Browsing by Subject "Soil"

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Ecosystemic Effect Indicators to assess Effects of agricultural Landuse on Ecosystems
(2000) Merkle, Andrea Hildegard; Kaupenjohann, Martin
Agricultural production and its material and non-material emissions may cause side-effects in ecosystems. These effects have to be assessed and evaluated. The aim of the present study is to provide a tool that relates emissions of agricultural production and affected ecosystems. This tool represents an indicator approach. The needed indicators are defined as ecosystemic effect indicators (EEI). Within the study a multistage procedure is developed which should be pursued in identifying indicators. To assess which emissions must be regarded in detail an estimation of relevance by means of an emission and input classification preceeds the indicator development. Subsequently, EEI are developed for the relevant emissions and inputs. The derivation of EEI is carried out by the following steps: 1) One starts top-down at the target 'maintaining the ecosystem functioning' in this work depicted by the utility functions. A list with characteristics that are dependent on hierarchical levels is compiled for each relevant function. 2) Starting at one specific input a list of potential receptors is compiled bottom-up. These represent potential effect indicators. 3) By overlapping the lists of the steps 1 and 2 one yields EEI specific for the utility function and the input under consideration. The step 3 is performed by means of expert knowledge. The advantage of the indicator approach is its operativeness which is site-independent. The results of the study show that EEI may be deemed to be promising tools to picture human influences in particular of agricultural production on ecosystems. The results of the case study provide the basis to assess effects on ecosystems for some major stressors. In cases where critical values are available site specific quantitative statements concerning ecological effects within the frame of sustainable agriculture are enabled by the present method for the derivation of indicators. Subsequently, necessary measures can be deduced
Einfluss moderner Pflanzenschutzmittel auf die Mobilität von POP-belasteten Agrarflächen am Beispiel von DDT : ein Feldversuch
(2023) Neitsch, Julia Simone; Vetter, Walter
Due to their recalcitrance, the chloropesticide DDT and its structurally related compounds (DDX) are difficult to degrade. Consequently, farmers are still frequently confronted with DDX contamination in their fields that was left over from the 1960s. This problem is particularly prevalent in contaminated soils that are intended to cultivate plants of the Cucurbitaceae family. These plants release so-called root exudates, which function as natural surfactants that mobilize the DDX present in the soils. Furthermore, surfactants are a common constituent of modern plant protection product (PPP) formulations, which can likewise cause DDX mobilization. The higher mobility of DDX caused by these surfactants can result in the absorption and accumulation of chlorinated pesticides in plants. The side effects of such surfactant-containing PPP formulations have historically been overlooked in the context of standard spraying protocols. The potential mobilization of DDX in soils and its accumulation in Cucurbita pepo due to the surfactants present in standard PPPs formulations was investigated using two field trials. One field was treated with a conventional PPP, while the other was treated with a biological PPP; a control field was left untreated, within which pumpkins were cultivated. Soil samples were taken before and after the application of PPP. The DDX content was subsequently determined in extracts from the soil phase samples and soil water fractions. The background DDX contamination of the soils was comparable in all three test fields. The comparative evaluation showed that the field treated with the biological PPP formulation exhibited a considerable increase in DDX mobility compared to the untreated and conventionally cultivated areas (Paper 1). An analysis of its respective water fraction revealed that it was more contaminated with DDX than the control treatments. This increase suggests a higher bioavailability that can be traced back to the presence of surfactants and oils in the PPP formulations (Paper 1). This higher bioavailability may have been accompanied by an increase in the DDX uptake of the cultivated plants. Furthermore, it was found that treatment with specific formulations of emulsifiable concentrates (EC) promoted DDX mobilization. This mobilizing effect was most likely due to the differing composition of the surfactant and proportions of oils in the PPPs. The second field test focused on differential DDX accumulation in Cucurbita pepo cv. Howden by different PPPs. Fields were treated with PPP in accordance with the official spraying plans and regulations set out by the Federal Ministry of Food and Agriculture (BMEL). Samples from the pumpkin plants roots, shoots, as well as the pumpkins themselves were taken during the cultivation period. The DDX content in the roots from the control fields and the fields with conventional PPP treatments remained virtually unchanged; however, the DDX content increased in the biologically treated area (Paper 2). The pumpkin shoots did not exhibit any increases in DDX concentration during the growing phase regardless of the field sampled. However, an increased DDX content was detected in the shoots of the plants in all test fields shortly before harvesting. At the end of the growing phase, fruits from the biologically treated area showed a higher DDX content than those from the control and conventionally treated areas. In addition, the most critical DDT metabolite, DDE, was found to have been transported to distant parts of the plant, while DDD was detectable in the roots and shoots but not in the fruits of the pumpkins (Paper 2). An assessment of the results of both experiments confirmed a direct correlation between DDX mobilization in the soil and plant uptake. In addition, the bioaccumulation factors of the biologically treated areas were markedly higher than those seen in the conventionally treated and control areas. The results of the field trials show that the mobilization of DDT, as well as the likely mobilization of other lipophilic contaminants, can become problematic for farmers using surfactant-containing EC formulations. However, this observation also provides opportunities for improved phytoremediation by applying EC formulations with high mobilization potentials. The field trials indicate that the mobilizing effects of DDT prompted by EC mixtures depend on the surfactant content in the PPP formulations as well as environmental conditions such as soil conditions, soil water content, and precipitation. Unravelling the optimal range of surfactant-rich formulations and environmental conditions could lead to a promising strategy for soil phytoremediation.
