Showing papers by "Ernst Detlef Schulze published in 1988"

Performance of two Picea abies (L.) Karst. stands at different stages of decline : VII. Nutrient relations and growth.

Abstract: A declining, closed-canopy Picea abies (L.) Karst. stand produced as much crown biomass as a healthy stand, although some trees were chlorotic due to magnesium deficiency. The production of wood per unit of leaf area in both stands was related to the foliar magnesium concentration. Although leaf area index and climate were similar at both sites, stemwood production was 35% lower in the declining than in the healthy stand. Nutritional disharmony, rather than a deficiency in a single element, was identified as the mechanism for reduced tree vigor. The role of nutrient stress in forest decline was detected by partitioning the season into three periods reflecting different phenological stages: a canopy growth period in spring, a stem growth period in summer, and a recharge period during the non-growing season. Needle growth was associated with nitrogen supply. Most of the magnesium supply required to meet the demand for foliage growth was retranslocated from mature needles. Magnesium retranslocation was related to concentration of nitrogen and magnesium in those needles before bud break. Retranslocation from mature needles during the phase of canopy production resulted in chlorosis in initially green needles if the magnesium concentration before bud break was low. Nitrogen concentration in 0-year-old needles generally remained constant with increasing supply, indicating that foliage growth was restricted by the supply of nitrogen. In contrast, magnesium concentration generally increased with supply, indicating that magnesium supply for needle growth was sufficient. Much of the magnesium required for wood production was taken up from the soil because stored magnesium was largely used for canopy growth. Uptake at the declining site was probably limited because of restricted root expansion and lower soil magnesium compared to the healthy site. For this reason only wood growth was reduced at the declining site. Because the recharge of magnesium during the non-growing period is dependent on uptake from the soil, it was more limited at the declining that at the healthy stand. However, as nitrogen uptake from the atmosphere may account for an appreciable proportion of the total uptake, and as its supply in the soil at both sites was similar, an unbalanced recharge of nitrogen and magnesium may have occurred at the declining site. If mature needles are unable to recharge with magnesium in proportion to the uptake of nitrogen, chlorosis is likely to occur during the next canopy growth period.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : II. Photosynthesis and leaf conductance.

Abstract: CO2 assimilation rate (A) and leaf conductance (g) were measured in the field on intact branches of 35-year-old Picea abies (L.) Karst. trees, in five plots each in a healthy and a declining stand. The declining site included trees with yellow needles. In order to separate atmospheric effects on gas exchange from effects of nutrient deficiency, direct effects of atmospheric pollutants were studied on green needles of different age classes in plots of trees at different stages of visible decline. The effects of nutrient deficiency on gas exchange were studied on a different group of trees showing needles of various degrees of yellowing. CO2 assimilation of green needles at the same leaf conductance fell somewhat only when needles had reached 5 years of age, the oldest age examined in this study. Leaf conductance decreased with increasing needle age, but green needles in the declining stand had leaf conductances similar to those of needles in the healthy stand. Stomata of needles with different magnesium concentrations responded to light and air humidity in all age classes. Thus, as long as needles were green, no dese effect was detectable up to 5 years of exposure to atmospheric emissions. Since all needles, green and yellow, were exposed to the same pollution levels, differences in gas exchange between green and yellow needles could not be explained simply in terms of long-term direct effects of air pollution. Needle magnesium contents were correlated with needle yellowing. Neither needle color change nor the magnesium concentration were related to g, but CO2 uptake at ambient CO2 levels declined with lower magnesium concentration and greater degrees of needle yellowing.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : V. Root tip and ectomycorrhiza development and their relations to above ground and soil nutrients.

Abstract: The development of root tips and apparent ectomycorrhizas was compared in the Fichtelgebirge (FRG) over one growing season in two 30-year-old Picea abies stands, both on soils derived from phyllite but showing varying symptoms of decline. Visual symptoms of tree decline reflected a lower relative and absolute mycorrhizal frequency, a lower number of ectomycorrhizas per m2 leaf area and an uneven vertical distribution of root tips and ectomycorrhizas. The number of apparent ectomycorrhizas per ground area was correlated with the amount of magnesium, calcium, and ammonium, and the pH in the free-drainage soil solution, and with the molar calcium to aluminium ratio in mineral soil extracts. The foliage concentrations of magnesium and calcium were correlated with the numbers of apparent ectomycorrhizas per m2 leaf or ground area. These observations were used to formulate testable hypotheses concerning the role of the root system and the soil environment in forest decline.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : I. Carbon relations and stand growth.

