The Impact of Roads on the Redistribution of Plants and Associated Arthropods in a Hyper-Arid Ecosystem.

The construction of vehicular roads likely affects the distribution of natural resources. Although the effects of roads on different ecosystem aspects have been extensively studied, studies in arid and, particularly, in hyper-arid ecosystems are scarce. In drylands, where water is the main limiting factor, the effect of roads on the redistribution of water may have strong subsequent effects on the ecosystem, especially when roads cross natural water flow paths. To fill this knowledge gap, we studied the effects of a road that runs across a slope on the distribution of plants and animals in a hyper-arid environment. Changes in shrub cover, below and above the road, were quantified by remote sensing and image classification, while plant-associated arthropods were vacuum-sampled from shrub canopies and from open (inter-shrub) areas. We found that the spatial distribution of shrubs, a vital resource facilitating many other organisms, was affected by the road, with an increase in the shrub cover immediately above the road and a decrease below it. Arthropod abundance generally followed shrub cover, but the exact pattern depended on the specific group sampled. While some arthropod groups (e.g., aphids, parasitic wasps and barklice) thrived under the disturbed conditions above the road, other arthropod groups (e.g., mites and true bugs) were less abundant in the disturbed patches. Our results highlight the strong effects of human-made structures on the distribution of flora and fauna in arid ecosystems.

Desert Vegetation Forty Years after an Oil Spill.

Deserts are the most frequent locations of terrestrial crude oil contaminations. Nevertheless, the long-term effects of petroleum hydrocarbons on desert ecosystems are still unknown, which makes risk assessment and decision making concerning remediation difficult. This study examined the long-term effects of petroleum hydrocarbons on perennial desert vegetation. The study site was a hyper-arid area in the south of Israel, which was contaminated by a crude oil spill in 1975. The contaminated area was compared to uncontaminated reference areas. The composition of perennial plants 40 yr after the oil spill was not significantly affected by the contamination. However, the size distribution of the two most dominant shrub species, Baker and (Moq.) Iljin., and the only tree species, Savi and (Forssk.) Hayne, were different from the reference. These differences can be explained by decreased recruitment. The estimated recruitment of in the last 40 yr post oil spill was 74% less than recruitment in the reference area. Low recruitment of may in the future lead to the loss of tree cover, which would change the entire ecosystem, as are keystone species on which a number of microorganisms, plants, and animals rely. Remediation of oil spills and preventative measures are recommended.

Towards the co-ordination of terrestrial ecosystem protocols across European research infrastructures.

The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long-term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long-term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above-ground plant biomass; decomposition; land use and management; leaf area index; soil mesofaunal diversity; soil C and N stocks, and greenhouse gas emissions from soils. These complement existing methods to provide a complete assessment of ecological integrity. These protocols offer integrated approaches to ecological data collection that are low cost and are starting to be used across the European Long Term Ecological Research community.