Treeline dynamics: Pattern and process at multiple spatial scales

The primary hypothesis of treeline formation, low growing season temperature limitation of growth, predicts that treeline position will track climatic changes. These hypotheses were generated from broad treeline patterns, which may overlook critical local variability. To assess the hypothesis that all treelines are limited by low temperature and will respond in kind, treeline response over the last 100 years was evaluated at 166 treeline sites in a meta-analysis. Treeline advance was variable and not related to climate warming in the way expected. Treelines that experienced strong winter warming were more likely to have advanced and treelines with a diffuse form were more likely to have advanced than those with an abrupt, Krummholz or island form. Diffuse treelines may be more responsive to warming because they are more strongly growth limited, whereas other treeline forms may be subject to additional constraints. The results suggest that mechanisms other than growing season temperature, such as winter dieback and recruitment failure, may also determine treeline position and dynamics. As treeline responses worldwide confirm a close link between form and dynamics, variability in treeline response may be explained by identifying the mechanisms controlling treeline form. The varying dominance of three mechanisms affecting tree performance - growth limitation, seedling mortality and dieback – modified by species traits, local climatic conditions, stressors and neighbour interactions is proposed to result in different treeline forms and the expected response of treelines to climatic change. The proposed mechanisms controlling treeline form and expected responses to climate warming were subsequently tested at the abrupt Nothofagus treeline in New Zealand. The role of growth, mortality (across all size classes) and recruitment in controlling treeline dynamics were evaluated using long-term data collected along seven abrupt Nothofagus treeline transects in the South Island, New Zealand. Demographic parameters were modelled over two periods, 1991-2002 and 2002-2008 within a Bayesian framework. Stem number increased above treeline over the 15-year study duration but stem distribution above treeline did not change; 90% of all stems and of new recruits occurred within 10 m of the treeline edge. Modelled growth, mortality and recruitment rates varied by period, transect and stem size. Results do not provide clear evidence of treeline advance but do indicate that recruitment is ultimately limiting advance. The causes of recruitment limitation were then tested through transplanted Nothofagus solandri var. cliffortioides and Pinus contorta seedlings along a 200 m vertical transect starting 50 m below treeline and with passive warming. Survival and growth of seedlings transplanted 150 m beyond the Nothofagus treeline did not decrease with distance from the treeline edge or improve with passive warming (repeated measures ANOVA, p > 0.05). Survival varied by species; P. contorta exhibited a greater overall probability of mortality than N. solandri. Relative growth rates did not significantly differ between species but pine exhibited a net increase in height whereas N. solandri exhibited a net decrease in height. At the seedling stage, low temperature is not limiting and N. solandri does not appear to be less well adapted to treeline conditions than northern hemisphere conifer species. The role of facilitation was subsequently tested by removing vegetation around N. solandri seedlings. Vegetation removal negatively affected N. solandri seedling survival. No effect of passive warming was observed. The results confirm that N. solandri can survive beyond their present limit but that growth and survival are limited to facilitative microsites. Treeline advance at the Nothofagus treeline in New Zealand is proposed to be limited by germination ability in dense vegetation and intolerance in the early life stages to sky exposure. Positive feedback, whereby established trees create ideal microsites for germination and seedling establishment, is proposed to be critical in determining recruitment patterns and the relative inertia to climatic change observed at the treeline. The results overall indicate that, globally, treeline response to climate change will be highly variable and not necessarily directly related to climate warming. Treeline form is a good indicator of the mechanisms controlling treeline dynamics and the potential response by treeline to climatic change

Influence of climate and regeneration microsites on Pinus contorta invasion into an alpine ecosystem in New Zealand

In many regions, alien conifers have spread widely at lower elevations and are increasingly found colonizing alpine areas. Although studies have addressed conifer invasions at low elevations, little is known about the rates and constraints on spread into higher elevations. Here, we assess the relative importance of climate and the availability of regeneration microsites on the establishment of the alien species <em>Pinus contorta</em> into a high elevation site in New Zealand. Spread has occurred from two stands planted at the elevation of the native treeline (1347–1388 masl) in the 1960s. Most stems established between 1350 and 1450 masl and <em>P. contorta</em> individuals were found up to 270 m above the original plantings. Although the population has increased by 180% in the last 20 years, population growth rate has been declining. Furthermore, comparisons with studies from other mountain ranges around the world and at low elevations in New Zealand suggest this is a relatively limited spread. Our results suggest that climate variation did not have a significant effect on establishment patterns, as opposed to availability of regeneration microsites. Soil and alpine mat microsites favoured establishment of<em> P. contorta</em> and, although these microsites did not appear to be saturated, microsite availability may be an important limiting factor for the spread of <em>P. contorta.</em> Thus management strategies should focus on preventing spread in addition to removing already established stems

Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperate reconstruction

Occupying 14% of the world’s surface, the Southern Ocean plays a fundamental role in global climate, ocean circulation, carbon cycling and Antarctic ice-sheet stability. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54˚S). Our annually-resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the mid-twentieth century, a phenomenon predating the observational record. Climate reanalysis and modelling shows a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer

Reviewing research priorities in weed ecology, evolution and management: A horizon scan

Weedy plants pose a major threat to food security, biodiversity, ecosystem services and consequently to human health and wellbeing. However, many currently used weed management approaches are increasingly unsustainable. To address this knowledge and practice gap, in June 2014, 35 weed and invasion ecologists, weed scientists, evolutionary biologists and social scientists convened a workshop to explore current and future perspectives and approaches in weed ecology and management. A horizon scanning exercise ranked a list of 124 pre-submitted questions to identify a priority list of 30 questions. These questions are discussed under seven themed headings that represent areas for renewed and emerging focus for the disciplines of weed research and practice. The themed areas considered the need for transdisciplinarity, increased adoption of integrated weed management and agroecological approaches, better understanding of weed evolution, climate change, weed invasiveness and finally, disciplinary challenges for weed science. Almost all the challenges identified rested on the need for continued efforts to diversify and integrate agroecological, socio-economic and technological approaches in weed management. These challenges are not newly conceived, though their continued prominence as research priorities highlights an ongoing intransigence that must be addressed through a more system-oriented and transdisciplinary research agenda that seeks an embedded integration of public and private research approaches. This horizon scanning exercise thus set out the building blocks needed for future weed management research and practice; however, the challenge ahead is to identify effective ways in which sufficient research and implementation efforts can be directed towards these needs

Increased applicability and engagement through interactive web applications

By reputation, IDEs are difficult to simulate. They are, however, extremely useful and beneficial for ecologists and resource managers addressing pressing ecological and environmental challenges such as climate change. The challenge is how to make our research and the advances that come from this workshop relevant and accessible to the average ecologist and resource manager that would benefit from these tools. In this talk, I will show how we have used RStudio and Shiny to build interactive web applications that allow users to engage with and gain a greater appreciation of IDEs. The tools presented are relatively easy to use with a basic knowledge of R. I use an IDE model developed to evaluate and predict the effects of climate change on species to demonstrate the power of this tool.Non UBCUnreviewedAuthor affiliation: University of WashingtonPostdoctora

Easy Online Data Dissemination and Research Tools: R Shiny and FISHEyE

The U.S. NOAA Northwest Fisheries Science Center has developed an online tool using the R package ‘Shiny' for the dissemination of data to the public (which is required under the NOAA plan for Public Access to Research Results (PARR)). However, the online application is very flexible and is useful to fishery managers, participants, scientists, and NGOs to evaluate the economic performance of the fishery and a catch share program that began in 2011. The FISHeries Economics Explorer (FISHEyE) is designed for easy access, data exploration, visual analysis, and data downloading. In this presentation, I'll introduce FISHEyE, demonstrate its usefulness in exploring questions pertinent to the fisheries management process, describe how we dealt with confidential information (which is a major stumbling block for economics programs attempting to comply with PARR), and show how other organizations can easily develop similar applications for their own data.Proceedings of the Eighteenth Biennial Conference of the International Institute of Fisheries Economics and Trade, held July 11-15, 2016 at Aberdeen Exhibition and Conference Center (AECC), Aberdeen, Scotland, UK

Plant distribution and climate data across western North America

Using an extensive network of occurrence records for 293 plant species collected over the past 40 years across a climatically diverse geographic section of western North America, we find that plant species distributions were just as likely to shift upwards (i.e., towards higher elevations) as downward (i.e., towards lower elevations) – despite consistent warming across the study area. Although there was no clear directional response to climate warming across the entire study area, there was significant region-to region- variation in responses (i.e. from as many as 73% to as few as32% of species shifting upward or downward). To understand the factors that might be controlling region-specific distributional shifts, we explored the relationship between the direction of change in distribution limits and the nature of recent climate change. We found that the direction of distribution limit shifts was explained by an interaction between the rate of change in local summer temperatures and seasonal precipitation. Specifically, species shifted upward at their upper elevational limit when snowfall declined at slower rates and minimum temperatures increased. By contrast, species shifted upwards at their lower elevation limit when maximum temperatures increased or both temperature and precipitation decreased. Our results suggest that future species' elevational distribution shifts will be complex, depending on the interaction between seasonal temperature and precipitation change