Characteristics Of Tree Species Research Articles

Community structure and regeneration types of Betula dahurica forest in Badaling forest center of Beijing

Using plant community analysis methods, we analyzed the floristic characteristics, species composition, community structure, population structure, and spatial distribution patterns of a Betula dahurica forest on the “1238” mountain of Badaling in Beijing, China. The results show that: 1) There are 33 plant species in the B. dahurica community, including 18 woody plant species. The B. dahurica forest is a monodominant community with 75.9% dominance. 2) Based on diameter at breast height (DBH) size class distribution, the population structure of B. dahurica and Acer mono—two heliophyllous and pioneer tree species—is cascade-type, with both in an increasing stage. The population structure of Tilia mandshurica and T. mongolica, two shade-tolerant tree species, is inverse-J type, and they have more young seedling individuals and regenerate more stably. They are associated species of the pioneer tree species. The population structure of Quercus mongolica, as the associated species of climax species in the community, is sporadic, and its regeneration is fluctuating and random. Fraxinus rhynchophylla is a shade-tolerant tree species which has a unibar population structure and climax characteristics of pioneer tree species. The relative frequency of young seedlings reached 0.4. 3) The dominant species B. dahurica is still in an increasing stage, and the regeneration of other species is steady or partly influences the community, putting the community in the pioneer species stage. From the population structure and distribution frequency of F. rhynchophylla, the B. dahurica forest will approach to a climax state in the future.

우리나라 참나무 천연림에 있어서 임내우의 수량변화 및 양분동태

This study was conducted to investigate nutrient dynamics and water quantity of throughfall and stemflow in natural oak stands in Korea. The ratio of the total throughfnll and stemflow to the amount of precipitation varied with locations. It was considered that the ratio was affected not only by the characteristics of tree species but also by regional, weather and other environmental conditions. It was, therefore, necessary to set up a water control system to launch a tending project for natural oak stands. Comparisons of nutrient amount in throughfall among regions reflected regional characteristics. and ions were leached from the canopy and yellow sand accumulation. and were marine-borne. and resulted from dry deposition of air pollutants. Nutrient amount in the stemflow was as low as about 10% of that in the total throughfall and stemflow. The pH of stemflow in natural oak stands in urban areas ranged from 3 to 5. Influx of the acidic stemflow to soil could, in the long term, affect pH in soil solution and nutrient dynamics around root zones.

Roles of disturbance and demographic non-equilibrium in species coexistence, inferred from 25-year dynamics of a late-successional old-growth subalpine forest

We investigated compositional and demographical characteristics of major tree species in an old-growth subalpine forest in central Japan, based on a 25-year study. The stand is minimally disturbed and thus canopy structure is fairly stable. During the census, species dominance ranks in terms of both number and basal area were maintained. But, proportion of population size of major species within community significantly differed, and reflecting limited or no recruitment, declines in population size were found for all species including highly shade-tolerant Abies, suggesting demographic non-equilibrium in this forest community. This is because, according to each species’ regeneration attributes, disturbances fluctuating in space and time are required for persistence of their populations. So, competitive exclusion of other dominants by Abies spp., proposed as a mechanism of succession in several subalpine forests, seems unlikely. In addition to such non-equilibrium process, life-history differences among dominants, expressed as the equilibrium concept, are also greatly involved in species persistence because trade-offs of mortality and abundance/recruitment were observed between species. However, juvenile recruitment is closely related to canopy dynamics and disturbances, so that species persistence and resultant coexistence cannot be fully explained only by such differential demography. Here, it is specifically notable that not only current disturbance regimes but also ancient disturbance histories are both fundamentally of paramount importance for community maintenance and species coexistence. Populations and communities are fluctuating on the template shaped by both ancient and recent disturbances, and hereby, even in the late-successional forest, they are demographically non-equilibrium. Thus, further careful consideration is needed to evaluate complexity of the role and variability of natural disturbances in old-growth forest ecosystems.