Abstract: This is the first in a series of papers on the growth, photosynthetic rate, water and nutrient relations, root distribution and mycorrhizal frequency of two Norway spruce forests at different stages of decline. One of the stands was composed of green trees only while the other included trees ranging in appearance from full green crowns to thin crowns with yellow needles. In this paper we compare the growth and carbohydrate relations of the two stands and examine relationships among growth variables in ten plots. The declining stand produced 65 percent of the wood per ground area compared with the stand in which all trees were green because its foliage produced less wood at any level of leaf area index. The difference in foliage efficiency between the sites could not be explained by differeneces in climate, competition or stand structure. The declining stand appeared to have lower carbon gain as indicated by a smaller increase in reserve carbohydrates before bud break, and weaker sinks for carbohydrates as indicated by less use of the stored carbohydrates than the healthy stand. Thus, growth reduction was probably related to factors which affect both photosynthesis and, even more, the sinks for carbohydrate.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : IV. Xylem sap concentrations of magnesium, calcium, potassium and nitrogen.

Abstract: The nutrient relations (nitrogen, magnesium, calcium, potassium, and manganese) of the xylem sap of spruce trees, Picea abies (L.) Karst., growing at a healthy and a declining site in Northern Bavaria, were followed on a diurnal and seasonal basis between April and October 1985. There were significant differences between the two sites in the xylem sap concentrations of all elements investigated except nitrogen. Nutrient concentrations remained constant diurnally despite changes in transpiration and xylem water potential. However, during periods between precipitation events, concentrations of elements in xylem sap decreased with decreasing xylem water potential. Apparent differences in needle chlorosis of spruce trees at the two sites were associated with consistent differences in nutrient contents of their xylem sap and needles.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : VI. Nutrient concentration.

Abstract: A declining Picea abies (L.) Karst. stand produced as much foliage and branches as a healthy stand but less stemwood at a similar leaf area index and climate. Nutrient analyses revealed that most biomass components at the declining site had lower concentrations of calcium and magnesium, but similar nitrogen and potassium (except for lower potassium in younger needles) and higher phosphorus, manganese and aluminum than the respective components at the healthy site. Comparison of these data with the results from studies on the nutrition and growth of P. abies seedlings (Ingestad 1959) led to the conclusion that the healthy stand is in a balanced nutritional state, while trees at the declining stand have only 56% of the foliar magnesium concentration required to permit growth at a rate which could be achieved at their nitrogen status. It appears that acidic deposition, which involves an input of nitrogen and a leaching of cations from the soil, causes an imbalance in the availability of nitrogen and magnesium. Growth is eventually reduced as magnesium becomes limiting.

Carbon uptake and respiration in above-ground parts of a Larix decidua x leptolepis tree

Abstract: Shade needles of hybrid larch (Larix decidua × leptolepis) had the same rates of photosynthesis as sun needles per dry weight and nitrogen, and a similar leaf conductance under conditions of light saturation at ambient CO2 (Amax). However, on an area basis, Amax and specific leaf weight were lower in shade than in sun needles. Stomata of sun needles limited CO2 uptake at light saturation by about 20%, but under natural conditions of light in the shade crown, shade needles operated in a range of saturating internal CO2 without stomatal limitation of CO2 uptake. In both needle types, stomata responded similarly to changes in light, but shade needles were more sensitive to changes in vapor pressure deficit than sun needles. Despite a high photosynthetic capacity, the ambient light conditions reduced the mean daily (in summer) and annual carbon gain of shade needles to less than 50% of that in sun needles. In sun needles, the transpiration per carbon gain was about 220 mol mol−1 on an annual basis. The carbon budget of branches was determined from the photosynthetic rate, the needle biomass and respiration, the latter of which was (per growth and on a carbon basis) 1.6 mol mol−1 year−1 in branch and stem wood. In shade branches carbon gains exceeded carbon costs (growth + respiration) by only a factor of 1.6 compared with 3.5 in sun branches. The carbon balance of sun branches was 5 times higher per needle biomass of a branch or 9 times higher on a branch length basis than shade branches. The shade foliage (including the shaded near-stem sun foliage) only contributed approximately 23% to the total annual carbon gain of the tree.

