Lluís

To choose among conservation actions that may benefit many species, managers need to monitor the consequences of those actions. Decisions about which species to monitor from a suite of different species being managed are hindered by natural variability in populations and uncertainty in several factors: the ability of the monitoring to detect a change, the likelihood of the management action being successful for a species, and how representative species are of one another. However, the literature provides little guidance about how to account for these uncertainties when deciding which species to monitor to determine whether the management actions are delivering outcomes. We devised an approach that applies decision science and selects the best complementary suite of species to monitor to meet specific conservation objectives. We created an index for indicator selection that accounts for the likelihood of successfully detecting a real trend due to a management action and whether that signal provides information about other species. We illustrated the benefit of our approach by analyzing a monitoring program for invasive predator management aimed at recovering 14 native Australian mammals of conservation concern. Our method selected the species that provided more monitoring power at lower cost relative to the current strategy and traditional approaches that consider only a subset of the important considerations. Our benefit function accounted for natural variability in species growth rates, uncertainty in the responses of species to the prescribed action, and how well species represent others. Monitoring programs that ignore uncertainty, likelihood of detecting change, and complementarity between species will be more costly and less efficient and may waste funding that could otherwise be used for management.

Contabilización de la Complementariedad para Maximizar el Poder de Monitoreo para el Manejo de Especies

Para seleccionar entre acciones de conservación que puedan beneficiar a muchas especies, los administradores necesitan monitorear las consecuencias de estas acciones. Las decisiones sobre que especies monitorear de un conjunto de diferentes especies que se están manejando son impedidas por la variabilidad natural en las poblaciones y la incertidumbre de ciertos factores: la habilidad del monitoreo para detectar un cambio, la probabilidad de que la acción de manejo sea benéfica para una especie, y que tan representativas son las especies una con la otra. Sin embargo la bibliografía proporciona poca dirección sobre cómo responder a estas incertidumbres cuando se decide que especies monitorear para determinar si las acciones de manejo entregan resultados. Diseñamos una aproximación que aplica la ciencia de las decisiones y selecciona el mejor juego complementario de especies para monitorear para cumplir con objetivos específicos de conservación. Creamos un índice para la selección de indicadores que responde a la probabilidad de detectar exitosamente una tendencia verdadera debido a la acción de manejo y si esa señal proporciona información sobre otra especie. Ilustramos el beneficio de nuestra aproximación al analizar un programa de monitoreo para el manejo de depredadores invasivos enfocado a la recuperación de 14 especies de mamíferos australianos nativos y de interés para la conservación. Nuestro método seleccionó a las especies que proporcionan mayor poder de monitoreo a costos relativamente bajos para la estrategia actual y a las aproximaciones que utilizan sólo una parte de las consideraciones importantes. Nuestra función de beneficio valió para la variabilidad natural en las tasas de crecimiento de especies, la incertidumbre en la respuesta de las especies a la acción prescrita y que tan bien las especies representan a otras. Programas de monitoreo que ignoran incertidumbres, la probabilidad de detectar cambios y la complementariedad entre especies serán más costosos y menos eficientes y pueden gastar recursos que podrían usarse para manejo.

Prescribed burning is increasingly being used in the deciduous forests of eastern North America. Recent work suggests that historical fire frequency has been overestimated east of the prairie–woodland transition zone, and its introduction could potentially reduce forest herb and shrub diversity. Fire-history recreations derived from sedimentary charcoal, tree fire scars, and estimates of Native American burning suggest point-return times ranging from 5–10 years to centuries and millennia. Actual return times were probably longer because such records suffer from selective sampling, small sample sizes, and a probable publication bias toward frequent fire. Archeological evidence shows the environmental effect of fire could be severe in the immediate neighborhood of a Native American village. Population density appears to have been low through most of the Holocene, however, and villages were strongly clustered at a regional scale. Thus, it appears that the majority of forests of the eastern United States were little affected by burning before European settlement. Use of prescribed burning assumes that most forest species are tolerant of fire and that burning will have only a minimal effect on diversity. However, common adaptations such as serotiny, epicormic sprouting, resprouting from rhizomes, and smoke-cued germination are unknown across most of the deciduous region. Experimental studies of burning show vegetation responses similar to other forms of disturbance that remove stems and litter and do not necessarily imply adaptation to fire. The general lack of adaptation could potentially cause a reduction in diversity if burning were introduced. These observations suggest a need for a fine-grained examination of fire history with systematic sampling in which all subregions, landscape positions, and community types are represented. Responses to burning need to be examined in noncommercial and nonwoody species in rigorous manipulative experiments. Until such information is available, it seems prudent to limit the use of prescribed burning east of the prairie–woodland transition zone.