Mineral nutrient status of tree species in relation to environmental factors in the subtropical rain forest of Taiwan

Until now, the mineral nutrition of rain forest trees is still poorly understood. Very few data are available on the nutrient characteristics of rain forest tree species and the influence of environmental factors especially for subtropical climates. This study evaluated the mineral nutrient status of the dominant tree species and its relation to environmental factors such as elevation, slope, landscape position, and soil nutrient status in a subtropical rain forest of southern Taiwan. Leaf, stem, and wood samples were collected for nutrient analysis from a total of 639 trees belonging to 20 dominant species from 27 contiguous 20 m × 20 m quadrants along an altitudinal transect ranging from 300 to 480 m. Composite soil samples were likewise collected from the 0–5 and 5–15 cm depths in the A horizon in each quadrant for chemical analysis. Soils in the study site ranged from well-developed, acidic with clayey subsoil Typic Paleudult in summit positions, to poorly developed and acidic Typic Dystrudept in backslope positions. Results revealed that leaf nutrient concentration was better correlated with the environmental factors than stem and wood nutrient concentrations. In addition, data showed generally wide concentration ranges for most mineral nutrients except P and Cu and most tree species were clustered at the lower end of the concentration ranges indicating they have low nutrient status. Among the macronutrients, P had the lowest and narrowest foliar concentration (0.25–2.8 g kg −1; mean = 0.8) while for the micronutrients, this was shown by Cu (3.88–17 mg kg −1; mean = 5.8). A few tree species were observed to accumulate (called “accumulator species”) some mineral nutrients like N, P, K, Ca, Mg, Cu and Zn indicating high absorption capacity for these nutrients. Foliar mineral nutrient concentration of the trees was generally correlated with the environmental factors such as elevation, topographic position, slope, vegetation type, and soil nutrient status. However, the effects were interrelated and difficult to isolate from each other although topographic position, vegetation type, and soil nutrient status appeared to be more related to the mineral nutrient concentration of the trees than the other environmental factors. In particular, plants on the footslope had generally higher concentration of N, P and K than those at the higher elevation of the upper backslope and summit. This suggests that the distribution of tree species in the study site is reflected by their foliar nutrient concentration. P appears to be the most limiting nutrient in the rain forest ecosystem studied although fertilization experiment is needed to verify the apparent P limitation.

Photosynthetic characteristics of dominant tree species and canopy in the broadleaved Korean pine forest of Changbai Mountains

Based on the light-photosynthesis response measurement at leaf level, combined with over-and under-canopy eddy covariance measurements, research on photosynthetic characteristics of single trees and forest canopy was conducted. The relationship between light intensity and photosynthetic rates for leaves and canopy can be well fitted by a non-rectangular hyperbola model. Mongolian oak presented a high light compensation point, Lcp (28 μmol·m−2·s−1), a light saturation point Lsp (>1800 μmol·m−2·s−1), and a maximal net photosynthetic rate Pmax (9.96 μmol·m−2·s−1), which suggest that it is a typical heliophilous plant. Mono maple presented the highest apparent quantum efficiency α (0.066) but the lowest, Lcp (16 μmol·m−2·s−1), Lsp (≈800 μmol·m−2·s−1), and Pmax (4.51 μmol·m−2·s−1), which suggest that it is heliophilous plant. Korean pine showed the lowest α value but a higher Pmax, which suggest that it is a semi-heliophilous plant. At the canopy level, the values of both α and Pmax approached the upper limit of reported values in temperate forests, while Lcp was within the lower limit. Canopy photosynthetic characteristics were well consistent with those of leaves. Both showed a high ability to photosynthesize. However, environmental stresses, especially high vapor pressure deficits, could significantly reduce the photosynthetic ability of leaves and canopy.

Stand Structure and Regeneration Pattern of Kalopanax septemlobus at the Natural Deciduous Broad-leaved Forest in Mt. Jeombong, Korea

Since the demands not only for value-added timber but the environmental functions of forests had been increased, native tree species has been, and is rapidly being replaced by foreign tree species in many parts of the world. However, the studies on population structure and regeneration characteristics of native tree species were not conducted enough. Regeneration of Kalopanax septemlobus growing among other hardwoods in natural forests is very difficult because of its low seed viability and germination rate. The study examined the distribution of mature trees of K. septemlobus and their regeneration pattern at the 1.12 ha study plot in natural deciduous broad-leaved forest of Mt. Jeombong. The density and mean DBH of K. septemlobus was 97 trees per ha and 32 cm, respectively. The spatial distribution of K. septemlobus showed a random pattern (aggregation index is 0.935) in the 1.12 ha study plot. The age of 90 trees among 99 sample trees of K. septemlobus ranged from 90 to 110 years and represented a single cohort, thus suggesting that K. septemlobus in advance regeneration has regenerated as a result of disturbances such as canopy opening.