Soil (chrono-) sequences on marine terraces : pedogenesis in two coastal areas of Basilicata and Agrigent, Southern Italy
(2009) Wagner, Stephen; Stahr, Karl
This work contributes to the understanding of the Quaternary history in Mediterranean landscapes in Southern Italy. The time frame of soil formation processes was therefore investigated on two sequences of marine terraces. A central question of this study was whether soil formation reflects progressive terrace ages. Chronofunctions were used to apply relative indices of soil development in different pedostratigraphic levels. The newly developed indices generally show incessant weathering on continuously older terraces and therefore true soil chronosequences. A few terraces may however once have formed a single terrace body which was later separated and uplifted by tectonic activity.
Towards regionalisation of soils in Northern Thailand and consequences for mapping approaches and upscaling procedures
(2008) Schuler, Ulrich
The purpose of this study was to identify the key factors of soil formation and distribution in North-western Thailand in order to enable predictive mapping. Further objectives were to investigate different soil mapping approaches, regarding their suitability for specific areas and scales and to assess the potential of local (soil) knowledge for soil mapping and land use planning. In order to cover the essential petrographic inventory of North-western Thailand three different petrographic areas were selected. The investigated topics were petrographic diversity, spatial organisation of soils and variability of their physical and chemical properties, as well as local soil knowledge of farmers in the respective areas. In addition thematic maps were generated comprising geology, WRB soil groups, and different soil properties. Soil mapping was carried out by using four different methods, the intensive mapping approach, maximum likelihood method, randomised grid cell approach, as well as elicitation of local knowledge. The intensive mapping approach comprised transect investigations, investigation points of the randomised grid cell approach, and additional investigation points, which were selected for areas with increased soil and petrographic variability. All maps based on the intensive mapping approach contained the highest sampling point density and maximum amount of information. These maps were used as a reference for the other mapping approaches applied here.
Tree growth and tree regeneration in two East African rain forests as related to the abiotic environment after human disturbance
(2010) Gliniars, Robert; Küppers, Manfred
This study deals with the stem growth and seedling regeneration of different native tree species in two East African rainforests influenced by human disturbance in Kenya (Kakamega Forest) and Uganda (Budongo Forest), also considering spatially and temporally variable environmental influences. In the lower montane rainforest (1500 to 1700 m a.s.l.) Kakamega Forest (KF) surveys were conducted on trees ≥ 5 cm diameter at breast height (DBH) on an overall area of 2.08 ha (1 ha plot and 27 plots x 400 m2, 2007 individuals, equalling 965 ha-1), 3 inventories in 7 years). At the same time 91 tree species from 39 families were identified. In addition, in subplots within the permanent plots, 8441 saplings and seedlings ≤ 5m DBH distributed among 59 tree species from 29 families were recorded (on 432 m2, over 6 years). In the lowland rainforest (1000 to 1100 m a.s.l.) Budongo Forest (BF) a total of 1010 trees (1403 ha-1), distributed among 91 tree species from 30 families, were recorded in surveys on an overall area of 0.72 ha (18 plots à 400 m2, 2 inventories in 5 years). During the observation period saplings and seedlings (on 72 m2, 708 individuals, in 3 years) belonging to 38 tree species from 18 families were recorded. The study areas were situated in forest areas characterised by different successional stages. These stages have emerged as a result of differing degrees of human disturbance for commercial purposes in the recent past. As this research was part of a joint project, highly resolved data on factors such as soil values, climate values, canopy characteristics and disturbance indices e.g. the Commercial Disturbance Index (CDI) was also available for a few permanent plots. It was established that the level of species richness and species diversity is low in areas with either no or very high levels of past commercial human disturbance (e.g. after clear-cutting), whereas areas with intermediate disturbance were seen to be richer or more diverse in species. The distribution of β-diversity also indicated a disturbance gradient. The degree of human disturbance was as well reflected in the successional stages within the structure of the forest areas. The mean stem volume of trees in BF increased as the disturbance index decreased, in KF however the highest stem volume occurred in areas with intermediate CDI. The tree populations in areas with a low level of disturbance in BF were characterised by high volumes together with lower stem numbers per plot and were more stable, as manifested in the lower turnover. The openness of the canopy varied in the differently disturbed areas and had a positive effect on seedling density in BF, which in turn underlines the importance of light for the regeneration of seedlings. In order to test the regeneration capacity of individual tree species for the most part in the intermediate stages of succession in both forests, the