Decade-long response of arid-land mallee vegetation to fire, flooding and grazing in south-eastern Australia

Australian arid vegetation has evolved within highly variable environments characterised by low rainfall and sporadic fire events. Episodic high rainfall events are a significant factor in plant species recruitment, but their unpredictability makes them difficult to study. We report on the response of vascular plants to a major rainfall event and flood in an arid region of south-eastern Australia. Fire that occurred two months before the flood was incorporated into the study. Paired fenced and unfenced plots were established at control locations and also in areas that had been either flooded, burnt, or flooded and burnt. Objectives were to quantify the long-term effects of fire, flood and vertebrate herbivory, and their interactions, on vegetation composition, plant life forms and species diversity. We found that relative to controls (i) there was a significant effect of flooding on vegetation composition, (ii) changes in life form abundance were driven by flooding and grazing, (iii) there was a strong positive relationship between grazer exclusion and species diversity that was maintained over time and (iv) there was little effect of fire. Understanding the long-term effects of both natural disturbances and vertebrate herbivory will benefit plant conservation in the arid zone. © 2015 Elsevier Ltd

Quantitative palynofacies analysis as a new tool to study transfers of fossil organic matter in recent terrestrial environments

International audienceClassical palynofacies method, which consists in an organic concentrate microscopic qualitative observation after mineral phase dissolution, is commonly used in order to study sedimentary organic matter. In the present study we develop a new quantitative palynofacies method that allows organic particles mass concentrations to be determined in studied samples. This method was developed to help quantify the input of fossil organic matter (FOM) into modern environments as a result of sedimentary rocks weathering. Studied samples were collected from different pools, like bedrocks, weathering profiles, soils and riverine particles in an experimental watershed "Le Laval". This watershed overlying Callovo-Oxfordian marls (1 km² in area) is located near Digne, Alpes-de-Haute-Provence, in France. In addition to palynofacies techniques, Rock-Eval 6 pyrolysis and Al2O3 content measurements (inductively coupled plasma emission spectrometry) were carried out on the samples. Obtained results show that this quantitative palynofacies method is suitable for FOM studies in modern environments, and FOM particles are quantified in the different pools. Results also give evidence that FOM alteration depends on the type of weathering, but also on the kind of organic particles. Soil formation under vegetation, resulting from the (bio)chemical weathering, lead to fossil organic particles concentration losses that do not exceed 30%. Elsewhere, mechanical weathering appears extremely fast and has no qualitative or quantitative influence on the observed FOM particles, which feeds directly into riverine stocks. FOM appears to be very resistant to weathering processes, this highlights its occurrence into supergene pools and then into carbon cycle. Quantitative palynofacies analysis is a new method adapted to a such study, but can also be applied to other palynological, paleoenvironmental or archeological studies

Trends in land use and land cover change in the protected and communal areas of the Zambezi Region, Namibia

Land management decisions have extensively modified land use and land cover in the Zambezi Region. These decisions are influenced by land tenure classifications, legislation, and livelihoods. Land use and land cover change is an important indicator for quantifying the effectiveness of different land management strategies. However, there has been no evidence on whether protected or communal land tenure is more affected by land use and land cover changes in southern Africa and particularly Namibia. Our study attempted to fill this gap by analyzing the relationship between land use and land cover change and land tenure regimes stratified according to protected and communal area in the Zambezi Region. Multi-temporal Landsat TM and ETM+ imagery were used to determine the temporal dynamics of land use and land cover change from 1984 to 2010. The landscape showed distinctive modifications over the study period; broad trends include the increase in forest land after 1991. However, changes were not uniform across the study areas. Two landscape development stages were deduced: (1) 1984–1991 represented high deforestation and gradual increase in shrub land; (2) 1991–2000 and 2000–2010 represented lower deforestation and slower agropastoral expansion. The results further show clear patterns of the dynamics, magnitude, and direction of land use and land cover change by tenure regime. The study concluded that land tenure has a direct impact on land use and land cover, since it may restrict some activities carried out on the land in the Zambezi Region. © 2017, Springer International Publishing Switzerland

Livelihood activities and skills in rural areas of the Zambezi Region, Namibia : Implications for policy and poverty reduction

