共查询到20条相似文献,搜索用时 11 毫秒
1.
Mitsuhisa Baba Shintaro Abe Makiko Kasai Toshihiro Sugiura Hiroshi Kobayashi 《Journal of Forest Research》2011,16(6):446-455
Understory vegetation may affect nitrate (NO3
−) leaching, even in coniferous forests. Our objective was to estimate the contribution of understory vegetation to nutrient
cycling, especially nitrogen, in a Japanese cedar (Cryptomeria japonica) stand. We therefore cut down and removed understory vegetation in one plot of the stand (the cutting plot) to compare nutrient
budgets in the cutting plot with those in a control plot in which understory vegetation was allowed to grow. We also examined
neutralization of the acid produced due to an increase in NO3
− leaching. A monitoring study on precipitation and soil-percolated water was carried out in both plots. When the understory
vegetation was cut down, NO3
− flux at a soil depth of 10 cm increased remarkably in summer, with values significantly higher than those in the control
plot. This resulted in an increase in proton load associated with N transformation ([H+]load). The increase in [H+]load enhanced mobilization of Ca2+, Mg2+, and SiO2 ([SiO2]mob). In addition, the correlations between [SiO2]mob and mobilization of each base cation were distinct in the cutting plot. These results indicated that the acids produced
because of N transformation were buffered not only by ion exchange but also by chemical weathering. The contribution of understory
vegetation to minimizing NO3
− leaching suggested that understory vegetation might reduce the risk of N saturation because of chronic atmospheric N inputs. 相似文献
2.
M. Carneiro A. Fabião M. C. Martins C. Cerveira C. Santos C. Nogueira M. Lousã L. Hilário André Fabião M. Abrantes M. Madeira 《European Journal of Forest Research》2007,126(4):475-480
The aim of this study was to assess the effect of different slash management practices on understory biodiversity and biomass
in Eucalyptus globulus coppices in Central Portugal. The experiment consisted of four treatments: (a) removal of slash (R), (b) broadcast over the
soil (S), (c) as in S but concentrating woody residues between tree rows (W) and (d) incorporation of slash into soil by harrowing
(I). Understory vegetation was surveyed during 1–6, 9, and 10 years, the proportion of soil cover by plant species estimated,
and diversity and equitability indexes determined. Above ground understory biomass was sampled in years 2–6, 9, and 10. The
highest number of species in most years occurred in plots where slash was removed. Differences between treatments in the proportion
of plant soil cover were never significant, whereas differences in diversity index were only occasionally significant and
apparently related to the number of species. Thus, differences in the equitability index were not significant. Understory
biomass did not decrease during the rotation period, and was usually highest in R and I, and lowest in S, but not significantly
different. At the end of the rotation period, understory biodiversity indices and biomass were apparently independent of slash
treatment. 相似文献
3.
Plant species distributions show patterns along elevation gradients. Regardless of the diverse Afromontane vegetation in Ethiopia(AFE), studies of elevation patterns of woody plants are limited and they are restricted to small areas or single/few Mountains. Moreover, there is no general consensus on the patterns of woody taxa distribution by elevation. The objectives of this study were to examine the elevation patterns of woody taxa richness and their relationship with elevation in the AFE. Data were collected and compiled from the Flora of Ethiopia and Eritrea(Vols. 1–7). About 5918 plant species of 243 families were examined and their elevational distributions were recorded. The distributional ranges of woody taxa were aggregated at 19 points(sites) at 100 m intervals starting from 1500 to 3400 m a.s.l. Single-factor analysis of variance(one-way ANOVA) was used to test the hypothesis that mean species richness of woody taxa decreases from the lower to the upper limit of AFE. Simple linear correlation and regression were used to show the relationships of woody taxa richness with elevation. We documented the presence of 505 woody taxa(441 species,31 subspecies and 33 varieties) representing 267 genera and 90 families in the AFE. In terms of habit, 279 taxa are shrubs, 178 are trees and 48 are lianas. The distribution of woody taxa(trees, shrubs and lianas) showed a slight increase at the lower portion and a monotonic decline with increasing elevation. Species richness of trees, shrubs and lianas was negatively and significantly correlated with elevation(r =-0.985,-0.984,-0.981, respectively; all p 0.001). Our hypothesis was accepted because mean richness significantly decreased from the lower to the upper limit of AFE(p 0.001). Generally, monotonic patterns of decline in richness were observed for trees, shrubs and lianas. The contribution of shrubs to total richness increased with increasing elevation whereas that of trees and lianas decreased. 相似文献
4.
