Agricultural productivity may be raised in a sustainable way by many different technologies such as biological fertilizers, soil and water conservation, biodiversity conservation, improved pest control, and changes in land ownership and distribution. Of these measures, biotechnology applications probably hold the most promise in augmenting conventional agricultural productivity, because biotechnology applications give not only the need to increase production, but also protect the environment and conserving natural resources for future generations. Biotechnology applications will have the possibilities to increase productivity and food availability through better agronomic performance of new varieties, including resistance to pests; rapid multiplication of disease-free plants; ability to obtain natural plant products using tissue culture; diagnosis of diseases of plants and livestock; manipulation of reproduction methods increasing the efficiency of breeding; and the provision of incentives for greater participation by the private sector through investments. Insect resistance through the transfer of a gene for resistance fromBacillus thuringiensis (Bt) is one of the most advanced biotechnology applications already being commercialized in many parts of the world. This paper reviews the development and the status ofBt technology and application ofBt transgenic plants in current agriculture, and discusses specific issues related to the transfer of the technology to the future of genetic engineered trees with emphasis on conifers.
The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands.
The N2O emission rates, photosynthesis, respiration and stomatal conductance of the dominant tree species from broadleaf/Korean pine forest in Changbai Mountain were measured by simulated water stress with the closed bag-gas chromatography. A total of five species seedlings were involved in this study, i.e.,Pinus koraiensis Sieb. et Zucc,Fraxinus mandshurica Rupr,Juglans mandshurica Maxim,Tilia amurensis Rupr, andQuercus mongolica Fisch. ex Turcz.. The results showed that the stomatal conductance, net photosynthetic rate and N2O emission of leaves were significantly reduced under the water stress. The stoma in the leaves of trees is the main pathway of N2O emission. N2O emission in the trees mainly occurred during daytime. N2O emission rates were different in various tree specie seedlings at the same water status. In the same tree species, N2O emission rates decreased as the reduction of soil water contents. At different soil water contents (MW, LW) the N2O emission rates ofPinus koraiensis decreased by 34.43% and 100.6% of those in normal water condition, respectively. In broadleaf arbor decreased by 31.93% and 86.35%, respectively. Under different water stresses N2O emission rates in five tree species such asPinus koraiensis, Fraxinus mandshurica, Juglans mandshurica, Tilia amurensis, andQuercus mongolica were 38.22, 14.44, 33.02, 16.48 and 32.33 ngN2O·g−1DW·h−1, respectively.
Effects of water and heat stress treatments on chlorophyll fluorescence of Chinese fir (Cunninghamia lanceolata), Masson pine (Pinus massoniana) and western redcedar (Thuja plicata D. Don)_seedlings were monitored during a three-cycle stress period. It was shown that ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) of these three species responded differently to water stress treatments. The Fv/Fm ratio of western redcedar decreased dramatically after water stress, while that of Chinese fir had only a slight reduction and that of Masson pine had no significant change. The experiment also showed that the Fv/Fm ratio of all three species differed significantly under heat stress treatments. Concerning three different water plus heat stress cycles, it was found that the Fv/Fm ratios of Chinese fir and Masson pine measured at the end of each water plus heat stress cycle were not significantly different. However, the Fv/Fm ratio of western redcedar was diminished significantly in response to an increase of stress time.
Dynamic quantitative assessment of soil organic C and N is an available approach to understand the exact impact of land management on soils fertility. In this study the biomass of plants and content of soil organic C and N were compared in four typical land use systems which were planted with Ryegrass (Lolium multiflorum Lam.), Bahiagrass (Paspalum notatum Flugge.), Citrus (Citrus reticulata Blanco.), and Masson pine (Pinus Massoniana Lamb.) during 10 years in south China. Although biomass of plants in these four land use systems was nearly at the same level in the former investigation, total biomass for Ryegrass (RG), Bahiagrass (BG) was 3.68 and 3.75 times higher than that for Citrus (CT), and 2.06 and 2.14 times higher than that for Masson pine (MP) over 10 years of cultivation, respectively. Especially, underground total biomass for both RG and BG was over 10 times larger than that for CT and MP, indicating that forage grasses was much more beneficial to increase organic C and N storage in soils than CT and MP. The change content of soil organic C and N mainly occurred within soil depth of the 0–40 cm. The increased content of soil organic carbon and nitrogen was for 1.5 t·hm−2 and 0.2 t·hm−2 in the soil with planting RG and BG, and was for 1.2 t·hm−2 and 0.02 t·hm−2 in the soil with planting CT. An average loss was for 0.4 t·hm−2 and 0.04 t·hm−2 in the soil with planting MP during 10-year period.
