Karel Prach

Using spontaneous succession for restoration of human-disturbed habitats: Experience from Central Europe

Abstract Total vegetation cover, cover of woody species, and participation of dominants in later (pre-forest) successional stages of 16 successional seres starting on bare ground in various human-disturbed habitats (Czech Republic, Central Europe) were compared and evaluated from the viewpoint of restoration ecology. Continuous vegetation was formed before the 15th year of succession in all the seres studied. The establishment and expansion of woody species tended to be easier under moderate environmental conditions and was retarded in rather extreme habitats (dry, wet, nutrient poor, acid). The later-successional dominants were all native species and some rare and endangered species were recorded in these stages. The main conclusion is that spontaneous succession can be relied upon in restoration projects except in the case of extreme, especially toxic substrata. To leave a site to allow spontaneous processes to revegetate it is especially advantageous if the disturbed site is small, surrounded by natural vegetation, and if site conditions were not principally altered by the disturbance. Spontaneous succession is cheap and spontaneously revegetated sites usually exhibit higher natural value.

Invasion dynamics of Impatiens glandulifera - a century of spreading reconstructed.

Abstract The invasion of Impatiens glandulifera in the territory of the Czech Republic, Central Europe, was reconstructed on the basis of floristic records. The first spontaneous occurrences were reported from the end of the 19th century. The exponential phase of invasion started in the 1930s and the highest increase in the cumulative number of localities reported occurred in the 1960s. Since its introduction, I. glandulifera has spread into 47·4% of available mapping squares. The species is closely confined to riparian habitats. At present it occupies 56% of the length of larger river systems. It is predicted that it will occur in all larger rivers in the Czech Republic by c . 2025, assuming that the rate of invasion remains constant. The rates of invasion in the Czech Republic, British Isles, Bavaria (Germany), and Slovakia are compared. In all the countries considered, the greatest increase occurred in recent decades, and was related to the date of escape from cultivation. Although the situation in the Czech Republic is at present not critical, the ability of I. glandulifera to outcompete native flora, and its predicted expansion along water courses, indicates that it could become a more serious threat to nature conservation in the future.

Four opportunities for studies of ecological succession

Lessons learned from the study of ecological succession have much to offer contemporary environmental problem solving but these lessons are being underutilized. As anthropogenic disturbances increase, succession is more relevant than ever. In this review, we suggest that succession is particularly suitable to address concerns about biodiversity loss, climate change, invasive species, and ecological restoration. By incorporating modern experimental techniques and linking results across environmental gradients with meta-analyses, studies of succession can substantially improve our understanding of other ecological phenomena. Succession can help predict changes in biodiversity and ecosystem services impacted by invasive species and climate change and guide manipulative responses to these disruptions by informing restoration efforts. Succession is still a critical, integrative concept that is central to ecology.

Changes in species traits during succession: A search for pattern

Cover data from 13 successional seres starting on bare ground in the western part of the Czech Republic were analysed. The following questions were addressed: (1) whether the participation of species with particular traits exhibits some trends, and (2) whether primary and secondary seres differ from each other in the course of the first 10 yr of succession. Primary seres were distinguished from secondary ones a priori on the basis of absence or presence of (a) organic topsoil, and (b) soil seed bank at the onset of succession. Traits important for the course of succession were considered, their relative importance expressed for each sere and year on the basis of species quantities, and tested for trends (increase, decrease, unimodal response, no evident trend or absence). The majority of traits considered exhibited some trends in the course of succession. Participation of C-strategists, phanerophytes, intensity of lateral spread, presence of VA mycorrhizae, dispersal by animals and wind, and height of plants significantly increased during the first 10 yr of succession, whereas the participation of R-strategists, therophytes, propagule weight, and capability of forming persistent seed bank decreased. Participation of S-strategists, geophytes, hemicryptophytes, and all relevant types of pollination did not exhibit any significant trend. Primary and secondary seres differed from each other neither in trends in life-history characteristics of constituent species nor in their relative importance after the first 10 yr of succession.

How do species dominating in succession differ from others

Abstract. Data on succession were collected from 15 seres starting on bare ground in man-made habitats (i.e. sites disturbed by various mining activities, bulldozed sites, ruderal urban sites, the exposed bottom of a destroyed water reservoir, and abandoned fields), all in the western part of the Czech Republic, Central Europe. The period for which the data on succession were available ranged from 12 to 60 yr. 56 species reaching dominance in some period of succession were selected (the criterion being: at least 25 % cover in at least one year in any sere); they were compared for biological and ecological traits with other species participating in the seres (167 species with at least 1 % cover in at least one year in any sere), and with the Central European flora as a whole. Significant differences between the species dominating in succession and others were found for the following traits: life form, life strategy, pollination mode, and ability of lateral spread. Dominant species differed from the regional flora in distribution of life strategies, pollination mode and immigration status. The results suggest that an ‘ideal successional dominant’ is a tall, wind-pollinated plant, often a geophyte capable of intensive lateral spread, requiring high nutrient supply and sufficient site moisture. The set of traits contributing to achieving dominance by a species in human-made habitats includes both features occurring independently of phylogenies (life strategy, pollination mode, plant height, moisture demands) and those which dominant species probably share due to their common ancestors (nutrient demands, capability of extensive lateral spread).

Clonal plants—What is their role in succession?

