Ecosytem services: A rapid assessment method tested at 35 sites of the LTER-Europe Network

The identification of parameters to monitor the ecosystem services delivered at a site is fundamental to the concept’s adoption as a useful policy instrument at local, national and international scales. In this paper we (i) describe the process of developing a rapid comprehensive ecosystem service assessment methodology and (ii) test the applicability of the protocol at 35 long-term research (LTER) sites across 14 countries in the LTER-Europe network (www.lter-europe.net) including marine, urban, agricultural, forest, desert and conservation sites. An assessment of probability of occurrence with estimated confidence score using 83 ecosystem service parameters was tested. The parameters were either specific services like food production or proxies such as human activities which were considered surrogates for cultural diversity and economic activity. This initial test of the ecosystem service parameter list revealed that the parameters tested were relatively easy to score by site managers with a high level of certainty (92% scored as either occurring or not occurring at the site with certainty of over 90%). Based on this assessment, we concluded that (i) this approach to operationalise the concept of ecosystem services is practical and applicable by many sectors of civil society as a first screen of the ecosystem services present at a site, (ii) this study has direct relevance to land management and policy decision makers as a transparent vehicle to focus testing scenarios and target data gathering, but (iii) further work beyond the scale investigated here is required to ensure global applicability

Demonstration in Ramon LTER site of the compensation hypothesis providing an alternative scenario to desertification

Climate changes bring a new era in which hot dry areas become even hotter and drier. This leads to state shifts and specifically desertification processes. Desertification includes the state shifts from non-desert to deserts and within deserts reduction of primary productivity. Studying shifts in ecosystem states and desertification requires long term ecosystem research and monitoring (LTERM). This can take decades and because temporal variability of precipitation in deserts is very high, it is difficult to distinguish between noise and trends. Space for time substitution is a tool aiding LTER research. Specifically hyper-arid ecosystems (HAE), the driest deserts on earth, are a good tool to study possible scenarios of climate changes. Understanding structure and function of HAE allows us to imagine possible dynamics that can occur in wetter ecosystems.Our new assertion is that if extreme climate change drives arid lands to function under alternate extreme conditions, then arid land ecosystems will function like an HAE as an alternative state, rather than progress to desertification. To support our assertion, we developed a conceptual framework of HAEs that includes a geo-hydrological “abiotic engine” that drives HAE function by soil moisture diversity and plant functional groups. Based on this conceptual framework, we suggest incorporating two new hypotheses in climate change studies to advance our understanding of responses of large-scale, water-limited ecosystems:Hydro-climatic extremes in water-limited ecosystems will reduce the degree of resource conservation by slope ecosystems due to reduction in plant cover and soil. The decreased ecosystem function on the slope will be compensated for by increasing the effect of the abiotic engine on the ephemeral stream, thus enhancing meta-ecosystem functioning in the ephemeral stream.In water-limited ecosystems, climate change toward hydro-climatic extremes will rescale the dominant hydro-ecological processes of pulse–reserve, source–sink, and connectivity along the semiarid, arid, and HA gradients in two ways:shrinking of both spatial and temporal dimensions; and shrinking in the temporal dimension and expanding in the spatial dimensions.The first rescaling trajectory is related to biodiversity–ecosystem function and the second to the abiotic engine processes.The forecasted increased frequency and intensity of extreme climatic events may strongly affect ecosystem structure and function in the future. It is unclear how ecosystems will function in the long run over a large spatial scale under a new extreme water cycle. This open question calls for a conceptual framework as a fundamental basis for theoretical and experimental exploration of ecosystem function on a large scale driven by an extreme climate envelope. We investigated hyper-arid ecosystems (HAEs) as natural tangible models that already function under an extreme climatic envelope. The results indicate that unique geological settings can retain runoff water from a single significant flash flood that is sufficient to sustain perennials even during drought years. We calculated a water balance for a large rain event and found that 38% of the rain water infiltrated to the main riverbed which supports local trees, 46% exited the watershed to a larger river and only 19% were lost to either evaporation or the bare slopes. We propose a modified pulse–reserve mechanism that provides water to large acacia trees during the hot dry summer in hyperarid areas

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

Abstract 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.</jats:p

Impact of spatial patterns on arthropod assemblages following natural dune stabilization under extreme arid conditions

Background: The cessation of anthropogenic activities in mobile sand dune ecosystems under xeric arid conditions has resulted in the gradual stabilization of dunes over the course of five decades.&nbsp;Our objective was to analyze the spatial patterns of arthropod assemblages along a gradient of different stabilization levels, which represents the different stages of dune stabilization - from the shifting crest of the dune to the stabilized crusted interdune.The study was carried out at the sand dunes of the northwestern Negev in Israel. Data was collected using dry pitfall traps over two consecutive years during the spring along northern windward aspects. Four dunes were chosen, characterized by three significant landscape units: shifting crest, semi-stabilized slope and stabilized interdune.Results: We identified three significant assemblages of arthropods along the gradient. The shifting dune crests are populated by psammophilic species found almost exclusively in sandy habitats in Egypt and the western Negev in Israel. The crusted, stabilized inter-dunes are populated mainly by loess-dwelling species, which are common in most of the Negev loess plains and have a wide distribution range, and the semi-stabilized slopes host species of both extreme landscape units but is distinguished by four species that show significant affinity to it.&nbsp;Conclusions: Our results demonstrate functional arthropod heterogeneity and emphasize the risk of regional species homogenization. Heterogeneity is a key property in maintaining sand dune biodiversity. Homogenization, as a result of sand stabilization, may lead to loss of psammophilic species.&nbsp;</p