Daxing'an Mountains was one of the most important forest areas in China, but it was also an area which was prone to suffering forest fire. The catastrophic forest fire that occurred in Daxing'an Mountains on May 6, 1987 devastated more than 1.33×106 hm2 of natural forests, which leaded to the formation of some mosaic areas with different burn intensities. Two forest farms of Tuqiang Forest Bureau (124°05′–122°18′E, 53°34′–52°15′N) were chosen as a typical area to analyze the post-fire landscape change by drawing and comparing the two digital forest stand maps of 1987 and 2000. The landscape lands of forest were classified into 12 types: coniferous forest, broadleaf forest, needle-broadleaf mixed forest, shrub, nursery, harvested area, burned blanks, agricultural land, swamp, water, built-up, grass. The results showed that: 1) The burned blanks was almost restored, some of them mainly converted into broadleaf forest land during the process of natural restoration, and coniferous forest land by the artificial reforestation, and the others almost changed into swamp or grass land; 2) The proportion of forest area increased from 47.6% in 1987 to 81.3% in 2002. Therefore, a few management countermeasures, such as the enhancing people's consciousness of fire-proofing and constructing species diversity, were put forward for forest sustainable development.
Dovetree (Davidia involucrate), one of the first-class protective plants in China, is a relic species of paleotropical kingdom in Tertiary period, belonging toDavidiaceae with a single genus. In recent years, the increase of regional developing projects has led to a sharp decrease of this ancient and rare plant in naturally distributed habitats and natural population. In this paper, the biological and ecological characteristics of Dovetree were described, and the geographically distributed condition of this species in different geologic periods as well as the major reasons for dynamic changes of its population were systematically analyzed in accordance with field researches and references. The investigations conducted in different years by setting up standard sample plots showed that the population number of Dovetree increased yearly in the areas without human interference but decreased yearly in the areas with human interference. With the increase of population density and human activities decreased as the logarithmic curve:Y=−100.7ln(x)+178.09, and it has turned from a dominant population into an endangered population. Based on the former and present studies on Dovetree, some protection strategies were put foreword for protecting this ancient and rare species.
Tamarix plant is widely distributed in the arid areas of China for its great tolerance of draught, salt and alkali and attracts more attention by its strong capacity in windbreak and sand-fixations. “Tamarix dunes” constitute special desert bio-landscape in arid area. During last several decades,Tamarix shrubs declined and “Tamarix dunes” were also severely destroyed due to the land exploitation and serious deforestation, etc. From the 1980s until now, the extending phenomenon ofTamarix shrubs caused by developmental projects such as building highway, railway was studied in the western dry area of China, including western section of Hexi Corridor of Gansu, railroads and highways around the two greatest basin in Xinjiang and interior regions in Gurbantonggut desert, through on-the-spot survey along the transportation lines and setting up sampling plots along the roads. It was found that large quantities ofTamarix plants grow in the catchment area of low-lying lands that were formed by bulldozer operation during road building period. The extension ofTamarix shrubs caused by engineering was similar to that of the other section of the area to some extent, but went beyond the original distribution. This extension is beneficial to the ecological restoration and re-vegetation of western region of China and plays an important role in control of the sandstorms and improvement of ecological environments. As a result, it is necessary to make a further study on the extending phenomenon ofTamarix shrubs and to seek approach to promote wider extension ofTamarix shrubs in suitable habitats.
A review of the period of unregulated exploitation of forests in the state of West Virginia (U.S.) and in Shaanxi Province, PRC was presented. Economic and ecological recovery from exploitation has been different in the two regions due to basic differences in nature of the forest and in the degree and persistence of exploitive pressures. After a century since unregulated exploitation, West Virginia forests are well on the road to management for sustainability and conservation. Shaanxi's recovery from overuse and unregulated exploitation is less certain; forests are still in the early phases of ecological recovery there. Full recovery to a period of sustainability will take a century or longer. Suggestions are made for measures needed to enhance the forest recovery.
An exploratory study of the traditional homestead forest of two different religious groups (Hindu and Muslim) in one selected floodplain area of Bangladesh was conducted over a period of six months from January to June 2002. The species' (both tree and shrub) preferences, similarities, use and sources of planting materials, spacing and location of species in the homesteads of both Hindu and Muslim communities were studied. It was found thatMangifera indica as tree species andOcimum sanctum as shrub species were the best preferred species of the Hindu community.Artocarpus heterophyllus as tree species andLawsonia inermis as shrub species were found best preferred by the Muslim community. Floristic similarities between the two groups were found 86.57% in tree species and 78.48% in shrub species. Both seed and seedlings of tree and shrub species as planting materials were used by the highest percentage of both the religious communities. For tree species, homegarden was reported to be the highest source (39%) and for shrub species, nature was the highest source (40%), which was found in the Hindu community.
