Decomposition process for buried rat (Rattus norvegicus,Berkenhout 1769) carcasses in Riyadh city,Saudi Arabia: A preliminary study

The present report outlines the initial observations from an ongoing study examining the decomposition rate of buried rat (Rattus norvegicus, Berkenhout 1769) carcasses in Riyadh city, Saudi Arabia. Eight rat carcasses were buried in separate holes at depths of 20 and 40 cm (four holes per depth) to allow natural decomposition and examined at 10-day intervals up to 40 days. During the study period, environmental factors such as humidity, soil temperature, and air temperature were monitored at each depth on a daily basis. At the end of each burial period, one carcass from each depth was exhumed and the degree of decay and presence of insect activity were examined. The results showed that burial depth and temperature were major factors affecting the decomposition rate, whereas no insect activity was observed. The findings of this study can be used to more accurately estimate the time since burial of carcasses.     

Burial depth and diameter of the rhizome fragments affect the regenerative capacity of a clonal shrub

Clonal plants in highly disturbed habitats are often broken into small fragments of various sizes and buried at various soil depths. As a storage organ, rhizome fragments play an important role in enabling plants to survive in such habitats. But few studies have been concerned about the regenerative capacity of rhizome fragments of clonal shrubs of different rhizome diameter and at different burial depths. Here, we investigated whether deeper burial decreased, and diameter of the rhizome fragment increased, the regenerative capacity of a clonal shrub. Research samples of rhizome fragment (rhizome diameters of 2, 5, 10, 15, and 20 mm) of the clonal shrub Calligonum arborescens were buried at different depths (0, 1, 5, 10, and 20 cm). Increasing the diameter of the rhizome fragments significantly increased the survival rate of fragments, and increased the above-ground, below-ground and total biomass production of fragments. Vegetative reproduction ability also increased with an increase in diameter of the rhizome fragments. With an increase in sand burial depth, above-ground, below-ground, total biomass production and vegetative reproduction ability first decreased and then increased, and no fragments survived at the 0 cm burial depth. These results indicate that sand burial depth and diameter of the rhizome fragments significantly affected the regeneration capacity of C. arborescens. Sand burial is one of the essential prerequisites for C. arborescens rhizome fragments’ survival. Moderate burial depth (5 cm) and larger fragment diameter (20 mm diameter) were more suitable for biomass production and vegetative reproduction. These results indicate that reserves stored in rhizome fragments can contribute greatly to the regeneration capacity of the C. arborescens—responses that are very important for C. arborescens survival and establishment in frequently disturbed habitats.     

Seed germination ecology of the annual grass Leptochloa panicea ssp. mucronata and a comparison with L. panicoides and L. fusca

Leptochloa panicea ssp. mucronata is an annual grass that grows in relatively dry habitats. Requirements for dormancy loss and germination were determined for seeds of this species and compared to those of two species from wet habitats. Seeds of L. panicea were dormant at maturity in autumn, but when exposed to actual or simulated autumn temperatures (e.g. 20/10, 15/6 °C), they entered conditional dormancy and thus germinated to high percentages in light at 35/20 °C. Seeds buried in non-flooded soil exposed to natural seasonal temperature changes in Kentucky (USA) were non-dormant by the following summer and germinated to 80–100 % in light at 25/15, 30/15 and 35/20 °C. Seeds buried in non-flooded soil exhibited an annual conditional dormancy/non-dormancy cycle, with seeds mostly germinating to 80–100 % in light at 30/15 and 35/20 °C throughout the year but to 80–100 % in light at 25/15 °C only in summer. Results for L. panicea were compared to published data for L. panicoides and L. fusca. Whereas seeds of L. panicea buried in flooded soil failed to come out of dormancy, those of L. panicoides, an annual of moist habitats such as mudflats, exhibited an annual conditional dormancy/non-dormancy cycle, and those of L. fusca, a semi-aquatic, required flooding for both dormancy loss and germination. Differences in dormancy breaking and germination responses of seeds of Leptochloa species may help to explain why this genus occupies a wide range of habitats with regard to soil moisture conditions.     

Distribution and biomass assessment of macroalgae from Moroccan Strait of Gibraltar.

