不同林型凋落物土壤微生物数量动态的研究

本文主要对柏木纯林、桤柏混交林凋落物分解袋地表土土壤微生物年动态变化进行分析。分析结果表明，在桤柏混交林内，细菌数量最多，放线菌次之，真菌最少；在柏木纯林中，细菌和放线菌数量基本相同，真菌较少。在两种林型中，三大微生物种群数量在３月最少，６～９月最多。微生物生理类群数量分析结果为桤柏混交林中的固氮菌、硝化菌、氨化细菌均大于柏木纯林。纤维分解菌类两者基本相同。柏木纯林反硝化菌类多于桤柏混交林。     

桤柏混交幼林群落特征及生物量调查

桤柏混交林是川中盆地钙质紫色土区主要造林模式之一。因其群落稳定、生产力高,深受群众喜爱。对7年生桤柏混交林进行群落特征及生物量调查的结果表明:7年生桤柏人工幼林已郁闭成林,形成复层林冠层,垂直结构明显;桤木高4.37m,覆盖度32％;柏木高1.19m,覆盖度30％;草被均高0.5m,覆盖度95％;桤木根深30cm,柏木根深15cm。桤柏混交林群落植物种类为18种,总生物量14.794t/ha。纯柏林群落植物种类7种,总生物量3.583t/ha。柏木根系侧根发达,主根不明显.<0.2cm根量占总根量的23.1％。桤木根系主根明显,垂直根系发达,水平根少、<0.2cm根量占总根量的3.4％。桤柏混交幼林群落植物体内含水量与总生物量大致相等。乔木层各器官水分系数排序为:叶>枝 根>干。     

桤柏混交林的效益探讨

桤柏混交林是川中丘陵区的主要造林类型。本文对不同年龄阶段的桤柏混交林进行了对比研究。结果表明：２６年生的混交林中其柏木在单位面积上的蓄积最比纯柏木林大８０．６％，地上中分生物量比纯林高４７．２％；混交林柏木的Ｎ，Ｐ，Ｋ，Ｃａ等营养元素含量分别 比纯柏林高６５．４７％，５０．４３％，７．７０％和１７．９６％；混交林内空气相对湿度比纯柏木林大９．４－１０．５％，混交林能改善生态环境，提高土壤肥力。     

人工桤柏混交林光合生理生态机理研究

本文对四川盆地紫色土区人工桤柏木桤柏木混交的光合生理生态机理进行了探讨。研究表明,桤、柏木混交的光合生理生态机制在于：桤、柏木的光合作用在日变化和季节变化上存在时间匹配效应,在林木结构上存在光合作用的空间匹配效应,因而使桤柏木能充分有效地利用林地上各层次水平的光能资源,大大提高混交林群体的光能利用效率,使之成为川中丘降紫色土区的高产林分类型。研究还表明,桤柏混交林林冠光合作用的日变化和季节变化进程基本上与桤木的变化趋势一致,这主要由桤柏木的生物生态学特性决定;桤柏林林冠光合作用主要受气温、光照和CO2浓度的影响,温度因子的影响相对较小。     

绵阳新桥镇防护林体系桤柏混交林光合作用日变化研究

本文利用美国产ＬＩ—６２００便携式光合作用分析系统、ＬＩ—３０００叶面积仪配合照度计、通风干湿球温湿度计、土壤湿度计等测定了绵阳新桥防护林体系生长季节中桤柏混交林树种南、北面叶片光合作用每小时日变化进程，探讨了桤木和柏木光合作用率及其变动程度，指出了它们的光合作用日变化类型，从日射量、温度、ＣＯ２浓度等外界条件及内生节奏方面阐述了光合作用日变化机理，同时计算和分析了桤柏混交林平均光合作用率日变化类型和量子产额。结果表明桤木光合作用日变化为中午降低型，柏木为正规型曲线，桤木上午光合作用率高于下午，柏木为上午低于下午，它们都具有较高的量子产额，其光合作用日变化不存在着时间效应，为防护林功能研究提供依据。     

