Differences between species in seed bank and vegetation helps to hold functional diversity in a floodable Neotropical savanna

Aims Our objective was to quantify the contributions of the seed bank and the established vegetation to the species composition, functional composition and diversity, and discuss the implications of these differences in regeneration and persistence of floodplain plant communities. Methods We sampled all ground cover vegetation up to 1.5 m height and seed bank in 25 plots (10 m × 1 m) distributed across five sites in dry and rainy seasons in a periodically flooded savanna in the Pantanal wetland, Brazil. We evaluated the soil seed bank by seedling emergence method. Important Findings The seed bank species had traits that conferred regeneration to the communities, while persistence traits characterized the vegetation. The seed bank had higher functional richness and lower functional evenness than the vegetation. The existence of different plant traits between seed bank and vegetation allowed the coexistence of species with functionally contrasting persistence and regeneration traits, which may help maintain functional diversity. It may allow the community to be more resilient when dealing with different environmental filters such as drought, fire and flood.

Kelimpahan Vegetasi dan Simpanan Biji Gulma pada Pertanaman Jagung Berbeda Sejarah Pola Tanam di Lahan Kering

Weed management is an important aspect in the dry land; however, weed resides in dry land like East Nusa Tenggara is rarely reported. The study aimed to evaluate weed species and its seed bank on maize fields from the different history of cropping patterns in order to develop effective weed control. The research was conducted in April-June 2019 at farmer fields at Kupang District, East Nusa Tenggara, Indonesia. Weeds were evaluated from four maize fields experienced a different history of cropping pattern (L1, L2, L3, and L4), and its seed bank from the depth of 0-10, 11-20, 21-30, and 31-40 cm were evaluated using seedling emergence method. The evaluation revealed 13 species at which 4 species exclusively were found in vegetation analysis, 2 species in the seed bank and 7 species in both vegetation and seed bank analysis. Dominant weed at podzolic L2 and L3 that experienced fallow for two months was Chloris barbata, while without fallow of podzolic L1 and grumusol L4 were Digitaria adscendens and Mazus japonicus, respectively. Cropping history and soil depths affected weed density, but depths of 0-20 cm had the highest density irrespective preceding the cropping pattern. Research implies both vegetation and seed bank analysis should be addressed and integrated in weed management. Keywords: dry land, fallow, weed management, East Nusa Tenggara, vegetation analysis

Banco de semillas después de un incendio en un matorral xerófilo

Through the seedling emergence method we studied the effects of fire on the soil seed bank of a xerophytic shrubland in two consecutive years. We compared its composition and abundance in two sites, one burned and one unburned. An important proportion of seeds died due to the high temperatures reached by fire. In addition, species richness and, diversity were also negatively affected. These variables showed statistical differences between sites and years. After one year, seed bank abundance and diversity reached higher values. Dominant species were perennial herbs in terms of species number, and in terms of seedling abundance the dominant life form was a tree. However, fire was not a determinant factor in terms of species composition. These results are important to explain the changes in vegetation after a fire, specially if we consider that this site is a natural preserve immersed in an urban area.

High potential of sub-Mediterranean dry grasslands for sheep epizoochory

There is a general decline of grasslands across Europe due to habitat loss and degradation. Ensuring plant dispersal thus becomes a key process for preserving grassland patches in all scales. We examined diaspore dispersal by sheep epizoochory in the pastures of the North Adriatic Karst (NW Slovenia) and determined the qualitative and quantitative features of diaspores in fur. We recorded 25,650 diaspores of 141 plant taxa (with 107 taxa and 23,350 diaspores determined to species level), using three different methods: (i) the “whole-coat method”, (ii) the “part-of-thecoat method” and (iii) a “seedling emergence method”. A comparison of these techniques revealed that the “wholecoat method” provided the highest number of diaspores and plant species. All diaspores were clustered into five emergent groups based on seven functional traits (diaspore weight, length, width, height, volume, specific weight and the diaspore surface structure). Our research revealed that sheep represent an important dispersal vector, since about half of the plant species recorded in the pastures were found as diaspores in fur. This study contributes to knowledge about the modes of seed dispersal in seminatural grasslands. Taking into account that livestock play a key role in vegetation dynamics, understanding their effects on seed dispersal is essential for conservation and restoration of these species-rich grassland communities.

Vegetation diversity influences endozoochoric seed dispersal by moose (Alces alces L.)

Research on moose-mediated seed dispersal is limited. However, its potential role in transferring seeds in patchy landscapes may be of great importance. In this work we examined how seasons and vegetation diversity influence the species richness and abundance of seeds dispersed endozoochorically by moose. Samples of moose faeces were collected year-round, fortnightly, from contrasting vegetation types, dominated by diverse, species-rich wetland or poor, dry pine forest. The viable seed content of dung was studied by the seedling emergence method. The mean number of emerged seedlings per 0.8 L sample and the mean number of plant species per 0.8 L sample were several times higher in the diverse wetland vegetation than in the poor pine forest vegetation. Maximum species richness and seed abundance was observed during the fructification period, and the minimum during spring. The species richness of samples did not differ between winter and the growing season, although the composition of plant species was different. The results of this study suggest that moose are efficient seed vectors, especially of grasses typical for grasslands and wetlands. The species richness and abundance of dispersed seeds coincides with the diversity of the vegetation of the animal’s habitat.

