An investigation of two methods for assessing the vertical structure of forest stands

In this study we investigate the limitations of two methods for assessing forest structure: vertical point sampling with a camera and laser point quadrat sampling. Vertical point sampling with a camera is a method by which the height squared per unit area of a forest can be quickly estimated. First, we derive the bias incurred for failing to adjust for slope when implementing this sampling method, and we show that slope can generally be ignored as long as the majority of sample points occur on slopes less than 35 degrees. In the second part of this study we outline the equivalence between survival analysis methods and laser point quadrat analysis methods. We use a survival-based parametric regression model to analyze laser point quadrat data and estimate canopy structure and density. The results show that survival analysis techniques can yield improved results over traditional non-parametric point quadrat analysis methods

Darwinian Selection and Non-existence of Nash Equilibria

We study selection acting on phenotype in a collection of agents playing local games lacking Nash equilibria. After each cycle one of the agents losing most games is replaced by a new agent with new random strategy and game partner. The network generated can be considered critical in the sense that the lifetimes of the agents is power law distributed. The longest surviving agents are those with the lowest absolute score per time step. The emergent ecology is characterized by a broad range of behaviors. Nevertheless, the agents tend to be similar to their opponents in terms of performance.Comment: 4 pages, 5 figure

Road-Edge Effects on Herpetofauna in a Lowland Amazonian Rainforest

The impact of roads on the flora and fauna of Neotropical rainforest is perhaps the single biggest driver of habitat modification and population declines in these ecosystems. We investigated the road-edge effect of a low-use dirt road on amphibian and reptile abundance, diversity, and composition within adjacent lowland Amazonian rainforest at San José de Payamino, Ecuador. The road has been closed to vehicle traffic since its construction in 2010. Thus, effects from vehicle mortality, vehicle-related pollution, and road noise were not confounding factors. Herpetofauna were surveyed using both visual encounter surveys and drift fences with pitfall and funnel traps at varying distances from the road. Structural and microclimate features of the forest were measured at each sampling distance. Several habitat variables were found to differ at intermediate and interior sampling distances from the road compared to forest edge conditions, suggesting the road-edge effect began to attenuate by the intermediate sampling distance. However, the edge effect on amphibians and reptiles appeared to extend 100 m from the road edge, as abundance and diversity were significantly greater at the interior forest compared to the forest edge. Additionally, assemblage composition as well as the hierarchical position of species shifted between sampling distances. Habitat predictor models indicate that amphibian abundance was best predicted by vine abundance, while both vine and mature tree abundance were the best predictors for species richness and diversity. Overall, and contrary to what might otherwise be expected, our results demonstrate that small, little-used road disturbances can nonetheless have profound impacts on wildlife

The use of artificial media in fungal ecology

Can experiments conducted in agar really help us to understand the complexity of fungal systems? This question has been the focus of persistent and ongoing debate between fungal ecologists that favor reductionist versus holistic approaches. On one hand, artificial media are unrealistic and fail to reflect the heterogeneity and complexity of natural systems. But on the other hand, they offer simplified model systems that allow us to isolate mechanisms that would otherwise be obscured in natural systems. Following various technological advances that enable us to describe various aspects of complex fungal communities in situ, the dial appears to be tipping in favor of observational field studies, and the use of artificial media has declined. However, we argue that the loss of artificial media from experimental studies would impair our capacity to disentangle the complexities of fungal communities. Here, we discuss the pros and cons of artificial media in fungal ecology and outline the types of questions that are best addressed using fungi growing in artificial media. We conclude that renewed emphasis on the value of artificial media could help us to generate the mechanistic understanding that might be critical to explaining the exciting patterns that are emerging from real-world fungal ecology studies

The global biogeography of tree leaf form and habit

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.EEA Santa CruzFil: Ma, Haozhi. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Crowther, Thomas W. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Mo, Lidong. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Maynard, Daniel S. University College London. Department of Genetics, Evolution, and Environment; Reino UnidoFil: Renner, Susanne S. Washington University. Department of Biology; Estados UnidosFil: van den Hoogen, Johan. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Zou, Yibiao. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); SuizaFil: Liang, Jingjing. Purdue University. Department of Forestry and Natural Resources; Estados UnidosFil: de-Miguel, Sergio. University of Lleida. Department of Agricultural and Forest Sciences and Engineering; EspañaFil: de-Miguel, Sergio. Joint Research Unit CTFC - AGROTECNIO – CERCA; EspañaFil: Nabuurs, Gert-Jan. Wageningen University and Research; Países BajosFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral.; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Zohner, Constantin M. Institute of Integrative Biology. ETH Zurich (Swiss Federal Institute of Technology); Suiz

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5,6,7, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions.EEA Santa CruzFil: Delavaux, Camille S. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Crowther, Thomas W. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Zohner, Constantin M. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Robmann, Niamh M. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Lauber, Thomas. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: van den Hoogen, Johan. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Kuebbing, Sara. Yale University. The Forest School at The Yale School of the Environment; Estados UnidosFil: Liang, Jingjing. Purdue University. Department of Forestry and Natural Resources; Estados UnidosFil: de-Miguel, Sergio. University of Lleida. Department of Crop and Forest Sciences; EspañaFil: de-Miguel, Sergio. Joint Research Unit CTFC–AGROTECNIO–CERCA; EspañaFil: Nabuurs, Gert-Jan. Wageningen University and Research; Países BajosFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Maynard, Daniel S. Swiss Federal Institute of Technology. Institute of Integrative Biology; SuizaFil: Maynard, Daniel S. University College London. Department of Genetics, Evolution, and Environment; Reino Unid

Change and Aging Senescence as an adaptation

Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by random chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces always win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes.Comment: 19 pages, 4 figure

Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

Brief of Tax Law Professors as \u3ci\u3eAmici Curiae\u3c/i\u3e in Support of Petitioner in \u3ci\u3eLoudoun County, Virginia v. Dulles Duty Free, LLC\u3c/i\u3e

Amici are professors of tax law at universities across the United States. As scholars and teachers, they have considered the doctrinal roots and practical consequences of judicial limits on state and local taxation. Amici join this brief solely on their own behalf and not as representatives of their universities. A full list of amici appears in the Appendix to this brief