Showing papers by "Ernst Detlef Schulze published in 1989"

Air Pollution and Forest Decline in a Spruce (Picea abies) Forest

Abstract: Symptoms of forest decline of spruce in Europe range from needle yellowing and loss to tree and stand mortality. In a study area in northeast Bavaria, West Germany, where forest decline was initially detected, exposure to high concentrations of gaseous pollutants, SO2, NOx, and ozone has had no long-lasting direct effect on needles, and pathogens have only been secondary agents. Deposition of sulfur, nitrate, and ammonium, however, have significantly modified plant nutrition and soil chemistry. Spruce roots apparently take up ammonium rather than nitrate with an antagonistic effect on uptake of Mg. Nitrate left in the soil solution is leached together with sulfate to ground water, accelerating soil acidification and decreasing Ca/Al and Mg/Al ratios in the soil solution. Soil solution chemistry affects root development, and water and nutrient uptake. Had all nutrients become equally deficient, spruce trees probably could have adjusted by retarding their growth. However, canopy uptake of atmospheric nitrogen in addition to root uptake stimulated growth and caused a nitrogen to cation imbalance to develop; this imbalance resulted in the decline symptoms.

Critical loads for nitrogen deposition on forest ecosystems

Abstract: Critical loads for N deposition are derived from an ecosystem's anion and cation balance assuming that the processes determining ecosystem stability are soil acidification and nitrate leaching. Depending on the deposition of S, the parent soil material, and the site quality critical N deposition rates will range between 20 to 200 mmol m−2 yr−1 (3 to 14 kg ha−1 yr−1) on silicate soils and reach 20 to 390 mmol m−2 yr−1 (3 to 48 kg ha−1) on calcareous soils.

Forest decline and air pollution: a study of spruce (Picea abies) on acid soils.

Abstract: During the last decade, forest decline has become increasingly apparent. The decline in forest health was often reported to be associated with air pollution. The present study on Norway spruce stands in the Fichtelgebirge analyses various processes interacting within forest ecosystems. It covers transport and deposition of air pollutants, the direct effects of pollutants on above-ground plant parts, the responses of soil to acid rain, and the changing nutrient availability, and the accompanying effects on plant metabolism and growth. The role of fungi, microorganisms and soil animals in the decline of these stands is also assessed. The volume is concluded with a synthesis evaluation of the influence of different factors, and their interactions on forest decline.

Uptake of water and solutes through twigs of Picea abies (L.) Karst

Abstract: Uptake of water and magnesium chloride solution was investigated through the outer surface of twigs of Picea abies (L.) Karst. Water uptake was determined by using pressure/volume (P/V) curves of the twigs as a basis for calculation to avoid problems of superficial extraneous water. When water was sprayed on bark and needles of 3- to 7-year-old twigs at a xylem water potential of -1.00 MPa, they absorbed as much as 80 mm3 water in 200 min/g twig dry weight as the twig water potential recovered to -0.15 MPa. With fluorescent dyes, pathways for absorption of water and solutes through the twig bark were found, particularly through the radially orientated ray tissue. In addition to uptake by mass flow, magnesium could also diffuse along a concentration gradient from the twig surface into the xylem. In the field, the magnitude of these uptake processes would depend on the concentration of elements deposited by atmospheric precipitation, the concentration gradient between the plant surface and the xylem sap, the xylem water potential and the intensity and duration of each precipitation event.

Atmospheric Pollutants and Plant Metabolism

Abstract: Large amounts of sulfur dioxide (SO2) and nitrogen oxides (NOx) are continuously released into the atmosphere. When they react with water, these gases can form sulfurous acid (H2SO3), nitrous acid (HNO2) and nitric acid (HNO3). The weak acids are easily oxidized to the strong acids sulfuric acid and nitric acid. Photodissociation of nitrogen dioxide (NO2) in the atmosphere produces oxygen radicals which give rise to the formation of ozone (O3).

Nutritional Disharmony and Forest Decline: A Conceptual Model

Abstract: A base cation deficiency has been implicated in the decline of European forests (Abrahamsen 1980; Ulrich 1983; Franz 1983; Zech and Popp 1983; Tomlinson 1985; Hauhs and Wright 1986; Rehfuess 1987; Cape et al. 1988). However, it is puzzling to find that a tree, dying from a lack of a cation such as Mg at one site, may have more of that cation than a healthy tree at another site (see Bosch et al. 1983). Plant nutrition studies have revealed that for maximum growth to occur, requisite elements must be supplied to trees in a certain ratio which differs between species (Mulder 1956; Ingestad 1959, 1979a,b; see review by Powers 1984). The harmony in the supply of elements to trees, or in the uptake by trees, is the core of the following conceptual model of forest decline.