This paper examined livelihood activities and skill sets available within rural households in the Zambezi Region of Namibia. Specifically, the study addressed three key questions: (i) what livelihood activities do rural people pursue? (ii) what demographic factors are associated with these activities? and (iii) what measures can be taken to diversify and sustain income from these livelihood activities? In order to address these questions, semistructured interviews covering 424 households were used to collect the data. The questionnaire consisted of questions corresponding to the sustainable livelihood framework including (1) human assets (2) financial assets and major sources of income (3) physical and natural assets and (4) social assets. A series of logistic regressions were fitted from which the estimated odds ratios (y) were derived to ascertain the effect of the predictors on the livelihood activities and skills. Odds ratios were used to measure the magnitude of strength of association or non-independence between binary data values. The results showed that the use of various livelihood activities and skills in different combinations is of significant importance to rural livelihoods. Five percent of the respondents obtained income from only one source, with 95 % of the respondents engaged in a combination of farming and non-farming activities. Most of the respondents had various reasons for diversifying into other activities vis-a-vis agricultural income, limited skills, large family size, availability of opportunities, seasonal nature of agricultural produce, favourable demand for goods and services or a combination of these. In addition, the results showed that gender, age, designation and education significantly (p < 0.05) influenced the choice of household's skills. The study concludes that a combination of rural household activities and skills influenced by a variety of factors have led to improved livelihoods in the study area. For policy purposes, this suggests that state interventions in rural livelihood skill development can play a significant role in promoting more sustainable rural livelihoods. © 2018, African Scholarly Science Communications Trust (ASSCAT)

Satellizing Galileo? Non-state Authority and Interoperability Standards in the European Global Navigation Satellite System

This paper explores the extent and limits of non-state authority in international affairs. While a number of studies have emphasised the role of state support and the ability of strategically situated actors to capture regulatory processes, they often fail to unpack the conditions under which this takes place. In order to probe the assumption that structural market power, backed by political support, equates regulatory capture, the article examines the interplay of political and economic considerations in the negotiations to establish worldwide interoperability standards needed for the development of Galileo as a genuinely European global navigation satellite system under civil control. It argues that industries supported and identified as strategic by public actors are more likely to capture standardisation processes than those with the largest market share expected to be created by the standards. This suggests that the influence of industries in space, air and maritime traffic control closely related to the militaro-industrial complex remains disproportionate in comparison to the prospective market of location-based services expected to vastly transform business practices, labour relations and many aspects of our daily life

Spatial diversity of dry savanna woodlands : Assessing the spatial diversity of a dry savanna woodland stand in northern Namibia using neighbourhood-based measures

The dry woodland savannas of Namibia are of significant socio-economic importance. The paper tests the suitability of a number of diversity indicators developed for species poor systems in Europe in the woodland context. The indicators that were tested included the species specific mingling index, MSp, the measure of surround and the uniform angle index. The simple application of the methods permit relatively unschooled crews to conduct an enumeration in the field.The results show that the indicators do not only display current diversity status, but also reflect the ecological context of the individual species

The woody weed encroachment puzzle : Gathering pieces

Increases in woody plant densities in savanna grazing lands worldwide have resulted in a decline in the grazing, capacity of these rangelands. At present. the actual cause of the problem is unknown although a vast body of literature deals with various aspects relevant to the issue. It is generally assumed, however. that the changes in the tree : grass ratio are a response to changes in soil-water development brought about by rangeland utilization. These utilization patterns differ from those under which the savanna system evolved. While changes in physiognomy are very prominent. these are generally preceded by changes in grass species assemblage. The development of species composition has been used as an indicator of rangeland condition for many years; the increase or decrease of individual species is considered in this context. Thus far. however, the shift from perennial to annual grasses has not been evaluated for its effect on soil moisture development, and subsequent implications for woody plant establishment and growth. The review presented here consolidates the existing information in order to provide a basis for understanding the woody weed encroachment problem. Copyright (C) 2008 John Wiley & Sons. Ltd

The behaviour of the measure of surround in relation to the diameter and spatial structure of a forest stand

Forestry inventory practices have, in the past, concentrated on obtaining information primarily required for timber management. To assess the ecological impact of exploitation, particularly under continuous cover forest management, diversity measures are required that consider the structural diversity in a forest stand. The measure of surround that was initially developed in Germany may be used to quantify the spatial interspersion of different tree size classes as a measure of spatial diversity. While the measure of surround has been applied to practical problems in the past, little is known about its actual performance in relation to stand compositions. This study investigate the behaviour of the index using a number of simulated age class distributions under various degrees of interspersion to provide a norm against which it may be compared. The measure of surround applied to diameter distributions is closely related to the diameter structure of a stand. When diameter classes are interspersed completely randomly within a stand the relative cumulative frequency of the diameter class provides an estimator of the size specific measure of surround. This provides a baseline from which the index may be interpreted. © Springer-Verlag 2007.C