Best management practices to face degraded territories occupied by Cistus ladanifer shrublands – Portugal case study

Land degradation in the Mediterranean Basin is clearly connected to the resilience of perturbed ecosystems, contributing to land abandonment, recurrent fires and biodiversity loss, with the prevalence of secondary shrublands that tend to occupy large areas. This is the case of Cistus ladanifer shrublands, one of the most widespread shrub communities in the Iberian Peninsula and a poor, uniform and resilient system. Here, we analyse the impact of several management practices in the recovery of territories largely occupied by this shrubland. We tested “non-intervention”, “cut”, “fire”, “mechanical mobilisation” and “pasture” in 100-m² plots of Cistus ladaniferus L., in Central Portugal, and followed them from 1993. Flora were analysed using Braun–Blanquet's methodology and the plots were compared with hierarchical cluster analysis and principal component analysis. An analysis of variance was also performed to investigate differences in management practices, both between plots and between two periods of time. The results show that extensive grazing or continuous cut have a high impact on plant diversity and community structure, with extensive grazing being the best way to improve plant diversity in a short period of time, using fewer resources.     

Plant composition and diversity in a semi-natural Mediterranean island landscape: the importance of environmental factors

Abstract

Islands crucially contribute to the Mediterranean Basin’s high floristic diversity, which, however, is at risk facing climate and land-use changes. Besides the identification of highly diverse areas, the knowledge about factors favouring diversity is of great importance. We analysed plant species diversity and composition related to environmental factors over varied vegetation units on a former Italian prison island in the northwest of Sardinia. Due to a long history of land use with grazing and later abandonment the nowadays protected island features a semi-natural landscape and can serve as an example for strongly anthropogenic altered insular ecosystems. Floristic composition, soil properties, microclimate and ungulate abundance were assessed. Relationships of vegetation composition and diversity with abiotic variables were examined by Canonical Correspondence Analysis, which indicated the importance of air temperature, soil moisture, slope gradient and C/N ratio for floristic differentiation. Most important abiotic factors for plant species richness were relative air humidity and soil moisture, while floristic diversity was mainly determined by air temperature and pH. Furthermore, observation data pointed to an adverse influence of ungulate abundance for plant species diversity. Regarding nature conservation, grazing intensity thus must be critically taken into account, especially for sensitive vegetation units like the coastal garrigue.     

Vegetation of trampled habitats in the Plitvice Lakes National Park in Croatia

Abstract

The vegetation communities of the trampled habitats in the Plitvice Lakes National Park were studied during 2005 and 2006. With the numerical classification of the relevés, six clusters were obtained, corresponding to the following specific communities: cluster 1 – ass. Matricario–Polygonetum arenastri– the intensively trampled and grazed habitats; cluster 2 – ass. Matricario–Polygonetum arenastri– the only intensively trampled habitats; cluster 3 – ass. Coronopodo–Polygonetum arenastri– very intensively trampled and grazed farmyards; cluster 4 –Trifolium fragiferum community – the trampled surfaces of moist habitats; cluster 5 – ass. Lolietum perennis– the moderately trampled surfaces of roads and yards; cluster 6 – ass. Prunello–Ranunculetum repentis– trampled surfaces of forest roads. The first three clusters belong to the vegetation of intensively trampled habitats of the class Polygono arenastri–Poetea annuae and the last three clusters belong to moderately trampled habitats of the class Molinio–Arrhenatheretea. In the analysis of the ecological factors it is established that separation of the relevés is influenced most greatly by the trampling intensity observed in the field, and of the Ellenberg indicator values, the most important are light, moisture, soil reaction and temperature. Using the analysis of the plant functional traits it is established that therophytes, annuals, biennials, species resistant to trampling and grazing, neophytes and archeophytes prevail in the intensively trampled habitats. In contrast, hemicryptophytes, perennials, and indigenous plant species prevail in the moderately trampled habitats. Representation of the C-S-R plant functional types shows also that trampling as a disturbance factor has a large influence on the differences in the relevés. In the intensively trampled habitats, there is a large proportion of ruderals, while in the moderately trampled habitats there is a large proportion of competitors.     

Improvement of carbon dioxide biofixation in a photobioreactor using Anabaena sp. PCC 7120

The biological photosynthetic process is useful and environmentally benign compared with other carbon dioxide (CO₂) mitigation processes. In the present study, Anabaena sp. PCC 7120 was utilized for carbon dioxide mitigation. A customized airlift photobioreactor was found to provide higher light utilization efficiency and a higher rate of CO₂ biofixation compared with that of a bubble column. The maximum biomass concentrations were 0.71 and 1.13 g L^?1 in the bubble column and airlift photobioreactor, respectively, using BG11₀ medium under aerated conditions. A lower mixing time in the airlift photobioreactor compared with that of the bubble column resulted in improved mass transfer. The CO₂ biofixation rate of Anabaena sp. PCC 7120 was determined using different phosphate concentrations at a light intensity of 120 μE m^?2 s^?1 and 5% (v/v) CO₂-enriched air in the airlift photobioreactor. However, it was observed that the specific growth rate was independent at higher light intensity. In addition, it was observed that increased light intensity, phosphate and CO₂ concentrations could enhance the CO₂ biofixation efficiency to a greater extent.     

Post‐fire regeneration in alpine heathland: Does fire severity matter?

