林分因子对成都绕城高速路域不同人工林群落物种多样性的影响

【目的】为探究林分因子对不同路域人工林群落物种多样性的影响,为成都路域人工林营造与管理提供参考。【方法】研究采用典型样地法对成都绕城高速路域现种植的5种不同人工林群落（Ⅰ,加杨纯林;Ⅱ,樟树、加杨混交林;Ⅲ,樟树纯林;Ⅳ,樟树、巨桉混交林;Ⅴ,巨桉纯林）进行全面踏查,调查林分因子及林下植被物种多样性。【结果】（1）研究区共记录植物184种,隶属于72科132属。5种不同人工林群落乔-灌-草三层的植物科属种数量均为草本层＞灌木层＞乔木层,其中樟树纯林记录到的林下物种数最多。（2）构树（Broussonetia papyrifera）和葎草（Humulus scandens）重要值占比大,分别占据不同人工林群落灌木层与草本层的优势地位。（3）在5种不同人工林群落中,樟树纯林的灌木物种丰富度指数D显著高于其他群落（P<0.05）;草本层的Shannon-Wiener指数H、Simpson指数H′和D大小变化趋势一致,表现为群落Ⅲ>Ⅳ>I>I>V,其中樟树纯林的H显著高于樟树、巨桉混交林外其他群落（P<0.05）。（4）冗余分析结果表明：乔木层平均冠幅与灌木层的D和H、草本层的H、H''、D、Jsw均呈显著正相关（P<0.01）,与灌木层的H''和Jsw均呈显著负相关（P<0.01）;乔木层平均枝下高与灌木层的H、H''、D、Jsw均呈显著正相关（P<0.01）。【结论】乔木层的树种组成、平均枝下高和平均冠幅显著影响路域人工林群落的物种多样性,选择合适树种并定期修枝管理,将有利于路域人工林良好乔灌草群落结构形成和林下植被物种多样性维持。 关键词 林分因子;路域人工林;林下植被;物种多样性     

Structure and floristics of secondary and old-growth forest stands in lowland Costa Rica

We characterized stand structure and floristic composition of woody life forms in three, 16–18 yr old secondary stands that regenerated after pasture abandonment, and three nearby old-growth stands of tropical rain forest in lowland Costa Rica. Basal area and stem density for each of four plant size classes (seedlings, saplings, treelets, trees) were similar among stand types, but density of adult canopy palms (individuals 10 cm DBH), was lower in the secondary stands. We estimate that 15% of the basal area of stems 10 cm DBH correspond to remnant trees in our secondary stands. The observed rapid woody regrowth compared to other published studies in the lowland neotropics, can be attributed to moderate land use and possibly, to the influence of nutrient-rich volcanic soils in the study area. Overall, plant species richness was lower in the secondary stands, but this difference was less pronounced in the smallest size classes (seedlings, saplings). Median percent similarity of all pairwise stand comparisons showed that floristic composition of saplings (stems 1 m tall and 5 cm DBH) was more similar between secondary and old-growth stands than for trees (stems 10 cm DBH). Because the potential value of secondary forests in conserving woody plant diversity appears highest for the young size classes, we suggest that further studies on floristic composition, especially those addressing the dynamics of the understory component, are needed to refine our understanding of the role of this natural resource in the maintenance of plant biodiversity in disturbed landscapes.     

Structure,biomass and production of a resprouted holm-oak (Quercus ilex L.) forest in NE Spain

When considered as a compartment of nutrients (biomass) and as a flux between compartments (production) vegetation plays an important role in the biogeochemical forest research that is carried out at the Prades research station in two adjacent catchments: L'Avic (51.6 ha) and La Teula (38.5 ha). The forest density at the Prades site, considering both the tree and shrub layers, is 9182 stems ha^–1, with 4527 stems ha^–1 being the tree layer. The predominant species is Quercus ilex with Arbutus unedo and Phillyrea media less common. The structure of the population, estimated by grouping the numbers of the stems in classes of 2.5 cm, shows a distribution which conforms, in both catchments, to a negative exponential equation following the Yoda law. The distribution observed at different altitudes shows great heterogeneity, the number of stems of Q. ilex increases with altitude, from 4000 stems ha^–1 at 800 m, to 14000 stems ha^–1 at 1000 m of altitude. The upper and the lower parts of the watershed show differences in forest production that explain this variation. In this paper the influence of human activities and physical factors on the origin of this structure is discussed. The tree and shrub biomass was calculated by applying allometric regressions for the three predominant species and has been estimated as 113.2 t ha^–1. The tree layer accounts for 92%. Net production was calculated from annual increases (by differences between the 1981 and 1986 basal area measures) of the woody part and the litterfall. The above-ground net production was about 6.5 t ha^–1 year^–1, 95.4% of it being from trees and shrubs and only 4.6% from grasses.     