The taxonomic richness, population structure, biomass assessment, and geographic distribution of macroalgae were studied between May 2017 and July 2018 from the Moroccan strait of Gibraltar. The study was based on the economic, ecological and environmental interests of macroalgae on a national scale. Samples were harvested by Scuba diving. Sixty-seven species, including one recently introduced in the Strait, have been identified. They were distributed over four classes: Bangiophyceae (2 species), Florideophyceae (36 species), Phaeophyceae (17 species), and Ulvophyceae (12 species). The distribution map of the most abundant agarophytes, Gelidium attenuatum and Pterocladia capillacea, was constructed from GPS and field data using System Information Geographic software. G. attenuatum stands extended from 1 to 7 m depth, with maximum biomass at 1 m. The population analysis revealed thalli up to 15.8 cm long, with the length class 11–13 cm mostly represented. As for the population of P. capillacea, it was located from 0 to 1.50 m depth, with highest biomass at 0–0.50 m depth. Unlike Gelidium, P. capillacea stands were distributed from 5 to 12 cm, with 85% measuring between 7 and 11 cm long. The estimated total biomass of G. attenuatum and P. capillacea was 7.77 ± 3.57 t of fresh weight and distributed on two sectors: Mrisat (66.66%) and Oued-Alian (33.34%). This Finding indicates a relatively low biomass in the strait.     

Assessment of Regeneration Potential in the Clonal Macrophyte Miscanthus sacchariflorus (Poaceae) after Burial Disturbance Based on Bud Bank Size and Sprouting Capacity

The demography of the bud bank and its sprouting capacity are important for understanding the population dynamics of clonal plants and their potential responses to disturbances. To this end, we investigated the size and composition of the bud bank of Miscanthus sacchariflorus (Maxim.) Hack. immediately after flooding (November), in winter (January), in spring (March), and before flooding (May) in the wetlands of Dongting Lake. We then examined the sprouting capacity of axillary buds after sediment burial at 0, 5, 10, 15, and 20 cm. Total bud density of M. sacchariflorus ranged from 2524 buds m^-2 in November to 4293 buds m^-2 in March. Rhizome segments with inactive axillary buds, which represented the majority of the bud population (88.7% in November, 93.3% in May), did not sprout during the 140 days of the experiment (n = 250). The sprouting ratio was the highest for active axillary buds buried at 0 cm (64%) and decreased when buried at 10–20 cm (34%–40%). Due to the large number of active axillary buds in the bud bank (211–277 buds m^-2 from November to the following March), M. sacchariflorus could completely replace its aboveground shoot population, except in May (142 buds m^-2). Increasing burial depth delayed bud emergence and reduced the growth period of shoots; however, burial depth did not affect the resulting plant height and only reduced the accumulated biomass at 20 cm. Therefore, the belowground bud bank and its strong sprouting capacity are important factors in the maintenance of local populations and colonization of new habitats for M. sacchariflorus after burial disturbances. The present methodology, which combined measurements of bud bank demography and sprouting capacity, may reflect the regeneration potential of clonal plants after burial disturbances.     

Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidagocanadensis and S. gigantea)

The two rhizomatous perennials Solidago canadensis and S. gigantea belong to the most widespread alien plants in Europe. Anecdotal observations suggest that they disperse also by rhizome fragments. For testing their resprouting ability, rhizome fragments of different sizes from both species were buried at four different soil depths (0, 5, 10 and 20 cm, respectively) in a common garden. Rhizome fragments of S. canadensis ranged 3–6 cm in length, those of S. gigantea 5–20 cm in length. Resprouting plants were harvested after 3 months and growth related traits measured to assess their vitality. Resprouting rate in S. gigantea was far higher than in S. canadensis (85 and 19%, respectively). In S. gigantea, fragments of all sizes resprouted from all soil depths whereas none rhizome of S. canadensis emerged from 20 cm burial depth. In S. gigantea, size related traits showed significant interactions between fragment size and burial depth, but not relative shoot growth rate. At all burial depths, vitality of plants emerging from small rhizomes was lower than plants emerging from large rhizomes. Effects of rhizome size became stronger with increasing burial depth. The results show that both species are able to resprout from buried rhizome fragments, and that succesful regeneration is more likely to occur in S. gigantea. Managing these species should avoid any activities promoting rhizome fragmentation and dispersal of fragments.     

