Impacts of dust on plant health,survivorship and plant communities in semi‐arid environments

There is a general perception that dust accumulation on plant surfaces causes negative impacts to plants. Consequently, it is common for environmental regulatory agencies to apply vegetation monitoring requirements to oil, gas and mining developments. We use two independent, medium‐term monitoring studies in semi‐arid Australia to examine this relationship at two scales: plant health and survivorship of a threatened subspecies (Tetratheca paynterae paynterae: Elaeocarpaceae) at Windarling Range between 2003 and 2014; and changes in plant health and floristic composition on Barrow Island between 2009 and 2014. Accumulation of dust decreased rapidly with distance from source. At Windarling Range, even at the site with the highest dust load, there was no significant impact on Tetratheca paynterae paynterae compared with the less dusty sites for 10 years. Similarly, there was no significant effect between distance from the source of dust and floristic composition on Barrow Island for 5 years. The probability of plants transitioning to a lower health condition between one year and the next did not appear to be related to dust load. This is further supported by comparing the same site before and after paving the road (removal of dust source), which showed no clear trends. Trends in plant health are likely to be driven more by the variability of cumulative rainfall in the preceding 5 months than dust load. The observed temporal variation in the mean dust load may also be related to variation in rainfall. In conclusion, in these case studies from semi‐arid Australia, we find no evidence to support the perception that, under the observed climatic condition and dust deposition rates up to 20 or 77 g m^?2 per month at Windarling Range and Barrow Island, respectively, dust accumulation on plants causes negative impacts.     

武陵山区蕨类植物研究

武陵山区蕨类植物资源丰富,现知有644种(包括变种),分属116属, 46科;蕨类区系属热带-亚热带山地类型;属的地理成份有12种类型,与日本、印度-马来西亚有密切关系;武陵山区蕨类区系属我国西南区系,与华中华东区关系密切,华南、华北区次之;蕨类垂直分布分四带。     

指掌骨骨折合并软组织损伤的微型锁定钢板皮外固定应用效果及对关节活动度的影响

摘要 目的：探讨指掌骨骨折合并软组织损伤的微型锁定钢板皮外固定的应用效果及对关节活动度的影响。方法：选取我院2015年7月到2020年7月共收治的80例指掌骨骨折合并软组织损伤的患者作为研究对象,将其随机分为观察组与对照组,各40例。对照组应用克氏针、微型螺钉、肌腱缝线或拉力螺钉进行内固定,观察组在对照组基础上联合应用微型锁定钢板皮外固定,并针对患者合并软组织损伤情况应用石膏外固定。对比两组患者的骨折愈合时间、围术期指标、Jamar握力、TAM、DASH评分、术后不良反应情况以及生活质量。结果：观察组手术时间高于对照组,骨折愈合时间和住院时间较对照组低（P＜0.05）;观察组患者的DASH评分明显低于对照组,TAM与Jamar握力明显高于对照组（P＜0.05）;观察组术后并发症发生率较对照组低（P＜0.05）;术后1个月两组患者生活质量评分均升高,高于对照组（P＜0.05）。结论：对指掌骨骨折合并软组织损伤的患者在常规克氏针内固定的基础上,应用微型锁定钢板皮外固定,再进行石膏固定,手术步骤、手术时间虽增加,但更有利于患者术后骨折愈合,减少术后并发症的发生,减少住院时间,促进患者出院后关节功能恢复,提高生活质量,值得临床应用推广。     

Estimating Fundamental Host Range: a Host-Specificity Study of a Potential Biocontrol Agent for Prosopis Species (Leguminosae)

One approach to predicting non-target attack by potential biological control agents is to first describe their fundamental host ranges and then to predict how it will be expressed under postrelease field conditions. In this paper, we illustrate how the fundamental host range can be estimated experimentally by excluding possible limiting factors such as time-dependent effects. The example we use is a host-specificity study of a leaf-tying moth (Gelechiidae: Evippe sp. #1) which was being assessed for the biological control of mesquite (Leguminosae: Prosopis spp.) in Australia. Females oviposited all eggs on plants, mostly into cracks and fissures. First instar larvae leaf-mined and subsequent instars leaf-tied. Oviposition was not host-specific in cage trials, although ten times more eggs were laid on Prosopis than on non-targets. The fundamental host range for initiation of larval feeding was restricted to Prosopis and Leucaena leucocephala which both belong to the same tribe, and the fundamental host range for complete larval development was restricted to Prosopis . We predict that if released in Australia Evippe sp. #1 will only attack Prosopis spp., although low levels of 'indiscriminate' oviposition might occur on other taxa, and might result in initiation of feeding on L. leucocephala .     