Cell water potential, osmotic potential, and turgor in the epidermis and mesophyll of transpiring leaves : Combined measurements with the cell pressure probe and nanoliter osmometer.

Abstract: Water potential, osmotic potential and turgor measurements obtained by using a cell pressure probe together with a nanoliter osmometer were compared with measurements obtained with an isopiestic psychrometer. Both types of measurements were conducted in the mature region of Tradescantia virginiana L. leaves under non-transpiring conditions in the dark, and gave similar values of all potentials. This finding indicates that the pressure probe and the osmometer provide accurate measurements of turgor, osmotic potentials and water potentials. Because the pressure probe does not require long equilibration times and can measure turgor of single cells in intact plants, the pressure probe together with the osmometer was used to determine in-situ cell water potentials, osmotic potentials and turgor of epidermal and mesophyll cells of transpiring leaves as functions of stomatal aperture and xylem water potential. When the xylem water potential was-0.1 MPa, the stomatal aperture was at its maximum, but turgor of both epidermal and mesophyll cells was relatively low. As the xylem water potential decreased, the stomatal aperture became gradually smaller, whereas turgor of both epidermal and mesophyll cells first increased and afterward decreased. Water potentials of the mesophyll cells were always lower than those of the epidermal cells. These findings indicate that evaporation of water is mainly occurring from mesophyll cells and that peristomatal transpiration could be less important than it has been proposed previously, although peristomatal transpiration may be directly related to regulation of turgor in the guard cells.

Processes leading to forest decline: A synthesis

Abstract: Recent forest decline in Central Europe has been manifested by a combination of symptoms, especially needle-yellowing and loss, and reduced stand growth. Needle damage first became apparent in the late 1970’s on Norway spruce [Picea abies (L.) Karst.], the dominant coniferous tree species planted today. Decline was observed in the early 1980’s over a large forest area on several major forest species. It was the large geographic distribution of visible change in conifers and in broadleaf species, as well as the large number of opposing hypotheses on possible causes, which led to the present case study. In the mountain range of the Fichtelgebirge, most of the forests at elevations above 750 m currently display different degrees of visual decline symptoms, although some forests at lower elevations have partially recovered. At 900–1000 m elevation, a stand which 10 years earlier first displayed visual symptoms is now totally dead. In this book we analyze possible pathways which have led to the decline of forests in this area and which may explain the observed temporal symptomatic variations.

Leaching and Uptake of Ions Through Above-Ground Norway Spruce Tree Parts

Abstract: Increasing air pollution in Central Europe during the last century has resulted in a substantial input of inorganic ions into the forest ecosystem. Deposition mainly occurs through snow and rainfall, fog and cloudwater impaction, dry deposition of particles, and upon solution of acidic gases in the water films of wet surfaces, e.g., after dewfall (see Part 1).

Nutrient Relations of Trees in Healthy and Declining Norway Spruce Stands

Abstract: The effects of nutrient relations on tree vigor become complex under conditions of acid rain. The visible symptoms of needle-yellowing has been associated with magnesium deficiencies on silicate soils, potassium deficiencies on limestone, and manganese deficiencies on dolomite (Abrahamson 1980; Hauhs and Wright 1986; Forschungsbeirat Waldschaden 1986). In order to balance nutrition, plants should respond to a low supply of a single element by reducing growth (Ingestad 1982; Schulze and Chapin 1987). It is not yet understood which processes lead a single element deficiency to being expressed in acid-rain affected forests, so that these forests reduce their wood production while maintaining their production of new canopy components (Schulze et al. 1987; Oren et al. 1988a).

Root and Mycorrhizal Development in Healthy and Declining Norway Spruce Stands

Abstract: Roots link the soil-plant-continuum. Their health depends on both, soil environment and tree canopy function. Changes in any one of these compartments lead to a root response (Persson 1980). The health status of the root in return determines multiple aboveground plant functions, such as water and nutrient exchange (Chapin 1980), growth (Ingestad 1982), and hormonal root/shoot interactions (Schulze 1986). Figure 1 illustrates the interrelationships between the tree canopy and the root system. The canopy supplies carbohydrates for root growth (Marshall and Waring 1985) while roots supply water and nutrients to the canopy. However, root growth, mineral concentration, and the formation of root tips are determined by such soil chemical and physical properties as the nitrogen supply (Meyer 1985) and soil acidification. Soil acidification processes change molar ratios of Ca:Al and Ca:protons in the root environment (Ulrich 1981; Rost-Siebert 1985).