Reevaluación del Uso de Fuego como Herramienta de Manejo en Bosques Deciduos de América del Norte

La quema planeada cada vez se usa más en el bosque deciduo del este de Norteamérica. Sin embargo, trabajos recientes sugieren que la frecuencia histórica de los fuegos se ha sobrestimado al este de la zona de transición entre la pradera y el bosque, y su introducción podría reducir la diversidad de hierbas y arbustos del bosque. Recreaciones históricas del fuego derivadas de carbón sedimentario, cicatrices de fuego en los árboles y estimaciones de quemas por los nativos americanos, sugieren tiempos de regreso al punto que van desde 5–10 años hasta siglos y milenios. Los tiempos de retorno actuales probablemente fueron más largos porque tales registros sufren de muestreo selectivo, tamaño pequeño de las muestras y un sesgo probable de publicación hacia el fuego frecuente. Evidencias arqueológicas muestran que los efectos ambientales del fuego pueden ser severos en la vecindad inmediata de una aldea nativa americana. Sin embargo parece que la densidad de población fue baja a lo largo de casi todo el Holoceno y las aldeas estuvieron agrupadas en una escala regional. Por esto, parece que la mayoría de los bosques del este de los Estados Unidos estuvo poco afectada por las quemas antes del establecimiento europeo. El uso de quemas planeadas asume que la mayoría de las especies del bosque son tolerantes al fuego y que la quema tendrá un efecto mínimo sobre la diversidad. Sin embargo, adaptaciones comunes como la serotinia, los brotes epicórmicos, el rebrote de rizomas y la germinación iniciada por humo no existen en casi toda la región decidua. Los estudios experimentales de la quema muestran respuestas de la vegetación que consisten en la remoción de tallos y basura: éstas son similares a las respuestas a otras formas de perturbación y no implican necesariamente la adaptación al fuego. La carencia general de adaptación puede causar una reducción en la diversidad si se introduce la quema. Estas observaciones sugieren la necesidad de una revisión cuidadosa de quemas históricas con muestreos sistemáticos en los que estén representadas todas las subregiones, posiciones de paisaje y tipos de comunidad. Las respuestas a la quema necesitan ser revisadas en especies no comerciales y no leñosas en experimentos con manipulación rigurosa. Hasta que tal información esté disponible, parece prudente limitar el uso de quemas planeadas al este de la zona de transición entre pradera y bosque.

1. In a rapidly changing world, understanding and predicting population change is a central aim of applied ecologists, and this involves studying the links between environmental variation and vital rates (survival, fecundity, etc.). Demographic analysis and modelling can be daunting for practicing ecologists, and here we provide an overview of some of the most important issues and methods.
2. Collection of demographic data should follow standardized protocols and the statistical power to detect links with environment is critically dependent on long time-series. Candidate environmental covariates should be carefully selected with a view to reducing the risk of spurious correlations. The relevant sample size for environment–demography links is typically the number of years and mixed models with random year effects offer a powerful framework to enforce this.
3. Data on individually marked animals are the best source of information on demography. These data can be analysed and demographic parameters estimated using a wide variety of capture–mark–recapture models, available in standard software packages.
4. Population models integrate all demographic variables and provide estimates of population growth rate. Two common classes of models are matrix models and integrated population models, where the latter combine parameter estimation and dynamic modelling.
5. Synthesis and applications. Careful demographic analysis and modelling has provided solutions for many real-world problems in population management, as well as assisting the development of general principles. The tools currently available are flexible and powerful, and the main limitations to their more general use are data availability and training.

The joint spatial and temporal fluctuations in community structure may be due to dispersal, variation in environmental conditions, ecological heterogeneity among species and demographic stochasticity. These factors are not mutually exclusive, and their relative contribution towards shaping species abundance distributions and in causing species fluctuations have been hard to disentangle. To better understand community dynamics when the exchange of individuals between localities is very low, we studied the dynamics of the freshwater zooplankton communities in 17 lakes located in independent catchment areas, sampled at end of summer from 2002 to 2008 in Norway. We analysed the joint spatial and temporal fluctuations in the community structure by fitting the two-dimensional Poisson lognormal model under a two-stage sampling scheme. We partitioned the variance of the distribution of log abundance for a random species at a random time and location into components of demographic stochasticity, ecological heterogeneity among species, and independent environmental noise components for the different species. Non-neutral mechanisms such as ecological heterogeneity among species (20%) and spatiotemporal variation in the environment (75%) explained the majority of the variance in log abundances. Overdispersion relative to Poisson sampling and demographic stochasticity had a small contribution to the variance (5%). Among a set of environmental variables, lake acidity was the environmental variable that was most strongly related to decay of community similarity in space and time.