Fifteen successional seres from man-made habitats in central Europe were compared and the occurrence of clonal species assessed on the basis of cover data. The effects of soil moisture and nitrogen (expressed using Ellenberg indicator values) on the performance of clonal plants were also considered. Clonal species formed the dominant component of vegetation cover in the majority of the seres studied. In moist sites, their dominance was more pronounced and the peak in their relative cover occurred earlier in succession. The relative importance of species with guerilla type growth tended to increase with time in most seres and after 10 years these were mostly more important than those exhibiting phalanx type growth. The prevalence of guerilla species after 10 years was more obvious in moist seres. Clonal species were able to become dominant regardless of soil conditions, whereas the dominance of non-clonal species tended to be restricted to very wet and nutrient-poor sites. Clonal plant species appeared to maintain their dominance for a longer period than non-clonal plants.

Spontaneous succession in Central-European man-made habitats: What information can be used in restoration practice?

Abstract The results of previous studies concerning spontaneous vegetation succession in various man-made or disturbed habitats in Central Europe are discussed in relation to restoration ecology. An attempt is made to answer the main questions which are important to restoration programs. These concern the rate and direction of succession; participation of target species and communities, woody species, ruderals and aliens; arresting or diverting succession; changes in species diversity; variability of successional pathways and the role of abiotic environmental conditions. The great potential for using successional theory in restoration programs is emphasized. Nomenclature: Kubát et al. (2002).

Spontaneous vegetation succession in disused gravel-sand pits: Role of local site and landscape factors

Abstract Questions: What is the variability of succession over a large geographical area? What is the relative importance of (1) local site factors and (2) landscape factors in determining spontaneous vegetation succession? Location: Various regions of the Czech Republic, Central Europe. The regions represent two categories characterized by agrarian lowlands, with a relatively warm and dry climate, and predominant woodland uplands with a relatively cold and wet climate. Methods: Gravel-sand pits ranged in age from 1–75 years since abandonment. Three types of sites were distinguished: dry, wet and hydric in shallow flooded sites. Vegetation relevés were recorded with species cover (%) visually estimated using the space-for-time substitution approach. Local site factors, such as water table and soil characteristics, and landscape characteristics, namely climatic parameters, presence of nearby (semi-) natural plant communities and main land cover categories in the wider surroundings, were evaluated. Results: Ordination analyses showed that water table was the most important local site factor influencing the course of spontaneous vegetation succession. Succession was further significantly influenced by soil texture, pH, macroclimate, the presence of some nearby (semi-) natural communities and some land cover categories in the wider surroundings. Spontaneous vegetation succession led to the formation of either shrubby grassland, deciduous woodland, Alnus and Salix carrs, and tall sedge or reed and Typha beds in later stages depending predominantly on the site moisture conditions. Conclusions: Although the water table was the most influential on the course of vegetation succession, the landscape factors together explained more vegetation variability (44%) than local site factors (23%). Nomenclature: Kubát et al. (2002).

On the rates and patterns of spread of alien plants in the Czech Republic, Britain, and Ireland.

ABSTRACT The rates and patterns of spread of 63 species in the Czech Republic and seven in Britain and Ireland were determined from quadrat records, mapovací pole (11- × 12-km mapping zones in the Czech Republic), and 10- × 10-km hectads in Britain and Ireland. Species that have straight sections on logarithmic, square root, and arithmetic plots were found; the last group (10 of them) are generally casuals. Straight square root plots (52 found) are expected from Fisher-Skellam reaction diffusion models, logarithmic equivalents (36 found) where the dispersal kernel has a thicker tail or where spread involves scattered colonies. The greater frequency of the straight square root plots is unexpected. The straightness of so many plots shows that there is no significant variation in recorder bias. About a third of the species showed lags, and many species showed a later slowing of the rate of spread, called here bends. Lags may indicate an initial casual phase as well as slower growth; bends, a lack of further areas to spread to. Typically, with much variation, areas of occupancy double in about 10 y (logarithmic mode) or spread at about 2 km · y−1 (square root mode). Both speeds indicate that most spread is from human activity. The reasons for the major phenomena (the occurrence of the two types of spread predicted by models, their distinctness, and the distribution in rates) may reflect economic and landscape features as well as biological ones. The straightness, speed, and patterns found are all new results for invasion biology.

Vegetation succession in basalt quarries: Pattern on a landscape scale

Abstract A spatio-temporal variation of vegetation during spontaneous succession was studied in 56 basalt quarries spread over 1800 km2 in the České středohoří Hills (NW Czech Republic, Central Europe). Differences in the particular habitats inside a quarry, i.e. steep rocky slopes, bottoms and levels; dumps; and screes were considered. The habitats ranged in age from 1 to 78 yr since abandonment. Macroclimate (mean annual temperature and precipitation) significantly influenced the course of succession, which led to a formation of shrubby grassland, shrubby woodland or tall woodland. Participation of target species typical of steppe-like communities significantly depended on the occurrence of the communities in the vicinity, up to a distance of 30 m from a quarry. Disused quarries may become refugia for rare plant species. Spontaneous successional processes led in the reasonable time of ca. 20 yr to semi-natural vegetation. Thus, they can be successfully exploited in restoration programs scheduled for the disused quarries. Nomenclature: Hennekens (1995) for taxa; Oberdorfer (1992) for syntaxa.