绵阳新桥镇防护林系桤柏混交林光合作用日变化研究

本文利用美国产ＬＩ－６２００便携式光合作用分析系统，ＬＩ－３０００叶面积仪配合照度计，通风干湿球温湿度计，土壤湿度计等测定了绵阳新桥防护林体系生长季节中桤柏混交林树种南，北面叶片光合作用每小时日变化进程，探讨了桤木和柏木光合作用率及其变动程度，指出了穴们的光合作用日变化类型，从日射量，温度，ＣＯ２浓度等外界条件及内生节奏方面阐述了光合作用日变化机理，同时计算和分析了桤柏混交林平均光合作用率日变化类     

柏木混交林类型分布立地条件的研究

本项研究应用主成分排序方法研究四川盆地4种天然柏木混交林分布与立地条件的关系,结果表明:区域内影响柏木混交林类型分布的主导立地因子是地形、土层厚度、水湿状况、土壤碳酸钙含量、pH值等。桤柏混交林主要分布在山中下部平缓的台阶低洼地带,水湿条件较好,土层深厚的地方;栎柏混交林主要分布在山中上部干燥瘠薄的立地上,生产力低;桤栎柏混交林介于二者之间;松柏混交林要求土壤中碳酸钙含量低,土壤呈微酸性至中性反应。林下灌木树种分布与立地条件因子无明显规律性。     

桤木冬播春移育苗好

桤木生长快、具根瘤,能固氮,是组成混交林的优良速生树种,开化县林场自1978年从四川引种后,现已营造桤木纯林410亩,桤柏、桤杉混交林520亩。在适宜条件下,5年生桤木平均胸径10.6厘米,平均树高10.5米,开化县现已普遍种植,并向全省各     

四川盆地丘陵区主要森林群落结构特征研究

本文对四川盆地丘陵区主要森林群落--人工柏木纯林、次生栎柏混交林和桤柏混交林的群落结构特征进行了研究.结果表明：在群落的物种组成、生活型、层片结构以及Shannon-Wiener多样性指数、Pielou均匀度指数和Simpson生态优势度指数表征的群落综合特征上,次生混交林与人工林具有很大差异.人工柏木纯林物种数量少,乔、灌、草层的物种多样性和均匀度较低,生态优势度较高;次生栎柏混交林和桤柏混交林物种数量较多,乔、灌、草层有较高的物种多样性和均匀度,较低的生态优势度.     

桤木冬播春移育苗试验

<正> 桤木(Alnus cremastogyne Burk)是优良速生用材树种,具根瘤能固氮,是组成混交林的理想树种。开化县林场自1978年以来,已从四川引种营造桤木纯林410亩,桤柏、桤杉混交林520亩,通过大面积造林试验表明,在适宜条件下,5年生桤木平均胸径10.6厘米,平均     

Energy efficiency of large cardamom grown under Himalayan alder and natural forest

Energy efficiency of agroforestry systems of large cardamom grown under N₂-fixing Himalayan alder (alder-cardamom) and natural forest (forest-cardamom) was studied in the Sikkim Himalaya. Large cardamom (Amomum subulatum), the most important perennial cash crop of the region, is widely cultivated with Himalayan alder (Alnus nepalensis) as shade tree. Energy fixation, storage, net allocation in agronomic yield, and heat release and exit from the system were respectively 1.57, 1.44, 2.24 and 2.22 times higher in the alder-cardamom compared to the forest-cardamom system. Energy conversion efficiency and net ecosystem energy increment were also higher in the alder-cardamom than the forest-cardamom system. Energy fixation efficiency and energy conversion efficiency of large cardamom increased under the influence of Himalayan alder. Energy efficiency in N₂-fixation of Himalayan alder was also high (67.5 g N₂ fixed 10⁴ kJ^-1 energy). Quantum and flux of energy increased in the alder-cardamom compared to the forest-cardamom system that optimized the production potential of the cash crop under the influence of the Himalayan alder. Climatic sympatry of the large cardamom and Himalayan alder, and their synergetic energy efficiency makes this association ecologically and economically viable for the mountain regions.This revised version was published online in November 2005 with corrections to the Cover Date.     

Long-term nutrient cycling patterns in Douglas-fir and red alder stands: a simulation study

Long-term patterns in nutrient cycling in regrowing Douglas-fir (Pseudosuga menziesii Mirb. Franco) and red alder (Alnus rubra Bong.) on native soils plus soils previously occupied by other species were simulated using the nutrient cycling model. Simulations of regrowing stands were also compared with observations of nutrient cycling in mature Douglas-fir and red alder. We hypothesized that (1) prolonged presence of red alder will cause a depletion in soil base cations due to increased nitrification and NO₃⁻ leaching; (2) lower base cation availability under red alder will ultimately cause biomass production to decline; (3) high N availability in red alder soils will favor regrowth of Douglas-fir; (4) higher base cation and P status of the Douglas-fir soils will favor growth of red alder both in the short- and long-term, since N is not limiting to red alder; and (5) in regrowing red alder, NO₃⁻ leaching will increase with time as a result of increased N fixation. All hypotheses were confirmed, but the effect of soil type on biomass production was minimal both for red alder and Douglas-fir. The higher soil organic matter content in the mature red alder stand most likely reflected previous occupation by old-growth Douglas-fir and also a large litter input from the understory vegetation. In general, the nutrient cycling model simulated differences in nutrient cycling patterns at least qualitatively between Douglas-fir and red alder and was helpful in identifying potential gaps in the understanding of biogeochemical cycling as well as uncertainties in the data. The nutrient cycling model did not fully elucidate differences in P cycling between Douglas-fir and red alder and overestimated weathering rates under Douglas-fir. Uncertainties in the data included: (1) temporal patterns in N fixation in the regrowing stands; (2) understory litterfall; and (3) site history and, consequently, presence of pre-existing differences in site conditions.     

Autumnal changes of sulfur fractions and the ratio of organic sulfur to total nitrogen in leaves and adjacent bark of eastern cottonwood, white basswood and actinorhizal black alder

Autumnal changes in organic-S, sulfate-S, total-S and the ratios of organic-S to total-N and sulfate-S to organic-S were followed in leaves and adjacent bark of actinorhizal (Frankia-nodulated) black alder (Alnus glutinosa (L.) Gaertn.) and eastern cottonwood (Populus deltoides Bartr. ex Marsh.) trees growing on a minespoil site high in extractable soil sulfate, and in black alder and white basswood (Tilia heterophylla Venten.) trees growing on a prairie-derived soil in Illinois. Organic-S concentrations decreased significantly (P < 0.05) during autumn only in foliage of trees growing on the prairie-derived soil where losses of leaf organic-S were 65% for black alder and 100% for white basswood. Leaf sulfate concentrations were relatively stable throughout autumn in white basswood growing on prairie-derived soil and in black alder at both sites. Sulfate-S concentrations in leaves were significantly (P < 0.05) higher in trees at the minespoil site than in trees growing in the prairie-derived soil (5.1 mg g(-1) for the minespoil site and 1.2 mg g(-1) for the prairie-derived soil), and in the non-actinorhizal species during late summer. During the autumn, the ratio of organic-S to total-N doubled in leaves of eastern cottonwood at the minespoil site, but in black alder and white basswood growing on the prarie-derived soil, it decreased by 60 and 74%, respectively. Organic-S concentrations in bark increased more during autumn in species unable to fix atmospheric N(2), than in black alder. The results suggest that patterns of autumnal translocation of leaf S can be site-dependent and that leaf S and leaf N are, at least in part, translocated independently in the fall. Black alder and eastern cottonwood seemed to incorporate sulfate-S readily into organic substances in leaves when grown in soils with a high sulfate content.     

Red alder leaf decomposition and nutrient release in alder and conifer riparian patches in western Washington,USA

