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Population surveys of Nile crocodiles (Crocodylus niloticus) in the Murchison Falls National Park, Victoria Nile, Uganda

Abstract

1. A 12-month-long survey (April 2013 to March 2014) for Nile crocodiles (Crocodylus niloticus) was conducted along a section of the Victoria Nile/Ramsar site of Murchison Falls National Park, in order to update the historic information on crocodile populations in the area, locating nesting areas, determining seasonality patterns and habitat use, and assess the current abundance and the population size trends since the 1960s. The methods employed included visual encounter surveys, transect counts and opportunistic methods, by using boats. 2. In general, there were diurnal and seasonal fluctuations in the number of crocodile sightings. The crocodile sightings peaked between the months of June and August, with the highest mean number of sightings encountered on any single day being 67 (in July 2013), and the second peak was between January and March with the highest mean of 118 recorded in January 2014. The second peak also coincided with the crocodile breeding season. This clearly shows that the distribution of the sub-population sampled followed a climatic regime. 3. Crocodiles were observed most frequently in water (37%). Grassy banks, islands, river mouths and sandy banks constituted about 47% of the habitats utilised by the crocodile population. Although basking was the most frequent type of activity performed by crocodiles (50%) over the entire survey period, their key activities varied significantly from month to month. Nesting was very visible during the last quarter of the year and the first quarter of the New Year. 4. There was a clear decline of the abundance of crocodiles in this population between 1960s and nowadays. This declining trend was obvious also taking into account the various survey methodologies employed over the decades.

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Postmodern landscape architecture: theoretical, compositional characteristics and design elements with the analysis of 25 projects

Abstract

This paper endeavours to highlight three aspects of postmodern landscape design: theoretical basis, composition and design elements. Postmodern theories, philosophy influenced the language of the postmodern landscape architecture and got materialized in the use of narratives, eclecticism, the Rhizome-principle. Postmodern landscape composition can be associated with anti-hierarchy, unusual structures, landforms, and playful moods. Postmodern design elements consist of the strong graphical use of colour and pavements, bizarre water features, unusual structures and buildings, postmodern sculptures and thematic garden details. 25 analysed projects try to capture the essence of postmodernism in landscape architecture as well as to reveal points of intersection within these projects.

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Some Perspectives on Rocket as a Vegetable Crop: A Review

Some Perspectives on Rocket as a Vegetable Crop: A Review

Baby leaf rocket is consumed worldwide as a salad vegetable. It is usually mixed with other baby leaf crops, such as spinach and lettuce, to form a mesclun-type salad. Rocket crops have become popular due to their distinct taste and textural appearance in mixed salads. There are two common forms of rocket that are commercially cultivated, a perennial species (Diplotaxis tenuifolia (L.) DC.) known as perennial wall rocket and an annual species (Eruca sativa Mill.) known as annual garden rocket. The popularity of baby leaf crops has increased in recent years due to consumer demand for a convenient, nutritious and easily accessible product. The baby leaf salad sector is now a significant part of the leafy vegetable market, with growth in this sector estimated to continue. The leaves of cultivars of perennial wall rocket and annual garden rocket have been bred to look similar, allowing for a year-round supply of produce. Despite this, there are many differences between the species that affect their responses to abiotic factors during growth and storage. This paper aims to provide some perspectives on the historical importance, botanical classification and cultivation techniques of these economically important plants.

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The economic, financial and legal situation of private estates in Poland during the interwar period

Abstract

The bad economic situation for agro-forest farms in Poland during the interwar period was caused by war damage, a global economic crisis, crop failure, indebtedness prior to World War I, and by tribute payments towards rebuilding the country. Although the timber harvest was substantial, farm owners were forced to take loans. In 1938, the debt level of agro-forest farms accounted for 18 per cent of their total value. The average debt level for this period oscillated between 9.8 and 126.0 PLN/ha-1. The assistance programme implemented by the government provided for a reduction in the interest rate of loans, particularly for farms with an area up to 300 ha.

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Distribution of the Common Adder Vipera berus and the Slow Worm Anguis fragils in Silesia, SW Poland

Abstract

During the years 2004-2008 the distribution of the Common Adder and the Slow Worm were studied in Silesia through questionnaire directed to forest inspectorates (n=871); 83.8% of them responded. These data were tested through field work in several randomly selected inspectorates. Both species were found to be widespread in the region, with a few strongholds identified in Sudety Mts. and larger forest complexes. The Common Adder was recorded in 68.5% of forest districts which responded, while the Slow Worm – in 73.6% of those districts. Changes in distribution and population trends could not be derived, since no reliable data were available from previous years.

Open access
What is the use of the research carried out on the permanent plots in the Białowieża National Park?

Abstract

The purpose of the strictly protected area of the Białowieża National Park (BNP) established in early 1900s, was to protect a compact block of the Białowieża forest from any direct human influence and activity. Its founders considered it a ‘laboratory of nature’ In 1936, five rectangular plots with a total area of 15.5 ha (ca. 0.3% of the BNP) were set up for regular monitoring of stand development with regards to the initial state and variability of soil conditions. During the first 76 years of the project, a steady increase in the proportion of hornbeam and lime tree at the expense of shade-intolerant species was observed. This trend has been interpreted by the researchers involved in the monitoring of the permanent BNP plots to constitute a biodiversitythreatening development caused by preservation efforts. Such an interpretation has been widely incorporated in the public debate by political authorities and the forestry sector. In this critical article I challenge the major arguments presented by the key expert in silviculture, Prof. B. Brzeziecki. My criticism is directed at the methodological approach as well as at the data interpretation.