5.
为明确徐州山地现有侧柏人工林下层木本植物的自然更新状况,依据40个20m×20m样地群落的调查数据,分析了林下自然更新的木本植物的组成及其相似性。结果表明,侧柏人工林下层自然更新的木本植物中单科种、单属种优势明显,林下木本植物区系组成复杂,出现的12种区系地理成分中,温带成分占主体,热带成分占较大比例。侧柏人工林下层出现的木本植物种类较多,但不同生境下群落的物种丰富度和多样性不高、组成树种的相似性极高,尤其是乔木树种的相似性明显高于灌木树种。林下木本植物的种类组成受立地条件和种子传播方式的显著影响,建议改善立地条件以提高林下木本植物的丰富度和多样性,同时控制外来树种的侵入以促进人工林的地带性演替。 相似文献
6.
The effects of root exclusion and planted tree species on soil nitrogen (N) dynamics were examined at two plantations, one
planted with Japanese cedar and the other with Japanese cypress. We set up ten 1 × 1 × 0.2-m-deep trenched sites and ten untrenched
control sites at each plantation. We measured the pool size and leaching of inorganic N at each site for 2 years and the net
N mineralization 1 and 2 years after trenching. Despite similar soil conditions, the cedar plantation showed higher net N
mineralization than the cypress plantation. Stopped tree uptake of N was expected to cause an increased pool size and leaching
of inorganic N at the trenched sites. Nevertheless, we found no significant increase in those variables at both plantations.
The trenched cypress sites showed no decrease in the net N mineralization during the 2 years after trenching. However, the
net nitrification at the trenched cypress sites increased remarkably at the deeper horizons in comparison with that at the
control sites. Enhanced nitrification might result from improved ammonium availability through root exclusion. Net N mineralization
at the trenched cedar sites decreased more than 60% compared with that at the control sites 2 years after trenching. Higher
nitrification potential at the cedar plantation and enhanced nitrification potential at the trenched cypress sites never resulted
in increased leaching of N, due to added fine root litter which acted as an immobilization agent for excess N, thus preventing
N loss. 相似文献
7.
We studied the effects of line thinning on stand structure, microclimate and understory species diversity of two Cryptomeria japonica D. Don plantations in south-central Japan. In each of two study sites we compared stand structure between the thinned stand
and an adjacent unthinned stand and found that line thinning increased the growth rate of residual trees such that stand basal
area may recover within 10 years after thinning. In the thinned stand, more open canopy conditions resulted in higher maximum
temperatures on the forest floor during the early growing season than in the unthinned stand. The thinned stand had greater
understory plant species richness and biomass than the unthinned stand. This study suggested that line thinning could potentially
enhance biodiversity while simultaneously increasing tree-growth rates in overstocked Cryptomeria japonica plantations. 相似文献
8.
Satoshi Ito Satoshi Ishigami Yasushi Mitsuda G. Peter Buckley 《Journal of Forest Research》2006,11(4):243-251
We compared the occurrence of woody plants present in sugi (Cryptomeria japonica D. Don) plantations and evergreen broad-leaved natural forests in a warm-temperate region in order to characterize the understory
vegetation of sugi plantations. The influence of stand attributes on species occurrence in the plantations was evaluated using
logistic regression analysis. Out of 163 species, 65 plantation-preferring species and 31 natural forest-preferring species
were detected. The plantation-preferring species group contained deciduous species (38 of 65 species) that are characteristic
of coppice woodland, but all the natural forest-preferring species were evergreen plants. This indicates that the composition
of the woody understory in sugi plantations of the region is characterized by the species of open, disturbed habitats. Stand
age and the distance from the nearest natural forests were found to significantly affect the occurrence of evergreen shrubs
and plants with gravity-dispersed seeds, respectively, but the light environment of the stand had less effect. According to
the regression model analyses, long-term strategies such as lengthening the rotation (logging age) or creating patch mosaics
of plantations in the matrix of natural forests appeared to be effective in conserving woodland species that are characteristic
of evergreen, broad-leaved forests. On the other hand, increasing light penetration through thinning practices is a short-term
strategy that is less likely to be effective in promoting these species. 相似文献
9.
