Das Ziel der Arbeit war die Untersuchung der Kohlenstoff- und Stickstoffdynamik in Waldböden unter dem Einfluß atmogener Stickstoffeinträge. Dabei wurden biotische und abiotische Schlüsselprozesse zweier unterschiedlich stark stickstoffbelasteter Waldböden des Nordwest- und Nordostdeutschen Tieflandes (Kreinitz und Thülsfeld) analysiert und miteinander verglichen. Um detaillierte Informationen über potentielle Kohlenstoff- und Stickstoffumsätze zu erhalten, wurden die untersuchten Böden sowohl horizont- als auch tiefenstufenbezogen stratifiziert. Über einen Zeitraum von 14 Wochen wurden sämtliche Kohlenstoff- und Stickstoffeinträge sowie -austräge zwischen den einzelnen Tiefenstufen beobachtet und analysiert. Nach Beendigung der Versuche wurden die einzelnen Bodenhorizonte mit spezifischen Kohlenstoff- und Stickstoffextraktionsverfahren aufgeschlossen. Mit Hilfe dieser Versuchsanordnung war es möglich, eine vollständige tiefenstufenbezogene Kohlenstoff- und Stickstoffbilanzierung für den Kreinitzer und Thülsfelder Boden zu erstellen. Zur Prüfung der Übertragbarkeit der Laborergebnisse auf aktuelle Standortbedingungen wurde ein Langzeitfeldversuch (ein Jahr) mit einer ähnlichen Versuchsanordnung am Standort Kreinitz durchgeführt. Folgende Ergebnisse wurden in dieser Arbeit erzielt: 1. Der TOC-Gehalt war der Hauptparameter, in dem sich der stark stickstoffbelastete Standort Thülsfeld von dem weniger stark stickstoffbelasteten Standort Kreinitz zu Beginn der Untersuchung deutlich unterschied. 2. Der KCl-extrahierbare mineralische Stickstoff (NminKCl) reagierte an beiden Versuchs-standorten am stärksten auf die Stickstoffdüngung und wurde mit Hilfe der Diskriminanzanalyse als Hauptsensitivitätsparameter für Stickstoffeinträge im Boden ermittelt. 3. Die Kreinitzer organische Auflage reagierte in bezug auf die mittelfristig umsetzbare Kohlenstoff- und Stickstofffraktion (Chwe, Nhwe) deutlich stärker auf die N-Einträge als die Thülsfelder Auflage. Infolgedessen besitzt die Kreinitzer Auflage ein höheres Kohlenstoff- und Stickstoffmobilisierungspotential, die hochkomplexen organischen C- und N-Verbindungen in weniger komplexe Verbindungen abzubauen. 4. Der Thülsfelder Mineralboden 5. besitzt aufgrund der höheren Anteile des Nhwe am TN ein höheres Mobilisierungspotential für den kurz- und mittelfristig umsetzbaren Stickstoff (Nhwe) als der Kreinitzer Mineralboden. 6. Die für die Mikroorganismen verfügbaren Kohlenstoffquellen scheinen sich durch die historischen und die zusätzlich simulierten Stickstoffeinträge vom POC in der Sand-Braunerde zum WSOC und CKCl im Sand-Podsol zu verschieben. 7. Als verfügbare Stickstoffquelle nutzen die Mikroorganismen am Standort Kreinitz den PN, während sich für den Standort Thülsfeld keine eindeutige Stickstofffraktion als Hauptnahrungsquelle ermitteln ließ. 8. Sowohl in den Laborversuchen als auch im Freilandversuch führten die Stickstoffeinträge zur Verengung nahezu aller C/N-Verhältnisse in den untersuchten Extraktionsverfahren.

