Pathways towards a sustainable future envisioned by early-career conservation researchers

Scientists have warned decision-makers about the severe consequences of the global environmental crisis since the 1970s. Yet ecological degradation continues and little has been done to address climate change. We investigated early-career conservation researchers' (ECR) perspectives on, and prioritization of, actions furthering sustainability. We conducted a survey (n = 67) and an interactive workshop (n = 35) for ECR attendees of the 5th European Congress of Conservation Biology (2018). Building on these data and discussions, we identified ongoing and forthcoming advances in conservation science. These include increased transdisciplinarity, science communication, advocacy in conservation, and adoption of a transformation-oriented social–ecological systems approach to research. The respondents and participants had diverse perspectives on how to achieve sustainability. Reformist actions were emphasized as paving the way for more radical changes in the economic system and societal values linked to the environment and inequality. Our findings suggest that achieving sustainability requires a strategy that (1) incorporates the multiplicity of people's views, (2) places a greater value on nature, and (3) encourages systemic transformation across political, social, educational, and economic realms on multiple levels. We introduce a framework for ECRs to inspire their research and practice within conservation science to achieve real change in protecting biological diversity.</p

Implementation of the land-sharing and land-sparing framework in agro-ecological corridors

Maintaining adequate food supply while conserving biodiversity is one of the great challenges in conservation today. There is a fundamental controversy between land sparing and land sharing[1]: Land sparing favors intensive agriculture that allows maximal food production in a small area and spares land for conservation, while land sharing favors agro-environmental practices that create multifunctional agroecosystems. While land sparing has proven more advantageous in intact forests, evidence from long-history agricultural landscapes is mixed[2]. Using the sparing-sharing framework, we assessed costs and benefits of agriculture and conservation in planning an ecological corridor in the Jezreel Valley, Israel. We compared land sharing - using environmentally-friendly practices to create a corridor (100 km2) -- with land sparing of wide, intact natural patches (50-300m). To assess these two alternatives, we surveyed biodiversity of five taxonomic groups throughout the agricultural season in six common crops, across two land-sharing practices (uncultivated field-margins and reduced-tillage), and large, spared natural patches. Then we assessed the economic costs (profit and revenue) of these alternatives. Results indicate that uncultivated field-margins are highly biodiverse, despite suffering from a high level of disturbance. Surprisingly, arthropods (ground-dwelling arthropods, butterflies and parasitic wasps) show higher or similar diversity in field-margins as compared to natural patches. This pattern is not consistent with diversity of plants and birds, which is higher in natural patches. Composition analysis shows unique communities in field-margins and higher species turnover for arthropods, emphasizing field-margins contribution at large-scales. Unlike field-margins, reduced-tillage did not affect biodiversity. Economically, field-margins are correlated with higher revenue of some crops, which could be attributed to the pest-control services they provide. Our results indicate that in long-history agricultural landscapes, sparing is better than sharing in creating ecological corridors, but the optimal strategy is a combination of both. Thus, wide, natural patches should be the foundation of the agro-ecological corridor because they support the greatest biodiversity. In addition, field-margins make a better land-sharing strategy than reduced tillage; we found that reduced tillage did not affect biodiversity, regardless of its benefit in reducing soil erosion. The addition of field-margins further improves biodiversity, increasing habitat diversity in the landscape, and enhancing pest-control services that provide economic benefit to farmers. [1] Phalan et al. 2011. Reconciling food production and biodiversity conservation: land sharing and land sparing compared. Science. [2] von Wehrden et al. 2014. Realigning the land-sharing/land-sparing debate to match conservation needs: Considering diversity scales and land-use history. Landscape Ecol.peerReviewe

Quantifying Competitive Exclusion and Competitive Release in Ecological Communities: A Conceptual Framework and a Case Study

<div><p>A fundamental notion in community ecology is that local species diversity reflects some balance between the contrasting forces of competitive exclusion and competitive release. Quantifying this balance is not trivial, and requires data on the magnitude of both processes in the same system, as well as appropriate methodology to integrate and interpret such data. Here we present a novel framework for empirical studies of the balance between competitive exclusion and competitive release and demonstrate its applicability using data from a Mediterranean annual grassland where grazing is a major mechanism of competitive release. Empirical data on the balance between competitive exclusion and competitive release are crucial for understanding observed patterns of variation in local species diversity and the proposed approach provides a simple framework for the collection, interpretation, and synthesis of such data.</p></div

Results of ordination analysis (Nonmetric Multidimensional Scaling, NMDS) showing the effect of treatment (grass removal, grazing, and control) on forb species composition in the two habitats (valleys <i>vs</i>. slopes).

