Notes on Succession in Old Fields in Southeastern Ontario: the Herbs

Abstract

Two abandoned hayfields in southeastern Ontario were selected as sites in which to investigate possible effects of insect herbivory on early stages of secondary succession. The location, geology, history of land use, and soils have been described earlier (Crowder and Harmsen 1998). Their nutrient status was discussed by Epp and Aarssen (1988). Estimates of increasing cover and abundance of trees, shrubs and vines (51 species) during 1976-1998 were shown to follow classic suc cessional models, although with unusual pioneer species. After two decades the structure of the vegeta tion had become heterogeneous, with groves of small trees, shrub thickets, patches dominated by macroforbs and patches still dominated by grasses. Cover varied with fluctuations of weather from year to year, while soil differences influenced cover and species richness.Most successional studies on old fields use synoptic records from fields of different ages, a method which obscures minor fluctuations and differences between fields. In this paper, year-to-year observations are used to follow temporal changes in the herbaceous commu nity and to relate its cover and species richness to those of the woody layers. Herbaceous species found in 27 experimental plots are listed to allow comparisons with other areas; lichens and bryophytes are omitted. Differences in soil texture (Crowder and Harmsen 1998) influenced cover and richness.Within the herbaceous community, details of temporal change in selected groups of plants and some specific interactions are reported here. Grasses were the main constituents of the hayfields, including both agricultural and adventives species. Legumes also included sown and invasive species. Invasive macroforbs, mainly Solidago and Aster species, dominated parts of the fields; population changes of 15 species are re ported. Taraxacum officinalis, Dandelion, was selected to represent rosette plants. Sedges, horsetails and a few other minor components are described.During the decades when vegetation was monitored, arthropods were also sampled (McBrien et al. 1983). Two insect populations had repetitive outbreaks which caused significant decreases of plant cover, and are therefore the only arthropods reported here. Larvae of the hesperiid European Skipper (Thymelicus lineola) grazed on grasses, particularly on Timothy, Phleum pratense (Henderson 1986 Vegetation in abandoned hayfields was monitored during 1976-1998. An earlier successional stage followed ploughing. Changes in tree, shrub and vine populations have been reported earlier and showed expected increases in species richness and cover. Highest species richness of herbs occurred three years after ploughing. Non-woody species richness trended irregularly downward, while non-woody cover was variable, peaking in 1987. Within the herbaceous community, year-toyear changes in cover and frequency of species in the following selected groups are reported here: 18 grasses including sown and adventive species; 13 legumes including two sown species; 14 macroforbs of the Compos...

Secondary Succession in Two South-eastern Ontario Old-fields

“…Absolute percent cover was chosen as it best represents the biomass present and allows for the relative success of plant species to be incorporated into the measure ͑Smartt et al 1974͒. Percent cover was assessed as per Phillips ͑1959͒, in June and September of each year from 1976to 1989, in 1995and in 1998 Insect data were collected, during the same years as the plant data, using a standard 30 cm diam. sweep net.…”

Woody plant encroachment in granite barrens on the Frontenac Arch, eastern Ontario, Canada

“…Today's forests are dominated by sugar maple and northern red oak ( Quercus rubra L.). However, this is highly variable as local heterogeneity in soil properties (depth and texture) in the QUBS area has been shown to exert a strong influence on woody species composition (Crowder & Harmsen, 1998).…”

“…Today's forests are dominated by sugar maple and northern red oak (Quercus rubra L.). However, this is highly variable as local heterogeneity in soil properties (depth and texture) in the QUBS area has been shown to exert a strong influence on woody species composition (Crowder & Harmsen, 1998). Gillespie et al (1966) classified soils in the QUBS region as part of the podzolic Monteagle series, an extensive sandy-loam complex that is generally acidic and nutrient-poor.…”

Особенности Естественного Восстановления Лесных Экосистем На Бывших Сельскохозяйственных Землях (На Примере Южного Агроклиматического Района Карелии)

“…Большое количество зарубежных и отечественных работ посвящено изучению сукцессионных процессов на бывших сельскохозяйственных землях [22,25,41]. Показано, что лесовосстановление в одних и тех же физикогеографических условиях может проходить по разным сценариям [8,19], но в целом следует в направлении формирования зональных типов экосистем [6,7,13].…”