Generally there are only few studies that focus on the interrelation of species composition, habitat properties and indicator species of young and old grasslands , and the few existing oftentimes have contradictory findings. This is surprising, as decision-makers are oftentimes forced to concentrate efforts on areas of highest conservation value due to financial restrictions.
In this study, we assumed that habitat age and land-use history have verifiable effects on the present vegetation community. We analyzed a total of 14 study sites at the southern slopes of the Kyffhäuser Mountains, at the northern border of the federal state of Thuringia, Germany. The area is renowned for its richness in fauna and especially flora, constituting the western-most outpost of Eurasian steppic grasslands. The study area was analyzed with the help of historical maps, post-war aerial survey photographs and presentstate orthophotographs. For each study site 12 relevés, 6 on historically old and 6 on relatively young grasslands on former arable land were conducted. A total of 88 environmental variables ranging from Ellenberg Indicator Values, orographic and edaphic conditions, soil contents and properties, to species inherent traits, were tested for their power to explain the observed occurrence and abundance patterns. Results clearly show that land use history and habitat age has a significant effect on species composition. Concordantly, an Indicator species analysis identified 28 indicator species for old and 21 for young calcareous grasslands. Most significant differences between the two groups were the Ellenberg Indicator Values for moisture and nutrients for the occurring species, which were much higher for young sample sites. Accordingly, there was a higher proportion of ruderalists on grasslands of younger age, while old patches were dominated by stress-strategists. In total, strong relationships could be found for 17 of the tested variables. While α-diversity was only slightly higher for old sites, occurrence of threatened species was more than doubled.
We conclude that the identification of historic calcareous grassland patches is desirable and, where absolutely necessary, old sites should take precedence in management efforts over sites of younger origin. However, considering recent findings in literature, ideally a mosaic of different successional stages should be aspired for, as it can harbor the widest range of plant species and associated invertebrates.
Table of Contents
1. Introduction
1.1. Background
2. Material and Methods
2.1. The Study Area
2.2. Area Analysis and Vegetation Sampling
2.3. Laboratory Soil Analysis
2.4. Species Biological Traits, Indicator Values and other Parameters
2.5. Statistical Analysis
3. Results
3.1. Diversity Measures
3.2. Indicator Species
4. Ordinations
4.1.1. DCA
4.1.2. NMDS
5. Discussion
5.1. Field Work
5.2. Ordinations
5.2.1. Environmental Variables & Life Strategy Types
5.2.2. Species Dispersal & Seed Longevity
5.3. Diversity and Conservational Values
5.4. Management
5.5. Conclusion
Objective and Research Focus
The primary objective of this study is to investigate the interdependencies between habitat age and land-use history and their subsequent effects on vegetation composition and conservation values in steppic grasslands within the Kyffhäuser region.
- Analysis of species composition in young versus historically old grasslands.
- Evaluation of environmental variables and indicator species using DCA and NMDS ordinations.
- Investigation of life strategy types and species dispersal mechanisms in relation to habitat age.
- Assessment of conservation values and biodiversity indices in fragmented grassland remnants.
- Development of recommendations for holistic management strategies in calcareous grasslands.
Book Excerpt
5.2.1. ENVIRONMENTAL VARIABLES & LIFE STRATEGY TYPES
As expected old grasslands patches had a reduced soil moisture and nutrient content. Logically, the history inherent to young grassland patches, determines the quality of some of the environmental variables. Land reclamation was selective, as for instance steep slopes and exceptionally dry patches were avoided, while soil types with higher colloid contents and resulting nutrient retention potential were likely favored. Re-cultivation was also accompanied by intense fertilization. These fundamental differences in environmental properties were accounted for, by a conscious selection of the sample sites in the field. The paired study design allowed finding sample sites of very similar conditions (soil type, slope, exposition etc.). However, differences of soil moisture and nutrient contents between the two sample groups were to be accepted as study inherent given factors. For both ordination results the horizontal axis 1 is the main explaining floristic gradient, as it distinguishes old and young sample sites into strong groups and highly correlates with age-related environmental factors. Unsurprisingly, both DCA and NMDS results show a strong negative correlation of indicator values of nutrients and moisture with age (axis 1, Pearson’s r for DCA = -0.77, for NMDS = -0.80) (indicator values after Flora Indicativa (Landolt et al., 2010), Ellenberg indicator values yielded in similar results, see Tab. 7). In contrast, soil moisture contents showed only a slight correlation (Pearson’s r DCA = 0.10) with the main explaining DCA axis 1 (eigenvalue 0.4). This can be explained with the exceptional weather conditions during the sample period. After an extended dry period, heavy precipitation satiated the soils shortly before all soil samples were taken. Differences in water holding capacity of the different soil types thus became extenuated. The already becoming apparent difference though, explains the observed
Summary of Chapters
1. Introduction: Provides an overview of European calcareous grasslands, their cultural formation history, and the current challenges regarding fragmentation and biodiversity loss.
2. Material and Methods: Details the study area in the Kyffhäuser Mountains, the sampling design involving pairs of old and young sites, and the statistical methodologies including DCA and NMDS ordinations.
3. Results: Presents the findings of species diversity measures and identifies specific indicator species associated with either old or young grassland types.
4. Ordinations: Analyzes the environmental factors influencing community structure using multivariate techniques, confirming significant differences based on habitat age.
5. Discussion: Interprets the ecological findings, specifically focusing on environmental variables, life strategies, dispersal mechanisms, and management implications for conservation.
Keywords
Calcareous grasslands, habitat age, land-use history, species composition, Kyffhäuser Mountains, indicator species, biodiversity, conservation biology, DCA ordination, NMDS, life strategy, vegetation sampling, fragmentation, steppic grasslands, environmental variables
Frequently Asked Questions
What is the core subject of this thesis?
This thesis examines the differences in plant diversity and functional species traits between young and historically old calcareous grasslands in the Kyffhäuser region of Thuringia, Germany.
What are the primary themes addressed?
The main themes include the impact of historical land use on vegetation, the use of multivariate statistics to detect ecological gradients, and the conservation value of different successional grassland stages.
What is the main research question?
The research investigates how habitat age and land-use history influence current species composition and associated conservation values in semi-natural grassland ecosystems.
Which scientific methods were applied?
The study employed vegetation sampling in 14 sites, laboratory soil analysis, and multivariate ordination techniques (DCA and NMDS) alongside Indicator Species Analysis (ISA).
What topics are covered in the main body?
The main body discusses study site characteristics, vegetation sampling methodologies, the statistical processing of species and environmental data, and a critical analysis of results regarding diversity and management strategies.
Which keywords define this work?
Key terms include calcareous grasslands, habitat age, biodiversity, ordination analysis, and conservation management.
How did the dry weather in 2011 affect the study?
The extended dry period caused a delay in plant growth and maturity, which necessitated a follow-up revision of the vegetation samples in August to ensure data accuracy.
What is the conclusion regarding management?
The author concludes that while old grasslands are of the highest conservation value, a holistic approach that maintains a mosaic of different successional stages is ideal for preserving the full spectrum of biodiversity.
- Citation du texte
- Alice Mercier (Auteur), 2012, Biodiversity Differences between Young and Historically Old Steppe Grasslands in Thuringia, Munich, GRIN Verlag, https://www.grin.com/document/911577