Thesis (MSc(For))--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Recognizing the biological significance of gaps, the South African Department of Water Affairs and Forestry (DWAF) in 1989 initiated a Gap Dynamics Project in the indigenous forests of Tsitsikamma (Eastern Cape, South Africa). This consists of three sub-projects: Koomansbos (9300 m2), created by a ground fire in 1989; Plaatbos (1600 m2), made by a Podocarpus falcatus (Thunb.) R. Br. ex Mirb. (Podocarpaceae) windfall in 1994; and nine gaps of different sizes, artificially created by selective tree felling in 1995: three small (100-150 m2), three medium (300-500 m2) and three large (800-1000 m2). All the gaps were surveyed after creation and permanent plots were established for subsequent monitoring. The current timber harvesting system practiced in South African indigenous forests attempts to minimize gap size. It has been proposed by Euston-Brown et al. (1996) that this practice is likely to benefit the more shade tolerant species, but may inhibit the regeneration of less shade tolerant plants in the forest. Therefore, the present study aimed to verify two hypotheses: gaps may close in a process that is determined by their size, their origin and the plant species characteristics; soil quality might change inside those gaps. For the purpose of the study, the gaps cited above were re-surveyed between 2002 and 2003. It was found that: 1) there was little clear difference in the community structure of plant species between gaps of different sizes and origins; as expected from the species-area relationship, large gaps had higher species richness, plant diversity and herbaceous percentage cover than medium and small gaps; diversity indices were higher in the large windfall gap than in the large fire and artificial gaps; generally, context and stochastic events were largely more important in determining gap diversity and regeneration than gap sizes and origins; 2) diversity indices in the gaps were higher than recorded previously; 3) soil pH and Electrical Conductivity were respectively lower and higher inside the gaps than adjacent to them; these variations were statistically significant. Present data on the vegetation in the gaps were compared to past measurements, and future vegetation structure has been predicted, as a function of current gap vegetation. Recommendations have been made for sustainable management of the indigenous forest of Tsitsikamma. / AFRIKAANSE OPSOMMING: Voortspruitend uit die erkenning van die biologiese belang van gapings, het die Suid-Afrikaanse Departement van Waterwese en Bosbou (DWB) in 1989 'n projek oor gapingsdinamika in die inheemse woude van Tsitsikamma (Oos-Kaap, Suid-Afrika) geïnisieer. Dit bestaan uit drie subprojekte: die gaping in Koomansbos (9300 m2) wat in 1989 deur 'n grondvuur geskep is; die gaping in Plaatbos (1600 m2) wat veroorsaak is toe bome van die spesie Podocarpus falcatus (Thunb.) R. Br. ex Mirb. (Podocarpaceae) in 1994 omgewaai is; en nege gapings van verskillende groottes wat in 1995 kunsmatig deur geselekteerde boomkappery geskep is: drie is klein (100-150 m2), drie mediumgrootte (300-500 m2) en drie groot (800-1000 m2). Alle gapings is ná hulle ontstaan opgemeet en ondersoek en permanente terreine is vir daaropvolgende monitering gevestig. Die stelsel wat tans vir die oes van hout in Suid-Afrikaanse inheemse woude gebruik word, poog om die grootte van gapings te minimaliseer. Euston Brown et al. (1996) doen aan die hand dat hierdie praktyk spesies wat meer skaduweeverdraagsaam is waarskynlik sal bevoordeel, maar die regenerasie van plante in die woud wat minder skaduweeverdraagsaam is, kan inhibeer. Hierdie studie het dus ten doel gehad om twee hipoteses te verifieer: Gapings kan toegroei in 'n proses wat deur hul grootte, oorsprong en die eienskappe van die plantspesies bepaal word; en die gehalte van die grond binne daardie gapings kan verander. Die gapings waarna hierbo verwys is, is vir die doel van hierdie studie tussen 2002 en 2003 weer gemonitor. Daar is bevind dat: 1) daar min duidelike verskille was tussen die gemeenskapstruktuur van plantspesies tussen gapings van verskillende groottes en oorsprong; soos van die verhouding tussen spesies en area verwag kan word, het groter gapings 'n hoër spesierykheid, plantdiversiteit en persentasie niehoutagtige dekking as medium- en klein gapings gehad; diversiteitsindekse was hoër in die groot Plaatbosgaping as in die groot Koomansbosgaping of die kunsmatige gapings; in die algemeen was konteks en stochastiese gebeure grootliks belangriker in die bepaling van gapingsdiversiteit en -regenerasie as gapingsgrootte of -oorsprong; 2) diversiteitsindekse in die gapings was hoër as wat voorheen aangeteken is; en 3) grond-pH en elektriese geleidingsvermoë was onderskeidelik laer en hoër binne die gapings as neffens hulle; hierdie variasies was statisties beduidend. Huidige data oor die plantegroei in die gapings is met vorige metings vergelyk, en 'n toekomstige plantegroeistruktuur is as 'n funksie van huidige gapingsplantegroei voorspel. Aanbevelings is gemaak rakende die volhoubare bestuur van Tsitsikamma se inheemse woud.