The effects of different types of woodstand disturbance on the persistence of soil seed banks

The research was conducted on four patches of thermophilous oak wood in Białowieża Primeval Forest: A – with a woodstand: oak + approx. 30-year-old hornbeam + hornbeam brushwood; B – with a hornbeam stand formed by natural seed fall after logging (ca. 1920) oaks; C – after logging oaks and replanted (ca. 1965) with pine and oak; D – with a natural low-density oak stand. Species composition and seed bank density were estimated using the seedling emergence method. Seedling emergence was observed over two vegetation seasons. Research demonstrated that: 1) the species abundance of the seed banks depends on canopy cover (A, B approx. 50 species; C, D approx. 70 species); 2) the floristical similarity (Sørensen's index) of the seed bank and ground vegetation is higher in the undisturbed patch D (0.50) than in disturbed patches (0.30-0.35); 3) species diversity in plots A, B, C, D (H'=12.5; 13.4; 15.5; 16.9) and seed bank density per m² (432.5; 958.0; 1486.5; 2268.0) are negatively correlated with the degree of patch shading; 4) the average weight of diaspores in the seed banks of shady plots is lower (A, B approx. 0.003 g) than that of sunny plots (C, D approx. 0.08 g); 5) the share of long-lived diaspores increases in patches after logging.

The pattern of seed banks during secondary succession on poor soils

Studies on the soil seed banks of fallow lands of different ages were carried out on poor soil abandoned fields and in a fresh coniferous forest in north-eastern Poland. The size and diversity of seed banks was studied with the seedling emergence method. Species abundance (<em><strong>i</strong></em>), density (<em><strong>ii</strong></em>), number of species from different biological groups (<em><strong>iii</strong></em>) and distribution and mean <em>LI</em> value (<em><strong>iv</strong></em>) were analysed as the function of fallow land age. It was found that: (<em><strong>i</strong></em>) species diversity, number of species and ln of density are linear declining function of the fallow land age; (<em><strong>ii</strong></em>) for approx. 25 years the share of diaspores of identified species groups has been relatively similar. Seed banks of 40-50-year-old fallow lands are dominated by <em>Calluna vulgaris</em>, while the seed bank of the old fresh coniferous forest is dominated by dicotyledonous perennials and grasses; (<em><strong>iii</strong></em>) within the first 50 years of succession the persistence of seed banks measured by the Longevity Index increases gradually.

Comparison of the vegetation and seedbanks of soybean fields, adjacent boundaries, and hedgerows in Ontario

Patterns of plant assemblages in habitats located within agroecosystems are poorly understood. A study of the seedbank and standing vegetation in 10 soybean [Glycine max (L.) Merr.] fields, their adjacent boundaries, and adjoining woody hedgerows was undertaken in Ontario. The objective was to examine the composition of plants of conservation value and weedy species in these habitats. The seedbank of each habitat was determined from soil cores in quadrats located at regular intervals along transects, using the seedling emergence method in the greenhouse. The vegetation was surveyed in plots adjacent to the seedbank sampling areas. There was no significant difference in total species richness of vegetation or the seedbank among habitat types. However, there was a marked difference in species composition. In the seedbank, no difference in weed species richness among habitats was observed. In vegetation, however, fields harboured significantly more weedy species than adjacent boundaries and hedgerows. The dissimilarity between the seedbank and the vegetation was confirmed in detrended correspondence analyses, which showed that hedgerow vegetation, and to a lesser extent boundary vegetation, differed from field vegetation and all the habitats of the seedbank. The analysis of soil properties indicated that organic matter and nutrient levels were often higher in hedgerows than in fields. It can be concluded that hedgerows are valuable habitats for plant diversity and that weed species represent a minor component of their overall vegetation composition. Key words: Agroecosystems, field boundaries, hedgerows, soil seedbank, vegetation composition

Defining transient and persistent seed banks in species with pronounced seasonal dormancy and germination patterns

The most often used time-line for distinguishing a transient seed bank from a persistent seed bank is one calendar year. Thus, species whose seeds live in or on the soil for <1 year have a transient seed bank, whereas those whose seeds live for ≥1 year have a persistent seed bank. However, dormancy cycling of seeds buried in soil has not been given due consideration in these models. When dormancy cycling is considered, it is shown that seeds of both autumn-germinators and spring-germinators are in the dormant state when they are 1 year old. Thus, unless the seeds live until at least the second germination season (i.e. usually 16–18 months following dispersal), they are, in effect, part of a transient seed bank, having lived through only one germination season. We propose that for seeds of such species to be considered part of a short-term persistent seed bank, they should remain viable and germinable until at least the second germination season, and to be part of a long-term persistent seed bank, until at least the sixth germination season. Our definitions are applicable to seeds with physiological, physical or morphophysiological dormancy, which often require >1 year after maturity to come out of dormancy in nature. We discuss modifications of the seedling emergence method for detection of a soil seed bank, so that they correspond to our definitions of seed-bank strategies.