Background : Old fields are abandoned agricultural areas that are undergoing secondary succession. A variety of factors influence the assembly, invasibility, and species turnover during secondary succession in old fields. Old fields are important ecological research locations as an increasing amount of agricultural land is abandoned worldwide. Objectives : 1) To determine if exotic and native "invaders" display differences in invasion success in an old field, and 2) To observe how native and exotic species abundances change over the course of secondary succession under predictable disturbance regimes and resource levels with regards to the Core-Satellite Species (CSS) hypothesis. Methods : An old field located in southern Illinois subject to three levels of fertilization (control, annually fertilized, and fertilized every 5 years) crossed with three levels of mowing treatments (control, spring mowed, and spring/fall mowed) established in 1996 was used to test objectives Seedlings of C3 grasses (native and exotic) were planted within one fertilizer treatment to compare invasion success. Species composition data (species occurrence and abundance at three heights) in all blocks were previously collected from 1996 to 2002 and the sample plots were resampled in 2013. Species sampled in 2013 were assigned to core or satellite categories per the CSS hypothesis. Results : Invading exotic seedlings had higher survivorship than invading native seedlings from the same functional group within the same fertilizer level, and added fertilizer increased seedling survivorship. The number of core and satellite species varied early after experiment establishment in 1996 but has since leveled off, and the ratio of exotic to native species cover at heights <1m ratio was affected by an interaction between mowing treatment and time. The species occupancy distribution of all species in 2013 was not bimodally distributed, but the occupancy distribution of exotic species in 2013 was bimodally distributed.The community composition of the plots varied among blocks, but was affected by an interaction between fertilizer treatment and mowing. Conclusions : Exotic invading grass seedlings in a successional community were relatively more successful than native invading grass seedlings. However, overall survivorship of all invading grass seedlings was low, a typical finding in grasslands. The identity of core and satellite species continued to fluctuate through time following 17 years of secondary succession. Resource availability and disturbance regime affects on community composition throughout secondary succession, and may result in many alternative stable states. This research supports the `CSS' and `parallel dynamics' hypotheses and indicates that presence of exotic species within a community does not necessarily facilitate invasion by new exotic species.

A plant ecological study was conducted in the grasslands of Transkei to develop a better understanding of the distribution, structure and composition of the plant communities found in the area. The agricultural sector in developed and rapidly developing areas of southern Africa is faced with problems like veld deterioration and the loss of natural areas that effectively contribute to the depopulation of rural areas. The Grassland Biome Project was initiated to address the problem of increased destruction of natural resources because the most suitable area for agriculture falls within the grasslands of South Africa. The aim of the Grassland Biome Project is to integrate knowledge, comprehension and expertise, which will enable scientists to forecast the results of the available options of grassland management programs. Vegetation of Transkei forms part of this project. The study area (Transkei) borders on the kingdom of Lesotho in the north and Indian Ocean in the southeast. In the northeast it borders on KwaZulu-Natal and in the northwest, and in the west on the eastern Cape Province. Relevés were compiled in 379 random sample plots and four major plant communities, namely: Bush and Grassland vegetation of drier areas, Wet and Disturbed grassland, Grassland of Undulating Areas, and Moist Grasslands on Flat Plains, were found. The vegetation was classified by means of TWINSPAN and Braun-Blanquet procedures were found. The vegetation was classified by means of TWINSPAN and Braun-Blanquet procedures. / Dissertation (MSc)--University of Pretoria, 2005. / Geography, Geoinformatics and Meteorology / Unrestricted

The main aim of this thesis was to identify the main factors influencing development and diversity of vegetation on old fields around village Svatá Helena in Romania. I evaluated the influence of age of an old field, its management (mowing, pasture, burning and fallowing), soil chemical properties, topography and surrounding vegetation. Using phytosociological relevés I collected data about species composition and coverage of species of the old field vegetation. With the assistance of local inhabitants I found out the age of the old fields and the type of applied management. I performed chemical analysis of soil properties, determined amount of available phosphorus, total carbon and nitrogen and pH. I also performed floristic survey of surrounding vegetation. The data showed a unimodal trend in plant diversity during succession. The maximal diversity was recorded on 12 years old old fields. The diversity was also influenced by C/N ratio of soils. Growing C/N ratio had a negative effect on plant diversity. Analysis also showed some interesting connections between soil properties and topographic factors. Organic C and N in soils were rising with age of old field, rate of accumulation is higher on slopes. The results showed that soil chemical properties have the highest influence on species...

Thesis (MSc (Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / Swartland Shale Renosterveld is restricted to fertile fine-grained soils in the winter rainfall region of the Western Cape. Between 91% and 97% of this vegetation type is transformed, mostly due to agriculture. Remaining fragments have an irreplaceable conservation value due to a high richness of endemic geophytes. Information on renosterveld vegetation composition and response to disturbance is sparse. Research occurred at three sites near Wellington: Voëlvlei Provincial Nature Reserve (CapeNature), Elandsberg Private Nature Reserve (Elandsberg Farms (Pty.) Ltd.), and Krantzkop munitions factory (Armscor/Somchem) forming a contiguous fragment in the Agter- Groeneberg Conservancy. The primary research aim was to identify or ascertain patterns of plant succession in Swartland Shale Renosterveld and associated different-aged old fields (previously ploughed), with the interaction of grazing. The key research questions are: (1) What are the plant communities of unploughed renosterveld and different-aged old fields which originated in habitats of ploughed renosterveld? (2) What are the most characteristic features of the floristic and ecological relationship between the described plant communities in terms of ecological factors operating within the studied system? (3) Does total species and life-form group richness differ between natural vegetation and old fields? (4) Is life-form richness influenced by ploughing and grazing or the interaction between these disturbances? (5) Is life-form cover-abundance influenced by ploughing and grazing or the interaction between these disturbances? (6) Does alien plant species richness differ amongst seres, and with different levels of grazing intensity? A comparison of life-form richness and cover-abundance of old field vegetation was made with adjacent natural unploughed “controls”. The effects of ploughing on community structure, with the inclusion of grazing was established. These life-form richness comparisons also occur across a gradient of increasing large mammalian herbivore grazing intensity. Sampling was conducted in winter and spring using nested 1000m2 relevés. A hierarchical classification, description and floristic interpretation of renosterveld and old field vegetation were made using TWINSPAN, SYN-TAX 2000 and CANOCO. The samples were classified with TWINSPAN and two communities were described at the association level, namely: Ursinia anthemoides–Cynodon dactylon Grassland Community (with two variants) and the Pterygodio catholici–Elytropappetum rhinocerotis Shrubland Community (with two subassociations), respectively. The vegetation data were further hierachically classified using SYNTAX 2000 which revealed similar clustering of sample objects to that resulting from classification and ordination. Following ordination of sample objects with CANOCO, select groups of species were used to depict their response curves in relation to seral development. Briefly it was found that the effects of grazing vs. non-grazing was more pronounced on old fields than in unploughed vegetation. Overall total species and life-form richness was reduced by ploughing with old fields requiring a recovery period of 30 years to resemble unploughed vegetation. Keywords: Swartland Shale Renosterveld, phytosociology, vegetation patterns, life-forms, succession, disturbance, ploughing, grazing, old fields.

This thesis is focused on succession in old fields in Central Europe. Repeated sampling, analysis of surrounding vegetation and soil measurements were conducted in the Bohemian Karst Landscape protected area. Samples from the Doupovské hory Mountains and the rest of the Czech Republic were added to discover basic principles of old field succession at the larger scale of landscapes.