Alien plant species list and distribution for Camdeboo National Park, Eastern Cape Province, South Africa

Protected areas globally are threatened by the potential negative impacts that invasive alien plants pose, and Camdeboo National Park (CNP), South Africa, is no exception. Alien plants have been recorded in the CNP since 1981, before it was proclaimed a national park by South African National Parks in 2005. This is the first publication of a list of alien plants in and around the CNP. Distribution maps of some of the first recorded alien plant species are also presented and discussed. To date, 39 species of alien plants have been recorded, of which 13 are invasive and one is a transformer weed. The majority of alien plant species in the park are herbaceous (39%) and succulent (24%) species. The most widespread alien plant species in the CNP are Atriplex inflata (= A. lindleyi subsp. inflata), Salsola tragus (= S. australis) and cacti species, especially Opuntia ficus-indica. Eradication and control measures that have been used for specific problematic alien plant species are described

P5_3 Pigs on the Wing

This article explores the possibility of a pig flying over Battersea Power Station, as shown on the Pink Floyd album ’Animals,’ and the time it would take for the pig’s height to exceed the height of the chimneys. Using the lift force equation, we graphically show the minimum wind velocity required to lift a 70 kg pig 101 m, the height of the Battersea Power Station. We find that for a pig of this mass, a wind velocity of 20.4 ms-1 was required. Furthermore, in order to measure the time for the pig to reach the height of Battersea Power Station, an acceleration of 3.8 ms-2 was calculated; this assumes a severe gale wind velocity of 24 ms-1 as defined by The Met Office. We find that it would take 7.3 s to travel the required height, assuming only vertical movement.

P5_1 ”Everybody knows the Moon is made of cheese...”: Return of the Cheddar

This Letter explores the repercussions of the Moon turning into cheddar, and finds that with the same volume and lighter mass of m = 2.49 × 1022kg, it would escape the Earth’s sphere of influence. We looked at two possible escape trajectories, prograde and retrograde, and found the new orbital distances to be between 0.73AU and 1.00AU, and between 1.00AU and 1.51AU, respectively. Thus potentially carrying the Moon very near to the orbits of Venus or Mars.

P5_2 Spaghettification: Surviving a Black Hole Event Horizon

We found that it is possible to stay conscious falling through the event horizon of aBlack Hole if the mass exceeds 19,000M_sol. This assumes the average person is ofgood health and can stay conscious with a relative force less than 5 g acting upon them

Factors influencing the distribution of Cactoblastis cactorum, a biological control agent of Opuntia stricta in Kruger National Park, South Africa

Cactoblastis cactorum, a phycitid moth, has been used with considerable success as a biological control agent against several different cactus species in many parts of the world, including Opuntia stricta in Kruger National Park [KNP], South Africa. Although the moth has become widespread and abundant in KNP, its populations have not reached levels where it is able to provide the desired level of control on the alien species which has invaded more than 35 000 ha of the park and continues to spread. Although several factors, especially acquired predators and parasitoids, are known to curb the abundance of C. cactorum in South Africa, the extent to which this applies in KNP is unknown. Logistic regression and Canonical Community Analysis were used to determine the biotic and abiotic factors affecting the distribution and abundance of C. cactorum in KNP. To do this, maps of the ranges of the insect and host plant were constructed and integrated with other environmental features. The logistic regression showed that O. stricta density had no influence on whether or not C. cactorum was present in an area. The Canonical Community Analysis suggested that a high fire frequency, the herbicide control programme and the presence of small host plants may be important in limiting the distribution of C. cactorum, either directly or indirectly, through impacts on associated predators or parasitoids

Environmental factors influencing the distribution of Opuntia stricta, an invasive alien plant in the Kruger National Park, South Africa

Opuntia stricta (Cactaceae), an alien weed, has invaded an area of more than 35 000 ha in the Skukuza region of the Kruger National Park [KNP]. The distribution of the plant and features of the environment were used to identify biotic and abiotic factors which may be affecting the distribution and density of the plant. A Canonical Community Analysis revealed that none of the environmental factors that were monitored influenced the distribution or abundance of O. stricta in KNP. There were no apparent natural barriers that might limit the occurrence of O. stricta within the KNP. The study provides insight into the relationship between the invader and host environment, showing that there is a high probability that, unless there is appropriate intervention, O. stricta will eventually colonise the entire KNP

A cross-scale approach for abundance estimation of invasive alien plants in a large protected area

Efficient management of invasive alien plants requires robust and cost-efficient methods for measuring the abundance and spatial structure of inva- sive alien plants with sufficient accuracy. Here, we present such a monitoring method using ad hoc presence-absence records that are routinely collected for various management and research needs in Kruger National Park, South Africa. The total and local abundance of all invasive alien plants were estimated using the area-of-occupancy model that depicts a power-law scaling pattern of species occupancy across scales and a detection-rate-based Poisson model that allows us to estimate abundance from the occupancy, respectively. Results from these two models were consistent in predicting a total of about one million invasive alien plant records for the park. The accuracy of log-transformed abundance estimate improved significantly with the increase of sampling effort. However, estimating abundance was shown to be much more difficult than detecting the spatial structure of the invasive alien plants. Since management of invasive species in protected areas is often hampered by limited resources for detailed surveys and monitoring, relatively simple and inexpensive monitoring strategies are important. Such data should also be appropriate for multiple purposes. We therefore recommend the use of the scaling pattern of species distribution as a method for rapid and robust monitoring of invasive alien plants in protected areas. Not only do these approaches provide valuable tools for managers and biologists in protected areas, but this kind of data, which can be collected as part of routine activities for a protected area, provides excellent opportunities for researchers to explore the status of aliens as well as their assemblage patterns and functions