Two outstanding papers on restoration and succession are briefly discussed as model papers for the type of research papers Appl. Veg. Sci. should publish. The paper on restoration concentrates on the introduction of hay to a site in order to speed up the introduction of target species. The paper on succession discusses the importance of plant colonization ‘windows’ opened by extreme weather events for succession and for offering optimum periods for intervention in restoration practice.

Some remarks are also made on the electronic availability of ecology papers.

Question: Can recent satellite imagery of coarse spatial resolution support forest cover assessment and mapping at the regional level?

Location: Continental southeast Asia.

Methods: Forest cover mapping was based on digital classification of SPOT4-VEGETATION satellite images of 1 km spatial resolution from the dry seasons 1998/1999 and 1999/2000. Following a geographical stratification, the spectral clusters were visually assigned to land cover classes. The forest classes were validated by an independent set of maps, derived from interpretation of satellite imagery of high spatial resolution (Landsat TM, 30 m). Forest area estimates from the regional forest cover map were compared to the forest figures of the FAO database.

Results: The regional forest cover map displays 12 forest and land cover classes. The mapping of the region's deciduous and fragmented forest cover remained challenging. A high correlation was found between forest area estimates obtained from this map and from the Landsat TM derived maps. The regional and sub-regional forest area estimates were close to those reported by FAO.

Conclusion: SPOT4-VEGETATION satellite imagery can be used for mapping consistently and uniformly the extent and distribution of the broad forest cover types at the regional scale. The new map can be considered as an update and improvement on existing regional forest cover maps.

Abbreviations: ASEAN = Association of Southeast Asian Nations; FAO = Food and Agriculture Organization of the United Nations; IUCN = International Union for Conservation of Nature; LCCS = Land Cover Classification System; MRC = Mekong River Commission; NDVI = Normalized Difference Vegetation Index; NIR = Near infrared; S10 = Ten day standard composites; SWIR = Short wave infrared; VGT = SPOT4-VEGETATION.

Hypothesis: For any one time and place a ‘functional signature’ can be derived for a sample of herbaceous vegetation in a way that concisely represents the balance between the different clusters of functional attributes that are present among component species.

Methods: We developed a spreadsheet-based tool for calculating functional signatures within the context of the C-S-R system of plant functional types. We used the tool to calculate and compare signatures for specimen British vegetation samples which differed in management regime and location in time.

Conclusion: The integrative power of the ‘C-S-R signature’ is useful in comparative studies involving widely differing samples. Movements in the signature can be used to indicate degree of resistance, resilience, eutrophication and dereliction. Systems of plant functional types other than C-S-R might also be approached in this way.

Availability: The tool can be downloaded free of charge from the first author's web pages or from the journal's electronic archive.

Nomenclature: Stace (1997).

Question: Is demographic performance of Primula vulgaris correlated with habitat characteristics of the small landscape elements in which it occurs? Can we use this species as an indicator for species-rich semi-natural habitats?

Location: Flanders, Belgium.

Methods: To capture differences in demographic traits and habitat characteristics, both within and between populations, a two-level survey was carried out. Population size and structure of 89 P. vulgaris populations in different types of small landscape elements was recorded in 1999. At plot level, densities of different life stages were determined and these were related to edaphic conditions and vegetation structure and composition.

Results: Three different population types were distinguished: (1) dynamic populations, characterized by seedling and juvenile proportions, (2) normal populations with relatively more adults, but with considerable numbers of seedlings and juveniles and (3) senescent populations, mainly consisting of adults. Senescent populations were significantly smaller than populations with a dynamic demographic structure. At plot level, comparison of demographic characteristics between different management regimes revealed that recruitment rates and total plant density of P. vulgaris were highest in plots that received a regime that included mowing and clearing of ditch banks whereas densities were lower along forest edges. For these plots, it was shown that nutrient levels were higher. Densities of adults as well as juvenile and seedling densities were negatively correlated with vegetation height.

Conclusions: Local disturbance and heterogeneity may mask the relationship between unfavourable conditions and demographic characteristics at population level, but it is clear that in small populations recruitment needs to be lifted to guarantee its persistence. Performance of P. vulgaris in small landscape elements can be a first indication of plant species diversity in small landscape elements.

Nomenclature: Lambinon et al. (1998).

Question: Has the vegetation of Sphagnumbogs been affected by more than 200 years of human activities?

Location: Bas-Saint-Laurent region, southeastern Québec, Canada.

Methods: Data (species assemblages, abiotic and spatio-historical variables) were collected in 16 bogs ranging from 2 to 189 ha, and incorporated in a geographical information system. Major gradients in vegetation composition were identified using DCA. CCA was used to relate vegetation gradients to abiotic and spatio-historical variables.