The link between aboveground net primary productivity (ANPP) and resource gradients generated by complex terrain (solar radiation, nutrients, and moisture) has been established in the literature. Belowground ecosystem stocks and functions, such as soil organic carbon (SOC), dissolved organic carbon (DOC), and belowground productivity have also been related to the same topography and resource distributions, and therefore it is expected that they share spatial and temporal patterns with ANPP. However, stand structure on complex terrain is a function of multiple trajectories of forest development that interact with existing resource gradients, creating feedbacks that complicate the relationships between resource availability and ANPP. On a 96 ha forested watershed in the H.J. Andrews Experimental Forest in the Western Cascades range of Oregon, spatiotemporal heterogeneity in the secondary succession of a replanted Pseudotsuga menziesii stand following harvest results from the interaction of stand composition and abiotic drivers and may create unique "hot spots" and "hot moments" that complicate gradient relationships. In this dissertation, I tested the hypotheses that (chapter 3) multiple successional trajectories exist and can be predicted from a general linear model using specific topographic, historical, and biological parameters and that an estimated "maximum ANPP" may better represent stand characteristics than ANPP measured at a particular moment in time. I also test that (chapter 4) the distribution of light fraction carbon (LFC; C with a density of less than 1.85 g/cm��) is spatially variable, elevated on hardwood-initiated sites (hardwood biomass > 50% of biomass), and positively correlated with litter fall and ANPP. Chapter 4 also tests that heavy fraction carbon (HFC; C with a density of greater than 1.85 g/cm��) is a function of both soil mineralogy, stand composition, and ANPP, such that edges observed spatially in site mineralogy (changes in soil type) are reflected in sharp changes in the composition of the forest community and the magnitude of HFC stores. Finally, I hypothesized (chapter 5) that in complex terrain, dissolved organic carbon (DOC) export can be predicted from landform characteristics, relates to ANPP, and may be measured by several methods which are well-correlated with one another. In chapter 6, I discuss how litter fall measurements can be extrapolated to a watershed extent, and use litter fall as an example of the error that can occur in scaling up measurements taken at a small scale, within a heterogeneous stand on complex terrain, to a landscape scale extent. / Graduation date: 2013

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.

In North America, the acceleration of the eutrophication of surface waters due to nutrient pollution is still present. Soil studies have not entirely succeeded in linking nutrient and sediment losses to field hydrology because relationships between discharge and dissolved ions/sediments are complicated by a hysteresis effect which has been only described qualitatively. The objective of this thesis was to better understand the effects of hydrology on N, P, and sediment transfer from agricultural and forest soils to surface waters. This was done by developing a technique, called the H index, to quantify the hysteretic behaviour of ion and sediment transport in stream/overland water. The chemical and sediment concentrations in a stream of a forested watershed in the Sierra Nevada during snowmelt and in overland runoff of two agricultural fields during rain events in the Montreal area were examined. In the stream of the forested watershed, H indices for suspended sediment increased (looser hysteresis loop) with the availability of sediments and the lag between peaks in suspended sediment concentrations and discharge. In agricultural fields, nutrient concentrations increased with time during each event with presence of counterclockwise and clockwise hysteresis. The hysteretic behaviour of suspended sediments was not significantly related with either prior soil moisture content or rainfall characteristics. In order to simultaneously monitor P and N in the stream and soils of the forested watershed, a laboratory study was conducted to investigate the efficacy of various mixedbed exchange resins in absorbing dissolved organic and inorganic N and P. Results showed that mixed-bed resin was adequate for characterizing P on a short-time scale but longer exposure periods were required for N. Results from the resin exchange reveal the possibility that the spring time pulse of NOs'-N in stream water was due to the melting of the snowpack.