Species and structural diversity of church forests in a fragmented Ethiopian Highland landscape

Question: Thousands of small isolated forest fragments remain around churches (“church forests”) in the almost completely deforested Ethiopian Highlands. We questioned how the forest structure and composition varied with altitude, forest area and human influence. Location: South Gondar, Amhara National Regional State, Northern Ethiopia. Methods: The structure and species composition was assessed for 810 plots in 28 church forests. All woody plants were inventoried, identified and measured (stem diameter) in seven to 56 10 m x 10‐m plots per forest. Results: In total, 168 woody species were recorded, of which 160 were indigeneous. The basal area decreased with tree harvest intensity; understorey and middle‐storey density (<5 cm DBH trees) decreased with grazing; overstorey density (>5 cm DBH trees) increased with altitude. The dominance of a small set of species increased with altitude and grazing intensity. Species richness decreased with altitude, mainly due to variation in the richness of the overstorey community. Moreover, species richness in the understorey decreased with grazing intensity. Conclusions: We show how tree harvesting intensity, grazing intensity and altitude contribute to observed variations in forest structure, composition and species richness. Species richness was, however, not related to forest area. Our study emphasizes the significant role played by the remaining church forests for conservation of woody plant species in North Ethiopian Highlands, and the need to protect these forests for plant species conservation purposes.     

Effects of topography on tropical lower montane forests under different geological conditions on Mount Kinabalu,Borneo

Species composition and forest structure change with topography.However, mechanisms for topographical vegetation changes are still not wellunderstood, because a topographical gradient is a complex environmentalgradientinclusive of many factors. The foot of Mt. Kinabalu is covered with three typesof geological substrates, i.e. Quaternary and Tertiary sedimentary rocks andultrabasic (serpentine) rock. Quaternary and Tertiary sedimentaryrocks are different in site age, but controlled in primary minerals. Tertiarysedimentary and ultrabasic rocks are contrasting in primary minerals, but arecomparable in age. This setting provides an opportunity to examine thevegetation differentiation along topographical gradients that are contrastinginmajor-nutrient supply due to the difference in site age and parent rock.We established a total of nine study plots by choosing three topographicalunits(ridge, middle- and lower-slope) on each substrate inthe tropical lower montane forest. Pool size and supply of soil N and Pdecreased upslope on each substrate, and the magnitude of the reduction fromslope to ridge decreased in the order of Quaternary sedimentary > Tertiarysedimentary > ultrabasic rock. Between-substrate difference in soilnutrient condition was greater on the lower-slopes than the ridges.Maximum tree size decreased and stem density increased upslope on eachsubstrate. Detrended correspondence analysis demonstrated that speciescomposition also changed along topographical gradients on all substrates.However, the magnitude of topographical changes in forest structure and speciescomposition varied with substrate and decreased from Quaternary sedimentary>Tertiary sedimentary > ultrabasic rock. The greatest between-substratedifference in vegetation occurred on the lower-slopes. Accordingly, ourresults suggest that the magnitude of vegetation changes due to topographybecomes smaller with decreasing pool size and supply of nutrients.     