With increasing pressures on land for human use, it is important to identify the habitat requirements of key species, not just in terms of a correlation with a given habitat feature, but also the relationship between species presence and its coverage, proximity to other habitat types, and importance at different spatial scales. We used maximum entropy to estimate the optimal proportions of 18 habitat types, plus elevation and habitat richness associated with the presence of leks of Black Grouse Tetrao tetrix within an 800-km² study area in Perthshire, Scotland. We repeated the analysis at several radii (0.2–3 km) to assess how the importance of different habitats changed with proximity to lek and scale. We then examined habitat features or combinations of features that were associated with large leks or positive lek growth. Models at all radii had satisfactory predictive power. Using response curves from maxent, we constructed ideal habitat mixes for leks at each radius. At the 2-km radius, suitability was highest with around 20% each of three moorland types and open/mixed forestry, whereas close to leks (0.2 km), higher proportions of grouse moor and lower proportions of closed-canopy woodland were optimal. The relationship between habitat and lek size or direction of lek growth was complex, indicating that a landscape containing large or productive leks can be the result of more than one combination of habitats. This demonstrates a degree of flexibility in designing landscapes for Black Grouse conservation, so landowners can prioritize combinations of habitats that are the most practical and/or economical, while still serving the requirements of the target species.

Aim

Location

Methods

Results

Main conclusions

1. Information about when and where animals die is important to understand population regulation. In migratory animals, mortality might occur not only during the stationary periods (e.g. breeding and wintering) but also during the migration seasons. However, the relative importance of population limiting factors during different periods of the year remains poorly understood, and previous studies mainly relied on indirect evidence.
2. Here, we provide direct evidence about when and where migrants die by identifying cases of confirmed and probable deaths in three species of long-distance migratory raptors tracked by satellite telemetry.
3. We show that mortality rate was about six times higher during migration seasons than during stationary periods. However, total mortality was surprisingly similar between periods, which can be explained by the fact that risky migration periods are shorter than safer stationary periods. Nevertheless, more than half of the annual mortality occurred during migration. We also found spatiotemporal patterns in mortality: spring mortality occurred mainly in Africa in association with the crossing of the Sahara desert, while most mortality during autumn took place in Europe.
4. Our results strongly suggest that events during the migration seasons have an important impact on the population dynamics of long-distance migrants. We speculate that mortality during spring migration may account for short-term annual variation in survival and population sizes, while mortality during autumn migration may be more important for long-term population regulation (through density-dependent effects).

The authors use satellite telemetry to describe when and where migratory raptors die during the annual cycle. Daily mortality is six times higher during migration than during stationary periods (breeding and wintering), but total mortality is surprisingly equal between seasons, as ‘dangerous’ migration periods are shorter than ‘safe’ stationary periods.

Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous insects such as lepidopteran larvae. Here, we show that great tits (Parus major) discriminate between caterpillar-infested and uninfested trees. Birds were attracted to infested trees, even when they could not see the larvae or their feeding damage. We furthermore show that infested and uninfested trees differ in volatile emissions and visual characteristics. Finally, we show, for the first time, that birds smell which tree is infested with their prey based on differences in volatile profiles emitted by infested and uninfested trees. Volatiles emitted by plants in response to herbivory by lepidopteran larvae thus not only attract predatory insects but also vertebrate predators.

Drought affects more people than any other natural disaster but there is little understanding of how ecosystems react to droughts. This study jointly analyzed spatio-temporal changes of drought patterns with vegetation phenology and productivity changes between 1999 and 2010 in major European bioclimatic zones. The Standardized Precipitation and Evapotranspiration Index (SPEI) was used as drought indicator whereas changes in growing season length and vegetation productivity were assessed using remote sensing time-series of Normalized Difference Vegetation Index (NDVI). Drought spatio-temporal variability was analyzed using a Principal Component Analysis, leading to the identification of four major drought events between 1999 and 2010 in Europe. Correspondence Analysis showed that at the continental scale the productivity and phenology reacted differently to the identified drought events depending on ecosystem and land cover. Northern and Mediterranean ecosystems proved to be more resilient to droughts in terms of vegetation phenology and productivity developments. Western Atlantic regions and Eastern Europe showed strong agglomerations of decreased productivity and shorter vegetation growing season length, indicating that these ecosystems did not buffer the effects of drought well. In a climate change perspective, increase in drought frequency or intensity may result in larger impacts over these ecosystems, thus management and adaptation strategies should be strengthened in these areas of concerns.

