Research in progress: report on the ICAIL 2017 doctoral consortium

This paper arose out of the 2017 international conference on AI and law doctoral consortium. There were five students who presented their Ph.D. work, and each of them has contributed a section to this paper. The paper offers a view of what topics are currently engaging students, and shows the diversity of their interests and influences

Evaluating structural and compositional canopy characteristics to predict the light‐demand signature of the forest understorey in mixed, semi‐natural temperate forests

Questions: Light availability at the forest floor affects many forest ecosystem processes, and is often quantified indirectly through easy‐to‐measure stand characteristics. We investigated how three such characteristics, basal area, canopy cover and canopy closure, were related to each other in structurally complex mixed forests. We also asked how well they can predict the light‐demand signature of the forest understorey (estimated as the mean Ellenberg indicator value for light [“EIVLIGHT”] and the proportion of “forest specialists” [“%FS”] within the plots). Furthermore, we asked whether accounting for the shade‐casting ability of individual canopy species could improve predictions of EIVLIGHT and %FS. Location: A total of 192 study plots from nineteen temperate forest regions across Europe. Methods: In each plot, we measured stand basal area (all stems >7.5 cm diameter), canopy closure (with a densiometer) and visually estimated the percentage cover of all plant species in the herb (7 m). We used linear mixed‐effect models to assess the relationships between basal area, canopy cover and canopy closure. We performed model comparisons, based on R2 and the Akaike Information Criterion (AIC), to assess which stand characteristics can predict EIVLIGHT and %FS best, and to assess whether canopy shade‐casting ability can significantly improve model fit. Results: Canopy closure and cover were weakly related to each other, but showed no relation with basal area. For both EIVLIGHT and %FS, canopy cover was the best predictor. Including the share of high‐shade‐casting species in both the basal‐area and cover models improved the model fit for EIVLIGHT, but not for %FS. Conclusions: The typically expected relationships between basal area, canopy cover and canopy closure were weak or even absent in structurally complex mixed forests. In these forests, easy‐to‐measure structural canopy characteristics were poor predictors of the understorey light‐demand signature, but accounting for compositional characteristics could improve predictions

Light availability and land‐use history drive biodiversity and functional changes in forest herb layer communities

1. A central challenge of today's ecological research is predicting how ecosystems will develop under future global change. Accurate predictions are complicated by (a) simultaneous effects of different drivers, such as climate change, nitrogen deposition and management changes; and (b) legacy effects from previous land use. 2. We tested whether herb layer biodiversity (i.e. richness, Shannon diversity and evenness) and functional (i.e. herb cover, specific leaf area [SLA] and plant height) responses to environmental change drivers depended on land‐use history. We used resurvey data from 192 plots across nineteen European temperate forest regions, with large spatial variability in environmental change factors. We tested for interactions between land‐use history, distinguishing ancient and recent (i.e. post‐agricultural) forests and four drivers: temperature, nitrogen deposition, and aridity at the regional scale and light dynamics at the plot‐scale. 3. Land‐use history significantly modulated global change effects on the functional signature of the herb layer (i.e. cover, SLA and plant height). Light availability was the main environmental driver of change interacting with land‐use history. We found greater herb cover and plant height decreases and SLA increases with decreasing light availability in ancient than in recent forests. Furthermore, we found greater decreases in herb cover with increased nitrogen deposition in ancient forests, whereas warming had the strongest decreasing effect on the herb cover in recent forests. Interactive effects between land‐use history and global change on biodiversity were not found, but species evenness increased more in ancient than in recent forests. 4. Synthesis. Our results demonstrate that land‐use history should not be overlooked when predicting forest herb layer responses to global change. Moreover, we found that herb layer composition in semi‐natural deciduous forests is mainly controlled by local canopy characteristics, regulating light levels at the forest floor, and much less by environmental changes at the regional scale (here: warming, nitrogen deposition and aridity). The observed disconnect between biodiversity and functional herb layer responses to environmental changes demonstrates the importance of assessing both types of responses to increase our understanding of the possible impact of global change on the herb layer