Results: A clear segregation of species assemblages was observed, from open and undisturbed bogs to forested and highly disturbed sites. Among abiotic factors, tree basal area, water table level and peat thickness had a significant influence on plant species composition. Among spatio-historical factors, disturbance level, area loss and fire were the most influential factors. Variance partitioning between these groups of factors suggests that spatio-historical factors had a major influence on peatlands, representing 22% of the variation observed in the plant species assemblages while abiotic factors represent only 17% of the variation.

Conclusions: The results highlight the influence of agricultural and other anthropogenic activities on plant assemblages and suggest that even wetlands apparently resistant to disturbances, such as peatlands, can be severely affected by anthropogenic factors. Plant species assemblages of ombrotrophic peatlands of the Bas-Saint-Laurent region were, and still are, largely influenced by human activities.

Nomenclature: Anderson et al. (1990) for mosses; Esslinger & Egan (1995) for lichens; Marie-Victorin (1995) for vascular plants.

Abbreviation: GIS = Geographical information system.

Question: Are the recruitment patterns of deliberately introduced wildflower species influenced by cutting frequencies and disturbance treatments? To what extent do these different treatments affect productivity and sward structure of an agriculturally improved grassland?

Location: A mesic lowland grassland near Göttingen, Lower Saxony, Germany.

Methods: Recruitment success of eight sown wildflower species was studied in a permanent grassland treated by a factorial combination of different pre-sowing cutting intervals (1, 3 or 9 wk), post-sowing cutting intervals (1, 3 or 9 wk) and disturbance (control, harrowing, removal of sward). Seedling emergence and survival, biomass production and sward structure were followed over two years.

Results: For most species seedling emergence was highest in the harrowing treatment. The complete sward removal did not further increase seedling emergence. Seedling survival was strongly influenced by the post-sowing cutting frequency with highest mortality in the 9 wk cutting interval compared to one and 3 wk cutting intervals. Annual dry matter yield varied between 4.4, 5.9 and 9.4 t.ha⁻¹ in the 1, 3 and 9 wk pre-sowing cutting treatment, respectively. In June, when the seeds were sown, the tiller number of the 1 wk cut plots was twice as high as for the 9 wk cut plots and five times higher than in the harrowing treatment.

Conclusions: Disturbance by harrowing provided the optimal environmental cues to trigger germination, whereas seedling survival was facilitated by increased light penetration due to frequent cutting. The investigation revealed the overriding importance of frequent standing crop removal in the early phase of seedling establishment on agriculturally improved grassland.

Nomenclature: Oberdorfer (1994).

Question: How well does the use of NDVI predict secondary productivity at landscape scales? What is the influence of vegetation quality and phenology over secondary productivity?

Location: Magellanic steppe in Tierra del Fuego, Argentina. (52°45′ to 54° S, 68°15′ to 67°30′ W).

Methods: Monthly and yearly integrated NDVI (NDVI-I) were calculated from AVHRR/NOAA 14, as estimators of phenology and aerial net primary productivity respectively. From a vegetation map we obtained the proportional cover of different physiognomic types and calculated the palatable fraction (forage) productivity that were used as estimators of vegetation quality. Data were analysed through correlations and regressions.

Results: NDVI-I was not related with secondary productivity indices, while December and annual maximum NDVI, proportion of lawns and tussock grasslands and forage productivity were positively related with secondary productivity. A negative relationship was found between the proportion of heathlands and secondary productivity, but a positive relationship between heathland's proportion and NDVI-I was found.

Conclusions: NDVI-I is not a good predictor of secondary productivity at the scale of our study. These results could be due to: (1) NDVI-I is not related to primary productivity and (2) primary productivity is not related to secondary productivity.

Abbreviations: ANPP = Above-ground net primary productivity; aPAR = Absorbed photosynthetic active radiation; AVHRR = Advanced very high resolution radiometer; NDVI = Normalized difference vegetation index; NDVI-I = Integrated normalized difference vegetation index; NOAA = National Oceanic and Atmospheric Administration.

Question: Which restoration measures (introduction of donor diaspore material, application of straw mulch, alteration of residual peat depths) contribute to the establishment of a fen plant community on minerotrophic surfaces after peat mining?

Location: Rivière-du-Loup peatland, southern Québec, Canada at 100 m a.s.l.

Methods: The effectiveness of introducing fen plants with the application of donor diaspore material was tested. The donor diaspore material, containing seeds, rhizomes, moss fragments, and other plant propagules, was collected from two different types of natural fens. We tested whether the application of straw mulch would increase fen species cover and biodiversity compared to control plots without straw mulch. Terrace levels of different peat depths (15 cm, 40 cm, and 56 cm) were created to test the effects of different environmental site conditions on the success of re-vegetation.