Fire severity is thought to be an important determinant of landscape patterns of post‐fire regeneration, yet there have been few studies of the effects of variation in fire severity at landscape scales on floristic diversity and composition, and none within alpine vegetation. Understanding how fire severity affects alpine vegetation is important because fire is relatively infrequent in alpine environments. Globally, alpine ecosystems are at risk from climate change, which, in addition to warming, is likely to increase the severity and frequency of fire in south‐eastern Australia. Here we examine the effects of variation in fire severity on plant diversity and vegetation composition, 5 years after the widespread fires of 2003. We used floristic data from two wide‐spread vegetation types on the Bogong High Plains: open heathland and closed heathland. Three alternative models were tested relating variation in plant community attributes (e.g. diversity, ground cover of dominant species, amount of bare ground) to variation in fire severity. The models were (i) ‘linear’, attributes vary linearly with fire severity; (ii) ‘intermediate disturbance’, attributes are highest at intermediate fire severity and lowest at both low‐ and high‐severity; and (iii) ‘null’, attributes are unaffected by fire severity. In both heathlands, there were few differences in floristic diversity, cover of dominant species and community composition, across the strong fire severity gradient. The null model was most supported in the vast majority of cases, with only limited support for either the linear and intermediate disturbance models. Our data indicate that in both heathlands, vegetation attributes in burnt vegetation were converging towards that of the unburnt state. We conclude that fire severity had little impact on post‐fire regeneration, and that both closed and open alpine heathlands are resilient to variation in fire severity during landscape scale fires.     

Enhancement of astaxanthin production from Haematococcus pluvialis under autotrophic growth conditions by a sequential stress strategy

Abstract

The study of microalgal culture has been growing in recent decades, because the cellular structure of microalgae has diverse highly valuable metabolites that have attract attention of numerous companies and research groups. The pigment astaxanthin is considered one of the most powerful antioxidants in nature. The microalga Haematococcus pluvialis was proposed as one of the best natural astaxanthin sources, because it can accumulate high amount of the pigment. In this work, we studied different stress treatments on H. pluvialis growth cultures as well as astaxanthin production under autotrophic growth conditions. The results showed that extending nitrogen starvation before increasing radiation intensity up to 110?μmol photons m^?2 s^?1 during late the palmella cell phase incremented the astaxanthin concentration up to 2.7% of dry biomass with an efficient light energy utilization during the stress stage.     

Spatial analysis of rangeland's vegetation intensity as related to selected physical soil variables over ABQAIQ municipality of Saudi Arabia

Through most of the natural rangelands of Saudi Arabia, overgrazing, sand drifting, and off-road vehicles driving are almost the major contributing factors that lead to vegetation damage and land degradation in natural landscapes. The current study aimed at examining the dynamic nature of Abqaiq rangelands' vegetation, generating a vegetation intensity map, and investigating possible impacts caused by the spatial variability of obtained soil texture, sand content (%), and the derived available water capacity (DAW capacity (%)) on the intensity distribution of vegetation cover. Ordinal-nominal correlation type and spatial autocorrelation processes were adopted throughout the study to analyze the spatial correspondences as well as the interrelated patterns of the given variables. The resultant correlation between vegetation and soil texture (ordinal versus nominal variables) has yielded a significant (p-value < 0.001) relevancies, where, silt loam texture class, in particular, has proven to have the most correlated values to the most intensive vegetation habitats, where 5%, 35%, and 28% of the silt loam class were occupied by 80%, 60%, and 40% of vegetation intensities, respectively. Whereas, for the continuous variables, correlation outcomes have achieved a substantial negative spatial autocorrelation concerning vegetation intensity and sand content percentage, revealing a total absence of green biomass over the sandy soils. Additionally, vegetation intensity versus DAW capacity percentage significantly yielded a positive autocorrelation, revealing a high clustering of green biomass cover that associates with high clustering of high-water capacity soils. The autocorrelation strength identifier (Morn's I), produced an approximate value of 0.3 with a pseudo p-value of 0.001, for both relationships. The findings of this study would help researchers and relative authorities to grasp the reasons, consequences and behaviors of rangeland flora, considering Abqaiq's area as an example.     

长期中小强度有氧运动对大鼠左心室肌蛋白质组差异表达的影响*

目的:探讨长期中小强度有氧运动对大鼠左室肌蛋白质组差异性表达的影响,筛选出对中小强度有氧运动刺激敏感的目标蛋白质,丰富运动健身的基础理论及为慢性心血管疾病的康复治疗提供新的思路和实验依据。方法:20只雄性SD大鼠随机分为运动组(E组)和对照组(C组)(n=10)。建立大鼠长期中小强度有氧运动跑台训练模型,采用双向凝胶电泳(2-DE)对大鼠左心室肌全蛋白样品进行分离。采用串联飞行时间质谱蛋白质仪对部分分离后差异表达量上调大于5倍或下调超过80%的蛋白质点进行质谱鉴定。结果:与C组比较,E组大鼠心脏重量指数(HWI)增加了32.0%,具有显著性差异(P＜0.05);与C组比较,E组有71个蛋白质点表达上调≥2倍或下调≥50%,对4个表达上调≥5倍或下调大于等于80%的蛋白质点进行质谱鉴定,鉴定出3个蛋白质和1个未知蛋白质。结论:长期中小强度有氧运动后,大鼠心脏发生了良好的适应性改变;大鼠左心室肌蛋白质组发生了明显变化,长期中小强度有氧运动能有效增强大鼠心肌抗氧化能力。