Social environments have an important effect on a range of ecological processes, and form a crucial component of selection. However, little is known of the link between personality, social behaviour and population structure. We combine a well-understood personality trait with large-scale social networks in wild songbirds, and show that personality underpins multiple aspects of social organisation. First, we demonstrate a relationship between network centrality and personality with ‘proactive’ (fast-exploring) individuals associating weakly with greater numbers of conspecifics and moving between flocks. Second, temporal stability of associations relates to personality: ‘reactive’ (slow-exploring) birds form synergistically stable relationships. Finally, we show that personality influences social structure, with males non-randomly distributed across groups. These results provide strong evidence that songbirds follow alternative social strategies related to personality. This has implications not only for the causes of social network structure but also for the strength and direction of selection on personality in natural populations.

1. Measurements of community resemblance in ecology are often based on species composition, and the starting point for calculations is usually a site-by-species data table. However, resemblance measurements may not be sufficiently accurate when communities are described using species composition only. Characteristics such as the size of their constituting organisms are also important to understand community organization.
2. Here, we provide a framework that generalizes conventional resemblance measurements by incorporating the size structure of the compared communities. We first introduce the concept of cumulative abundance profile, which generalizes traditional species abundance values, and describe how to calculate it. We then explain our approach to compare cumulative abundance profiles in community resemblance measurements and use a small simulation study to determine which resemblance coefficients appropriately deal with compositional and structural differences. After that, we present an illustrative example where we study the structural and compositional variation between and within six Douglas-fir forest plots in British Columbia, Canada.
3. According to our investigations, the generalizations we suggest for the percentage difference (alias Bray–Curtis dissimilarity) and the Ružička coefficients are appropriate to measure community resemblance in terms of size structure, species composition or both.
4. Our framework allows community resemblance to be measured in terms of either size structure or species composition, or both. A broad range of applications is expected. In the case of terrestrial plant communities, potential applications include analyses of community dynamics and classification of vegetation.

International Expert Workshop on the Conceptual Framework Workshop for IPBES took place 25 - 26 August 2013, in Cape Town, South Africa, convened by the IPBES Multidisciplinary Expert Panel (MEP) and co-hosted by the Governments of South Africa, the United Kingdom and with additional support from the Government of Japan. The report is now available from here.

Please note that the registration deadline for Governments to attend the second session of the IPBES plenary (IPBES-2) has been extended to Monday, 30 September.

For government delegations that have yet to complete the online registration, kindly do so now from here.

The IPBES Bureau has reviewed applications for admission of new Observers to IPBES-2.

The list is available here.

Any member of the Platform may communicate its view on the recommendations of the Bureau by 25 November 2013 by sending an email to secretariat@ipbes.net

The Provisional Agenda for IPBES-2 is available here.

Watch the video produced by the German Science-policy platform on biodiversity (NeFO) at the pan-european stakeholder consultation hosted by UFZ, held in Leipzig, Germany on 16 -18 July.

Using an exclosure experiment in managed woodland in eastern England, we examined species and guild responses to vegetation growth and its modification by deer herbivory, contrasting winter and the breeding season over 4 years. Species and guild responses, in terms of seasonal presence recorded by multiple point counts, were examined using generalized linear mixed models. Several guilds or migrant species responded positively to deer exclusion and none responded negatively. The shrub-layer foraging guild was recorded less frequently in older and browsed vegetation, in both winter and spring. Exclusion of deer also increased the occurrence of ground-foraging species in both seasons, although these species showed no strong response to vegetation age. The canopy-foraging guild was unaffected by deer exclusion or vegetation age in either season. There was seasonal variation in the responses of some individual resident species, including a significantly lower occurrence of Eurasian Wren Troglodytes troglodytes and European Robin Erithacus rubecula in browsed vegetation in winter, but no effect of browsing on those species in spring. Ordinations of bird assemblage compositions also revealed seasonal differences in response to gradients of vegetation structure generated by canopy-closure and exclusion of deer. Positive impacts of deer exclusion in winter are probably linked to reduced thermal cover and predator protection afforded by browsed vegetation, whereas species that responded positively in spring were also dependent on a dense understorey for nesting. The effects on birds of vegetation development and its modification by herbivores extend beyond breeding assemblages, with different mechanisms implicated and different species affected in winter.