Dorfchriften der in den fürftlich fürftenbergifchen Waldungen arbeitenden Ljalzhauer

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福建海岛植被面临的问题及保护开发策略研究

整理福建省4个有居民海岛和13个无居民海岛的植被现状,从地理环境影响和人为活动影响两方面综述福建海岛植被变化及面临的问题,包括土地风沙化严重,防护林效能衰退,园林植物生长遭受威胁,自然灾害破坏植物生境,以及海岛城市扩张,外来植物入侵威胁等。提出提高生态保护意识,推进海岛植被修复工作,发展生态旅游业,改善海岛防护林体系等福建海岛植被资源保护与开发策略。     

Responses to ultraviolet-B radiation by purely symbiotic and NO3-fed nodulated tree and shrub legumes indigenous to southern Africa

Purely symbiotic and NO3-fed nodulated seedlings of Virgilia oroboides (Bergius) T.M. Salter, Cyclopia maculata (L.) Vent and Podalyria calyptrata Willd. were exposed to biologically effective ultraviolet-B radiation (UV-B) to assess the effects of above- and below-ambient UV-B on growth, symbiotic function and metabolite concentrations. Seedlings were grown outdoors either on tables under ambient or 34 or 66% above-ambient UV-B conditions (UV-B100 control, UV-B134 and UV-B166, respectively), or in chambers providing below-ambient (22% of ambient) UV-B (UV-B22) along with a UV-A control and a photosynthetically active radiation (PAR) control. Exposure of seedlings to UV-B166 radiation reduced (P < or = 0.05) leaf and stem dry mass by 34 and 39%, respectively, in C. maculata, and reduced leaf nitrogen concentration (%N) by 12% in V. oroboides. Nodule %N in C. maculata and stem %N in P. calyptrata also decreased (P < or = 0.05) in response to UV-B22 radiation compared with the UV-A control, but not compared with the PAR control. Concentrations of flavonoids, soluble sugars and starch were unaltered by the UV-B treatments. Application of 1 mM NO3 to UV-B166-treated seedlings increased whole-plant dry mass of V. oroboides and P. calyptrata by 47 and 52%, respectively. Dry mass of organs, nodule %N and total N concentration of these species also increased with NO3 application. However, NO3 supply decreased (P < or = 0.05) nodule dry mass, stem %N and leaf %N as well as root and leaf anthocyanin concentrations in C. maculata. In terms of UV-B x N interactions, dry mass of stems, roots, nodules and total biomass of NO3-fed C. maculata seedlings were reduced, and nodule %N, total N and leaf anthocyanins were depressed by the UV-B134 and UV-B166 treatments relative to UV-B100-treated seedlings. Although we found that above-ambient UV-B had no effects on growth and symbiotic function of V. oroboides and P. calyptrata seedlings, feeding NO3 to these species increased (P < or = 0.05) seedling growth. In contrast, purely symbiotic C. maculata seedlings were sensitive to the UV-B166 radiation treatment, and adding NO3 further increased their sensitivity to both the UV-B134 and UV-B166 treatments.     

Acid mist and soil Ca and Al alter the mineral nutrition and physiology of red spruce

We examined the effects and potential interactions of acid mist and soil solution Ca and Al treatments on foliar cation concentrations, membrane-associated Ca (mCa), ion leaching, growth, carbon exchange, and cold tolerance of red spruce (Picea rubens Sarg.) saplings. Soil solution Ca additions increased foliar Ca and Zn concentrations, and increased rates of respiration early in the growing season (July). Soil Al treatment had a broad impact, reducing foliar concentrations of Ca, Mg, Mn, P and Zn, and resulting in smaller stem diameters, sapling heights and shoot lengths compared with soil treatments with no added Al. Aluminum treatment also reduced respiration when shoots were elongating in July and decreased net photosynthesis at the end of the growing season (September). Three lines of evidence suggest that Al-induced alterations in growth and physiology were independent of foliar Ca status: (1) Ca concentrations in foliage of Al-treated saplings were within the range of sufficiency established for red spruce; (2) mCa concentrations were unaffected by Al treatment; and (3) no Al x Ca interactions were detected. Acid mist treatment increased foliar Fe and K concentrations and increased leaching of Ca, Mg, Mn, Zn, Fe, and Al from foliage. Leaching losses of Ca were more than twice those of the element with the next highest amount of leaching (Zn), and probably led to the reductions in mCa concentration and membrane stability of acid-treated saplings. Acidic mist resulted in enhanced shoot growth, and consistent reductions in foliar cold tolerance in the fall and winter. Of the few significant interactions among treatments, most involved the influence of mist pH and Al treatment on foliar nutrition. In general, reductions in cation concentration associated with Al addition were greater for pH 5.0-treated saplings than for pH 3.0-treated saplings. We propose that H(+)-induced leaching of mCa from mesophyll cells is the mechanism underlying acid-induced reductions in foliar cold tolerance of red spruce.     

