Two photon absorption and photo-induced polymerization in partially polymerized crystals of polydiacetylene poly 4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)

We investigated the validity of noninteracting molecular chain theories for fully polymerized polydiacetylene crystals by measuring the two photon absorption spectrum of poly[4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)] chains isolated in their monomer matrix and comparing the results to those obtained previously from polydiacetylene single crystals. Data were taken over 800-940 nm using Z-scan and the measurements were found to be consistent with previously measured results in polydiacetylene single crystal poly[bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol], indicating the validity of the isolated molecule theoretical approach. We also report a low photo-induced polymerization threshold

Two photon absorption and photo-induced polymerization in partially polymerized crystals of polydiacetylene poly 4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)

We investigated the validity of noninteracting molecular chain theories for fully polymerized polydiacetylene crystals by measuring the two photon absorption spectrum of poly[4,6-dodecadiyn-1,10-diol-bis(n-butoxycarbonylmethylurethane)] chains isolated in their monomer matrix and comparing the results to those obtained previously from polydiacetylene single crystals. Data were taken over 800-940 nm using Z-scan and the measurements were found to be consistent with previously measured results in polydiacetylene single crystal poly[bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol], indicating the validity of the isolated molecule theoretical approach. We also report a low photo-induced polymerization threshold

Stakeholder mapping to support invasive non-native species management in South America

Peer reviewe

Revealing Historic Invasion Patterns and Potential Invasion Sites for Two Non-Native Plant Species

The historical spatio-temporal distribution of invasive species is rarely documented, hampering efforts to understand invasion dynamics, especially at regional scales. Reconstructing historical invasions through use of herbarium records combined with spatial trend analysis and modeling can elucidate spreading patterns and identify susceptible habitats before invasion occurs. Two perennial species were chosen to contrast historic and potential phytogeographies: Japanese knotweed (Polygonum cuspidatum), introduced intentionally across the US; and mugwort (Artemisia vulgaris), introduced largely accidentally to coastal areas. Spatial analysis revealed that early in the invasion, both species have a stochastic distribution across the contiguous US, but east of the 90th meridian, which approximates the Mississippi River, quickly spread to adjacent counties in subsequent decades. In contrast, in locations west of the 90th meridian, many populations never spread outside the founding county, probably a result of encountering unfavorable environmental conditions. Regression analysis using variables categorized as environmental or anthropogenic accounted for 24% (Japanese knotweed) and 30% (mugwort) of the variation in the current distribution of each species. Results show very few counties with high habitat suitability (≥80%) remain un-invaded (5 for Japanese knotweed and 6 for mugwort), suggesting these perennials are reaching the limits of large-scale expansion. Despite differences in initial introduction loci and pathways, Japanese knotweed and mugwort demonstrate similar historic patterns of spread and show declining rates of regional expansion. Invasion mitigation efforts should be concentrated on areas identified as highly susceptible that border invaded regions, as both species demonstrate secondary expansion from introduction loci

Widespread plant species : natives versus aliens in our changing world

CITATION: Stohlgren, T.J. et al. 2011. Widespread plant species: Natives vs. aliens in our changing world. Biological Invasions, 13:1931-1944. doi:10.1007/s10530-011-0024-9The original publication is available at https://www.springer.com/journal/10530Estimates of the level of invasion for a region are traditionally based on relative numbers of native and alien species. However, alien species differ dramatically in the size of their invasive ranges. Here we present the first study to quantify the level of invasion for several regions of the world in terms of the most widely distributed plant species (natives vs. aliens). Aliens accounted for 51.3% of the 120 most widely distributed plant species in North America, 43.3% in New South Wales (Australia), 34.2% in Chile, 29.7% in Argentina, and 22.5% in the Republic of South Africa. However, Europe had only 1% of alien species among the most widespread species of the flora. Across regions, alien species relative to native species were either as well-distributed (10 comparisons) or more widely distributed (5 comparisons). These striking patterns highlight the profound contribution that widespread invasive alien plants make to floristic dominance patterns across different regions. Many of the most widespread species are alien plants, and, in particular, Europe and Asia appear as major contributors to the homogenization of the floras in the Americas. We recommend that spatial extent of invasion should be explicitly incorporated in assessments of invasibility, globalization, and risk assessments.Publisher’s versio

Stakeholders' views on the global guidelines for the sustainable use of non‐native trees

A large number of non‐native trees (NNTs) have been introduced globally and widely planted, contributing significantly to the world's economy. Although some of these species present a limited risk of spreading beyond their planting sites, a growing number of NNTs are spreading and becoming invasive leading to diverse negative impacts on biodiversity, ecosystem functions and human well‐being. To help minimize the negative impacts and maximize the economic benefits of NNTs, Brundu et al. developed eight guidelines for the sustainable use of NNTs globally—the Global Guidelines for the Use of NNTs (GG‐NNTs). Here, we used an online survey to assess perceptions of key stakeholders towards NNTs, and explore their knowledge of and compliance with the GG‐NNTs. Our results show that stakeholders are generally aware that NNTs can provide benefits and cause negative impacts, often simultaneously and they consider that their organization complies with existing regulations and voluntary agreements concerning NNTs. However, they are not aware of or do not apply most of the eight recommendations included in the GG‐NNTs. We conclude that effectively managing invasions linked to NNTs requires both more communication efforts using an array of channels for improving stakeholder awareness and implementation of simple measures to reduce NNT impacts (e.g. via GG‐NNTs), and a deeper understanding of the barriers and reluctance of stakeholders to manage NNT invasions. Read the free Plain Language Summary for this article on the Journal blog

The role of protected areas in the avoidance of anthropogenic conversion in a high pressure region : a matching method analysis in the core region of the brazilian cerrado

Global efforts to avoid anthropogenic conversion of natural habitat rely heavily on the establishment of protected areas. Studies that evaluate the effectiveness of these areas with a focus on preserving the natural habitat define effectiveness as a measure of the influence of protected areas on total avoided conversion. Changes in the estimated effectiveness are related to local and regional differences, evaluation methods, restriction categories that include the protected areas, and other characteristics. The overall objective of this study was to evaluate the effectiveness of protected areas to prevent the advance of the conversion of natural areas in the core region of the Brazil’s Cerrado Biome, taking into account the influence of the restriction degree, governmental sphere, time since the establishment of the protected area units, and the size of the area on the performance of protected areas. The evaluation was conducted using matching methods and took into account the following two fundamental issues: control of statistical biases caused by the influence of covariates on the likelihood of anthropogenic conversion and the non-randomness of the allocation of protected areas throughout the territory (spatial correlation effect) and the control of statistical bias caused by the influence of auto-correlation and leakage effect. Using a sample design that is not based on ways to control these biases may result in outcomes that underestimate or overestimate the effectiveness of those units. The matching method accounted for a bias reduction in 94–99% of the estimation of the average effect of protected areas on anthropogenic conversion and allowed us to obtain results with a reduced influence of the auto-correlation and leakage effects. Most protected areas had a positive influence on the maintenance of natural habitats, although wide variation in this effectiveness was dependent on the type, restriction, governmental sphere, size and age group of the unit

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications