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Increasing field experiments have been conducted in forests to better understand the response of plant growth and photosynthesis to climatic warming. However,it is still unknown whether there is a general pattern in relation to how and to what extent warming impacts woody plants in forests. In this study, a meta-analysis was conducted to investigate the warming effects. When temperatures increased between 0.3 and 10 ℃, specific leaf area(SLA) was significantly increased by 5.9%, plant height by 7.8%, biomass by 21.9%, foliar calcium(Ca) and manganese(Mn) concentrations by 20.7% and 39.6% and net photosynthetic rate(Pn) by 9.9%. Enhanced growth and Pn may have a relationship with changing SLA, efficiency of PSⅡ(photosystem Ⅱ), photosynthetic pigment concentrations and foliar nutrients. The results will be useful to understand the underlying mechanisms of forests responding to global warming. 相似文献
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Salvage logging is a common practice carried out in burned forests worldwide, and intended to mitigate the economic losses caused by wildfires. Logging implies an additional disturbance occurring shortly after fire, although its ecological effects can be somewhat mitigated by leaving wood debris on site. The composition of the bird community and its capacity to provide ecosystem services such as seed dispersal of fleshy-fruited plants have been shown to be affected by postfire logging. We assessed the effects of the habitat structure resulting from different postfire management practices on the bird community, in three burned pine forests in Catalonia (western Mediterranean). For this purpose, we focused on the group of species that is responsible for seed dispersal, a process which takes place primarily during the winter in the Mediterranean basin. In addition, we assessed microhabitat selection by seed disperser birds in such environments in relation to management practices. Our results showed a significant, positive relationship between the density of wood debris piles and the abundance of seed disperser birds. Furthermore, such piles were the preferred microhabitat of these species. This reveals an important effect of forest management on seed disperser birds, which is likely to affect the dynamics of bird-dependent seed dispersal. Thus, building wood debris piles can be a useful practice for the conservation of both the species and their ecosystem services, while also being compatible with timber harvesting. 相似文献
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This paper reviews the researches on old-growth korean pine (Pinus koraoensis) forest in Northeast China. The ecological characteristics of the forest were summarized. According to the research results,
the importance of studying and reserving on the old-growth forest was addressed, which were the indispensable research laboratory
and classroom for forest managers. The conclusions indicate that the future of Korean pine forest management should be based
on the research results of old-growth forests. 相似文献
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Tree cavities play a critical role in the life history of cavity-using species and thus are an important structural feature of forests. Furthermore, some common forest management practices can have a profound negative effect on cavity quantity and quality. This is the first study to address cavity resources in Neotropical montane forests and with this information we hope to develop approaches to sustainable forest management that will assure the conservation of cavity nesters. Our study design consisted of two treatments (control and harvested forest) in both piedmont and cloud forests of the subtropical montane forests of the Andes. This study indicates that cavities are an uncommon feature even in control sites with only 3% of the trees harboring cavities in both forest types. Even more uncommon are potentially usable cavities for avian cavity nesters: only 0.15% of the trees have a potentially usable cavity in the piedmont forest and only 0.42% in the cloud forest. In logged forests there is a significantly lower density of potentially usable cavities (4.12 vs. 0.51 cavities/ha in piedmont forest and 3.91 vs. 1.64 cavities/ha in the cloud forest). Furthermore, we documented a high loss rate of potentially usable cavities (from 23 to 40%/year) that differs between tree species and DBH classes. More specifically, in the piedmont forest, large, decaying Calycophyllum multiflorum have a relatively greater probability of having potentially usable cavities, while in the cloud forest potentially usable cavities are disproportionably found in large, decaying Blepharocalyx gigantea. In both forest types, snags are also very likely to harbor a potentially usable cavity. In order for harvested stands in the subtropical montane forest of the Andes to regain some of their ecological value, it is necessary to retain trees that have potentially usable cavities and also trees with the highest probability of becoming usable cavity trees. 相似文献
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Climate warming has resulted in rapid range shifts of plant species, but it is not well known how species with different natural distribution ranges adapt to increase in temperature through physiological adjustment. We experimentally imposed a 1.8 °C increase of air temperature to the cuttings of two common poplar species Populus yunnanensis and Populus szechuanica naturally growing in southwest China using open-top chambers. Populus yunnanensis is distributed along a narrower elevation range compared with P. szechuanica. We determined some key physiological parameters and plant growth regulator activities during the growing season without soil water limitation. Our results showed that a 1.8 °C increase in air temperature increased shoot growth of P. szechuanica through an extension of its growth period but did not affect the growth of P. yunnanensis. Malondialdehyde content, guaiacol peroxidase activities and abscisic acid content increased while indoleacetic acid content decreased in P. yunnanensis. Our results suggest that the two common poplar species in southwest China should be able to adapt to the moderate increase in temperature projected for future climate. The growth of P. szechuanica may benefit through phenological adjustment but a further increase in temperature may inhibit the growth of P. yunnanensis. For poplar plantation management, selecting species with a wide natural distribution range could provide an adaptive alternative for buffering anthropogenic induced increase in temperature and help in sustaining productivity for the long term. 相似文献
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The effect of gap characteristics, including gap age, vegetation cover, and stage of regeneration, on water balance and drought stress was studied over a four-year period in natural and experimental gaps of various sizes in Dinaric silver fir--beech forest in Slovenia. A medium gap, two experimental clear-cut gaps, and a closed stand were selected in a traditional irregular shelterwood managed forest, and an irregular-shaped natural gap and part of the stand were selected in a semi-natural forest. Soil moisture, throughfall, and stemflow were measured in the gaps and stands, and incident precipitation was monitored in the open area. Evapotranspiration and drainage water fluxes were estimated using the water balance model BROOK90. To estimate drought stress, the ratio between simulated actual and potential evapotranspiration was used. Precipitation in the 2001 and 2003 growing seasons was considerably less than that in 2002 and 2004. The highest drainage fluxes were in the newly created clear-cut gaps with sparse ground vegetation cover, followed by the natural gap and medium gap, which had older and denser natural tree regeneration. On average, the clear-cut gap drainage fluxes were 18% (164?mm) higher than those in the forest stands. Evapotranspiration was lower in the natural gap and higher in the managed gap compared with the experimental clear-cut gaps. Water supply stress was greater for the forest stands than for the vegetation in the gaps. Drought stress was indicated to be lowest in the natural gap, which had patches of varying development phases and the highest water storage capacity of the soil and vegetation. 相似文献
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This paper provides an overview of the work reported at a symposium on age-related changes in the structure and function of forests in the United States Pacific Northwest. Some of the work presented at this meeting is reported in the peer-reviewed papers comprising this journal issue. Age-related changes in leaf structure, CO2 assimilation rate, stable carbon isotope ratio, nitrogen concentration and stomatal limitation were demonstrated at many organizational scales. At larger scales, age-related changes were reported in canopy structure and light profile, stand productivity, tree mortality and respiration. These data raise new questions about the potential interaction among the structural and functional changes in aging forests, and indicate many avenues for future research concerning tree growth and ecosystem functioning. 相似文献
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Amélie Collard Line Lapointe Jean-Pierre Ouellet Michel Crête Alain Lussier Claude Daigle Steeve D. Côté 《Forest Ecology and Management》2010
We examined the response of understory plants in mature maple-dominated forests of southern Québec, Canada, following about 30 years of high deer densities, using a deer exclosure experiment. An exclosure and a paired control of 625 m2 each were established on six sites in 1998. An exclosure and a paired control of 16 m2 were added at each of the same sites in 2003 but under a recent canopy gap to determine if light could enhance plant responses. We measured plant richness and abundance, and aboveground biomass of different plant groups for 8 years in the understory plots and for 3 years in the canopy gaps. Four herbaceous species were also monitored individually in the same plots. No significant differences between treatments were found in plots under forest cover, except for lateral obstruction at 0–50 cm height which was higher in the exclosures. Under canopy gaps, however, tree seedling and total plant abundance were higher in deer exclosures than in control plots. Trillium erectum recovered partially as individuals were taller, had larger leaves and more frequently produced a flower or a fruit in the absence of deer browsing under forest cover. To a lesser extent, Erythronium americanum and Maianthemum canadense also exhibited signs of recovery but were still at the single-leaf stage after 8 years of recovery. In general, the different plant groups exhibited little recovery following deer exclusion, possibly because of the low light levels that prevailed in the understory of undisturbed maple-dominated forests. The higher latitude of the present study could also contribute to the slow recovery rates of the different groups of plants compared to studies conducted in northeastern USA. Variability among sites and years had an effect on detection of statistically significant differences. Trends are however appearing over time, suggesting that many understory plants are recovering very slowly following deer exclusion. Our results emphasize the importance of studying large herbivore–forest interactions on different groups of plants, but also on specific species, and under different latitudes to be fully understood. 相似文献
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四川天然林资源保护工程1998、1999年试点启动，2000年正式实施，已三年多时间。在工程实施过程中，各级党政部门高度重视，广大干部群众真抓实干，不断探索，积累了丰富的经验，取得了可喜的成绩，文章针对有关主要试点建设情况、试点经验、存在问题及建议进行刍议。 相似文献
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油茶成林抚育和更新改造技术的探讨 总被引：1，自引：0，他引：1
金寨县油茶栽培历史攸久,早在70-80年代,就将油茶与蚕桑、板栗、茶叶和油桐一起作为主要经济林进行开发,建立了油茶基地10万余亩,有比较丰富的油茶栽培和管理经验。通过对安徽省金寨县76户经营油茶林大户的调查,总结了通俗易懂的油茶高产、稳产抚育和更新技术,为进一步提高林农收入服务。 相似文献
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选择四川省沐川县凉风坳亚热带次生常绿阔叶林为研究对象,在2004年5月、2004年12月和2005年5月对其林下土壤种子库、种子雨以及种子天然萌发状况等方面进行系统调查及分析研究。结果显示,种子下落前后土壤种子库储量,变动为643.2～889.2粒.m-2,物种和种子密度多年生草本物种均占优势。天然林土壤种子库Shannon-Wiener指数均在2004年5月最大,2004年12月次之,2005年5月最小;Simpson指数却和Shannon-Wiener指数H＇的变化趋势相反;Pielou均匀度指数在2004年12月有所降低,此后又升高。种子均呈明显垂直分布,其中0～2 cm土层种子数量最多,其次是枯枝落叶层,其数量随着土层加深而降低。土壤种子库年输入活力种子142.3粒.m-2,年输出活力种子268.9粒.m-2,动物取食是造成种子损失的主要原因。对照人工林土壤种子库物种和密度均低于天然林地;种子库与地上植被物种相似性系数,人工林较高,而天然次生常绿阔叶林较低。 相似文献
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《Forest Policy and Economics》2000,1(1):81-94
Policy development is a sequence of political events, each of which is improved with information resulting from scientific inquiry. Science can help identify important issues, broaden the range of policy options, clarify relationships between objectives and policies, and identify risk and uncertainty associated with policies. The National Research Council of the National Academy of Sciences reviewed the scientific basis for federal policies focused on non-federal forests (200 000 000 ha) in the United States. The science review resulted in seven broad recommendations for national action. In retrospect, the review demonstrated that complex administrative issues challenge science, discipline orientation of science often detracts from effective policy development, conflicting scientific evidence can complicate policy decisions, scientific models often suggest more certainty to policy development than actually exists, partisan driven science frequently confuses policy development, and scientific information can conflict with the political necessity to agree on a policy. 相似文献
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通过对0．4、0．6、0．9等3种不同郁闭度的刺槐林下白术生长的研究发现，药用白术在郁闭度0．4的刺槐林下，不仅生长良好，且药材品质优良，有很高的经济效益，平均每年产值约24919．5元／hm^2。栽培2a后对土壤也有一定的改良作用。 相似文献
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Emerging forests on abandoned land: Puerto Rico’s new forests 总被引：1，自引：0，他引：1
The species composition of forests change continuously as the earth’s biota evolves and adjusts to environmental change. Humans are accelerating the rate of species turnover by moving species around the planet and dramatically changing environmental conditions. Our focus is on new forests in Puerto Rico that emerge naturally on abandoned lands previously converted to agriculture and degraded. These forest stands have combinations of species that are new to the island’s landscapes. New forests exhibit high species dominance during forest establishment, which includes dominance by alien tree species. These alien tree species establish and maintain forest cover, which may facilitate regeneration of native tree species. Landscape analysis and literature review revealed that these emerging stands are highly fragmented (60% were <1 ha in 1991), function as refugia for native organisms, and at 60–80 years old have similar species richness and structural features as native stands of similar age. However, the island’s new forests exhibit important differences from mature native forests on unconverted forestlands. New forests have fewer endemic species and fewer large trees (≥55 cm dbh) than mature native forests; they have higher soil bulk density and lower soil carbon and litter stocks; and they accumulate aboveground biomass, basal area, and soil carbon more slowly than native forests of similar age. We suggest that new forests will become increasingly prevalent in the biosphere in response to novel environmental conditions introduced to the planet by humans. 相似文献
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This paper examines how foresters have adapted to important supply and demand driven shocks in the last century that affected timber prices and forest investments. Many of the adaptations that foresters made to changing economic conditions will be the same types of adaptations that society will need foresters to make in the future in order to adapt to climate change. These include changing rotation ages to adapt to shifting disturbance conditions, increasing intensification of management in response to dwindling old growth stocks, movement of species across regions to find better growing conditions, among other things. The paper presents results of an integrated assessment of climate change impacts in forestry and shows how projected future changes for the next century are well within the historical context. 相似文献
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Future harvesting pressure on European forests 总被引：1，自引：0，他引：1
G. J. Nabuurs A. Pussinen J. van Brusselen M. J. Schelhaas 《European Journal of Forest Research》2007,126(3):391-400
We provide quantitative insight in the spatial distribution of the future supply of wood as a raw material from European forests
(27 countries) until 2060. This supply is tested for two scenarios: ‘projection of historical management’ and ‘new management
trends’ and compared against a benchmark scenario. The new management trends scenario incorporates influences of issues as
nature-oriented management, carbon credits and increased demand for bio-energy. The results of these projections provide insight
in the state of the European forests and indicate that under the ‘new management trends’ supply can still increase to 729 million m3 by 2060 in Europe, whereby almost throughout Europe we allow harvest to be higher than increment for some time. Without linking
countries dynamically through international trade, we identify regions where harvesting pressure is highest. Under the new
management trends scenario, the harvested volume is reduced with 82 million m3/year (compared to ‘projection of historical management’) because of stricter management constraints. However, the management
regimes as parameterised here allow harvesting pressure to remain highest in Central Europe and some Scandinavian countries,
notably Finland and Norway.
相似文献
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