Results:Applying donor seed bank from natural fens was found to significantly increase fen plant cover and richness after the two growing seasons. Straw mulch proved to significantly increase fen plant richness. The intermediate terrace level (40 cm) had the highest fen plant establishment. Compared to reference sites, the low terrace level (15 cm) was richer in base cations, whereas the high terrace level (56 cm) was much drier.

Conclusions: The application of donor diaspore material was demonstrated as an effective technique for establishing vascular fen plants. Further rewetting measures are considered necessary at the restoration site to create a fen ecosystem rather than simply restoring some fen species.

Nomenclature: Gleason & Cronquist (1991) for vascular plants; Anderson (1990) for Sphagnopsida; Anderson et al. (1990) for other mosses.

Question: What is the population viability of a critically endangered seashore grass, Arctophila fulva var. pendulina.

Location: Liminka Bay, W Finland, 25°21′70 N, 64°51′90 E.

Methods: We constructed a matrix population model based on colonization and disappearance events and patch size changes of A. fulva. Patches were divided into hydric and non-hydric zones according to proximity to the seashore and intensity of disturbance. Perturbation analyses were carried out in order to identify transitions critical for population growth. Seed bank and seed germination studies provided background information for the model design.

Results: A. fulva patches observed in the more disturbed hydric zone (closest to the sea) increased in number, as did the total number of patches. However, the number of patches in the less disturbed non-hydric zone decreased.

Conclusions: Short-term dynamics of the A. fulva population at Liminka Bay seem to be determined by environmental fluctuations, which cause annual variation in transition rates between patch size classes. The long-term dynamics are probably governed by initiation of primary succession by isostatic land uplift. Increased disturbance at the water's edge may promote persistence of A. fulva through reduced interspecific competition. Our results suggest that shoreline disturbance of the hydric zone is sufficient for maintaining a viable population. Competitive exclusion of A. fulva in the non-hydric zone may be delayed by management practices, such as mowing.

Nomenclature: Hämet-Ahti et al. (1998).

Abbreviations: LTRE = Life table response experiment; TTC = 2,3,5-triphenyl-2H-tetrazolium chloride.

Question: Do large herbivores contribute to the dispersal of plant seeds between isolated habitats by epizoochory?

Location: Nature reserves in Flanders, Belgium.

Methods: Epizoochory was studied by brushing plant seeds from the fur of 201 domesticated large herbivores (Galloway cattle, donkeys and horses), grazing in 27 Flemish nature reserves. Several herbivores were examined after transport between different nature reserves as part of the seasonal grazing system in Flanders, allowing detection of seed dispersal both within and between reserves. The seedling emergence method was used to identify the dispersed plant species.

Results: In total, 6385 epizoochorous seeds from 75 species germinated, yet the real seed quantity was underestimated by the seedling emergence method. A wide variety of seed morphology, seed weights and plant heights was represented among the dispersed species, many of which had a transient seed bank. There was a gradual turnover in epizoochorous species composition in the course of the vegetation season, and seed dispersal occurred both within and between different nature reserves.

Conclusions: Domesticated large herbivores, as models for wild mammals in the present and the past, are important dispersers of many plant species. Through seasonal grazing, the herbivores function as ‘mobile link organisms’, connecting isolated nature reserves through seed dispersal, possibly influencing vegetation development and long-term survival of plant populations. As such, large herbivores are important instruments in ecological restoration, especially in fragmented ecosystems.

Nomenclature: Lambinon et al. (1998).

Question: Does the development of Brachystegia-Julbernardia (miombo) woodland after felling, and under a variable fire regime, occur via a seral stage of fire-tolerant species?

Location: Four sites in central Zambia, Africa.

Methods: Trees in replicate plots were clear-cut and stumps and resprouts enumerated. Species recruited into the tree layer (> 2.0 m tall) were monitored for 11 years (1991 – 2001) and fire occurrence and herbaceous biomass assessed annually to determine fuel loads.

Results: Fire frequency was variable at the study sites and fuel loads were generally too low to suppress woodland regeneration after felling. However, at one site a change from low to high fire frequency arrested woodland development and triggered a regression towards a ‘fire-trap’ vegetation type in which a few fire-tolerant species survived. There was no evidence to support the hypothesis that miombo woodland regeneration is facilitated by a sere of fire-tolerant species. All regrowth after felling was from resprouting plants present before felling. Trees with a previous history of felling sprouted more vigorously than trees that had not been felled before. Species richness in the tree layer increased with time since felling because resprout species had different height growth rates.

Conclusion: The resilience of miombo trees after clear-felling is largely due to their capacity to regenerate vegetatively from resprouts and stumps after release from frequent fires. Coppicing is therefore recommended as a suitable management technique for miombo woodland in central southern Africa.