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Forest development on Kihnu Island and the role of the human factor in it

Kihnu saare metsade areng ja inimfaktori osa selles

Of the total area of Kihnu Island (16.38 km2), 26% is under a 420-ha pine forest growing on sandy soils and dunes. The forest was estimated to cover about 130 ha (8%) in the early 19th century and 180 ha (11%) in 1949. In 1829-1935 the island's forest was managed predominantly by means of clear cuttings of 1.1 ha in size. Thereafter, it was treated as protection forest. In parallel with clear cutting, clear-cut areas and bare sandy zones were afforested where necessary. Altogether, 210 ha of forest plantations were established in 1829-1949. Intensive forest management and collateral use of forest (grazing on woodlands, gathering of forest litter) led to the impoverishment of the forest soils and stand diversity and deterioration of the forest growth conditions. In the last 75 years the island's forest has effectively enjoyed the status of protection forest, and its area has increased due to shrinking farming activity.

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Grasslands of intermontane basins of Central Caucasus: land use legacies and present-day state

Abstract

Mountain semi-natural grasslands of intermontane basins of Central Caucasus, North Ossetia-Alania and the history of its land use were studied. It was found that post-forest, meadow-steppe and partially subalpine grasslands in the study area had been used as croplands for centuries and have been transformed into grazing lands about 60 years ago. In the last 20 years, the grasslands have been underused. It was revealed that current spatial distribution of grasslands is different from the classic scheme of natural climate-induced vegetation distribution. Species composition of meadow steppes is similar in different locations and does not reflect climatic differences of “dry” leeward and “wet” windward slopes of the intermontane basins. Present-day soils reflect parent material differences and erosion degree, but not topography-induced local climate specificity. However, discovered buried soils showed contrasting soil diversity on the southern and northern slopes. It is assumed that the present convergence of soil cover and vegetation is a result of long homogenising human impact and relatively short grassland development.

Open access
The evolutionary ecology of interactive synchronism: the illusion of the optimal phenotype

Abstract

In this article, we discuss some ecological-evolutionary strategies that allow synchronization of organisms, resources, and conditions. Survival and reproduction require synchronization of life cycles of organisms with favourable environmental and ecological features and conditions. This interactive synchronization can occur directly, through pairwise or diffuse co-evolution, or indirectly, for example, as a result of actions of ecosystem engineers and facilitator species. Observations of specific interactions, especially those which have coevolved, may give the false impression that evolution results in optimal genotypes or phenotypes. However, some phenotypes may arise under evolutionary constraints, such as simultaneous evolution of multiple traits, lack of a chain of fit transitional forms leading to an optimal phenotype, or by limits inherent in the process of selection, set by the number of selective deaths and by interference between linked variants. Although there are no optimal phenotypes, optimization models applied to particular species may be useful for a better understanding of the nature of adaptations. The evolution of adaptive strategies results in variable life histories. These strategies can minimize adverse impacts on the fitness of extreme or severe environmental conditions on survival and reproduction, and may include reproductive strategies such as semelparity and iteroparity, or morphological, physiological, or behavioural traits such as diapause, seasonal polyphenism, migration, or bet-hedging. However, natural selection cannot indefinitely maintain intra-population variation, and lack of variation can ultimately extinguish populations.

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The Devil in the Deep: Expanding the Known Habitat of a Rare and Protected Fish

Abstract

The accepted geographic range of a species is related to both opportunity and effort in sampling that range. In deepwater ecosystems where human access is limited, the geographic ranges of many marine species are likely to be underestimated. A chance recording from baited cameras deployed on deep uncharted reef revealed an eastern blue devil fish (Paraplesiops bleekeri) at a depth of 51 m and more than 2 km further down the continental shelf slope than previously observed. This is the first verifiable observation of eastern blue devil fish, a protected and endemic southeastern Australian temperate reef species, at depths greater than the typically accepted depth range of 30 m. Knowledge on the ecology of this and many other reef species is indeed often limited to shallow coastal reefs, which are easily accessible by divers and researchers. Suitable habitat for many reef species appears to exist on deeper offshore reefs but is likely being overlooked due to the logistics of conducting research on these often uncharted habitats. On the basis of our observation at a depth of 51 m and observations by recreational fishers catching eastern blue devil fishes on deep offshore reefs, we suggest that the current depth range of eastern blue devil fish is being underestimated at 30 m. We also observed several common reef species well outside of their accepted depth range. Notably, immaculate damsel (Mecaenichthys immaculatus), red morwong (Cheilodactylus fuscus), mado (Atypichthys strigatus), white-ear (Parma microlepis) and silver sweep (Scorpis lineolata) were abundant and recorded in a number of locations at up to a depth of at least 55 m. This underestimation of depth potentially represents a large area of deep offshore reefs and micro-habitats out on the continental shelf that could contribute to the resilience of eastern blue devil fish to extinction risk and contribute to the resilience of many reef species to climate change

Open access