Forest biodiversity gradients and the human impact in Annapurna Conservation Area, Nepal

Patterns of biodiversity, environment and human impact were studied in 57 sample plots in an 1,178 ha forest area in a rural mountain area of Nepal that is administrated by the Annapurna Conservation Area Project. Alpha-, beta- and gamma-diversity was measured or estimated for six groups of organisms: trees, shrubs, climbers, herbs, polypores and mycorrhizal fungi, and the recorded patterns were correlated with a set of environmental variables. Human impact in terms of fuelwood collection, selective cutting and grazing was found to influence species diversity patterns in all organism groups. Species richness of trees, climbers and polypores at plot level (alpha-diversity) generally responded negatively to human impact, whereas species richness of herbs and shrubs showed a positive relation. Species turnover (beta-diversity), measured as length of the DCA first axis, was significantly correlated to distance to village for all species groups. This indicates that the human impact is very important for the biodiversity patterns in the study area, and that biodiversity connected to undisturbed forest habitats are potentially threatened in the area. The results are discussed in the context of practical conservation. A proposal for future management zones addressing protection of biodiversity without limiting the local use of the forest resource is put forward.     

Sapling growth as a function of light and landscape-level variation in soil water and foliar nitrogen in northern Michigan

Interspecific differences in sapling growth responses to soil resources could influence species distributions across soil resource gradients. I calibrated models of radial growth as a function of light intensity and landscape-level variation in soil water and foliar N for saplings of four canopy tree species, which differ in adult distributions across soil resource gradients. Model formulations, characterizing different resource effects and modes of influencing growth, were compared based on relative empirical support using Akaike’s Information Criterion. Contrary to expectation, the radial growth of species associated with lower fertility (Acer rubrum and Quercus rubra) was more sensitive to variation in soil resources than the high fertility species Acer saccharum. Moreover, there was no species tradeoff between growth under high foliar N versus growth under low foliar N, which would be expected if growth responses to foliar N mediated distributions. In general, there was functional consistency among species in growth responses to light, foliar N, and soil water availability, respectively. Foliar N influenced primarily high-light growth in F. grandifolia, A. rubrum, and Q. rubra (but was not significant for A. saccharum). In A. saccharum and A. rubrum, for which soil water availability was a significant predictor, soil water and light availability simultaneously limited growth (i.e., either higher light or water increased growth). Simple resource-based models explained 0.74–0.90 of growth variance, indicating a high degree of determinism. Results suggest that nitrogen effects on forest dynamics would be strongest in high-light early successional communities but that water availability influences growth in both early successional and understory environments.     

Composition,structure and diversity of cove forest stands in the Great Smoky Mountains: a patch dynamics perspective

Abstract. Cove forests of the Great Smoky Mountains are North American examples of old-growth temperate forest. Ecological attributes of seven stands were studied using one 0.6 - 1.0 ha plot per stand. Stand basal area (39 - 55 m²/ha) and biomass (326 - 471 Mg/ha) were high for temperate deciduous forest. Density ranged from 577 to 1075 stems/ha. All stands had a mixture of deciduous canopy species. Only rarely did a single species comprise more than half of the stand by density, basal area or biomass. Shade-intolerant species were present at low levels (1 - 5 % of total stand density). A wide range of stem diameters was characteristic of most species. However, some species lacked small stems, indicating discontinuous regeneration. Stands tended to have 10 - 20 tree species per ha and at least five species had biomass levels > 10 Mg/ha, indicating high evenness. Canopy gaps covered 10 % of the total area (2 - 21 % by stand). Gaps and conspecific patches of canopy trees > 0.05 ha in size were infrequent. Spatial analyses revealed a variety of patterns among species at inter-tree distances of 1 to 25 m. When all species were combined, juveniles showed aggregation, and adults were often hyperdispersed. Analyses for individual species confirmed that the mosaic of canopy species is influenced by non-random spatial processes. Adults of several species were aggregated at distances > 10 m. Juveniles of all major species exhibited aggregation. Several species exhibited regeneration near conspecific adults. This pattern suggested limited mobility for such species within the shifting mosaic. A diverse patchwork resulted despite the fact that many species did not exhibit segregation of adults and juveniles. Further understanding of patch dynamics and the potential for compositional steady state in cove forests requires long-term study with spatial data.     

