Impact of an invasive oak gall wasp on a native butterfly: a test of plant-mediated competition

Phytophagous insects commonly interact through shared host plants. These interactions, however, do not occur in accordance with traditional paradigms of competition, and competition in phytophagous insects is still being defined. It remains unclear, for example, if particular guilds of insects are superior competitors or important players in structuring insect communities. Gall-forming insects are likely candidates for such superior competitors because of their ability to manipulate host plants, but their role as competitors is understudied. We investigate the effect of invasive populations of an oak gall wasp, Neuroterus saltatorius, on a native specialist butterfly, Erynnis propertius, as mediated by their shared host plant, Quercus garryana. This gall wasp occurs at high densities in its introduced range, where we stocked enclosures with caterpillars on trees that varied in gall wasp density. Biomass production of butterflies was lower in enclosures on high-density than on low-density trees because overwintering caterpillars were smaller, and fewer of them eclosed into adults the following spring. To see if the gall wasp induced changes in foliar quality, we measured host plant quality before and after gall induction on 30 trees each at two sites. We found a positive relationship between gall wasp density and the percentage change in foliar C:N, a negative relationship between gall wasp density and the percentage change in foliar water at one site, and no relationship between the percentage change in protein-binding capacity (i.e., phenolics) and gall-wasp density. Additionally, there was a negative relationship between foliar quality and butterfly performance. Our results provide evidence for a plant-mediated impact of an invasive oak gall wasp on a native butterfly and suggest that gall wasps could act as superior competitors, especially when they occur at high densities.     

The role of ad hoc networks in supporting climate change adaptation: a case study from the Southeastern United States

To examine the factors that support adaptation within a regional and sectoral context, this article explores five climate-sensitive sectors in North and South Carolina (Forestry, Government Administration, Tourism, Water Management, and Wildlife Management) and the role of partnerships, collaborations, and networks in facilitating climate adaptation and related activities. Drawing from 117 online questionnaires and interviews with sector leaders across the Carolinas, the article highlights several key functions of networks in regard to supporting adaptation—intra-sector information sharing; monitoring, data collection, and research; and education and outreach. Furthermore, the analysis examines how climate networks in the region have facilitated the development of bonding, bridging, and linking social capital while also noting factors that have constrained the growth and success of both intra- and cross-sector collaboration. Although no formal, or discrete, state or regional cross-sector climate change network exists in the Carolinas, climate adaptations and capacity-building efforts have been supported by ad hoc and decentralized networks, emerging collegial partnerships within and across sectors, and collaborative efforts to pool expertise and resources. The role of different forms of social capital within these networks is discussed in the context of a contentious political environment where support for activities designed to address climate change is limited. These findings enhance our understanding of the social factors and relational processes that shape and influence capacity to adapt to climate change.     

Structuring expert input for a knowledge-based approach to watershed condition assessment for the Northwest Forest Plan, USA

Assessments of watershed condition for aquatic and riparian species often have to rely on expert opinion because of the complexity of establishing statistical relationships among the many factors involved. Such expert-based assessments can be difficult to document and apply consistently over time and space. We describe and reflect on the process of developing a computer-based decision support application from expert judgments for assessing aquatic and riparian conditions over the 100,000?km² managed by the US federal government under the Northwest Forest Plan. The decision support system helped structure and document the assessment process and provided consistency and transparency to the evaluation methodology. However, many decisions and trade-offs were required in the expert engagement and model-building processes. Knowledge elicitation in an interactive group had a number of benefits over nominal group or Delphi processes, but efficient knowledge capture required considerable planning and expertise in the subject matter and modeling process. Communicating model results for validation was problematic and only effectively accomplished via in-person workshops. The choice to use different expert groups for each biophysical province provided more opportunities for participation and promoted greater ownership in the assessment, but it also led to increased variation among the resulting model structures. We propose three possible approaches for better managing the consistency of assessment models when multiple expert groups are involved.     

Texas Nameplate Company: A Profile of Environmental Success

An initially ignored customer request started a small Texas company on the road to environmental excellence. Ten years later, it offers an example of solid accomplishment—with more achievements sure to come. © 2001 John Wiley & Sons, Inc.     

Abandonment landscapes: user attitudes,alternative futures and land management in Castro Laboreiro,Portugal

Land abandonment is an important process for the European Union, which primarily occurs in less productive, remote and mountainous areas with unfavourable conditions for agriculture. Future management directions of these abandonment areas are under debate, with increasing calls to adjust policies to the local characteristics, including the promotion of rewilding and the management of succession of larger areas of less-productive land. While there is an increase in studies focusing on the environmental impacts of land abandonment, there are few studies that focus on the perceptions of abandonment by different user groups, even though an understanding of local perceptions, opportunities and trade-offs associated with changing land management is crucial for landscape-related policies and planning measures. In a case study in Northern Portugal, we used a combination of statements, photograph rating exercises and open questions to assess the perceptions of local inhabitants, visitors and experts regarding land abandonment and their preferences of different possible trajectories after abandonment. The results show that all user groups have a negative response towards abandonment and associate it mainly with negative emotions and the loss of heritage and traditions. The assessment of the different abandonment stages and outcomes clearly yielded different preferences and explanations, which can be used as input for finding a common ground for landscape management, reducing conflict and as a starting point for a more spatially targeted and nuanced management approach.

     

Life around the North Water ecosystem: Natural and social drivers of change over a millennium

The formation of the North Water in Smith Sound about 4500 years ago, as evidenced by the establishment of bird colonies and human presence, also initiated a long-term anthropogenic agent as part of this High Arctic ecosystem. Different epochs have influenced the human occupation in the area: immigration pulses from Canada and Alaska, trade with meteorite iron throughout the Arctic, introduction of new technologies by whalers and explorers, exploitation of resources by foreigners, political sequestration, export of fox and seal skins and later narwhal products, and recently fishing. Physical drivers in terms of weather and climate affecting the northern hemisphere also impact accessibility and productivity of the ecosystem, with cascading effects on social drivers, again acting back on the natural ecologies. Despite its apparent isolation, the ecosystem had and still has wide ranging spatial ramifications that extend beyond the High Arctic, and include human activity. The challenge is to determine what is internal and what is external to an ecosystem.     

Perspectives of farmers and tourists on agricultural abandonment in east Lesvos,Greece

Regional Environmental Change - Multi-stakeholder perceptions of landscape changes are increasingly recognized as essential inputs to discussions on future landscape developments, particularly when...     

Local adaptation and sexual selection: a reciprocal transfer experiment with the grasshopper Chorthippus biguttulus

Immigration into locally adapted populations has been suggested, among other potential causes, to maintain genetic variance in fitness necessary for good-genes models. Using a reciprocal transplant experiment we examined whether females prefer native to transferred males in the grasshopper Chorthippus biguttulus. On average, native and transferred males did not differ in their attractiveness, measured as female response rate to playbacks of male acoustic courtship signals. In line with this result, we found no significant effect of transfer on body size, condition, fluctuating asymmetry or song traits. However, the reciprocal transplant experiment showed that environmental conditions did influence body condition and maximum loudness of the calling song, but that the genetic origin of male grasshoppers had no significant effect on any of the analysed traits.Communicated by L. Simmons