A total of 94 isolates of endophytic fungi were isolated from the bark of 200-yr.-oldTaxus cuspidata Sieb. et Zucc. in the primeval forest of the Changbai Mountain Natural Reserve, and 19 species of endophytic fungi were identified. Among the taxa 2 new species and 1 new varied species as well as the 6 known species of China had been described in a previous article published on Journal of Forestry Research, Vol. 14 (4): 290–294 (2003). This paper made a detail description on the morphological characteristics of the 9 new recorded-genus-species and 1 new record species with illustrations, includingStaphylotrichum coccosporum Meyer et Nicot,Botryodema lateritium Papendoorf & Upadhyay,Oedocephalum glomerulosum (Rulliard) Sacc.,Trichosporonoides oedocephalis Haskins & Spencer,Beniowskia sphaeroidea (Kal Chbrenner et Caeke) Mason,Thermomyces verrucosus Pugh, Blakeman & Morgan-jones,Gilmaniella humicola Brron,Arthrinum sphaerosperma (Per.:Fr.) Ellis,Ambrosiella brunnea (Verrall) Batra, andCytosporina notha Diedz (1 new record species). And the habitats, hosts, distributions and fruiting periods were recorded for the new recorded-genus-species. The determination result of thin layer chromatography (TLC) showed that the liquid fermentation metabolites of the strains could not react positively with taxoids developer— the vanillic aldehyde and dilute bismuth potassium iodide.
An Olethreutine speciesCymolomia hartigiana (Saxesen, 1840), attacking toAbies nephrolepis Max., is reported for the first time from Daxing'anling, Heilongjiang, China. The morphological characteristics are briefly re-described with illustrations. Also its damage and biology are noted.
The cutting technic for thePinus elliottii plantation of the multi-benefit management pattern in the hilly region of Jiangxi Province was studied by establishing the model of growth progress according to Richards function and simulating the tending cutting on computer by use of dynamic programming. The results showed that the best time for the initial thinning was at tree age of 8–10 and final cutting was at tree age of 25. The optimal thinning project was 3 times of thinning cutting including the first thinning, and the thinning time was at tree ages of 8, 12 and 16, respectively. Their thinning intensities were separately 950, 700 and 300 trunks per hectare, and the preserved density was 550 trunks per hectare until the final cutting
Totally 24 arbor tree species and 6 shrub species were measured on their absorption capacities to heavy metal Pb, Cd, Cr, and Hg by collecting and analyzing the leaves of trees along different streets in Harbin city in Sept. to Oct. of 2003. The results showed that all the measured species had certain absorbency to the pollutants (Pb, Cd, Cr and Hg), but there existed significant difference in absorption capacity for different species to different pollutants. The measured tree species were classified into three categories by their absorption quantum of heavy metal pollutants. Among the species measured,Betula platyphylla, Ulmus pumila var.pendula, andPrunus persicaf.rubro-plena had high capacity in absorbing Pb;Populus xiahei, P. nigra var.Italica, P. alba x P. berolinensis andSalix matsudana had had high capacity in absorbing Cd;Phellodendron amurense, Syringa oblata, Salix matsudana, Pinus tabulaeformis var.mukdensis, Picea koraiensis, Prunus persica f.rubro-plena, P. triloba andAcer negundo, etc. had high capacity in absorption of Cr;Prunus triloba, Quercus mongolica, Salix matsudana, Sambucus williamsii, Pyrus ussuuriensis andSpiraea fritschiana were good at absorption of Hg. This study might offer scientific foundation for selection of urban afforestation species in different polluted conditions caused by heavy metals.
Wood-polymer composites (WPC) were prepared from wood fiber and four kinds of plastics such as PE, PS, ABS, and SAN. The effects of different modifiers on the mechanical properties of the composites were studied. The results showed modifiers could raise the bonding strength of wood fiber with polymer and improve the mechanical properties of the composites. Different modifiers had different effects on the properties of wood-polymer composites, and comparatively the modifier of isocyanate produced a better result. Wood-polymer composite takes not only the advantages of both wood fiber and polymer, but waterproof, dimensional stability and dynamic strength are also significantly improved.
Three steam distillation devices (D-1, D-2 and D-4) or one simultaneous distillation (D-3, water-diethyl ether) as well as the process of CO2-SFE (Supercritical fluid extraction) were adopted in extraction of essential oils from Chinese-fir (Cunninghamia lancedata (Lamb) Hook.) and the chemical components of the extracted essential oil were analyzed by Gas chromatograph-MS analyses. The results showed that the essential oil could be almost extracted out within 2 hours and the device-3 had the highest extraction efficiency. The major chemical component of the oil was cedrol. The yield of the extracted essential oils from Chinese fir decreased gradually with the increase of the distillation time. The best condition for extraction by means of CO2-SFE is 100 kg·cm−2 in pressure and 40°C in temperature for.
Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m−2·s−1). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m−2·s−1 to 569.00 μmol·m−2·s−1 (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m−2·s−1 or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m−2·s−1 (8–961 lx), or 10 μmol·m−2·s−1 for above 6 h.