Current management practices encourage conversion of red alder (Alnus rubra) riparian forests to conifers in the Pacific Northwest U.S. Patches of young naturally regenerated conifers are commonly present in alder dominated riparian areas and an understanding of the soil processes in these patches will be helpful in guiding future riparian management. Study objectives were to: (1) determine decomposition rates of red alder leaves in riparian alder and conifer patches, (2) relate decomposition rates to environmental factors and litter chemistry, and (3) determine nutrient release from decomposing alder leaves in these patches. Study sites were riparian areas adjacent to Brown and Le Bar creeks in the Skokomish River basin, Olympic National Forest, Washington. Red alder leaves were placed in litterbags in red alder and conifer riparian patches along each stream in November 2000 and collected after 1 and 3 years. There was rapid mass loss of alder leaves in the first year in both patch types, but decomposition was significantly faster (p < 0.05) in alder patches (43.2% mass remaining, k = 0.855 year⁻¹) than in conifer patches (48.4% mass remaining, k = 0.734 year⁻¹). There was little mass loss after the first year and no significant difference in decomposition rates. After 3 years mass remaining was 44.2% (k = 0.283 year⁻¹) and 47.8% (k = 0.48 year⁻¹) in alder and conifer patches, respectively. Decomposition rate differences were attributed more to the effects of the different litters in each patch and the influence on soil microbial and faunal communities than differences in soil temperature and moisture. The forest floor was deeper in conifer patches (3.7 cm) than alder (1.8 cm) patches. This was ascribed to slower decomposition rates in conifer patches, greater litterfall in conifer patches, and/or removal of alder surface litter by flooding. Alder patches were lower in elevation (0.8 m above bankfull width) than conifer patches (2.2 m). Forest floor and soil C and N concentrations and pHs were not significantly different in alder and conifer patches. Nutrient release from decomposing alder leaves was not significantly different in conifer and alder patches, although there was a trend for C, N, P, K, and Ca to be lost faster from leaves in alder patches than conifer patches in the first year. Red alder litter input to riparian conifer patches will initially decompose rapidly and provide nutrients, particularly N and P to conifers, as well as enhancing soil C since long-term decomposition rates are slow.     

Aboveground biomass and nutrient accumulation dynamics in young black alder, silver birch and Scots pine plantations on reclaimed oil shale mining areas in Estonia

The growth, aboveground biomass production and nutrient accumulation in black alder (Alnus glutinosa (L.) Gaertn.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) plantations during 7 years after planting were investigated on reclaimed oil shale mining areas in Northeast Estonia with the aim to assess the suitability of the studied species for the reclamation of post-mining areas. The present study revealed changes in soil properties with increasing stand age. Soil pH and P concentration decreased and soil N concentration increased with stand age. The largest height and diameter of trees, aboveground biomass and current annual production occurred in the black alder stands. In the 7-year-old stands the aboveground biomass of black alder (2100 trees ha⁻¹) was 2563 kg ha⁻¹, in silver birch (1017 trees ha⁻¹) and Scots pine (3042 trees ha⁻¹) stands respective figures were 161 and 1899 kg ha⁻¹. The largest amounts of N, P, K accumulated in the aboveground part were in black alder stands. In the 7th year, the amount of N accumulated in the aboveground biomass of black alder stand was 36.1 kg ha⁻¹, the amounts of P and K were 3.0 and 8.8 kg ha⁻¹, respectively. The larger amounts of nutrients in black alder plantations are related to the larger biomass of stands. The studied species used N and P with different efficiency for the production of a unit of biomass. Black alder and silver birch needed more N and P for biomass production, and Scots pine used nutrients most efficiently. The present study showed that during 7 years after planting, the survival and productivity of black alder were high. Therefore black alder is a promising tree species for the reclamation of oil shale post-mining areas.     

Tolerance of 2-year-old Forestry Trees to Five Herbicides

There is a need for selective foliar-acting herbicides for transplantlines in forestry nurseries and new forestry plantings. Toleranceof 2-year-old pot-grown trees of beech, birch, sycamore, ash,cherry, oak, red alder, Japanese larch and Sitka spruce to contactherbicides applied at different dates in the growing seasonwas investigated.Clopyralid was safe to use on all species apartfrom some fresh weight reduction in Japanese larch. Bentazoneand phenmedipham caused initial necrosis on most species tested;however, most trees outgrew the effect of phenmedipham in thefollowing season. Bentazone, generally, had a long-term inhibitoryeffect on growth of alder and at the highest dose tested (5.2kg ha^–1 ) also affected ash and beech.Metsulfuron-methyland tribenuron-methyl were safe on most species tested.However,fresh weight reductions were caused by metsulfuron-methyl inash and cherry and by tribenuron-methyl in alder. Mecoprop damagedall species, apart from Sitka spruce.     

