Interaction of local and landscape features in the conservation of Hungarian arable weed diversity

Question: How do local and landscape management contribute to weed diversity in Hungarian winter cereal fields? Location: Central Hungary. Methods: Vascular plants were sampled in 18 winter cereal fields along an intensification gradient according to nitrogen fertilization, in the first cereal rows (edge) and in the interior part of the fields. Weed species were divided into groups according to their residence time in Central Europe (native species, archaeophytes, neophytes) and nitrogen preference (low to medium, LMNP, and high, HNP species). The percentage of semi‐natural habitats was calculated in the 500 m radius circle. Effects of fertilizer use, transect position and semi‐natural habitats were estimated by general linear mixed models. Results: We recorded 149 weed species. Fertilizer had a negative impact on the species richness of archaeophytes and LMNP species, and on the cover of native weeds. There was greater species richness and weed cover at the edge of the fields than in the centre. A higher percentage of seminatural habitats around the arable fields resulted in greater total species richness, especially of archaeophytes and LMNP species. We found an interaction between the percentage of semi‐natural habitats and transect position for species richness of archaeophytes and LMNP species. Conclusions: Reduced use of fertilizers and a high percentage of semi‐natural habitats would support native and archaeophyte weed diversity even in winter cereal fields, while large amounts of fertilizer may promote invasion of neophytes. However, the beneficial effect of the semi‐natural habitats and greater species pool on the arable flora may prevail only in the crop edges.     

Bias in vegetation databases? A comparison of stratified‐random and preferential sampling

Aim: Vegetation plots collected since the early 20th century and stored in large vegetation databases are an important source of ecological information. These databases are used for analyses of vegetation diversity and estimation of vegetation parameters, however such analyses can be biased due to preferential sampling of the original data. In contrast, modern vegetation survey increasingly uses stratified‐random instead of preferential sampling. To explore how these two sampling schemes affect vegetation analyses, we compare parameters of vegetation diversity based on preferentially sampled plots from a large vegetation database with those based on stratified‐random sampling. Location: Moravian Karst and Silesia, Czech Republic. Methods: We compared two parallel analyses of forest vegetation, one based on preferentially sampled plots taken from a national vegetation database and the other on plots sampled in the field according to a stratified‐random design. We repeated this comparison for two different regions in the Czech Republic. We focussed on vegetation properties commonly analysed using data from large vegetation databases, including alpha (within‐plot) diversity, cover and participation of different species groups, such as endangered and alien species within plots, total species richness of data sets, beta diversity and ordination patterns. Results: The preferentially sampled data sets obtained from the database contained more endangered species and had higher beta diversity, whereas estimates of alpha diversity and representation of alien species were not consistently different between preferentially and stratified‐randomly sampled data sets. In ordinations, plots from the preferential samples tended to be more common at margins of plot scatters. Conclusions: Vegetation data stored in large databases are influenced by researcher subjectivity in plot positioning, but we demonstrated that not all of their properties necessarily differ from data sets obtained by stratified‐random sampling. This indicates the value of vegetation databases for use in biodiversity studies; however, some analyses based on these databases are clearly biased and their results must be interpreted with caution.     

Introduced plants on Kilimanjaro: tourism and its impact

Kilimanjaro, a world heritage site and an icon of global change, not only suffers from climatic alterations but also is undergoing a drastic socio-economic upheaval. A strong increase of tourism enhances the risk of introducing alien plant species in particular in the upper zones of Kilimanjaro. One such species is Poa annua L., a cosmopolitan weed of European origin on roadsides and pastures. The aim of this study is to document its distribution, the speed of its propagation and risks for the indigenous vegetation of Kilimanjaro, and to compare the findings with other introduced species on this mountain. Based on a complete survey of the vegetation of Kilimanjaro with about 1,500 vegetation plots, plant communities invaded by Poa annua are determined. As with most of the other neophytes on Kilimanjaro, Poa annua invades only anthropogenic vegetation but not undisturbed natural vegetation. Similar to the situation in middle Europe, this neophyte is on Kilimanjaro a constituent of the vegetation of trampled ground, occurring between about 1,600 and 4,000 m asl along climbing routes or their vicinity. On a newly opened climbing route a rapid invasion (5.6 km in 3 months) was observed, which makes it likely that Poa annua spread on Kilimanjaro during the last 30 years in parallel to the increase of the climbing tourism. Although Poa annua is still in the stage of propagation, an invasion of natural vegetation types seems to be unlikely.     

The Banana Forests of Kilimanjaro: Biodiversity and Conservation of the Chagga Homegardens

Natural flora, vegetation, diversity and structure of 62 traditional coffee–banana plantations on Kilimanjaro were investigated and compared with the other vegetation formations on this volcano on basis of over 1400 plots following the method of Braun-Blanquet. The vegetation of the so-called Chagga homegardens belongs floristically to the formation of ruderal vegetation forming two main communities that are determined by altitude. These coffee–banana plantations maintain a high biodiversity with about 520 vascular plant species including over 400 non-cultivated plants. Most species (194) occurring in the Chagga homegardens are forest species, followed by 128 ruderal species, including 41 neophytes. Typical of the agroforestry system of the Chagga homegardens is their multilayered vegetation structure similar to a tropical montane forest with trees, shrubs, lianas, epiphytes and herbs. Beside relicts of the former forest cover, which lost most of their former habitats, there are on the other hand (apophytic) forest species, which were directly or indirectly favoured by the land use of the Chagga people. High demand of wood, the introduction of coffee varieties that are sun-tolerant and low coffee prizes on the world marked endanger this effective and sustainable system.     

Spread of alien invasive Impatiens balfourii in Europe and its temperature,light and soil moisture demands

Impatiens balfourii was introduced in the beginning of the 20th century from the Himalayas to Southern Europe where it was able to establish. In recent years an increasing number of more northern situated occurrences were recorded. An overview about the current distribution of Impatiens balfourii in Europe is given and new records for Germany are presented. To explore the range of potential habitat conditions, vegetation relevés and autecological experiments were conducted. Gas exchange measurements showed an optimum of net photosynthesis at 24–32 °C and light saturation above 700 μmol m⁻¹ s⁻¹ PPFD without any signs of photoinhibition. A moisture gradient experiment showed that Impatiens balfourii prefers fresh soils of moderate dampness. In contrast to the native I. noli-tangere and to the alien species I. glandulifera and I. capensis, which prefer moister or even wet habitats, Impatiens balfourii resembles in its soil moisture demands the alien Impatiens parviflora which originates also in Central Asia and which is invasive in Europe. But in contrast to I. parviflora and to all other established Impatiens species in Europe, I. balfourii is able to colonize even open habitats with high light intensities. Against this background, a further expansion of Impatiens balfourii in Europe appears to be likely.