Avaliação bromatológica de espécies arbóreas e arbustivas de pastagens em três municípios do Estado de Pernambuco

The research was conducted at the Experimental Fields of Itambé, Caruaru and Serra Talhada, owned by the Agricultural Research Company of Pernambuco (IPA). The aim was to analyze the chemical characteristics of tree and bush species grown on pasture land. In each Experimental Station, data was collected from a random sampling, during the dry and rainy seasons. Samples consisted of leaves and branches up to 5.0 cm of diameter. The average MS concentrations were 38.89, 48.27 and 55.20%. As for PB, the values observed were 15.87, 14.09 and 10.19%. The NFD and ADF concentrations were 52.37 and 37.63, 46.33 and 30.33, 50.25 and 35.07%, for Itambé, Caruaru and Serra Talhada, respectively. The studied species, independent of the region, presented better chemistry composition during the rainy season. Thus, for an adequate selection of species in silvopastoral systems, besides the evaluation of qualitative characteristics, other aspects should also be taken into consideration such as propagation, adaptation to the soil and climate conditions, animal type and objective of the animal system production.

STUDY OF DOMINANT PLANT POPULATIONS AND THEIR SPATIAL PATTERNS IN EVERGREEN BROADLEAVED FOREST IN TIANMU MOUNTAIN, CHINA

Evergreen broadleaved forest is an important vegetation type in Tianmu Mountain National Nature Reserve of Tianmu Mountain, Zhejiang Province. Study of dominant plant populations and their spatial patterns can reveal the roles of these populations and provide a theoretical basis for forest protection and restoration. A typical plot of 100 m×100 m was surveyed and dominance index analysis was applied to determine dominant plant populations. Ripley's K(d) function was applied to diagnose spatial patterns and spatial associations between species pairs.The number of dominant tree species increases with size class, but the degree of aggregation decreases. The evergreen shrub Camellia fraterna dominates seedling and small tree size class. Cyclobalanopsis gracilis, Cyclobalanopsis glauca and Lithocarpus brevicaudatus dominate mid- and large-tree classes and have structural characteristics of multi-dominant tree species. Camellia fraterna, Cyclobalanopsis gracilis and Cyclobalanopsis glauca have stable and significant aggregated spatial patterns. Spatial patterns of Litsea coreanavar.sinensis and Lithocarpus brevicaudatus vary greatly. In general, the five dominant populations have aggregated distributions. Camellia fraterna and Cyclobalanopsis gracilis or Lithocarpus brevicaudatus orLitsea coreana var.sinensis, Cyclobalanopsis gracilis and Lithocarpus brevicaudatus, andCyclobalan opsis glauca and Litsea coreana var. sinensis, are significahe association of species pairs and the wider the distance scale, the more stable the transference is. The dominant evergreen broadleaved tree species in Tianmu Mountain National Nature Reserve are significantly aggregated, and most are strongly associated.

Effects of thinning on microsites and natural regeneration in aLarix olgensis plantation in mountainous regions of eastern Liaoning Province, China

In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-oldLarix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003–2004. Five thinning treatments (0%, 10.2%, 19.8%, 29.7% and 40.3% thinned) were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density (PPFD), soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase (p=0.30) after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly (p<0.05). In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of individual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness wasPhellodendron amurense. This paper confirmed the following conclusions: after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing the regeneration.

Chemical and morphological characteristics of key tree species of the Carpathian Mountains

Concentrations of Al, B, Ca, Cu, Fe, K, Mg, Mn, N, Na, P, S and Zn in the foliage of white fir ( Abies alba), Norway spruce ( Picea abies) and common beech ( Fagus sylvatica) from 25 sites of the Carpathian Mts. forests (Czech Republic, Poland, Romania, Slovakia and Ukraine) are discussed in a context of their limit values. S/N ratio was different from optimum in 90% of localities when compared with the European limit values. Likewise we found increase of Fe and Cu concentrations compared with their background levels in 100% of locations. Mn concentrations were increased in 76% of localities. Mn mobilization values indicate the disturbance of physiological balance leading to the change of the ratio with Fe. SEM-investigation of foliage waxes from 25 sites in the Carpathian Mts. showed, that there is a statistically significant difference in mean wax quality. Epistomatal waxes were damaged as indicated by increased development of net and amorphous waxes. The most damaged stomata in spruce needles were from Yablunitsa, Synevir and Brenna; in fir needles from Stoliky, and in beech leaves from Malá Fatra, Morské Oko and Beregomet. Spruce needles in the Carpathian Mts. had more damaged stomata than fir needles and beech leaves. Spruce seems to be the most sensitive tree species to environmental stresses including air pollution in forests of the Carpathian Mountains. Foliage surfaces of three forest tree species contained Al, Si, Ca, Fe, Mg, K, Cl, Mn, Na, Ni and Ti in all studied localities. Presence of nutrition elements (Ca, Fe, Mg, K and Mn) on foliage surface hinders opening and closing stomata and it is not physiologically usable for tree species.