10.
Currently, the one of great threats to tropical biodiversity is the conversion of natural ecosystems to agriculture, and this threat is particularly critical on Hainan, the largest tropical island in China and a global biodiversity hotspot. Rubber (Hevea brasiliensis) has been planted on Hainan since the 1950s, resulting in extensive replacement of native forest, and the rate of this transformation has increased with latex prices since the 1990s. Rubber plantations now cover ca. 506,680 ha on Hainan and reach ca 1,000 m in elevation. To investigate the effect of this land-use change, we compared avian communities between a rubber plantation and a native secondary semi-deciduous monsoon forest. We found that species richness was higher in the native forest than in rubber, and that community composition differed greatly between the two habitats. No strict frugivores were recorded in rubber and no granivores in semi-deciduous monsoon forest. In both richness and abundance, more nectarivores and fewer insectivores occurred in rubber than in the native forest. Some common forest species, as well as protected species, were found only in native forest, including Hainan Partridge (Arborophila ardens), Red Junglefowl (Gallus gallus), Emerald Dove (Chalcophaps indica), Black-browed Barbet (Megalaima oorti), Blue-rumped Pitta (Pitta soror), Puff-throated Bulbul (Alophoixus pallidus), and Chestnut Bulbul (Hemixos castanonotus). Although ten babbler species were found in the native forest, only two were in rubber. Among the species missing in rubber was the endemic Hainan species Grey Laughingthrush (Garrulax maesi). Its endangerment through habitat conversion is of particular conservation concern. 相似文献
11.
Cindy E. Prescott Victor Nery Annette van Niejenhuis Toktam Sajedi Peter Marshall 《New Forests》2013,44(5):769-784
Recent re-measurements of silvicultural trials in conifer plantations on nutrient-poor cedar-hemlock (CH) cutovers on northern Vancouver Island have confirmed co-limitation by nitrogen and phosphorus. Repeated fertilization increased volumes of both cedar and hemlock on CH sites (at 2,500 stems ha?1) by about 100 m3 ha?1 relative to unfertilized plots 22 years following initial fertilization, and increased the productivity of regenerating conifers to a level approximating that of neighbouring hemlock-amabilis fir (HA) sites. More surprising was the response to fertilization on the more-productive HA sites. After 22 years, cedar in fertilized HA plots had produced an extra 180 m3 ha?1 compared to unfertilized HA plots, while hemlock had produced an extra 250 m3 ha?1 in fertilized plots (at 2,500 stems ha?1). Thus, contrary to expectations, the greatest volume responses of both hemlock and cedar to fertilization occurred on the good (HA) sites rather than on the poor (CH) sites. Ecological studies of CH and HA sites supported the hypothesis that the poor nutrient supply and productivity of CH sites is a long-term consequence of excessive moisture, and that the two site types bracket a critical ecological threshold of moisture, aeration and redox. 相似文献
12.
对位于漳州平和7年生的3种相思人工林生物量的分配格局和林下植被多样性进行研究,结果表明:马占相思林下植被Shannon-Wiener多样性指数最高(3.0936),黑木相思其次(3.0649),卷荚相思最低(2.2430);而与物种数目无关的Shannon均匀度指数则以黑木相思最高,表明其物种组成比较均匀;3种相思人工林林下植被群落相似性指数均在0.5~0.75之间,表现为中等相似;在3种相思人工林单株各器官生物量组成中,干材生物量所占的比例最大(55.30%~68.28%),其它组分依次为:根(14.72%~19.30%)>皮(10.59%~10.82%)>枝(3.96%~9.19%)>叶(2.42%~8.39%);3种相思人工林林下植被生物量大小顺序为:卷荚相思(6.69 t.hm-2)>马占相思(6.24 t.hm-2)>黑木相思(4.21 t.hm-2);3种相思人工林林分生物量的大小顺序为卷荚相思(75.21 t.hm-2)>黑木相思(49.19 t.hm-2)>马占相思(48.22 t.hm-2)。对3种相思人工林生物量分布格局的比较研究表明:卷荚相思生产力高,适宜在闽南山地营林生产实践中推广。 相似文献
13.