stem increment of 1198 trees (≥ 10 cm DBH) was measured monthly using dendrometer bands. At the same time the phenology of leaves, flowers and fruits of these trees was monitored over a period of three (in BF) and five years (in KF). In addition regeneration and establishment dynamics were analysed by counting, identifying and measuring seedlings (≤ 100 cm high) in the subplots every three months. The tree species could then be classified and allotted to their position along the pioneer-climax continuum. The early successional pioneer species were characterised by rapid growth and higher mortality rates, had no to few seedlings in the understorey and were shade intolerant. The late successional climax species however grew more slowly, had a low mortality rate, were well-established as seedlings in the understorey and shade tolerant. Most species possessed either characteristics somewhere in between these extremes or both characteristics of early and late successional species and were thus classified as intermediate. The annual stem increment varied considerably between tree species ranging from 0.6 to 2.5 mm in BF and from 0.6 to 4.4 mm in KF, and the relative diameter growth ranged from 0.3 to 1% in BF and from 0.25 to 1.58% in KF. The variability in the growth rates within tree species was even higher than that between species. Moreover the annual variability in growth within a species was higher in thinner than in thicker individuals. Individual trees however grew at a relatively constant rate. Beside the inherent growth potential, monthly changes in the climatic conditions also had an influence on the growth pattern of many of the tree species in KF and on all of the species in the more strongly seasonal BF. During the warm dry season the growth rate decreased and then increased again when the rainy season set in. This was confirmed by positive correlations between monthly growth rates and the sum of rainfall over two or three months respectively and also by strongly negative correlations between monthly growth and maximum temperature. The intensity of these relations varied according to species. The phenological features of most species were also dependent on the climate, e.g. leaf shedding or flowering in the dry season and fruiting in the rainy season. Seedling dynamics showed a tendency towards an increase in the populations in the rainy season and a decrease in the dry season depending on the species. The distribution of the tree parameters was not as clearly related to the spatial distribution of soil parameters. There were a few correlations between tree diversity and soil parameters in KF, positive correlations with acid-extracted Ca, C and N and negative with electrical conductivity. Furthermore significant correlations were established in KF between tree growth and Ca, C and N, as well as negative ones with Mn and Mg in the soil, whereby the intensity of the relationship was species specific. Seedling diversity also correlated positively with Ca, C and N, as well as negatively with Mn. The distribution and density of the seedlings was however more highly dependent on recurring pulses of newly recruited individuals at irregular intervals than on the abiotic environment. The study provides a first, precise insight into ecological regeneration processes of tree species populations and forest communities after human disturbance that have for the most part not yet been the subject of investigation, and can serve as a basis for forest management and forest models.
Untersuchungen zur Abundanz der Reblaus (Dactylosphaera vitifolii Shimer) und zur Nodositätenbildung in Abhängigkeit von Umweltfaktoren
(2000) Kopf, Andreas; Blaich, Rolf
The aim of the examinations was to investigate the abundance of Phylloxera (Dactylosphaera vitifolii Shimer), the occurrence of different biotypes of Phylloxera, the reaction of rootstocks to the infestation by Phylloxera and the influence of abiotic environmental conditions on the interaction between insect and plant. To investigate this interaction galls on rootlets (nodosities) and leaf galls were examined. The abundance of Phylloxera and the issue of the holocyclical reproduction in the wine region palatinate were evaluated in a field monitoring. In a special field trial the occurrence of different stages of Phylloxera and their damages on the rootstock were registered. With a dual aseptical in vitro system Phylloxera of different origins were examined on their aggressiveness to different varieties of rootstocks. In pot trials the influence of the type of soil and the effect of N-fertilization on the development of nodosities were investigated. The results of the examination show that Phylloxera can be found in nearly every part of the palatinate and that the improper cultivation of grafted rootstocks promotes the spreading of Phylloxera. Through shoots of rootstocks ? as they can be found in vineyards run wild - a holocyclical development of Phylloxera is made possible under appropriate climatical circumstances. Fitness, population dynamics of Phylloxera and the number of nodosities caused by the insects are correlating with their adaptation to a host rootstock. Pot studies have demonstrated that Phylloxera populations develop better in clay soil than sandy soil. High densities of Phylloxera in combination with a lack of N-supply increase a growth depression on grafted roots. It could also be proved that N-fertilization reduces the Phylloxera populations and the development of nodosities up to 98 %.