Martin Šenfeldr

Effects of Prostrate Dwarf Pine on Norway Spruce Clonal Groups in the Treeline Ecotone of the Hrubý Jeseník Mountains, Czech Republic

Abstract Global temperature increase would seem likely to result in general upwards shifts of altitudinal margins of tree stands. However, range expansion of trees could be significantly affected by both negative and positive interactions with alpine shrubs in existing treeline ecotones. We examined the effects of dwarf pine (Pinus mugo) shrubs on the vegetative propagation and height growth of Norway spruce (Picea abies) trees in the treeline ecotone of the Hrubý Jeseník Mountains, Czech Republic. Here, the non-native dwarf pine was planted above timberline during the 19th and 20th centuries. In the treeline ecotone, vegetative propagation is important both for generation of clonal groups from seed-originated individuals and for persistence of such stands. We found that increasing density of dwarf pine stands strongly reduced vegetative propagation of spruce, as shown by the spruce clonal groups surrounded by dense pine having fewer layering branches and ramets than such groups outside pine stands. This has likely resulted from competitive pressure of pine causing decreased spruce layering mainly through mechanical damage and shading. In contrast, dense pine stands increased spruce height growth, presumably by providing shelter against wind and/or browsing. Our results indicate that interactions of prostrate dwarf pine and Norway spruce clonal groups include both competitive and facilitative components, which probably change in importance along climatic stress gradients.

Field Survey of Dracaena Cinnabari Populations in Firmihin, Socotra Island: Methodology and Preliminary Results

Abstract Between 2010 and 2011 a field survey dedicated to Dracaena cinnabari (DC) population was conducted in Firmihin, Socotra Island (Yemen). It’s main goal was to collect data that would make it possible to unbiasedly estimate main characteristics of the local DC population. Our motivation was to provide reliable information to support decision-making processes as well as other research activities. At the same time we were not aware of a survey which could provide this kind of statistical-sound estimates for the whole population covering an area of almost 700 ha. This article describes how the survey has been planned and carried out in practice. In addition, we also provide a set of preliminary estimates of the main DC population figures - totals and per hectare densities of stems, overall and partitioned according to predicted crown age. Among estimated parameters there are also mean crown age and proportions of predefined age classes on the total number of living DC stems. These estimates provide an explicit information on age structure of the whole DC population in Firmihin. Although we collected data on more than one hundred randomly located plots, the reported accuracy of our estimates is still rather limiting. We discuss several possibilities to obtain more accurate results or at least to approach the supposedly lower true variance that can’t be calculated by approximate techniques applied here. The design and concept of our survey makes it possible to evaluate changes over time on stem by stem bases and to generalize these stem-level details to the whole population. Mortality, regeneration and even change of population’s mean crown age can be estimated from a future repeated survey, which would be extremely useful to draw firm conclusions about the dynamic of the whole DC population in Firmihin.

Variation in canopy openness among main structural types of woody vegetation in a traditionally managed landscape

The decrease in canopy openness after the abandonment of traditional coppicing in the twentieth century has been previously identified as the main reason behind changes in species composition and diversity in lowland woodlands in Europe. However, little is known about the role of other traditional practices in shaping woody vegetation and canopy cover in the past. In a traditionally managed landscape of the Banat region, western Romania, where long-established activities, such as human-induced burning, coppicing and grazing of woody vegetation are still being practised, we studied woody vegetation structure and canopy openness in 70 plots. Using a set of structural traits, we classified woody vegetation into four groups: active coppices, scrubs, abandoned coppices and high forests. Surprisingly, the lowest canopy openness was found in active coppices, probably due to high canopy recovery rate and selection coppice system. Scrubs, in which grazing and browsing were the most common activities in the past, were the most open type of woody vegetation. Our results emphasize the role of other traditional management practices in addition to coppicing in keeping canopy openness relatively high and spatially heterogeneous.

Effects of Dwarf Pine Stands on Slope Deformation Processes, as a Basis for their Management in the Hrubý Jeseník Mountains

Abstract This paper studies non-indigenous dwarf pine stands in the Hrubý Jeseník Mountains, from the perspective of their spatial and genetic relations to slope phenomena of deformation character. The paper contains a typology of regional slope deformations, data on their spatial distribution and specific properties, including risk estimates of their origination or further development in case of potential future dwarf pine stand clearings, as well as a three-stage categorization of dwarf pine stands based on this tendency. The results were processed using data from literary sources, map documents and aerial photos, as well as an extensive field survey. Three main types of slope deformations were distinguished on sites with highly variable geomorphological features - extensive complex phenomena with numerous subforms, linear debris flows and local shallow landslides. The acquired data show that while dwarf pine stands have no great effect on the development of large slope phenomena, they play a more significant reinforcement role in the prevention of smaller surface deformations, the origination of which is predominantly related to steeper slopes. The results of this study can serve for future decision making on the management of dwarf pine stands

Growth Dynamics of Endemic Dracaena cinnabari Seedlings In Situ on Socotra Island

Dragon ́s blood tree, a flagship endemic species of Socotra, is threatened with extinction 23 due to lack of natural regeneration, likely because of goat herbivory and/or climatic factors. Loss of 24 dragon ́s blood tree would result in loss of other native flora, heightening the importance of 25 formulating a conservation strategy for it. Although artificial afforestation might be used to offset 26 the lack of natural regeneration, it would have to overcome the same threats faced by naturally 27 occurring seedlings. Moreover, there is no published information on the growth dynamics of 28 seedlings in plantations in situ on Socotra. To fill this information gap, we compared seedling 29 growth over an 8-year period after planting at three sites that differed in the degree to which goats 30 were excluded and in whether they were watered regularly over the period. In addition to 31 developing a new classification of the growth stages, which will enable better tracking of population 32 dynamics, we found that continuous goat exclusion was necessary to prevent seedling mortality. 33 Also, although seedling growth overall was slow, growth parameters of regularly irrigated 34 seedlings ranged from 156 % to 446 % of those not regularly watered, suggesting that this treatment 35 can speed seedlings’ escape from goat browsing. 36

The Above-Ground Biomass Production and Distribution in White Willow Community During 11 Years of Primary Succession

In 1996 the water level in the studied area, the central lake of the Nove Mlyny Reservoir, was reduced by 85 cm. The reason was the implementation of a project with the aim to remedy the negative effect of the reservoir on the biological function of the river corridor. Within the project two islands across the reservoir were to be constructed. After the water level was reduced, seedlings of White Willow appeared immediately on the uncovered sediments. The area of the Nove Mlyny Reservoir thus became a unique natural laboratory of the succession of soft floodplain forest in several dozens of hectares (Bucek et al., 2004). The initial stages of the White Willow community, originating from the primary succession (Bergmann, 1999; Matic et al., 1999), prove to be highly productive ecosystems. The aim of research was to monitor the development of the successive community not only regarding the number and growth of individuals but also other production indicators, such as the biomass of stems, branches and leaves, the LAI or the stem volume, in order to create a natural model of community succession. A natural succession model can both bring some light into the principles of community growth and be a suitable source of knowledge concerning the cultivation of fast-growing woody plants on energetic plantations.