Emerging mechanisms of ecosystem functioning in a warmer and drier world

<p>Ecosystems are expected to face a significantly warmer and drier climate in the coming decades. Experiments have tried to unravel drought responses of ecosystems in mesic and humid biomes, but the structure and functioning of these systems may change when climatic regime shifts occur. Here, we summarize major mechanisms typical of drylands and indicate how these may come into play when current mesic ecosystems face tipping points in a warmer and drier world.</p><p>These dryland mechanisms of ecosystem functioning encompass (i) processes of vegetation development, such as self-organization of vegetation patchiness and formation of biological soil crust, (ii) biologically driven biogeochemical and physiological processes, such as drying-wetting cycles and hydraulic redistribution, and (iii) abiotically driven biogeochemical processes, such as photochemical degradation of organic matter and soil hydrophobicity. We present insights from published studies and original model simulations and mapping, and formulate hypotheses on thresholds and spatial locations beyond which dryland mechanisms are expected to operate in non-xeric ecosystems. Notably, for dryland mechanisms to get activated elsewhere there is no need for non-xeric biomes to become actual drylands. With a globally increasing area exposed to gradually rising temperatures, moderate decline in precipitation, and increasing frequency, duration and intensity of extreme heat and drought events, we envision that dryland mechanisms will increasingly control ecosystem functioning in many regions of the world.</p>

Meloidae of Namibia (Coleoptera): taxonomy and faunistics with biogeographic and ecological notes

The blister beetle (Coleoptera: Meloidae) fauna of Namibia is studied. The species are arranged within a catalogue containing information on their general distribution, including a list of localities and brief taxonomic remarks. Zoogeographic and ecological analyses were carried out and a photographic appendix, with images and maps of almost all Namibian species, is included. According to a chorological analysis, the Namibian blister beetle fauna appears to be zoogeographically distinct because of the dominance of western southern African elements. The faunistic levels of similarity among distinct areas in Namibia are also analysed. Several of the endemic species are related to the xeric ecosystems referable to the Namib Desert, Succulent Karoo and Nama Karoo biomes, but the highest diversity is related to the ecosystems referable to the Savannah biome. A total of 148 species belonging to 28 genera, eight tribes and three subfamilies (Eleticinae, Meloinae, Nemognathinae) are recorded from this southern African country. Five new genera (Namibeletica gen. nov., Eleticinae Eleticini; Dilatilydus gen. nov. and Desertilydus gen. nov., Meloinae Lyttini; Paramimesthes gen. nov. and Namylabris gen. nov, Meloinae Mylabrini) and a total of 13 new species are described: 11 new species from Namibia (Psalydolytta gessi sp.nov., Paramimesthes namibicus sp.nov., Namylabris adamantifera sp.nov., Hycleus arlecchinus sp.nov., H. planitiei sp.nov., H. dvoraki sp.nov., H. aridus sp.nov., H. san sp.nov., Nemognatha fluviatilis sp.nov., “Zonitoschema” deserticola sp.nov., Zonitoschema dunalis sp.nov.); a new Namibeletica from the Angolan Namib (N. angolana) and a new Afrolytta Kaszab, 1959 from the S African Namaqualand (A. namaqua), both close to Namibian borders. Fourty-eight species and the genus Apalus Fabricius, 1775 are recorded for the first time from Namibia, and a few other species from South Africa (1), Zambia (1), Botswana (1) and Congo (1). The following new synonymies are proposed: Lytta pleuralis var. inpleuralis Pic, 1911 = Lydomorphus (Lydomorphus) thoracicus (Erichson, 1843), syn. nov.; Lytta benguellana Pic, 1911 = Prionotolytta melanura (Erichson, 1843), syn. nov.; Actenodia amoena ssp.anthicoides Kaszab, 1955b = Hycleus amoenus (Marseul, 1872), syn. nov.; Decapotoma csikii Kaszab, 1953 = Hycleus benguellanus (Marseul, 1879), syn. nov.; Nemognatha capensis Péringuey, 1909 = Nemognatha peringueyi Fairmaire, 1883, syn. nov. Several new combinations in the genus Hycleus Latreille, 1817 are also established.

Range-wide declines of a key Neotropical ecosystem architect, the Near Threatened white-lipped peccary Tayassu pecari

We report a range-wide status assessment of a key Neotropical ecosystem architect, the white-lipped peccary Tayassu pecari, categorized as Near Threatened on the IUCN Red List, using published information and unpublished data from 41 scientists in 15 range countries. We estimate that the white-lipped peccary has been extirpated in 21% of its historical range over the last 100 years, with reduced abundance and a low to medium probability of long-term survival in another 48% of its current range. We found major range declines in Argentina, Paraguay, southern Brazil, Colombia, Venezuela, north-east Brazil, Mexico and Costa Rica. This species is particularly at risk in more xeric ecosystems, especially the caatinga, cerrado and pampas. Hunting and habitat destruction are the most severe threats, although there are also unexplained sudden die-offs suggestive of disease. We evaluate our results in light of this species’ important interspecific interactions and its role as an ecosystem architect. One of our recommendations is that conservation efforts should focus on landscape conservation of large, continuous and ecologically intact areas containing a mosaic of different habitat types.

Factors limiting the species richness of bees in Saharan Africa

There is a severe shortage of knowledge of bee biogeography. Some former studies have highlighted a link between bee diversity and xeric ecosystems, but we know practically nothing of the macro-ecological factors driving bee diversity. The present study aims to analyse the main macro-ecological factors driving bee species-richness in the Saharan region. Our dataset includes 25,000+ records for localities in Africa, between 37° and 10°N. Maps and GIS were used to get a first overview of the distribution of the studied taxa. Partial least squares analysis (PLS) was used to study the impact of a set of ecological factors on the bee species richness (SR). The mapping highlighted the clustering of the highest bee SR values in some parts of the Saharan area (e.g. Maghreb, western Africa). In Central Sahara, there is an obvious topological coincidence of the high SR, the local mountain chains and the inland waters. The PLS helped to quantify the relationships between bee SR and a set of eco-climatic variables. It also highlighted a residual variance not explained by the considered descriptors. Our results recover the tight link between bee SR and xeric ecosystems. They also suggest that, within these ecosystems, bee SR is driven by an optimum of the energy-water balance (on which adjustment is allowed by the above gradients).