The increased demand for wood and fiber from a continually shrinking land base has resulted in the use of intensively managed forest plantations. The concentration of timber production on the most suitable sites allows the world's demand for forest products to be met on less land and enable native forests to be conserved. Because much of the water flowing in rivers in the U.S. originates as precipitation in forests, there is a justified concern about the impacts of forest management on water quality. Nutrient concentrations were measured in eight streams from October 2002 to September 2011 to assess nutrient response to contemporary forest practices at the Hinkle Creek Paired Watershed Study in the Oregon Cascades. This period of time included a two-year pre-treatment calibration between control and treatment watersheds, a fertilization treatment of both basins in October 2004, and a post-treatment period from 2005 to 2011. A treatment schedule comprised of two temporally explicit harvest entries was used to assess the effects of clearcutting at the non-fish-bearing headwater scale and the fish-bearing watershed scale. Stream water samples were analyzed for nitrogen, phosphorus, calcium, sodium, potassium, magnesium, sulfate, chloride, and silicon as well as specific conductance, pH, and alkalinity. Programmable water samplers were used to take water samples during fall freshets in November 2009 to assess the stream water discharge versus NO₃ + NO₂ concentration relationship. All treatment watersheds showed a statistically significant increase in NO₃ + NO₂ concentrations after clearcutting (p < 0.001). The slope of the streambed through the disturbance was a stronger predictor of the magnitude of the response than was the magnitude of disturbance. Ammonia and organic nitrogen displayed notable increases after harvest treatment, but these increases were attributed to increases in the control watersheds. Phosphorus showed a response to timber harvest in one headwater stream. The remaining nutrients showed a small decrease in the control and treatment watersheds for the period after harvest. There was some evidence to suggest that the addition of urea nitrogen to both basins may have caused an increase in in-stream biota uptake of these nutrients. The storm response results showed that NO₃ + NO₂ concentrations in stream water increase with discharge during small storms that occur after periods of negligible precipitation. Concentrations of NO₃ + NO₂ observed during the calibration period were similar to concentrations observed in an old-growth forest in the H.J. Andrews, suggesting that nutrient processing within the Hinkle Creek watershed had returned to levels that existed prior to its initial harvest sixty years ago. This finding helps to assess long-term impacts of shorter rotation timber harvest of regenerated Douglas-fir stands characteristic of industrialized timber harvest in Oregon. / Graduation date: 2012

Saltwater Forest is a Dacrydium cupressinum-dominated lowland forest covering 9000 ha in south Westland, South Island, New Zealand. Four thousand hectares is managed for sustainable production of indigenous timber. The aim of this study was to provide an integrated analysis of soils, soil-landform relationships, and soil-vegetation relationships at broad and detailed scales. The broad scale understandings provide a framework in which existing or future studies can be placed and the detailed studies elucidate sources of soil and forest variability. Glacial landforms dominate. They include late Pleistocene lateral, terminal and ablation moraines, and outwash aggradation and degradation terraces. Deposits and landforms from six glacial advances have been recognised ranging from latest Last (Otira) Glaciation to Penultimate (Waimea) Glaciation. The absolute ages of landforms were established by analysis of the thickness and soil stratigraphy of loess coverbeds, augmented with radiocarbon dating and phytolith and pollen analysis. In the prevailing high rainfall of Westland soil formation is rapid. The rate of loess accretion in Saltwater Forest (ca. 30 mm ka⁻¹) has been low enough that soil formation and loess accretion took place contemporaneously. Soils formed in this manner are known as upbuilding soils. The significant difference between upbuilding pedogenesis and pedogenesis in a topdown sense into an existing sediment body is that each subsoil increment of an upbuilding soil has experienced processes of all horizons above. In Saltwater Forest subsoils of upbuilding soils are strongly altered because they have experienced the extremely acid environment of the soil surface at some earlier time. Some soil chronosequence studies in Westland have included upbuilding soils formed in loess as the older members of the sequence. Rates and types of processes inferred from these soils should be reviewed because upbuilding is a different pedogenic pathway to topdown pedogenesis. Landform age and morphology were used as a primary stratification for a study of the soil pattern and nature of soil variability in the 4000 ha production area of Saltwater Forest. The age of landforms (> 14 ka) and rapid soil formation mean that soils are uniformly strongly weathered and leached. Soils include Humic Organic Soils, Perch-gley Podzols, Acid Gley Soils, Allophanic Brown Soils, and Orthic or Pan Podzols. The major influence on the nature of soils is site hydrology which is determined by macroscale features of landforms (slope, relief, drainage density), mesoscale effects related to position on landforms, and microscale influences determined by microtopography and individual tree effects. Much of the soil variability arises at microscales so that it is not possible to map areas of uniform soils at practical map scales. The distribution of soil variability across spatial scales, in relation to the intensity of forest management, dictates that it is most appropriate to map soil complexes with boundaries coinciding with landforms. Disturbance of canopy trees is an important agent in forest dynamics. The frequency of forest disturbance in the production area of Saltwater Forest varies in a systematic way among landforms in accord with changes in abundance of different soils. The frequency of forest turnover is highest on landforms with the greatest abundance of extremely poorly-drained Organic Soils. As the abundance of better-drained soils increases the frequency of forest turnover declines. Changes in turnover frequency are reflected in the mean size and density of canopy trees (Dacrydium cupressinum) among landforms. Terrace and ablation moraine landforms with the greatest abundance of extremely poorly-drained soils have on average the smallest trees growing most densely. The steep lateral moraines, characterised by well drained soils, have fewer, larger trees. The changes manifested at the landform scale are an integration of processes operating over much shorter range as a result of short-range soil variability. The systematic changes in forest structure and turnover frequency among landforms and soils have important implications for sustainable forest management.