Altered growth with blue rings: comparison of radial growth and wood anatomy between trampled and non-trampled Scots pine roots

Our understanding of wood anatomy and radial growth in tree roots remains very incomplete, particularly with respect to how ecological factors affect root growth at a relatively small spatial scale, i.e., within a single root system. Here, we compared root growth with and without trampling exposure on a hiking trail. We conducted a quantitative analysis of radial growth and wood anatomical changes, including compression wood (CW) and blue rings (BRs), of two adjacent Scots pine roots in high resolution. A total of 32 cross sections from two roots sampled every 25 cm at the same distance from the respective stem were compared. The buried root (B) was completely buried and had an unexposed segment on a hiking trail. In contrast, the exposed root (E) had an exposed segment that was trampled. 1706 growth rings were analysed for the common period 1954–2015.We found that the volume of the E root in the trampling zone exceeded ten times the volume of the B root. The root surface area of the exposed sections of the E root was on average 14 times larger than that of the unexposed B root section in the trampling zone. The highest number of missing rings was found in the B root. Root sections sampled at the shortest distance from the stem showed the highest coherence in radial growth pattern, which decreased with increasing distance from the stem.BRs were recognized for the first time in tree roots. In total 25 tree rings contained BRs, and their occurrence was restricted to cross sections of the exposed root. BRs were formed over the course of 25 calendar years, i.e., in 40% of tree rings from the common period 1954–2015. Mean monthly temperatures for the years with and without BRs formation showed that colder November (p = 0. 012) and, albeit only slightly, colder September (p = 0.051) temperatures favoured formation of BRs in Scots pine roots. In addition, mean monthly precipitation in July (p = 0.017) was significantly higher for BR years, suggesting an impact of moisture availability on the formation of BRs in Scots pine roots. The study highlights a high rate of growth discrepancies within a single root system. Further, altered growth of trampled roots with high proportions of BRs opens a new challenge for future dendroecological studies on tree roots.     

Deep soil flipping increases carbon stocks of New Zealand grasslands

Sequestration of soil organic carbon (SOC) has been recognized as an opportunity to off‐set global carbon dioxide (CO₂) emissions. Flipping (full inversion to 1–3 m) is a practice used on New Zealand's South Island West Coast to eliminate water‐logging in highly podzolized sandy soils. Flipping results in burial of SOC formed in surface soil horizons into the subsoil and the transfer of subsoil material low in SOC to the “new” topsoil. The aims of this study were to quantify changes in the storage and stability of SOC over a 20‐year period following flipping of high‐productive pasture grassland. Topsoils (0–30 cm) from sites representing a chronosequence of flipping (3–20 years old) were sampled (2005/07) and re‐sampled (2017) to assess changes in topsoil carbon stocks. Deeper samples (30–150 cm) were also collected (2017) to evaluate the changes in stocks of SOC previously buried by flipping. Density fractionation was used to determine SOC stability in recent and buried topsoils. Total SOC stocks (0–150 cm) increased significantly by 69 ± 15% (179 ± 40 Mg SOC ha^‐1) over 20 years following flipping. Topsoil burial caused a one‐time sequestration of 160 ± 14 Mg SOC ha^‐1 (30–150 cm). The top 0–30 cm accumulated 3.6 Mg SOC ha^‐1 year^‐1. The chronosequence and re‐sampling revealed SOC accumulation rates of 1.2–1.8 Mg SOC ha^‐1 year^‐1 in the new surface soil (0–15 cm) and a SOC deficit of 36 ± 5% after 20 years. Flipped subsoils contained up to 32% labile SOC (compared to <1% in un‐flipped subsoils) thus buried SOC was preserved. This study confirms that burial of SOC and the exposure of SOC depleted subsoil results in an overall increase of SOC stocks of the whole soil profile and long‐term SOC preservation.     

