Artemisia adamsii is a weed with low palatability to livestock and is thus recognized as an indicator of rangeland degradation in Mongolia. We investigated the germination characteristics of this species, phytotoxic suppression of its germination by its own residue, and the applicability of such germination behaviour to the control of this species. We also discussed the ecological consequence of these factors regarding the vegetation dynamics of the Mongolian steppe. Germination of A. adamsii was tested at different light and temperature conditions. Germination was also tested for A. adamsii and four native grassland species in the presence or absence of A. adamsii residue. Germination of A. adamsii was light-demanding and temperature-dependent. Artemisia adamsii residue showed autotoxic but sub-fatal suppression of germination, and the chemicals causing that suppression were shown to be aqueous and volatile. Phytotoxicity of A. adamsii residue on the germination of grassland species was low, except for in Artemisia frigida. The applicability of the observed sub-fatal autotoxicity for controlling this species was likely to be low, but the elucidated germination characteristics could contribute to developing a strategy for controlling this species. The autotoxicity in A. adamsii germination was suggested to have an ecological consequence that mediates species transition from A. adamsii to other species in degraded land occupied by A. adamsii. As low-palatability A. adamsii can act as a nurse plant of palatable species under grazing conditions, the invasion of A. adamsii into disturbed grasslands may facilitate the recovery of such grasslands in terms of improving pasture quality.

In the hinterland of the desert, valuable archives of paleoenvironmental evolution are scarce. Calcareous root tubes (CRTs) have a strong potential for reconstructing paleoenvironmental conditions. It is still unclear, however, whether chemical elements in the CRTs can provide insights into paleoenvironmental conditions. In this study, the major- and trace-element composition of 32 CRT samples from the Alashan Desert were analyzed by X-ray fluorescence spectrometry. Results showed that the elemental composition and content change were controlled by the parent material and climatic conditions at the time of CRT formation. Ca, Mg, and Sr were significantly affected by climate, whereas the enrichment of P is likely related to the growth of plants. Higher (lower) Mg/Ca and Sr/Ca ratios corresponded to higher (lower) effective moisture and a higher (lower) Mg/Sr ratio indicated a higher (lower) temperature during the middle Holocene (8–5 cal ka BP). The reconstruction results for effective moisture were consistent with those in the Asian monsoon margin of northwestern China, which were caused by higher monsoon precipitation and lower evaporation. Therefore, chemical elements in the CRTs can reflect changes in paleo-effective moisture and paleotemperature at a millennial resolution in this area.

Jatropha curcas L. is a stem-succulent shrub that produces high concentrations of seed oils that are convertible into biodiesel. In this study, the incidence of four insect pests on Jatropha, Strabala rufa, Gnathamitermes tubiformans, Pempelia morosalis, and Acanthoplus discoidalis was recorded over three years in a semi-arid climate in Gaborone, Botswana. The occurrence of these insects was concentrated in the summer season from October to April, while lower numbers of all species were found in May as the temperature began to reduce towards the winter season, suggesting that insect pests of Jatropha exhibit a unique temporal pattern in this region. A considerable variation was observed among Jatropha accessions regarding the insect pest occurrence, indicating a vast difference in the susceptibility to insect pests among Jatropha accessions.

In the hinterland of deserts, it is difficult to reconstruct paleovegetation using fossil pollen because of the low pollen concentration. Therefore, an efficient method is needed to reconstruct the paleovegetation of desert regions. In this study, 34 Holocene calcareous root tube (CRT) samples were collected from the Alashan Desert in northwest China, and lipid molecular proxies from CRTs were selected to address this deficiency. The results show that n-alkanes mainly maximized at C27, C29, and C16, and that the carbon preference index is close to 1. Thus, the sources of n-alkanes from CRTs were the roots of higher plants and microorganisms, and thus changes in n-alkanes from CRTs could reveal variations in vegetation cover. The n-alkane Cmax of long-chain n-alkanes (C>25) in CRTs, maximizing at C27, indicated that vegetation in the Alashan Desert was characterized by shrub vegetation during the Holocene. Changes in the ratio of (C27+C29)/(C31+C33) indicated that the biomass of shrub vegetation increased during the period 7–2 cal ka BP. Moreover, the relative concentration of short-chain to long-chain n-alkanes decreased from 7 to 2 cal ka BP, suggesting that the effective moisture decreased during that period.

Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropogenic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale monitoring of critical bush densities should be used to better organize conservation plans (protection and/or restoration of areas) for the Moorish tortoise.