Nutrient Balance and Element Cycling in Healthy and Declining Norway Spruce Stands

Abstract: Forest ecosystems are open systems which gain elements from the atmosphere through wet and dry deposition, and from bedrock through weathering, and lose elements through leaching to groundwater. Element flow may be partitioned into three major paths (Fig. 1): (1) atmospheric input, which is modified by canopy processes and results in a throughfall, and by soil processes, which result in seepage out of the system. This flux interacts with the other two paths. (2) Plant uptake is balanced by growth and net canopy exchange, i.e., the result of canopy uptake and leaching. (3) Nutrient uptake for growth is the sum of nutrients required for biomass increment and litterfall if the canopy is at steady state. Elements are returned to the soil via decomposition of the organic material. This cycle loses elements to the immobilized element pool in woody biomass and receives elements through mineral weathering.

Water relations of two Norway spruce stands at different stages of decline

Abstract: Understanding water relations is necessary to assess forest vigor, since numerous plant processes are influenced by the water status of the soil and the plant, e.g., growth, nutrient uptake, the production and release of growth substances and leaf gas exchange (Bradford and Hsiao 1982; Schulze 1986). However, the availability of water for sustaining these processes is not only dependent on control mechanisms at the individual plant level, but is also determined by the canopy structure and boundary conditions at the stand level (Jarvis and MacNaughton 1985; Jarvis 1987). The balance between rainfall and evapotranspiration at the stand level determines to a large extent the transport of substances into and out of the ecosystem. Water percolating through the soil profile carries nutrients which may be leached below the root zone into the groundwater (Ulrich 1987). The physical properties of the soil will in turn affect the availability of water and nutrients for plant uptake.

Introduction: The Problem of Forest Decline and the Bavarian Forest Toxicology Research Group

Abstract: Forest decline first came to public attention when the dominant silvicultural tree of Germany showed damage on a large geographic scale. Damaged Norway spruce, Picea abies (L.) Karts., displayed symptoms which could not be explained by known pathogens or other factors. In the Fichtelgebirge (northeast Bavaria, Federal Republic of Germany), the earliest observations of the typical decline symptoms of needle chlorosis and needle loss were made in 1978 (Zech, personal communication). When these symptoms appeared over a larger area, research on permanent observation plots began in 1981–82 (Bayerische Staatsforstverwaltung 1982–87). Research first focused on classifying the damage according to the various degrees of chlorosis and needle loss (Table 1).

In memoriam Michael Evenari (formerly Walter Schwarz) 1904–1989

Abstract: ~ Evenari's work on the ecophysiology of plant seeds represents an important achievement and pioneering contribution to ecology. His investigation and reconstruction of historical run-off farming in the desert are an outstanding and highly original contribution to applied botany and form an important practical service to mankind. His work on desert farming began with historical and archaeological studies of the biblic farms of the Nabataeans in the Negev desert of Israel. These studies led to hypotheses concerning productive irrigationless run-off-farming under extreme desert conditions. These were subjected to tests by practical reconstruction of several such farms in the Negev desert. With an appropriate catchment area and water storing soil, a lush culture of pastures, vegetables and fruit trees proved possible without artificial irrigation. Evenari's work was supported by detailed investigations of the techniques of run-off farming and by thorough study of its scientific background, covering the fields of meteorology, soil science, plant ecology and physiology. Evenari's model farms are an important practical application of historical and scientific research. It would be inappropriate to compare them with high-technological agriculture in developed countries, but Evenari's model farms provide an impetus and opportunities for countries in arid climates which are threatened by famine.\" With these words the International Balzan Foundation, which honors \" the most deserving humanitarian and cultural work through the world\", summarized and praised the scientific achievements of Michael Evenari when he was awarded the Balzan Prize 19881. He himself called this prestigious distinction the summit of his scientific life, a life full of successful scientific achievements, honours, and deserved awards. He accepted the Balzan Prize November 1988 from the President of the Italian Republic, Francesco Cossiga, in the library of the venerable Accademia Nazionale dei Lincei in Roma. It was an impressive speech that he gave during the ceremony for the solemn proclamation of the prize winners. He did not speak about his scientific work. Instead, inspired by one of the main goals of the Balzan Foundation, to promote humanity, peace and brotherhood among all peoples, he addressed the future of mankind, which might be achieved if it would follow the principles of the Foundation. But, this is not the case. Science and technology are developing at an ever increasing pace. We call this \"progress\" but often forget that while the application of scientific dis-