The role of traditional forest gardens in the conservation of tree species in West Kalimantan, Indonesia

We compared forest gardens, or tembawang, in twoareas in West Kalimantan, Indonesia, to patches of primary forest in terms ofsuccessional stage, mode of dispersal and characteristics of human use ofnon-planted tree species. This information was acquired for 144 tree speciesinventoried in six tembawang forest gardens and two intactnatural forest patches, through interviews at the site and a survey of theliterature. In particular older tembawang were found tohave practically the same proportions of species of different successionalstages and modes of dispersal as natural forests, thus emphasising the potentialof tembawang in conserving tree species. Non-planted treespecies of tembawang and natural forests also havepractically indistinguishable spectra of human uses, indicating that themanagement of these tembawang does not significantlydiscriminate between species with certain uses. However, we also identified twoaspects that should be taken into account in considering the conservation roleof tembawang. The floras of the two study areas showedsignificant regional differentiation, implying that efficient conservation inWest Kalimantan needs to have a rather dense network. We also found that latesuccessional species and animal-dispersed species oftembawang were more commonly geographically widespread thanspecies of the same ecological characteristics found in natural forests. Thus,even if tembawang are similar to natural forests in termsof numbers of species with different ecological characteristics, the compositionof non-planted tree species in tembawang is not a randomsample from natural forest, but overrepresents species that are easily dispersedand/or established.

Fuelwood characteristics of tree species in homegardens of Kerala, India

Indiscriminate use of natural resources in the past has lead to fuelwood shortages in many parts of the tropical world. To surmount this domestic energy crisis, not only degraded sites must be planted with trees having high fuel value potential, but also agroforestry promoted on arable lands. To enable choice of species for such energy plantations/agroforests in the humid tropics of peninsular India, we assessed the heat of combustion and physical properties that determine combustion of phytofuels, such as ash content, specific gravity and moisture content. Bark and wood samples of 45 multipurpose tree species in the homegardens of Kerala, India and three fuel materials of local importance (coconut [Cocos nucifera] endocarp, dried coconut spathe and dehiscent rubber [Hevea braziliensis] pericarp) were evaluated. Variations abound in the calorific values and physical properties of species and tissue-types. In general, heat of combustion and specific gravity followed the sequence: heartwood > sapwood > bark, while mean ash percentage followed a reverse order (bark > sapwood > heartwood). Ash content had a negative correlation with heat of combustion, but specific gravity exerted a positive influence. Furthermore, ash content and wood specific gravity were inversely related. Although green moisture content increased in the order: bark < heartwood < sapwood, it failed to show any predictable relationship with heat of combustion.

Fuelwood characteristics of indigenous tree species of north-east India

Fuelwood characteristics viz. moisture content, ash, silica, carbon, nitrogen, volatile matter, density and calorific value of 35 indigenous tree species of the age group of 10–15 years growing in their natural habitat in north-eastern region of India were determined and Fuel Value Index (FVI) of each of them was calculated. From the experimental data and the FVIs, it is found that Acacia nilotica, Acacia auriculiformis, Albizzia lebbeck, Albizzia procera, Pinus kesiya and Elaeognus umbellata possess better fuelwood characteristics and they may be considered for inclusion in energy plantation programme in the region.

Canopy disturbance patterns in a bottomland hardwood forest in northeast Arkansas, USA

We characterized canopy disturbance patterns in a bottomland hardwood forest and identified linkages to tree species characteristics and interannual flooding patterns. We located 116 newly formed canopy gaps created by 136 gapmakers of 13 species. Over 83% of the gapmakers were snapped or uprooted (i.e., windthrow). The probability of any given gapmaker snapping or uprooting differed among years, species, and elevations. Neither wood properties nor diameter were major factors in determining the probability of snapping versus windthrow. Quercus texana, which had individuals with larger diameters-at-breast height than trees of other dominant species, was the most frequent gapmaker. The effects of elevation and flooding on the probability of snap versus windthrow seem to be tempered or amplified by interspecific rooting habits and tree morphology. Across species, windthrow occurred at lower elevations than snaps, and Q. texana and Q. lyrata showed differences in elevation between the two disturbance types. The total amount of area in newly-formed canopy gaps, as well as gap size, was relatively low compared to estimates for other forests. Our results suggest that natural disturbance patterns in bottomland hardwood forests are complex and are affected by the interactions among forest structure and composition and flooding patterns.

