnoticed if samples were pooled across locations. These results suggest considering structure at both the patch and within patch scales may help to elucidate patterns when studying the effects of fragmentation on ecosystem processes, with implications for the services they support

Landscape connectivity and insect herbivory: A framework for understanding tradeoffs among ecosystem services

Current theory suggests that ecosystem services in fragmented landscapes can be maintained by preserving connectivity of remaining habitat patches. However connectivity does not always influence services positively. For example, outbreaks of destructive insect herbivores can be facilitated by connectivity among forest patches. Understanding the positive and negative effects of connectivity on ecosystem processes is needed to help scientists and managers anticipate tradeoffs among services that result from forest fragmentation or restoration. In this paper we use a vote counting meta-analytic approach in combination with a literature survey to explore how connectivity affects ecosystem service provisioning using insect herbivory as a model process. Our results indicate that landscape connectivity affects herbivory in diverse ways, and that implications for services depend on whether we consider outbreaking species. Under non-outbreak conditions, herbivory positively affects services such as timber production, soil formation, and recreation by stimulating tree growth and enhancing soil productivity, but under outbreak conditions, herbivory negatively affects services by reducing timber yields and the aesthetic value of forests. We present a framework that shows herbivory is an important mechanism through which connectivity affects ecosystem services. Using case studies we demonstrate the applicability of the framework to management of two forest insect pests: the mountain pine beetle and forest tent caterpillar

Herbivory by patch connectivity and location within patch.

<p>Mean herbivory index (+/-SE) for patches with different connectivities (connected vs. isolated), and for different locations within patches (edge vs. interior understory, and canopy vs interior understory). Means and standard errors are back-transformed predicted values from the mixed effects model with trees nested within patches as random effects. Significant results of multiple comparisons tests are indicated by a star (*), with Interior Connected > Edge Connected in 2011 (p<0.05), and Canopy Isolated < Edge Isolated (p<0.0001) and < Interior Isolated (p<0.05) in 2012.</p

Map of Field Sites used in this study.

<p>Map of forest patches (grey shaded areas) in which herbivory data were collected in 2011 and 2012. Patches are located in southern Quebec, Canada just east of Montreal. Individual size and connectivity metrics for each patch are outlined in the figure. Size is reported in hectares, and connectivity is reported as a proximity index (<i>PROX</i>) described in [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150843#pone.0150843.ref054" target="_blank">54</a>]. Large sites are indicated by squares, while small sites are indicated by circles. Connected sites are indicated by solid shapes, isolated sites are indicated by hollow shapes. Black shapes indicate sites that were used in both years, light grey shapes are sites that were used only in 2011, and dark grey shapes are sites that were used only in 2012. Complete site characteristics and GPS coordinates are included in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150843#pone.0150843.s003" target="_blank">S2 Table</a>.</p

Herbivory by forest patch landscape characteristics.

<p>Mean herbivory index (+/- SE) for different forest patch sizes (large vs. small) and connectivity (isolated vs. connected) for both 2011 and 2012. There were no significant differences among treatments when data for the different locations were pooled.</p

Results of mixed effects models testing the effects of sampling period, landscape characteristics and locations within forest patches on herbivory.

<p>Results of mixed effects models testing the effects of sampling period, landscape characteristics and locations within forest patches on herbivory.</p

Herbivory over the course of the sampling season.

<p>Mean herbivory index (+/-SE) for each of 5 sampling rounds performed throughout the spring and summer in 2011 and 2012. In both years, herbivory was measured on 12 understory trees and 2 canopy trees in 20 forest patches throughout southern Quebec. There was a significant increase in herbivory with time of season in both 2011 and 2012 (p<0.0001).</p

Network analysis as a tool for quantifying the dynamics of metacoupled systems: an example using global soybean trade

The metacoupling framework provides grounds for characterizing interactions within and between coupled human and natural systems, yet few studies quantify the nuances of these systems. Network analysis is a powerful and flexible tool that has been used to quantify social, economic, and ecological systems. Our objective was to evaluate the utility of network analysis for quantifying metacoupled systems by assessing global soybean trade among 217 countries from 1986 to 2013. We identified and quantified sending and receiving systems, subnetworks and flow pathways, changes over time and across scales, feedbacks, and associations between trade and tropical deforestation. Although a total of 165 distinct cliques were identified within the network, a few key players were disproportionately influential in the 2872 partnerships, including Brazil (37.5%), China (48.6%), and the USA (72.3%). Total network density increased five-fold over the study period with an increasingly smaller set of countries heavily engaged in trade, posing sustainability and food security concerns. We found evidence of a positive feedback where countries with established trade partnerships were more likely to expand trade relationships over the study period. Trade patterns were not explained by regional or continental geography, highlighting limitations of neighborhood analyses commonly used in ecology. We also found evidence of a link between soybean trade and tropical deforestation; in pantropical countries participating in soybean trade, cumulative soybean exports for the period 2000-2012 were strongly associated with remotely sensed estimates of forest loss by country (Rsq = 0.35 , p < 0.0001). We demonstrated that network analyses can be used to quantitatively assess relationships between metacoupled social-ecological systems. Increased data access and platforms for integrating diverse data sources using multidisciplinary tools will be key to pushing the boundaries of quantitative metacoupled systems research

The montérégie connection: Linking landscapes, biodiversity, and ecosystem services to improve decision making

To maximize specific ecosystem services (ES) such as food production, people alter landscape structure, i.e., the types of ecosystems present, their relative proportions, and their spatial arrangement across landscapes. This can have significant, and sometimes unexpected, effects on biodiversity and ES. Communities need information about how land-use activities and changes to landscape structure are likely to affect biodiversity and ES, but current scientific understanding of these effects is incomplete. The Montérégie Connection (MC) project has used the rapidly suburbanizing agricultural Montérégien landscape just east of Montreal, Québec, Canada, to investigate how current and historic landscape structure influences ES provision. Our results highlight the importance of forest connectivity and functional diversity on ES provision, and show that ES provision can vary significantly even within single land-use types in response to changes in landscape structure. Our historical analysis reveals that levels of ES provision, as well as relationships among individual ES, can change dramatically through time. We are using these results to build quantitative ES-landscape structure models to assess four future landscape scenarios for the region: Periurban Development, Demand for Energy, Whole-System Crisis, and Green Development. These scenarios integrate empirical and historical data on ES provision with local stakeholder input about global and local social and ecological drivers to explore how land-use decisions could affect ES provision and human well-being across the region to the year 2045. By integrating empirical data, quantitative models, and scenarios we have achieved the central goals of the MC project: (1) increasing understanding of the effects of landscape structure on biodiversity and ES provision, (2) effectively linking this knowledge to decision making to better manage for biodiversity and ES, and (3) creating a vision for a more sustainable social-ecological system in the region