Sowing and transplantation of Adonis ramosa (Ranunculaceae) for the establishment of a new population in a seminatural broad-leaved deciduous forest floor

Adonis ramosa (Ranunculaceae) is a plant whose risk of extinction is increasing in Japan. In this study, we show that there is a significant possibility of establishing an A. ramosa population by sowing seeds or transplanting plants in a seminatural broad-leaved deciduous forest floor. Immediately after seed collection in early June, seeds were sown either in pots that were watered periodically or in a deciduous forest floor where the soil surface was prepared. In the following spring, 30–40% of the seeds germinated. Of the one-year-old plants buried at a depth of 2 cm and two-year-old plants buried at a depth of 2 or 8 cm in the fall, 96% sprouted leaves in the following spring. However, 79% of the one-year-old plants buried at a depth of 8 cm sprouted leaves. In spring, the number of leaves, the widths of individual plants, and the heights of the two-year-old plants were greater than those of the one-year-old plants. The dry weights of one- and two-year-old plants in fall after one spring growing season increased by 1.6–2.3 times and by 2.3–5.1 times, respectively, compared to the dry weight at the time of transplanting. Also, the dry weights of the plants transplanted at a depth of 8 cm were higher than those of plants transplanted at a depth of 2 cm for both one- and two-year-old plants. The results suggest that the growth conditions at a depth of 8 cm are more favorable than those at a depth of 2 cm.     

Calcimicrobial cap rocks from the basal Triassic units: western Taurus occurrences (SW Turkey)

A post-extinction calcimicrobial cap rock occurs above the giant Permian skeletal carbonate platform exposed in the western Taurus Mountains (southern Turkey). It was formed during the main step of a very rapid and large-scale platform flooding (Earliest Triassic) and has been found also in other Tethyan localities. This calcimicrobial cap rock, 20 to 40 m thick, consists of thrombolitic and stromatolitic build-ups at the base and most oolitic grainstone in the upper part. It was terminated by a sudden input of fine terrigenous sediments. The domal, columnar and conical stromatolites are ‘anachronistic’ deposits as are the abundant botryoidal and fanning aragonite crystal pseudomorphs. This again shows the uniqueness of the Earliest Triassic period and indicates a delayed biotic recovery. To cite this article: A. Baud et al., C. R. Palevol 4 (2005).     

Study on ascending and descending vertical dispersal behavior of third instar larvae of Chrysomya megacephala (Fabricius) (Diptera:Calliphoridae): An evidence that blowflies survive burial

Although the pupation behavior of blowflies has been widely studied, this preliminary study was done on the vertical dispersal behavior (both ascending and descending) and fly emergence rate of third instar larvae of Chrysomya megacephala (Fabricius) to evaluate weather immature stages of blowflies survive burial and emerge out as adult. Third instar larvae of Chrysomya megacephala were placed at three different depths (5 cm, 25 cm and 45 cm) of soil under laboratory conditions to determine the impact of soil depth on the ascending and descending vertical dispersal behavior and the subsequent emergence of adults. The results of this study, although preliminary, but valuable to the field of forensic entomology because they provide new information about both ascending and descending vertical dispersal behavior of Chrysomya megacephala forensically important species of blowfly. In all the cases, maximum number of pupae recovered at the depth of 0 to 5 cm are 35.5 ± 4.5, 34 ± 1, 25 ± 5, when food was located at 5 cm, 25 cm and 45 cm depth respectively. This means that maximum no of larvae reached to the depth of 0 to 5 cm by ascending dispersal irrespective of at which depth they are placed. Paramount pupae were recovered from shallow burial depth of 0–5 cm in ascending dispersal and showed highest eclosion success i.e. 90.1% followed by 25 cm and 45 cm i.e. 71.7% and 55% respectively. While the number of pupae recovered as well as eclosion success was less in descending dispersal with an average of 62.8%, 39.25% and 33.9% at depths of 5, 25 and 45 cm respectively. This manifest if larvae disperse ascendingly, it increases their chance of survival.     