The nitrogen balance of Raphanus sativus x raphanistrum plants. II. Growth, nitrogen redistribution and photosynthesis under NO3− deprivation

Abstract: . Wild radish plants deprived of, and continuously supplied with solution NO−3 for 7 d following 3 weeks growth at high NO−3 supply were compared in terms of changes in dry weight, leaf area, photosynthesis and the partitioning of carbon and nitrogen (NH2-N and NO−3-N) among individual organs. Initial levels of NO−3-N accounted for 25% of total plant N. Following termination of NO−3 supply, whole plant dry weight growth was not significantly reduced for 3 d, during which time plant NH2-N concentration declined by about 25% relative to NO−3-supplied plants, and endogenous NO−3-N content was reduced to nearly zero. Older leaves lost NO−3 and NH2-N, and roots and young leaves gained NH2-N in response to N stress. Relative growth rate declined due both to decreased net assimilation rate and a decrease in leaf area ratio. A rapid increase in specific leaf weight was indicative of a greater sensitivity to N stress of leaf expansion compared to carbon gain. In response to N stress, photosynthesis per unit leaf area was more severely inhibited in older leaves, whereas weight-based rates were equally inhibited among all leaf ages. Net photosynthesis was strongly correlated with leaf NH2-N concentration, and the relationship was not significantly different for leaves of NO3−-supplied compared to NO−3-deprived plants. Simulations of the time course of NO−3 depletion for plants of various NH2-N and NO−3 compositions and relative growth rates indicated that environmental conditions may influence the importance of NO−3 accumulation as a buffer against fluctuations in the N supply to demand ratio.

Performance of two Picea abies (L.) Karst. stands at different stages of decline : III. Canopy transpiration of green trees.

Abstract: The water relations of Picea abies in a healthy stand with green trees only and a declining stand with trees showing different stages of needle yellowing were investigated in northern Bavaria. The present study is based on observations of trees differing in their nutritional status but apparently green on both sites in order to identify changes in the response pattern which might be caused by atmospheric concentrations of air pollutants and could lead to the phenomenon of decline. Transpiration was measured as water flow through the hydroactive xylem using an equilibrium mass-flow measurement system. Total tree transpiration was monitored diurnally, from July 1985 until October 1985 at both sites. The relationship between transpiration and meteorological measurements indicated that transpiration was a linear function of the vapor pressure deficit. No differences in transpiration of green trees were observed between the two sites. Canopy transpiration was 57%-68% of total throughfall and 41%-54% of total rainfall. Due to this positive water balance, soil water potential at 10 and 20 cm depths remained close to-0.02 MPa (max.-0.09 MPa) for most of the summer. Soil water potential was correlated with the difference between the weekly precipitation and transpiration. No differences in the water relations of apparently healthy trees in the two P. abies stands were observed. It is concluded that differences between green trees at the two sites in terms of nutrient relations or growth rate cannot be explained by changes in whole-tree transpiration or soil water status.

The effect of humidity and light on cellular water relations and diffusion conductance of leaves ofTradescantia virginiana L.

Abstract: Turgor (Ψp) and osmotic potential (Ψs) in epidermal and mesophyll cells, in-situ xylem water potential (Ψ-xyl) and gas exchange were measured during changes of air humidity and light in leaves ofTradescantia virginiana L., Turgor of single cells was determined using the pressure probe. Sap of individual cells was collected with the probe for measuring the freezing-point depression in a nanoliter osmometer. Turgor pressure was by 0.2 to 0.4 MPa larger in mesophyll cells than in epidermal cells. A water-potential gradient, which was dependent on the rate of transpiration, was found between epidermis and mesophyll and between tip and base of the test leaf. Step changes of humidity or light resulted in changes of epidermal and mesophyll turgor (Ψp-epi, Ψp-mes) and could be correlated with the transpiration rate. Osmotic potential was not affected by a step change of humidity or light. For the humidity-step experiments, stomatal conductance (g) increased with increasing epidermal turgor.Δg/Ψp-epi appeared to be constant over a wide range of epidermal turgor pressures. In light-step experiments this type of response was not found and stomatal conductance could increase while epidermal turgor decreased.

Soil drying and its effect on leaf conductance and CO2 assimilation of Vigna unguiculata (L.) Walp : I. The response to climatic factors and to the rate of soil drying in young plants.