Saltwater Forest is a Dacrydium cupressinum-dominated lowland forest covering 9000 ha in south Westland, South Island, New Zealand. Four thousand hectares is managed for sustainable production of indigenous timber. The aim of this study was to provide an integrated analysis of soils, soil-landform relationships, and soil-vegetation relationships at broad and detailed scales. The broad scale understandings provide a framework in which existing or future studies can be placed and the detailed studies elucidate sources of soil and forest variability. Glacial landforms dominate. They include late Pleistocene lateral, terminal and ablation moraines, and outwash aggradation and degradation terraces. Deposits and landforms from six glacial advances have been recognised ranging from latest Last (Otira) Glaciation to Penultimate (Waimea) Glaciation. The absolute ages of landforms were established by analysis of the thickness and soil stratigraphy of loess coverbeds, augmented with radiocarbon dating and phytolith and pollen analysis. In the prevailing high rainfall of Westland soil formation is rapid. The rate of loess accretion in Saltwater Forest (ca. 30 mm ka⁻¹) has been low enough that soil formation and loess accretion took place contemporaneously. Soils formed in this manner are known as upbuilding soils. The significant difference between upbuilding pedogenesis and pedogenesis in a topdown sense into an existing sediment body is that each subsoil increment of an upbuilding soil has experienced processes of all horizons above. In Saltwater Forest subsoils of upbuilding soils are strongly altered because they have experienced the extremely acid environment of the soil surface at some earlier time. Some soil chronosequence studies in Westland have included upbuilding soils formed in loess as the older members of the sequence. Rates and types of processes inferred from these soils should be reviewed because upbuilding is a different pedogenic pathway to topdown pedogenesis. Landform age and morphology were used as a primary stratification for a study of the soil pattern and nature of soil variability in the 4000 ha production area of Saltwater Forest. The age of landforms (> 14 ka) and rapid soil formation mean that soils are uniformly strongly weathered and leached. Soils include Humic Organic Soils, Perch-gley Podzols, Acid Gley Soils, Allophanic Brown Soils, and Orthic or Pan Podzols. The major influence on the nature of soils is site hydrology which is determined by macroscale features of landforms (slope, relief, drainage density), mesoscale effects related to position on landforms, and microscale influences determined by microtopography and individual tree effects. Much of the soil variability arises at microscales so that it is not possible to map areas of uniform soils at practical map scales. The distribution of soil variability across spatial scales, in relation to the intensity of forest management, dictates that it is most appropriate to map soil complexes with boundaries coinciding with landforms. Disturbance of canopy trees is an important agent in forest dynamics. The frequency of forest disturbance in the production area of Saltwater Forest varies in a systematic way among landforms in accord with changes in abundance of different soils. The frequency of forest turnover is highest on landforms with the greatest abundance of extremely poorly-drained Organic Soils. As the abundance of better-drained soils increases the frequency of forest turnover declines. Changes in turnover frequency are reflected in the mean size and density of canopy trees (Dacrydium cupressinum) among landforms. Terrace and ablation moraine landforms with the greatest abundance of extremely poorly-drained soils have on average the smallest trees growing most densely. The steep lateral moraines, characterised by well drained soils, have fewer, larger trees. The changes manifested at the landform scale are an integration of processes operating over much shorter range as a result of short-range soil variability. The systematic changes in forest structure and turnover frequency among landforms and soils have important implications for sustainable forest management.

No description available.