Factors affecting overwinter survival of the American burying beetle, <Emphasis Type="Italic">Nicrophorus americanus</Emphasis> (Coleoptera: Silphidae)

The endangered American burying beetle (Nicrophorus americanus) is relatively abundant at Fort Chaffee Maneuver Training Center in northwestern Arkansas. There is a paucity of basic life-history information available, particularly with respect to factors affecting overwintering success. In a field experiment we: (1) captured beetles at Fort Chaffee; (2) bred them in captivity; (3) in the fall on Fort Chaffee placed offspring individually in well-ventilated, lidded 21.1-l buckets containing original soil plugs in grassland or woodland, either provisioned or not with a rat carcass as potential food; (4) overwintered the beetles; (5) checked in the spring to determine survival; and (6) released surviving beetles. Overall, 59.6% of 104 beetles survived the winter, with 77.1% and 44.6% survival in provisioned and nonprovisioned buckets, respectively. No differences were evident between habitats. Beetle age was an important survival predictor, with older beetles having a higher survival probability, but only if nonprovisioned. Gender and body size were not predictive of survival. Many surviving beetles were at or near the surface; depth averaged 6.0 cm, with some as deep as 20 cm. Our findings suggest that American burying beetles will have a higher probability of overwinter survival if carcasses are readily available as winter approaches.     

Beetles succession on different microhabitats of small mammals in Riyadh,Kingdom of Saudi Arabia

The decay of small carcasses is considerably neglected although it may provide important forensic data. This study differentiates the beetle species correlated with rat, Rattus norvegicus and mouse, Mus musculus (L. 1758) carcasses placed in two different habitats at King Saud University in western Riyadh. Decay processes and beetle succession were analyzed from January to February 2018. We collected an average of 268.67 beetles belonging to nine species from eight families, including Histeridae, Dermestidae, Cleridae, Tenebrionidae, Staphylinidae, Coccinellidae, Melolonthinae, and Pyrrhocoridae. Collected specimens were identified morphologically and by molecular techniques based on the mitochondrial cytochrome oxidase subunit I (COI) gene. Their presence rose in the bloated and decaying stages of decomposition. The beetle communities differed between the two habitats. In addition, a distinctive beetle community was found in the decaying stage compared to the other stages. The lowest number of beetles was reported in the dry stage. The abundance of beetles was associated with carcass size (rat or mouse) and habitat type.     

Recent status and life history traits of endangered soft‐mouth trout,Salmo obtusirostris in the River Neretva catchment (Bosnia and Herzegovina) as a consequence of river alteration

Soft‐mouth trout, Salmo obtusirostris has disappeared from most of its historical distribution range in the River Neretva catchment. Remnant groups are highly fragmented and distribution of the species is restricted to only 15% of it's historical area. The most abundant length range of remnant individuals is between 20 and 40 cm; with a significant decrease of the bigger individuals. Age population structure is dominated by younger fish aged 2, 3 and 4 years, however, age class 4⁺ and 6⁺ predominated in the lower river part. Specimens older than 8 years were not observed, and estimated fishing mortality (F) was high, particularly in the upper part of the river (0.786). The River Neretva soft‐mouth trout population is under heavy pressure including anthropogenic habitat changes and illegal fishery, leading to disappearance in number of formerly inhabited areas. The Upper and Lower Neretva are the only areas where the species is still abundant. However, the collapse of the number of old individuals increases the risk of extinction of the remaining wild subpopulations.     

Environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau,China

Plant biomass is a key parameter for estimating terrestrial ecosystem carbon (C) stocks, which varies greatly as a result of specific environmental conditions. Here, we tested environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau, China. We found that above-ground biomass (AGB) and below-ground biomass (BGB) had a similar change trend in the order of Stipa bungeana > Leymus secalinus > Artemisia sacrorum > Artemisia scoparia, whereas shoot ratio (R/S) displayed an opposite change trend. There was a significantly positive linear relationship between the AGB and BGB, regardless of plant species (p < 0.05). Furthermore, more than 50% of the AGB were found in 20–50 cm of plant height in Compositae plants (A. sacrorum, A. scoparia), whereas over 60% of the AGB were found in 20–80 cm of plant height in Gramineae plants (S. bungeana, L. secalinus). For each plant species, more than 75% of the BGB was distributed in 0–10 cm soil depth, and 20% was distributed in 10–20 cm soil depth, while less than 5% was distributed in 20–40 cm soil depth. Further, AGB and BGB were highly affected by environmental driving factors (soil properties, plant traits, topographic properties), which were identified by the structural equation model (SEM) and the generalized additive models (GAMs). In addition, AGB was directly affected by plant traits, and BGB was directly affected by soil properties, and soil properties associated with plant traits that affected AGB and BGB through interactive effects were 9.12% and 3.59%, respectively. However, topographic properties had a weak influence on ABG and BGB (as revealed by the lowest total pathway effect). Besides, soil organic carbon (SOC), soil microbial biomass carbon (MBC), and plant height had a higher relative contribution to AGB and BGB. Our results indicate that environmental driving factors affect plant biomass in natural grassland in the Loess Plateau.     