Abstract: Well watered plants of Vigna unguiculata (L.) Walp cv. California Blackeye No. 5 had maximum photosynthetic rates of 16 μmol m-2 s-1 (at ambient CO2 concentration and environmental parameters optimal for high CO2 uptake). Leaf conductance declined with increasing water vapour concentration difference between leaf and air (Δw), but it increased with increasing leaf temperature at a constant small Δw. When light was varied, CO2 assimilation and leaf conductance were correlated linearly. We tested the hypothesis that g was controlled by photosynthesis via intercellular CO2 concentration (c i). No unique relationship between (1) c i, (2) the difference between ambient CO2 concentration (c a) and c i, namely c a-c i, or (3) the c i/c a ratio and g was found. g and A appeared to respond to environmental factors fairly independently of each other. The effects of different rates of soil drying on leaf gas exchange were studied. At unchanged air humidity, different rates of soil drying were produced by using (a) different soils, (b) different irrigation schemes and (c) different soil volumes per plant. Although the soil dried to wilting point the relative leaf water content was little affected. Different soil drying rates always resulted in the same response of photosynthetic capacity (A max) and corresponding leaf conductance (g(Amax)) when plotted against percent relative plant-extractable soil water content (W e %) but the relationship with relative soil water content (W e ) was less clear. Above a range of W e of 15%–25%, A max and g(Amax) were both high and responded little to decreasing W e . As soon as W e fell below this range, A max and g(Amax) declined. The data suggest root-to-leaf communication not mediated via relative leaf water content. However, g(Amax) was initially more affected than A max.

Tree Responses to Acid Depositions into the Soil a Summary of the Cost Workshop at Jülich 1985

Abstract: The review is based on the results of the 1985 COST workshop at Julich. The main pathway of tree responses to acid deposition are summarized in Fig. 1. It occurs, that leaching of nutrients causes a plant external nutrient cycle. Together with the overall proton and nitrate input, soil acidity and soil cation pools have changed. This has effects on root structure and performance which result in decreased nutrient uptake and needle ion deficits. But, the plant internal regulation of coping with nutrient deficits is additionally perturbed by the input of nitrogen which stimulates growth at low cation supply. This causes an inbalance of the needle nutrient status which in turn results in whole plant growth reduction and needle loss. The timing of the process contains a long-term component of sulphate inputs. More recently are nitrogen inputs. Both caused a predepostiton of the ecosystems. The short-term rapid increase of nutrient deficits, which have been observed as feature of forest decline, may be due to the soil physical process of soil-aggregation, which reduces the supply of cations in dry years.

Carbon Assimilation and Nutrition of Trees in Two Picea Abies (L.) Karst. Stands in Bavaria Exhibiting Apparent Decline Differences

Abstract: A significantly lower growth was found in a Norway spruce stand where some of the trees are becoming yellow, in comparison to a similar stand composed of green trees. The growth loss can only be explained by lower photosynthesis of yellow foliage because the green foliage in both stands photosynthesized similarly, and no difference in production below ground was detected. The yellowing of the foliage is a result of lower Mg++ uptake and, thus, lower Mg++ concentration in the foliage of the trees in the declining stand, including the foliage green trees. Correction of the leaf area index of the declining site, to account for the reduced productivity of the canopy, will result in a production which is appropriate for this effective leaf area index.

Ökologische Untersuchungen an der Verschiedenblättrigen Kratzdistel (Cirsium helenioides [L. Hill) in Oberfranken. Teil II: Heterophyllie und Standort.

Abstract: The ecology of the Melancholy Thistle (Cirsium helenioides, Asteraceae) is presented in a series of three papers: Phytosociology and synecology (REIF and WEISKOPF, part 1); autecology and heterophylly (WEISKOPF, ROMSTÖCK, REIF and SCHULZE, part 2); herbivores of the thistle heads (ROMSTÖCK, part 3). This first paper describes morphology, phenology, distribution, phytosociology and ecology of Cirsium helenioides. The areas studied are in the Fichtelgebirge and Frankenwald, Oberfranken, south-east Germany. In this area, the thistle occurs in grassland communities of the montane belt. Cirsium helenioides was found in 11 different plant communities above c. 550 m. Between 550 and 650 m, it was found most frequently in more nutrient-rich meadows, mainly in Geranio-Trisetetum, less frequently in Calthioncommunities and in a ,Poa-Trisetum-commumty\\ At higher altitudes, above c. 650 m, less nutrient-rich communities are more frequent; the thistle frequently was found also in these. Because of low fidelity, an association „Polygono-Cirsietum heterophylli” (Calth ion) cannot be established, at least in Oberfranken. But, this species may be used for geographical differentiation. Important site factors of the different plant communities with Cirsium helenioides were compared, using the indicator values (ELLENBERG 1974) of all species. The accompanying species indicate that 101 ©Floristisch-soziologische Arbeitsgemeinschaft; www.tuexenia.de; download unter www.zobodat.at