The population biology of Bromus tectorum in forests: distinguishing the opportunity for dispersal from environmental restriction

Summary With increasing elevation and corresponding changes in the macroclimate, forest zones in the Intermountain Region of western North America are often dominated in turn by Pinus ponderosa, Pseudotsuga menziesii, Abies grandis, an Thuja plicata. Bromus tectorum (cheatgrass), and introduced annual grass now abundant in the Region's steppe, is uncommon in mature stands representative of these forest zones. In order to determine whether B. tectorum is largely excluded from these forests by insufficient seed dispersal or environmental restriction(s), the grass's demography was compared in each of four years among populations experimentally-introduced into mature forests. The number of recruits did not differ among the Pinus, Pseudotsuga, and Abies sites; recruitment was however significantly lower on the coolest site dominated by Thuja. Emergence in both the low elevation Pinus and Pseudotsuga sites was about the same in autumn, winter, and spring. In the cooler, moister Abies and Thuja sites, emergence was limited to autumn and early winter. Survival in these forest sites ranged between 0 and 87%. The percentage of the total population to survive until harvest was highest in the Pseudotsuga site, intermediate in the Pinus and Abies sites, and lowest in the Thuja site. Compared with B. tectorum in the steppe, the surviving plants were small, and few produced seeds. All parents were members of either the autumn or winter cohort, and most parents produced only one seed. No seeds were produced at the Thuja site. Although phenotypic plasticity apparently contributes to the wide ecological amplitude of this grass, its growing season on these sites in most years is too short for it to reproduce. Consequently, these forest zones broadly define the current environmental limits to the distribution of cheatgrass in this portion of its new geographic range.     

Seasonal range selection in bighorn sheep: conflicts between forage quality,forage quantity,and predator avoidance

Summary The migratory and foraging behavior of individually marked bighorn ewes (Ovis canadensis) was studied to test the hypothesis that forage quality determined seasonal range selection. Forage quality was monitored through analysis of fecal crude protein. Ewes in the study population utilized two distinct ranges differing in elevation and possibly predation risk. Pregnant ewes migrated in May from the low-elevation winter range to lambing areas at higher elevation, before plant growth had started there. In so doing, they moved from a range of high-quality forage to one of low-quality forage, apparently to avoid predation on newborn lambs. Non-pregnant adult ewes migrated later. Most yearling ewes (which are not pregnant) migrated with the adult ewes to the lambing areas, but returned to the winter range within a few days, then migrated again to high-elevation areas in June. Forage quality was higher at high elevation from mid-June at least through July, but forage availability appeared to be lower than in the winter range. Seasonal range selection is likely determined by a combination of nutritional and antipredator constraints. The antipredator strategy of bighorn ewes does not always allow them to utilize the range with the best forage.     

Target detection and range resolution by the big brown bat (Eptesicus fuscus) using normal and time-reversed model echoes

Summary Big brown bats (Eptesicus fuscus) were tested for their ability to detect an electronically simulated target, and to discriminate differences in range to two simulated targets, when receiving either a model of their own sonar emissions or the model reversed in time as the echo. The theory of matched detection predicts a large decrease in performance if bats use matched filtering, unless they are somehow able to adjust their filter to match the novel, time-reversed signal. The detection thresholds we obtained were much lower than Møhl's (1986), but like him we found no difference in threshold for reversed models (Table 2). This suggests either that bats do not use matched filtering for target detection, or, possibly, that they are able to adapt their filter to a highly unnatural signal in some way as yet unknown.Unlike detection, range discrimination was much poorer with reversed echoes (Table 3). Threshold increased from about 1 cm range difference with normal model echoes to 18 cm or more with reversed model echoes. This suggests that range determination, which is based on measuring the time of arrival of echoes, does involve matched filtering. Whether such filtering is ideal (i.e., equivalent to cross-correlation detection) cannot be decided by our results, but there are some indications that the match between an echo and the presumed internal template (the match of matched filtering) must be fairly precise. Also, since performance with phantom targets generated using model echoes was as good as has been found with real targets, the internal template is probably fixed (or only slowly modifiable) rather than re-programmed with each sonar emission. Finally, because synchronization of emission and model echo was not perfect, the apparent distance to targets probably varied by 2 to 4 cm from emission to emission, although both targets would appear to move together thus keeping the range difference constant. This suggests that bats determined range to the targets simultaneously rather than sequentially, as is usually assumed.Abbreviations BP bat-produced echo - FM frequency modulated - M _d detection model echo - M _d reversed detection model echo - M _rd range discrimination model echo - M _rd reversed range discrimination model echo - rms root mean square - SCR signal-to-clutter ratio - SNR signal-to-noise ratio - SPL sound pressure level - XCF crosscorrelation function     

An approach to the edge effect in proof of the validity ofDice's assessment lines in small-mammal censusing

A second fieldwork for the sake of solving the edge-effect subject was carried out in almost the same ways and plans in summer of 1971 in succession to that of 1970. It was found out that the population density was reduced to two-thirds, but the data were sufficient to form the subsequent conclusions:

1. The initial population estimated by the removal census method turned out to be well compatible with the numbers of survivals and emigrants of marked voles calculated byJolly 's method.
2. The natural, entire home ranges of both sexes reached by determining observed range length and width with 24 voles, selected on rigid conditions, agreed with those of the range-conservative type in 1970 in both acreage and elliptic shape.
3. In the majority of the select specimens, considered to reveal the natural ranges, the random distribution in number of captures per station within range was proved by means of I_σ so far as such capture density as treated here is concerned. On the ground of the empirical evidence, the above range size approached by the routine observational method could be made surprisingly accordant with the range size in terms of r-values calculated byWierzbowska 's method.
4. From these proofs, the validity ofDice 's assessment lines makes evident, and besides, it could be further substantiated by use ofMarten 's notion of mouse-equivalents through the mediation ofWierzbowska 's method.
5. Consequently, I have largely come to the conclusion thatDice 's assessment lines stand on justifiable basis from theoretical and empirical angles.