Relevance of large litter bag burial for the study of leaf breakdown in the hyporheic zone

Particulate organic matter is the major source of energy for most low-order streams, but a large part of this litter is buried within bed sediment during floods and thus become poorly available for benthic food webs. The fate of this buried litter is little studied. In most cases, measures of breakdown rates consist of burying a known mass of litter within the stream sediment and following its breakdown over time. We tested this method using large litter bags (15 × 15 cm) and two field experiments. First, we used litter large bags filled with Alnus glutinosa leaves (buried at 20 cm depth with a shovel) in six stations within different land-use contexts and with different sediment grain sizes. Breakdown rates were surprisingly high (0.0011–0.0188 day⁻¹) and neither correlate with most of the physico-chemical characteristics measured in the interstitial habitats nor with the land-use around the stream. In contrast, the rates were negatively correlated with a decrease in oxygen concentrations between surface and buried bags and positively correlated with both the percentage of coarse particles (20–40 mm) in the sediment and benthic macro-invertebrate richness. These results suggest that the vertical exchanges with surface water in the hyporheic zone play a crucial role in litter breakdown. Second, an experimental modification of local sediment (removing fine particles with a shovel to increase vertical exchanges) highlighted the influence of grain size on water and oxygen exchanges, but had no effect on hyporheic breakdown rates. Burying large litter bags within sediments may thus not be a relevant method, especially in clogged conditions, due to changes induced through the burial process in the vertical connectivity between surface and interstitial habitats that modify organic matter processing.     

Niche Distribution of Paratrichodorus minor and Belonolaimus longicaudatus Following Fumigation on Potato and Cabbage

An experiment was conducted to determine population changes and niche variation in the soil at two depths (0 to 20 cm and 20 to 40 cm) of Paratrichodorus minor and Belonolaimus longicaudatus populations following fumigation. Eight plots each of potato (Solanum tuberosum) and cabbage (Brassica oleracea var. capitata), fumigated with 1, 3-dichloropropene or nonfumigated, were established. Eight plots of sorghum-sudangrass hybrid (Sorghum bicolor × S. arundinaceum var. sudanense) were also used to monitor depth distribution (0 to 20 cm and 20 to 40 cm) of B. longicaudatus and P. minor following each cabbage/potato season. Soil samples were taken 0 to 20 cm and 20 to 40 cm deep during the potato/cabbage, and sorghum-sudangrass growing seasons. During the 1993-94 and 1994-95 potato/cabbage seasons, P. minor was found at highest numbers at 20 to 40 cm, whereas numbers of B. longicaudatus were highest at 0 to 20 cm. During the 1994 and 1995 sorghum-sudangrass growing seasons, B. longicaudatus numbers were highest at 0 to 20 cm. Paratrichodorus minor numbers were highest at 0 to 20 cm and at 20 to 40 cm deep in the 1994 and 1995 sorghum-sudangrass growing seasons, respectively. Reduction by soil fumigation of B. longicaudatus at 0 to 20 cm deep did not affect depth distribution or cause P. minor populations to increase in potato or cabbage plots. Paratrichodorus minor numbers increased at 20 to 40 cm deep in the 1994-95 cabbage season after soil fumigation.     

