Development of spatial heterogeneity in vegetation and soil properties after land abandonment in a semi-arid ecosystem
ABSTRACT To mitigate erosion on abandoned fields in semi-arid ecosystems, it is important to understand how vegetation and soil properties and patterns develop after land abandonment. Our objective was to investigate the development of spatial heterogeneity in vegetation and soil properties after land abandonment. We described the vegetation composition, collected soil samples and made detailed aerial photographs for two series of abandoned fields on marl and calcrete in Southeast Spain. The images were classified into bare and vegetated patches, and spatial metrics were calculated for each site. Our results showed that recovery of vegetation and change in soil properties after land abandonment are slow and take at least 40 years in such a semi-arid environment. Succession on calcrete appeared to be faster than on marl, probably because more water is available due to the higher rock fragment cover. Organic matter, aggregate stability and electrical conductivity were all significantly higher under vegetated patches. We found a clear linear relationship between vegetation cover and most spatial metrics, which offers the possibility of upscaling spotted vegetation patterns. The results of our integrated approach to study spatial heterogeneity in vegetation and soil properties can be used to improve predictions of runoff and erosion.
- SourceAvailable from: Feng-Min Li[Show abstract] [Hide abstract]
ABSTRACT: The Loess Plateau of China has suffered from soil erosion for several decades. As part of the Chinese “Grain for Green” project, legume species have been introduced to restore degraded ecosystems in this region. However, information on how environmental variables influence the recovery of vegetation after legume introduction is scarce. We characterized the composition of plant communities and different environmental variables 11 years after the introduction of the legumes Medicago sativa L. and Melilotus suaveolens L. in abandoned fields of the Loess Plateau. The objectives of this research were to evaluate how environmental factors such as duration of experiment, precipitation, soil moisture, soil nutrition, and topography affect the changes in plant species composition, richness and diversity and to identify the key factors driving plant species succession. Multivariate analyses were used to evaluate the relationships between plant communities and environmental variables. These analyses showed that plant species composition varied through time, with annual species being replaced by perennial herbaceous species gradually. The introduction of Medicago and Melilotus to abandoned fields had different effects on later-successional species and changed the successional trajectory of vegetation in the abandoned fields studied. Time since restoration was the most important factor influencing the composition of vegetation. Slope position, soil moisture content, annual precipitation, and slope/aspect were also key factors driving the composition of the plant community. Our results have implications for studies of secondary succession and the topographic and climatic impacts on vegetation change in restoration ecosystems of the semi-arid Loess Plateau, and emphasize the importance of plant–topography–climate interactions in defining the structure and composition of plant communities.Ecological Engineering 06/2015; 79. DOI:10.1016/j.ecoleng.2015.03.012 · 3.04 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Land abandonment is the dominant form of land use change in the Mediterranean over the last decades, and determines the soil organic carbon (SOC) evolution during the secondary succession following abandonment. However, the rate of succession strongly depends on climatic conditions and the extent to which these determine the SOC dynamics is largely unknown. The aim of this study is determining these dynamics along a precipitation gradient (1085-650-350 mm yr−1) on noncalcareous rocks in southern Spain. Fields abandoned in different periods, as verified on aerial photographs taken in 1956, 1977, 1984, 1998, 2001, 2004 and 2009, were selected using a chronosequence approach. SOC was determined using a spectrometer, vegetation was described, and NDVI calculated from Landsat images. SOC and NDVI evolution were analysed subsequently. In the two wettest sites SOC increased after land abandonment until it approached a plateau. Mean accumulation rates were 0.11 kg C m−2 y−1 for the wettest and 0.06 kg C m−2 y−1 for the intermediate site. These sites reached the long-term state, similar to the stocks in (semi) natural fields, in c.a. 10 years (wettest) and c.a. 35 years (intermediate). SOC and NDVI followed parallel trends, so SOC stocks were mainly driven by inputs from vegetation. At the dry end of the gradient, where NDVI’s (<0.1) were very low, the SOC stocks did not respond to changes in NDVI for the 50 year period.Agriculture Ecosystems & Environment 01/2015; 199:114–123. DOI:10.1016/j.agee.2014.08.027 · 3.20 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Abstract Two chronosequences, one south (S-sequence) and one southwest (SW-sequence) with differing times since their abandonment (193, 142, 101, 63, 39 and 14 years), were studied on Tokaj Nagy-Hill. The sites were investigated in respect of vegetation characteristics, soil physico-chemical characteristics, total organic carbon stocks (TOC stocks), accumulation rates of total organic carbon (TOC accumulation rates), and soil profiles, which were classified according to the World Reference Base (WRB) 2007. The S-sequence was 25–35% sloped and strongly eroded, and the SW-sequence was 17–25% sloped and moderately eroded. Vegetation development at the S-sequence resulted in shrub-grassland mosaics, supplemented by protected herb species and forest development at the earliest abandonment. The SW-sequence was predominantly covered by forest vegetation, and trees were absent at the 63 and 14 year old abandonment sites. Soils of the S-sequence show shallow remnants of loess cover with redeposited soil materials containing 15–65% skeletal volcanic rock of weathering products coated by secondary calcium carbonates. The SW-sequence profiles are developed on deep loess or loess derivatives. The calcium-carbonate content was higher in profiles of the S-sequence (18.1 ± 10.4%) than in the SW-sequence (6.7 ± 2.7%); consequently, the pH of the topsoil was higher in the S-sequence, and correlated significantly negatively with the age of abandonment in both sequences (r = − 0.893; p = 0.01 in S, and r = − 0.739; p = 0.05 in SW). TOC stocks of the top 6 cm soil layers were higher in the S slope (1.82 ± 0.71 kg m− 2) than in the SW-sequence (0.95 ± 0.49 kg m− 2), and correlated significantly positively with the duration of abandonment. When calculated for the whole profile, TOC stocks were similar in both S- and SW-sequences (S: 8.21 ± 3.31 kg m− 2; SW: 8.24 ± 6.01 kg m− 2). The TOC accumulation rates of the top 6 cm soil layers exhibited 18.9 ± 10.0 g C m− 2 y− 1 in the S and 7.0 ± 4.2 g C m− 2 y− 1 in the SW-sequence. Sites with the same age of abandonment showed different vegetation and soil features in both chronosequences, indicating that time is not the most decisive factor in soil transformation processes after abandonment of viticulture on Tokaj Nagy-Hill. Additional directing factors were slope steepness and exposition. Keywords: soil transformation; soil organic carbon stocks; soil organic carbon accumulation rates; terraced soils; Calcisols; CambisolsCatena 12/2014; 123:88-89. DOI:10.1016/j.catena.2014.07.017 · 2.48 Impact Factor