Bird Community Changes in Response to Single and Repeated Fires in a Lowland Tropical Rainforest of Eastern Borneo

Our current understanding of bird community responses to tropical forest fires is limited and strongly geographically biased towards South America. Here we used the circular plot method to carry out complete bird inventories in undisturbed, once burned (1998) and twice burned forests (1983 and 1998) in East Kalimantan (Indonesia). Additionally, environmental variables were measured within a 25 m radius of each plot. Three years after fire the number of birds and bird species were similar for undisturbed and burned forests, but species diversity and turnover were significantly lower in the burned forests. The bird species composition also differed significantly between undisturbed and burned forests, with a strong decline of closed forest preferring bird species accompanied by a strong increase in degraded forest preferring species in burned forests. These differences were strongly related to differences in environmental conditions such as shifts in vegetation cover and layering and differences in ground and understorey vegetation structure. We also found significant shifts in body mass distribution, foraging height and feeding guilds between the bird communities in unburned and burned forests. Surprisingly, repeated burning did not lead to increasing impoverishment of the avifauna, and both once and twice burned forests still contained most of the bird species that were also present in undisturbed forest, even though their densities were considerably lowered.     

Interactions between climate change, competition, dispersal, and disturbances in a tree migration model

Potentially significant shifts in the geographical patterns of vegetation are an expected result of climate change. However, the importance of local processes (e.g., dispersal, competition, or disturbance) has been often ignored in climate change modeling. We develop an individual-based simulation approach to assess how these mechanisms affect migration rate. We simulate the northward progression of a theoretical tree species when climate change makes northern habitat suitable. We test how the rate of progression is affected by (1) competition with a resident species, (2) interactions with disturbance regimes, (3) species dispersal kernel, and (4) the intensity of climate change over time. Results reveal a strong response of species’ expansion rate to the presence of a local competitor, as well as nonlinear effects of disturbance. We discuss these results in light of current knowledge of northern forest dynamics and results found in the climatic research literature.     

长白山北坡阔叶红松林及其次生白桦林高等植物物种多样性比较

应用Ｓｉｍｐｓｏｎ和Ｓｈａｎｎｏｎ多样性指数及其相应的均匀度,对阔叶红松林及其次生白桦林的高等植物物种多样性进行了对比研究．结果表明,对于木本植物,次生白桦林物种多样性高于阔叶红松林;而对于草本植物,情况正好相反．但在次生白桦林中,无论木本植物还是草本植物,占优势的物种都是一些常见种,而许多阔叶红松林中的珍稀或特有物种在次生白桦林中数量很少,有些甚至完全消失．对群落各种群多度分布的检验表明,２种森林类型中,无论木本植物还是草本植物,各种群的多度分布都遵从对数级数分布．     

浙江仙居俞坑森林群落物种多样性研究

分别采用物种丰富度、物种多样性指数和群落均匀度指标对浙江省仙居县俞坑森林群落的物种多样性进行测定和分析。结果表明：本木植物的物种多样性以生境优越的常绿阔叶林为高,木本植物的物种丰富度、物种多样性指数明显大于草本植物。在群落垂直结构中,木本植物等2层的物种丰富度、物种多样性指数均显著大于第1层。物种丰富度以木本第3层最大,草本层最小;而物种多样性指数、群落均匀度则以木本第2层最大、草本层最小。木本植物各层次、草本层的物种多样性各项指标在群落各样地间均有一定的差异。     

Potential tree species extinction,colonization and recruitment in Afromontane forest relicts

Tree species regeneration determines future forest structure and composition, but is often severely hampered in small forest relicts. To study succession, long-term field observations or simulation models are used but data, knowledge or resources to run such models are often scarce in tropical areas. We propose and implement a species accounting equation, which includes the co-occurring events extinction, colonization and recruitment and which can be solved by using data from a single inventory. We solved this species accounting equation for the 12 remaining Afromontane cloud forest relicts in Taita Hills, Kenya by comparing the tree species present among the seedling, sapling and mature tree layer in 82 plots. A simultaneous ordination of the seedling, sapling and mature tree layer data revealed that potential species extinctions, colonizations and recruitments may induce future species shifts. On landscape level, the potential extinction debt amounted to 9% (7 species) of the regional species pool. On forest relict level, the smallest relicts harbored an important proportion of the tree species diversity in the regeneration layer. The average potential recruitment credit, defined as species only present as seedling or sapling, was 3 and 6 species for large and small forest relicts, while the average potential extinction debt was 12 and 4 species, respectively. In total, both large and small relicts are expected to lose approximately 20% of their current local tree species pool. The species accounting equations provide a time and resource effective tool and give an improved understanding of the conservation status and possible future succession dynamics of forest relicts, which can be particularly useful in a context of participatory monitoring.     