A comparison of annual transpiration and productivity in monoculture and mixed-species Douglas-fir and red alder stands

Although much is known about drivers of productivity in Douglas-fir and red alder stands, less is known about how productivity may relate to stand transpiration and water use efficiency. We took advantage of a 15-year-old experiment involving Douglas-fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in the western Cascade Range of western Oregon to test the following hypotheses: (a) more productive stands transpire more water, (b) the relationship between productivity and transpiration differs between species, and (c) the relationship between productivity and transpiration differs between sites varying in soil moisture and fertility. Furthermore, the experimental design included alder, a facultative nitrogen-fixing species, which could also affect fertility. Fixed area plots (20 × 20 m) were planted as monocultures of each species or in mixtures at a common density (1100 trees ha⁻¹) in a randomized-block design. Transpiration of Douglas-fir and red alder was measured using heat dissipation sensors installed in eight trees per plot and scaled to the plot level based on sapwood basal area for each species. Although up to 53% of the variability in tree transpiration was explained by basal area, irrespective of species or site conditions, the two stands with the highest biomass and sapwood basal area did not transpire the most. Instead of more productive stands transpiring more water, the greatest variability in both productivity and transpiration was determined by site conditions and to a lesser degree, species composition. For example, 70% of the variation in tree biomass increment (TBI) was determined by leaf area index, which was much higher at the site with higher fertility and soil moisture (p < 0.05). Despite marked phenological and physiological differences, Douglas-fir and red alder performed similarly. Only 19% of annual water use of Douglas-fir occurred between October and March when alder was leafless. Also, there was no evidence of a fertilization effect of the nitrogen-fixing red alder on the Douglas-fir: the nitrogen concentration and N-isotopic ratio of Douglas-fir needles did not differ whether trees were grown in monoculture or in mixtures with red alder. We conclude that lower soil fertility and contrasting microclimate at one site relative to the other suppressed NPP while maintaining higher transpiration, thus reducing water use efficiency.     

Productivity of European black alder (Alnus glutinosa) interplanted with black walnut (Juglans nigra) in illinois,U.S.A.

Fast-growing woody nurse crops planted among high value hardwoods can produce merchantable biomass early in the life of the plantation. On a productive site in south-central Illinois (U.S.A.), experimental interplantings of European black alder (Alnus glutinosa (L.) Gaertn.) and black walnut (Juglans nigra L.) were established and maintained under a factorial combination of two initial densities and two thinning regimes. This study evaluated the growth response of the alder component of this system. Although alder consistently overtopped walnut, alder mortality began to increase dramatically during the seventh growing season and was nearly complete following the nineteenth growing season. Mean alder cumulative dry mass through year 14 ranged from 19.05 to 58.62 Mg/ha among initial density and thinning treatments. Carbon sequestered in useable bolewood constituted approximately 25 of total biomass. The productivity of the interplanted alder was comparable to that of native forests while constituting only a portion of the stand and without negatively impacting walnut growth or bole quality. These results suggest that, if marketed, alder has the potential to partially offset costs associated with walnut plantation establishment and maintenance.     

Phytophthora disease of alder (Alnus glutinosa) in France: investigations between 1995 and 1999

A severe decline of alder associated with an undescribed Phytophthora species was identified for the first time in England in 1993. No generalized decline of alder was reported in France before 1990. The first diebacks and mortalities of common alder were observed at the beginning of the 1990s, but the so‐called alder Phytophthora was not isolated in France until 1996. First, a synthesis about alder declines that were known in France before 1995 is presented. Then, a survey was established in north‐eastern France; 108 sites were visited and the alder Phytophthora was isolated from 57 of them. All the main rivers were found to be affected and damage levels are significant along some of them. The frequency of the alder Phytophthora and other fungi isolated from declining alders is discussed. Finally, information on other alder declines in France is presented region by region, and a map summarizes the known distribution of the disease. The alder Phytophthora is quite common and widespread in France, with western and north‐eastern France being especially affected; however, the number of diseased or dead trees varies greatly from one site to another. All records are from Alnus glutinosa; other Alnus species were seldom seen in the surveys.