A modeling analysis of the interaction between forest age and forest responsiveness to increasing CO2 concentration

Typically, forests have rotations of 10-200 years. On that time scale, anthropogenic increases in atmospheric carbon dioxide concentration ([CO2]) and the associated changes in climate are expected to be substantial. These changes will, therefore, almost certainly affect the growth of presently established forest stands. Most studies on the effects of increasing [CO2] on tree growth have been made with young plants. However, the growth of trees within a forest stand varies with age. As a consequence, it is difficult to infer from the available experimental data how rising [CO2] will affect forest productivity over a full rotation. In this study, various mechanisms that may account for the slowing of forest growth with age were introduced into the forest growth model CenW, to assess how these processes affect the modeled growth response to increasing [CO2]. Inclusion of allocation shifts with tree height, individual tree mortality, changing respiration load and nutrient dynamics or age-based reductions in photosynthetic capacity had only small effects on the response to increasing [CO2]. However, when photosynthesis of mature trees was decreased as a function of size, then the growth response to increasing [CO2] was reduced because, at the same age, trees were larger in elevated than in ambient [CO2]. No simple and generally valid interactions between increasing [CO2] and forest age were identified because of the large number of interacting processes, all of which are incompletely understood. Important age x climate change interactions on productivity must occur in real forests and need to be considered to understand likely future trends. However, these interactions are complex and difficult to test. It is therefore not yet possible to predict with confidence the modification of the CO2 response by forest age.     

Effects of two iron sources on iron and cadmium allocation in poplar (Populus alba) plants exposed to cadmium

Effects of 10 microM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar (Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic) Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in long-distance transport of Fe rather than in acquisition of Fe by roots.     

Coumarins from the aerial part of Halocnemum strobilaceum

Four known coumarins, coumarin (1), 7-hydroxy-3-methylcoumarin (2), oreoselone (3) and heraclenin (4), were isolated from aerial part of Halocnemum strobilaceum. Their structures were determined by 1 and 2-D NMR techniques.     

Morphological and physiological adjustment to N and P fertilization in nutrient-limited Metrosideros polymorpha canopy trees in Hawaii

Leaf-level studies of Metrosideros polymorpha Gaud. (Myrtaceae) canopy trees at both ends of a substrate age gradient in the Hawaiian Islands pointed to differential patterns of adjustment to both nutrient limitation and removal of this limitation by long-term (8-14 years) nitrogen (N), phosphorus (P) and N + P fertilizations. The two study sites were located at the same elevation, had similar annual precipitation, and supported forests dominated by M. polymorpha, but differed in the age of the underlying volcanic substrate, and in soil nutrient availability, with relatively low N at the young site (300 years, Thurston, Hawaii) and relatively low P at the oldest site (4,100,000 years, Kokee, Kauai). Within each site, responses to N and P fertilization were similar, regardless of the difference in soil N and P availability between sites. At the young substrate site, nutrient addition led to a larger mean leaf size (about 7.4 versus 4.8 cm2), resulting in a larger canopy leaf surface area. Differences in foliar N and P content, chlorophyll concentrations and carboxylation capacity between the fertilized and control plots were small. At the old substrate site, nutrient addition led to an increase in photosynthetic rate per unit leaf surface area from 4.5 to 7.6 micromol m(-2) s(-1), without a concomitant change in leaf size. At this site, leaves had substantially greater nutrient concentrations, chlorophyll content and carboxylation capacity in the fertilized plots than in the control plots. These contrasting acclimation responses to fertilization at the young and old sites led to significant increases in total carbon gain of M. polymorpha canopy trees at both sites. At the young substrate site, acclimation to fertilization was morphological, resulting in larger leaves, whereas at the old substrate site, physiological acclimation resulted in higher leaf carboxylation capacity and chlorophyll content.     

Suppression of development of Callosobruchus maculatus (F.) (Col.: Bruchidae) in bambara groundnut seeds exposed to solar heat in the Nigerian savanna

The effect of solarization on the development of Callosobruchus maculatus was investigated in the Nigerian savanna during the hot season from April to May, 1999. Development of C. maculatus adult progeny was completely suppressed in seeds of bambara groundnut, Vigna subterranea bearing bruchid eggs or harbouring first and second instar larvae that were exposed to the sun in metal tins, clay pots or polypropylene sacks for 7, 14 or 28 h. Adults of C. maculatus developed only in seeds that were not exposed to sun. Solarization did not have a significant adverse effect on germinability of bambara groundnut seeds.