Seed bank and vegetation composition of forest stands of varying age in central Belgium: consequences for regeneration of ancient forest vegetation

Vegetation composition differs significantly between ancientand recent forest, due to slow colonization capacity of typical forest speciesand the higher abundance of early successional species in recent forest.However, little is known about differences in persistent seed bank compositionbetween ancient and recent forest and about the interaction between seed bankand vegetation in relation with forest age. We surveyed the seed bank and theunderstorey vegetationcomposition in transects from ancient to recent forest. Seed bank and fieldlayer vegetation characteristics and similarity between seed bank andvegetationwere analysed in relation to recent forest age and distance to the ancientforest. A total of 39 species and 14,911 seedlings germinated, whichcorresponds with a seed density of 12,426 seeds/m².Total seed density is significantly higher in the youngest recent forest parcel(55 years). Also the seed bank composition in the youngest forest parceldifferssignificantly from the other parcels. After a longer period of reforestation,the seed bank approaches that of the ancient forest, suggesting seed bankdepletion, although the seed bank is permanently replenished to some extent byseed bank forming species from local disturbances. Seed bank composition doesnot change significantly with distance to the ancient forest. Similaritybetween seed bank and vegetation composition, nomatter the forest age, is very low, but decreases with increasing forest age.The most frequent species in the vegetation are absent in the seed bank andvice versa. The contribution of forest species is highin the vegetation and they almost not occur in the seed bank, while species offorest edges and clearings, and species of disturbed environments are morefrequent in the seed bank. The seed bank is mainly composed of earlysuccessional species of former forest stages or species which temporary occurinsmall-scale disturbances. The seed bank may enhance the negative effects ofearlysuccessional, mainly competitive species to the forest species richness in therecent forest. In this respect, forest management should minimise forestdisturbances, to prevent germination of competitive species form buriedseeds.     

The response of herbaceous-layer vegetation to anthropogenic disturbance in intermittent stream bottomland forests of southern Indiana,USA

Between 1993 and 1995 we sampled herbaceous layer vegetation on 84 plots in Platanus/Asarum Wet-Mesic Bottomland forests to determine how these forests have responded to human disturbance. Four different disturbance types were sampled (abandoned agricultural are as, clearcuts, group-selection openings, and single-tree selection openings), and uncut 80–100 year-old reference stands were sampled for comparison. Detrended Correspondence Analysis (DCA), distance analyses (chord distance and normalized Euclidean distance) and similarity analysis (Bray-Curtis similarity coefficient) suggest that agricultural use has shifted herbaceous-layer vegetation composition away from that typical of the reference forests, but that clearcutting, group-selection harvest, and single-tree selection harvest have not greatly shifted herbaceous composition. This shift in vegetation on abandoned agricultural land resulted from a loss of indicator species, such as Cardamine concatenata (Michx.) Sw., Stellaria pubera Michx., and Laportea canadensis (L.) Weddell and an influx of disturbance, exotic, and nonforest species (e.g., Lycopodium complanatum L., Lonicera japonica Thunb. and Senecio aureus L.). However, only two species found in reference stands, Erigenia bulbosa (Michx.) Nutt. and Sphenopholis obtusata (Michx.) Scribn., were missing from clearcuts, group-selection openings, and single-tree selection openings. The species richness values of abandoned agriculture, clearcut, and group-selection plots were generally greater than those of single-tree selection and reference plots. Abandoned agricultural areas had much greater total species richness because of the influx of dry-site, exotic, disturbance, and non-forest species.     