Decrease in productivity of pastureland is a common problem in dry areas and needs to be enhanced through conservation and management of soil biodiversity and available plant resources. Diversity and population dynamics of soil arthropods, and soil nutrients were studied in different silvopastoral (tree-integrated grassland) systems for effective management and enhancement of grassland productivity. The most prominent combinations of trees and grasses in silvopastoral systems of the selected sites were Prosopis cineraria with Cenchrus ciliaris and C. biflorus (PC), Acacia nilotica with Elusine compressa and C. ciliaris (AN), Zizyphus nummularia with C. ciliaris and E. compressa (ZN), Capparis decidua with C. biflorus and Digitaria marginatus (CD) and A. senegal with C. ciliaris and D. marginatus (AS). Pure grass blocks outside tree canopy were selected as control plots. Acari, Myriapoda, Coleoptera, Isoptera, Collembola and other soil arthropods were the major soil faunal groups. Relative densities of Acari, Myriapoda and other arthropods were highest in silvopastoral systems and those of Coleoptera, Isoptera and Collembola were highest in pure grass plots. Variations in soil arthropod populations in response to rainfall, soil water content and soil temperature indicated greater sensitivity of these groups to environmental factors. The highest densities and negative relative tree effect (RTE) values of Acari, Myriapoda and other soil arthropods in the ZN, Coleoptera in the AS, Isoptera in the CD and Collembola in the AN systems indicated that these soil arthropods preferred the silvopastoral systems involved. Seasonal variations in soil organic matter and available NH4-N, NO3-N and PO4-P were similar to those of soil arthropods. The concentrations of soil nutrients were highest in the ZN system, which had the highest densities of soil arthropods. The other systems with high populations and soil nutrient status were the CD and AS. Silvopastoral systems based on Z. nummularia, C. decidua and A. senegal promoted soil arthropod populations and enhanced soil nutrient status, highlighting the positive role of tree presence and the need for proper management to promote soil biodiversity, nutrient cycling and sustained production in a fragile environment.

Municipal effluent is becoming an increasing environmental threat and needs appropriate disposal measures to safeguard soil and environmental quality. As an important source of water and nutrients, municipal effluent could be used to increase productivity in nutrient deficient dry areas. Acacia nilotica L. (Babool) seedlings were grown using municipal effluent. Five treatments comprised: irrigation of soil (without seedlings) with municipal effluent at potential evapotranspiration (PET) (treatment T1), irrigation of seedlings at 0.5 PET (T2), PET (T3), and 2 PET (T4), and canal water irrigation of seedlings at PET (T5). Seedlings in the T3 and T4 treatments attained greater height and collar diameter, and produced 22% and 54% more biomass than those in T5. After 24 months, biomass production was 7.43–12.96 t ha−1 as compared to 5.73 t ha−1 in T5. Nutrient concentrations in the seedlings were positively correlated with effluent quantity (r = 0.82, p < 0.01), being greater in foliage than in stems and roots. Uptake of nitrogen (N) was 2.70%, and of iron (Fe) 0.11%, of seedling biomass. Relative increase in metal concentration was greater than that in nutrients. The availability of potassium (K), copper (Cu), Fe, manganese (Mn) and zinc (Zn) in the soil increased twofold and that of NH4-N and PO4-P by 4.5- and 7.9-fold, respectively, in T4 relative to T5. Available NH4-N, PO4-P, Mg and K were highest in the 0–15 cm depth soil, whereas NO3-N, Na, Cu, Fe, Mn and Zn availability were highest in deeper soil layers. Relatively low soil nutrients in T3 compared to T1 indicated withdrawal and accumulation of these nutrients in the seedlings. In several respects municipal effluent benefited A. nilotica seedlings and soil properties, and produced 5.59–12.96 t ha−1 dry biomass. Municipal effluent could help to meet the fuel need of suburban areas, although long-term application of effluent would lead to metal accumulation in soil and plants.

Reactivation of sand drift is a common phenomenon in arid areas and needs suitable surface vegetation in association with overstorey trees for better stabilization. Regeneration and survival of Cassia angustifolia seedlings were studied in relation to different adult neighbours and soil water content with a view to developing effective surface vegetation and control of sand drift. Acacia tortilis, Prosopis juliflora and Calligonum polygonoides were the experimental adult neighbours. Observations were recorded at distances of 0–1.0 m (inner canopy [IC] zone), 1.0–1.5 m (outer canopy [OC] zone) and 1.5–2.5 m (outside the canopy [OS] zone) from the neighbours. Seeds and regenerated seedling densities were higher in the C. polygonoides plot than the other two neighbours and the control plots. The density was higher in the OC zone of the C. polygonoides and P. juliflora plots, the OS zone of the A. tortilis plot and the IC zone of the control plot. Both inter- and intraspecific competition resulted in high mortality during July–October in A. tortilis and P. juliflora plots. Seedling survival decreased in February and June, but the density, which was greater in the IC zone, was positively correlated with that in July and with the soil water content (SWC). The ultimate survival of seedlings was higher in the neighbour inclusion than control plots. The soil water content (SWC) was generally higher in the Calligonum polygonoides plot than that in the A. tortilis and P. juliflora plots. With distance from the adult neighbours, the SWC increased in the 25–50 cm and 50–75 cm and decreased in the 0–25 cm soil depth layers. Shoot height and biomass of one-year-old C. angustifolia seedlings were higher in the C. polygonoides plot than in the plots of other neighbours. A negative relative neighbour effect for most of the growth variables suggests that the adult neighbours facilitated regeneration, survival, growth and biomass of C. angustifolia seedlings. C. polygonoides was the best neighbour, with better soil water content at depth and the most positive influence on seedling growth; it is therefore a suitable planting partner for C. angustifolia in promoting the effective stabilization of dunes.