14.
The removal or maintenance of harvest residues in eucalypt plantations may influence site quality and productivity. Removal of slash from the site may facilitate further management operations and provide a valuable energy resource, but effects on site productivity and sustainability for a rotation time span were not yet assessed under Mediterranean conditions. Therefore, a study was carried out to assess the effects of slash (harvest residues plus forest floor litter) management and soil preparation options on stand productivity and understory vegetation dynamics, hypothesizing that those options influence tree growth, forest floor dynamics and understory biomass and diversity. An experiment was installed in West Central Portugal, consisting on: removal of slash without soil preparation (R); broadcast of harvest residues on the soil surface without soil disturbance (S); as in S, but concentrating the woody debris between tree rows (W); incorporation of slash into the soil by harrowing (I); removal of slash followed by harrowing (RH); and as in I followed by ripping (IS). The experiment was monitored for a rotation time span (140 months). Maintenance of slash followed by deep soil disturbance led to the highest wood production, but differences between treatments were not significant (p > 0.05). Forest floor load and understory biomass were also similar between treatments. Ground vegetation played an important role on nutrient cycling in early rotation stages, such effect being irrespective on slash management options. Incorporation of slash into the soil followed by ripping is probably the best option to match production and environmental sustainability of eucalypt plantations in Mediterranean conditions. 相似文献
15.
M. Abdul Maleque Hiroaki T. Ishii Kaoru Maeto Shingo Taniguchi 《Journal of Forest Research》2007,12(1):14-23
We investigated the effects of line thinning on the abundance of Hymenoptera in two Japanese cedar plantations in northern
Hyogo Prefecture, central Japan, in order to evaluate the effectiveness of this silvicultural treatment for ecosystem management.
Line thinning is a silvicultural treatment practiced in Japan, where linear stand sections are cut (25%–35% of the total number
of trees) retaining one to two rows of trees. We used Malaise traps to capture Hymenoptera from the line-thinned stand (treatment
plot, including thinned and retained sections) and the unthinned stand (control plot). Overall, the total number of Hymenoptera
was greater in the treatment plot than in the control plot. The treatment plot hosted more functional groups and families
of Hymenoptera than the control plot in both plantations. In the Kuchiotani plantation (high-elevation site), the overall
abundance of Hymenoptera and of many Hymenopteran functional groups were positively correlated with both species richness
and biomass of understory plants. In the Sugi plantation (low-elevation site), understory vegetation was less developed and
there was no correlation with abundance of Hymenoptera. Our study indicates that line thinning is an effective silvicultural
treatment for future management of overstocked Japanese cedar plantations because it can fulfill biodiversity objectives,
but the effectiveness may depend on silvicultural and landscape factors. 相似文献
16.
Diversity of naturally-regenerated native woody species in forest plantations in the Ethiopian highlands 总被引:1,自引:0,他引:1
Woody species diversity and ground layervegetation cover were studied in plantations ofPinus patula, Cupressus lusitanica,Grevillea robusta, and Juniperusprocera, and in surrounding natural forests inWondo Genet, Ethiopia. In the understory of theplantations, a total of 53 naturallyregenerated tree and shrub species belonging to31 families were recorded. Important indigenoustimber species were also represented. Treesaccounted for 72% of all naturally-regeneratedwoody plant species. On the average, 78% ofthe woody species found in plantations werealso found in the natural forest. There was nosignificant variation in understory woodyspecies richness among plantations. C.lusitanica plantations had a significantlyhigher abundance of woody species than those ofP. patula, but the difference wasnot significant in relation to J. procera,G. robusta and the adjacent natural forest.The herbaceous ground cover percentage in G. robusta and P. patula stands wasconsiderably higher than in C. lusitanicaand J. procera stands. Relative toplantations of other species, plantations ofthe native tree species J. procera hadhigher understory species richness, mediumwoody species abundance and low ground cover.Although there was a marked variation inoverstory plantation density, its effect onunderstory species richness and abundance wasnot significant. The density ofnaturally-regenerated woody species inplantations was over three times the usualplanting density in Ethiopia, indicating a highpotential of forest plantations for restoringthe natural forest ecosystems on degraded landsat a comparatively low cost. 相似文献
17.