Comparison of an aquatic invertebrate assemblage between an old-growth natural forest and planted coniferous forest basins in a Japanese temperate region: the Kuroson stream in the Shimanto River basin

The purpose of this study is to clarify the differences in the aquatic invertebrate assemblage between the two basins that have the most common types of Japanese headstream forests – an old-growth natural forest (ONF) and a planted coniferous forest (PCF) – in the Kuroson stream of the Shimanto River basin and to find the groups that tend to inhabit either the ONF basin or PCF basin. Abundance, the number of families and -diversity were not different between the two basins. However, a cluster analysis of similarity showed differences in aquatic invertebrate assemblages between the ONF and PCF basins and that this difference was brought about by specific characteristics of some families, such as the Taeniopterygidae and Athericidae. We suggest that differences in the aquatic invertebrate assemblages between the two basins are a reflection of differences in the composition of the forest vegetation.     

Plant species diversity in abandoned coppice forests in a temperate deciduous forest area of central Japan

We investigated plant species diversity as it related to stand structure and landscape parameters in abandoned coppice forests in a temperate, deciduous forest area of central Japan, where Fagus crenata was originally dominant. The species occurring in the study plots were classified into habitat types based on a statistical analysis of their occurrence bias in particular habitats (e.g., primary forest, coniferous plantation) in the landscape studied. The relationships between stand structure, which reflected the gradient of management, and forest floor plant species diversity (H and J) and richness (number of species per unit area) were not significant. However, these factors did influence the forest floor plant composition of the different types of habitat. According to the multiple regression analysis, species diversity and the richness of forest floor plants was affected by landscape parameters rather than by stand structure. For trees, species richness was mainly affected by the relative dominance of F. crenata, which is one of the stand structure parameters that decreases with intensive management. This is probably because many of the tree species that are characteristic of coppice forests increase after F. crenata have been eliminated by management; these species are not dominant in the original forest, where they are suppressed by F. crenata, the shade-tolerant dominant species. The species diversity (H and J) of trees was positively correlated with some landscape parameters, including the road density around the study plot, which may be associated with the intensity of management activity. The number of disturbance-tolerant species increased with increasing road density. Stand structure mainly affected disturbance-intolerant forest floor plant species and disturbance-tolerant tree species. Thus, the species diversity responses differed between forest floor plants and trees. The impact of forest management on species diversity was more prominent for forest floor plants.     

Ecological implications of projected climate change scenarios in forest ecosystems in northern Michigan,USA

Changes in seasonal temperature and precipitation, as predicted by several global climate models, were utilized together with a stochastic daily weather stimulation model to evaluate the ecological impacts of projected global climate change scenarios on temperate forest ecosystems in northern Michigan, USA. The model simulated the impacts of these projected changes on ecologically significant weather variables, such as the length of the frost-free period, average growing season temperature, average growing season degree days (4.4° C basis), summer precipitation, potential evaporation during the growing season, and the ratio of precipitation to potential evaporation during July and August. The results indicate that even the lower range of predicted climate changes could lead to ecologically and commercially significant changes in the composition and productivity of these forests. Of particular concern is the possibility of climatically induced regional decline episodes for a number of important commercial species in the northern temperate forests of central North America.     

Tree diversity in primary forest and different land use systems in Central Sulawesi,Indonesia

We studied the tree communities in primary forest and three different land use systems (forest gardens, ca. 5-year-old secondary forests, cacao plantations) at 900–1200 m elevation in the environs of Lore Lindu National Park, Central Sulawesi. The primary forests had ca. 150 tree species 10 cm diameter at breast height (dbh) per hectare, which is unusually high for forests at this elevation in southeast Asia. Basal area in the primary forest was 140 m² ha^–1, one of the highest values ever recorded in tropical forests worldwide. Tree species richness declined gradually from primary forest to forest gardens, secondary forests, and cacao plantations. This decline was paralleled by shifts in tree family composition, with Lauraceae, Meliaceae, and Euphorbiaceae being predominant in primary forests, Euphorbiaceae, Rubiaceae and Myristicaeae dominating in the forest gardens and Euphorbiaceae, Urticaceae, and Ulmaceae in the secondary forests. Cacao plantations were composed almost exclusively of cacao trees and two species of legume shade trees. Forest gardens further differed from primary forests by a much lower density of understorey trees, while secondary forests had fewer species of commercial interest. Comparative studies of birds and butterflies demonstrated parallel declines of species richness, showing the importance of trees in structuring tropical forest habitats and in providing resources.