Nomenclature: White (1962) and Fanshawe (1971).

Question: Which are the success and failure of restoration measures, particularly sod-cutting and hydrological measures, in small wetlands on mineral soils in The Netherlands.

Location: Twente, in the eastern part of The Netherlands.

Methods: Success or failure of restoration measures has been assessed by comparing experimental plots with that in reference plots for (1) species richness, (2) re-establishment of endangered species and (3) species composition, including life forms and Red List species. In total 119 samples were taken in 42 permanent plots in fen meadows, small-sedge marshes, wet heathlands, and soft-water pools. Topsoil samples were analysed for pH, Ca, Mg, Na, K and Cation Exchange Capacity. Gradient analysis was carried out by means of Canonical Correspondence Analysis.

Results: Sod-cutting, in combination with re-wetting measures (infilling of ditches and drains), led to restoration of communities of soft-water pools and small sedge marshes within five years. This rapid recovery is probably related to the presence of persistent seed banks of the component species of these communities. Complete restoration of fen meadows took longer (10–15 yr). Apparently, many species of fen meadows have short-lived seed banks. Sod-cutting of a degraded wet heathland and a soft-water pool was only successful temporarily, probably as a consequence of low water tables.

Conclusions: To prevent depletion of (persistent) soil seed banks, sod-cutting in nutrient-poor wetlands is not recommended in areas where the groundwater regime and the base status of the soil can not be restored to levels required by plant communities of wet heathlands.

Nomenclature: van der Meijden (1990) for phanerogams, Smith (1980) for mosses and Schaminée et al. (1995, 1996) for syntaxa.

Abbreviations: AAS = Atomic absorption spectometry; CEC = Cation exchange capacity; H exch = Exchangeable H ; WC = Water content.

Question: What effects do leaf litter and rainfall regime have on seed germination (time and probability) and seedling survival of the endangered tree species Beilschmiedia miersii (Lauraceae)?

Location: The species is a native tree from the mediterranean climate region of Chile. Seeds were collected from La Campana National Park (Chile). The study was carried out under controlled conditions at the Laboratory of Ecology, University of Chile, Santiago, Chile.

Methods: During April 2001, 200 seeds were assigned to four experimental treatments: high precipitation, with and without litter and low precipitation, with and without litter. Each treatment had 50 individual seeds, each seed in an individual pot. For statistical purposes, we considered each seed as one replicate. High and low values of artificial rainfall corresponded to mean dry and wet years, respectively, for the period 1958 – 1993 in the central zone of Chile.

Results: Seeds germinated earlier, and in higher proportion, in the presence of leaf litter, but only under low rainfall. Seedling survival was insensitive to both litter and precipitation.

Conclusions: We conclude that the presence of litter in native populations facilitates seed germination and recruitment of B. miersii, particularly during dry years. We suggest that the reduction of leaf litter due to extraction for gardens and horticultural activities might preclude regeneration of this endangered species.

Questions: Can seed addition enhance the success of establishing species-rich grassland on former arable land? Are sowing date and cutting regime important in determining success?

Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species-rich grassland.

Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species-poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment.

Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species-rich grasslands.

Nomenclature: Clapham et al. (1987).

Question: How does vegetation and management affect the population stage structure of Serratula tinctoria, a species indicative of highly endangered and species-rich flood-plain meadows? Are different management regimes suitable to support viable populations of S. tinctoria?

Location: Flood-plain of the northern Upper Rhine, Germany.

Methods: We analysed the population structure of S. tinctoria at 24 meadow sites which differed in vegetation and management. In this comparative study the investigated meadows were either (1) late mown in September; (2) early mown in June or (3) mown in June and then grazed by sheep.

Results: The structure of the surrounding vegetation had a clear effect on the population structure of S. tinctoria. The percentage of bare soil, as well as the cover of bryophytes, were positively related, whereas the Ellenberg N-value of the established vegetation was negatively related to the density and proportion of seedlings. Generally, we found only slight differences between the population structure of S. tinctoria in early and late mown meadows. Both management regimes had high densities of seedlings. In contrast, the meadow pastures supported significantly lower densities of seedlings and generative adults but relatively high densities of juveniles and vegetative adults, indicating a greater importance of clonal propagation under grazing pressure.

Conclusions: Our results clearly showed that viable populations of S. tinctoria may occur in all of the studied management regimes. Although S. tinctoria was considered to be highly sensitive to early mowing, our findings suggest a facilitation of the species at more nutrient-rich sites by mowing in June, which is also a benefit for the integration of management in farming systems.

Abbreviation: PAR = Photosynthetically active radiation.