<p>Analyses were performed at the cluster scale (1m²) using the Jaccard index as a measure of dissimilarity.</p

A map of the experimental system and the sampling design.

<p>Blocks located on the slopes are marked by yellow dashed lines; blocks located in the valleys are marked by white dashed lines. In each habitat there are three blocks with three treatments per block (grazing, grass removal, and control) and four blocks with two treatments (grazing and control). Each plot is 20x20m, but sampling was limited to the inner area of 10x10m. This area was sampled by 25 quadrates of 0.04m² organized in five clusters of 1m². Clipping experiments were conducted in the peripheral areas of control plots.</p

The CR-CE space as a framework for analyzing the balance between competitive release and competitive exclusion.

<p>Systems in which the releasing factor fully compensates for competitive exclusions fall on the line y = x (the 'compensation line', points A and B in (a)). Systems characterized by partial compensation fall below the compensation line (C, D, E in (a)). Note that points C and D have the same effectiveness although they differ in the magnitude of competitive exclusion. Point E shows a lower effectiveness than points C and D although the magnitude of competitive release is similar to point D. If data on both forces are available for a set of sites within the same system, the effectiveness of the releasing factor can be expressed by the slope of a linear regression fitted to the data (b).</p

Results of a small-scale clipping experiment mimicking the effect of biomass removal by the cattle on the vegetation in the study area (removal of all shoots higher than 7 cm).

<p>The experiment was conducted within experimental units of 0.16m² protected from grazing (see Appendix B in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160798#pone.0160798.s005" target="_blank">S1 File</a> for details). (a, e) Clipped biomass of forbs and grasses in the two habitats. (b, f) Seedling mortality. (c, g) Extinction rates. (d, h) Species richness at the end of the growing season. Bars represent 95% confidence levels. Significant differences between clipped biomass of grasses and forbs (a, c) and between clipping treatments (b-d, f-h) are marked by asterisks.</p

Effects of grazing and grass removal on forb richness in the study system.

<p>(a) A summary of the experimental results using the CR-CE framework. The dashed line is the compensation line (y = x). Each point represents a certain combination of habitat, block, and scale. Each line is a regression line fitted to a different scale (0.04m²: <i>R</i>² = 0.63, <i>P</i> = 0.059; 1m²: <i>R</i>² = 0.82, <i>P</i> = 0.012; 100m²: <i>R</i>² = 0.54, <i>P</i> = 0.095, all slopes are significantly lower than 1 and all intercepts do not differ significantly from zero, significance levels based on standard errors of the regression coefficients). (b) Effect size (log response ratio) of the grass removal and grazing treatments under each combination of habitat (slopes <i>vs</i>. valleys) and scale (0.04, 1, and 100m²). Log response ratio is quantified as Log(<i>S</i>_TREATMENT/<i>S</i>_CONTROL), where <i>S</i> = mean number of forb species under the relevant combination of treatment, habitat and scale.</p

Quantifying potential trade-offs and win-wins between arthropod diversity and yield on cropland under agri-environment schemes–A meta-analysis

In Europe, agri-environment schemes (AES) are a key instrument to combat the ongoing decline of farmland biodiversity. AES aim is to support biodiversity and maintain ecosystem services, such as pollination or pest control. To what extent AES affect crop yield is still poorly understood. We performed a systematic review, including hierarchical meta-analyses, to investigate potential trade-offs and win-wins between the effectiveness of AES for arthropod diversity and agricultural yield on European croplands. Altogether, we found 26 studies with a total of 125 data points that fulfilled our study inclusion criteria. From each study, we extracted data on biodiversity (arthropod species richness and abundance) and yield for fields with AES management and control fields without AES. The majority of the studies reported significantly higher species richness and abundance of arthropods (especially wild pollinators) in fields with AES (31 % increase), but yields were at the same time significantly lower on fields with AES compared to control fields (21 % decrease). Aside from the opportunity costs, AES that promote out-of-production elements (e.g. wildflower strips), supported biodiversity (29–32 % increase) without significantly compromising yield (2–5 % increase). Farmers can get an even higher yield in these situations than in current conventional agricultural production systems without AES. Thus, our study is useful to identify AES demonstrating benefits for arthropod biodiversity with negligible or relatively low costs regarding yield losses. Further optimization of the design and management of AES is needed to improve their effectiveness in promoting both biodiversity and minimizing crop yield losses