Steven A. Knowe 《New Forests》1991,5(3):175-193
A system for examining the effects of hardwood density and cover of herbaceous components on mean size in newly established loblolly pine plantations was developed using a site preparation study located in the piedmont province of Georgia (USA). Multispecies density models were derived to predict the sum of crown heights for eight important hardwood species using both the current or age 1 number of rootstocks and herbaceous vegetation to account for intra- and interspecific effects. The predicted sums of crown heights for the woody species were then used as predictors of mean height, diameter, and volume for loblolly pine. A seemingly unrelated regression procedure was used to compensate for correlations in error components within each system of equations that result from using predicted crown heights as regressor variables. The effects of varying sweetgum density and andropogon cover on the inter-related components of the systems based on current and age 1 competition were examined for mean height and mean diameter of the planted loblolly pines. The cumulative impacts of associated vegetation on loblolly pine growth and the relative sensitivity of height and diameter to competing vegetation were demonstrated. 相似文献
18.
The chemical structures of hemicellulose and lignin are different for two distinct types of wood, i.e., softwood and hardwood.
Such differences are expected to affect pyrolysis behavior. In this article, the differences are discussed for Japanese cedar
wood (a softwood) and Japanese beech wood (a hardwood) pyrolyzed in a closed ampoule reactor (N2/600°C/40–600 s). Oven-dried samples were used to eliminate the influence of initial water. Demineralized samples (prepared
by acid washing) were also used to determine the influence of the minerals contained in the wood samples. As a result, some
features were disclosed for secondary char (coke) formation, char reactivity, tar formation, and subsequent decomposition. 相似文献
19.
采取种群空间分布格局进行研究与分析,运用扩散系数,丛生指数,扩散指数,聚块性指数,Cassie R.M.指数等聚集度指标对塞罕坝大唤起林场华北落叶松林下植被的水平空间结构进行分析研究,发现多数草本在华北落叶松林下呈聚集分布,极少种类如景天三七、柳兰、柳叶沙参和狭叶荨麻等呈随机分布。结果表明,该地区华北落叶松林生物群落稳定,林下草本生物多样性高。 相似文献
20.
Philip J. Radtke Ralph L. Amateis Stephen P. Prisley Carolyn A. Copenheaver David C. Chojnacky Judd R. Pittman Harold E. Burkhart 《Forest Ecology and Management》2009
Forest management can have large impacts on the production and yield of coarse woody debris (CWD) in terrestrial ecosystems, yet few modeling tools exist to inform such efforts. The goal here was to develop a set of prediction equations for use in conjunction with loblolly pine (Pinus taeda L.) modeling and inventory systems to estimate CWD yields at scales ranging from individual trees to whole plantations. Permanent field plots from a 21-year study of thinning effects on plantation growth and yield across the commercial range of the species in the southern United States were surveyed to obtain sample data on CWD volume, density, and mass. Measured CWD properties were combined with inventory records of tree mortality over the study duration to characterize CWD production, decay and yield in a series of prediction equations. The resulting equations predict CWD attributes of dead trees including dry weight (kg) and fraction of standing versus downed woody material based on the time since death (years), tree diameter at breast height (cm) and height (m) at time of death and geographic coordinates of latitude and longitude. A stand-level equation predicts total CWD yield (Mg ha−1) for thinned or unthinned stands based on plantation age, stem density (trees ha−1), and the average height of dominant and codominant trees (m). Piece-level equations predict dry density (kg m−3) or nitrogen concentration (%) of CWD pieces based on their position (standing or down), ordinal decay classes, and latitude. The tree and stand-level prediction equations are designed for use in GIS or growth and yield modeling systems. The piece-level equations are designed to be used in inventory applications that survey CWD. The equations should facilitate the accurate and facile determination of mass, carbon, and nitrogen contents of CWD in planted loblolly pine forests of the southern United States. 相似文献