Floristic composition,plant species abundance,and soil properties of montane savannas in the Gran Sabana,Venezuela

Floristic composition, species abundance, and soil properties were studied in slope, flat and disturbed savannas in the northern part of the Gran Sabana, Venezuela. All savannas presented shallow soils (<30 cm depth) with high content of sand and low content of clay. In general, the soils were poor in nutrients and strongly acidified. The major difference between the soils was the content of the stony fraction, which was significantly higher (P<0.05) in the slope savannas than in the flat savannas. A total of 57 dicot, 42 monocot, and 7 fern species were recorded in all studied savannas. In the flat and slope savannas predominated the monocot species, while in the disturbed savanna predominated the dicots. The families with the largest number of species were Poaceae (19.8%), Cyperaceae (13.2%), Asteraceae (10.4%) and Melastomataceae (8.5%). The number of species in the flat savannas was higher than that of the slope savannas. The lowest plant species richness was associated to slope savannas and their high content of stony fraction of the soils. The highest floristic similarity was found between slope savannas, and the lowest between disturbed savanna and slope savannas. The most abundant life forms in the studied savannas were perennial (42.4%) and annual (24.5%) herbs, followed by suffruticoses (16.0%) and shrubs (12.3%), and the less frequent was lianas (4.7%). The disturbed savanna showed the higher richness and diversity index. Trachypogon plumosum (Poaceae) was the most abundant species in all studied savanna.     

The effect of soil depth and exposure to winter conditions on survival of the potato tuberworm,Phthorimaea operculella

The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is an important pest of solanaceous crops including potato [Solanum tuberosum L. (Solanaceae)]. Recent evidence of survival of the pest in the Columbia Basin of Oregon and Washington, USA, is surprising as potato tuberworm is most commonly a pest in tropical and subtropical regions. Potato tuberworm was studied in a manipulative experiment to determine how stage (egg, larva, and pupa) and soil depth affected the potential for winter survival. In early January 2007, eggs, tubers infested with larvae, and pupae were placed in the soil at 6, 10, and 20 cm depths, or left on the soil surface. Each potato tuberworm life stage was sampled at 7–17‐day intervals for 90 days and survival was estimated at each time period. Eggs survived up to 54 days with the greatest survival observed at 6‐cm soil depth and the lowest survival on the soil surface. However, egg survival was significantly reduced after 1 month of exposure to winter conditions. Larvae were able to survive up to 30 days with the greatest survival observed at 20‐cm soil depth. Tubers at the surface and buried at 6 cm were frozen; thus, no larval survival was recorded. The pupal stage showed a greater tolerance to winter conditions than the egg or larval stages, surviving up to 91 days of exposure. These results suggest that the pupal stage is probably the stage most likely to survive winter conditions in the northwestern USA.     

Species composition and colonization of dark septate endophytes are affected by host plant species and soil depth in the Mu Us sandland,northwest China

Investigations into the edaphic associations, host affiliations and soil depth of dark septate endophytes (DSE) in arid desert environments can help explain their spatial distribution and the response mechanisms in desert ecosystems. Soils were sampled to a depth of 50 cm in the rhizospheres of Psammochloa villosa, Hedysarum laeve and Artemisia ordosica in the Mu Us sandland of northwest China in July 2015. The plant species and soil depth significantly influenced the distribution and colonization of DSE. Hyphal and total root colonization were significantly higher under P. villosa than the others in the 0–20 cm layer. The maximum colonization of P. villosa and H. laeve occurred in the 10–20 cm and 20–30 cm soil layers, respectively, while 30–40 cm soil layer under A. ordosica. Of twelve DSE species isolated from the roots of these plants, Phoma radicina and Bipolaris zeae were reported in desert ecosystems for the first time. Hyphal colonization was significantly and positively correlated with soil total nitrogen (TN) and significantly and negatively correlated with the soil carbon/nitrogen (C/N) ratio. Microsclerotial colonization was significantly and positively correlated with soil organic carbon (SOC), and total colonization was significantly and positively correlated with soil TN and total phosphorus (TP) and significantly and negatively correlated with soil C/N. Variation of DSE colonization was mostly attributed to effects of plant species. We concluded that the species composition and colonization of the DSE fungi were influenced by the plant species, soil depth and soil nutrient availability in this desert ecosystem. This research provides a basis for further understanding the ecological adaptability of DSE and their roles in promoting vegetation restoration and reducing desertification in arid ecosystems.