Gas exchange characteristics of a Canarian laurel forest tree species (Laurus azorica) in relation to environmental conditions and leaf canopy position.

Diurnal courses of gas exchange were measured over a 1-year period in fully expanded current-year leaves in the upper (sun-exposed, 18 m above ground) and the lower (shaded, 12 m above ground) canopy of Laurus azorica (Seub.) Franco, a major canopy species of the Canarian laurel forest in Tenerife, Canary Islands, Spain. Laurus azorica exhibited high leaf plasticity in gas exchange characteristics, with a maximum carbon assimilation rate (Amax) of shade leaves about 50% that of sun leaves. This difference reflects the high leaf area index (LAI) of the stand and the correspondingly sharp light attenuation with increasing canopy depth. In sun leaves, Amax peaked at about 11 micromol m-2 s-1 and maximum transpiration (E) was about 8 mmol m-2 s-1, which corresponded with a maximum stomatal conductance (gs) of about 650 mmol m-2 s-1. Mean maximum instantaneous water-use efficiency (WUE) was 1.5 mmol mol-1 and the mean maximum A/gs was 20-35 micromol mol-1. Mean minimum internal CO2 concentration (Ci) was 225 micromol mol-1. Although high air vapor pressure deficit (VPD) caused a small decrease in gs, it remained high enough to maintain relatively high A and E. These gas exchange characteristics indicate a non-conservative use of water, which is appropriate for a species subject to droughts that are mild or of short duration. In this respect, Laurus azorica differs from its congener, L. nobilis L., of the Mediterranean region and other shrubs growing in Mediterranean-type climates in California and Chile that have to withstand more severe or more prolonged droughts.

Monitoring plant physiological characteristics to evaluate mine site revegetation: A case study from the wet-dry tropics of northern Australia

Biologically driven markers or monitors were used to evaluate plant and ecosystem health of uranium-mining affected sites. Plant water, nitrogen (N) and phosphorus (P) status were used to measure physiological characteristics of tree and shrub species at sites perturbed by mining activities (waste rock dumps: WRD 1, WRD 2; mine wastewater irrigated woodland) and of species at undisturbed woodland (tropical savanna). Plant water status was evaluated by measuring leaf relative water content (RWC) and carbon isotope discrimination (δ13C). Leaf RWC varied significantly (P<0.0001) between wet and dry season in species at the woodland sites with higher RWC in the wet season compared to the dry season. No seasonal differences were observed in RWC in species at the WRDs. Leaf δ13C was similar in species at woodland sites and WRD 2 (−28.8 to −28.1‰) but was significantly (P<0.05) lower in species at WRD 1 (−27.6‰). This suggests that species at WRD 1 had a lower water availability and/or lower water use compared to species at all other sites. WRD substrate had an up to 4-orders of magnitude greater availability of inorganic phosphate (Pi) compared to woodland soil as determined using in situ ion exchange resin. Pi concentrations in xylem sap of species at WRDs were 2- to 3-fold higher compared to species at woodland sites. Plant nitrate reductase (NR) activity was low in most species at woodland and WRD 1. In contrast, Eucalyptus and Acacia species had high NR activities of up to 300–700 pkat g-1 fw at WRD 2 indicating that these species had greater nitrate use than species at all other sites. Nitrate availability in the top five cm of the profile, as determined using in situ ion exchange resins, increased at all sites in the wet season, but no significant differences were observed between sites using this method. However, traditional soil analysis revealed that WRD substrate had a 2-times higher nitrate content (0 to 1000 mm depth) compared to woodland soil. Thus, it is likely that plants at WRD2 accessed nitrate from deeper parts of the profile. Proline, an indicator of plant stress, was found in appreciable quantities in leaves of herbaceous species but not in woody species. Soil and leaf δ15N were measured to investigate N-cycling and the contribution of diazotrophic N2 fixation to plant N nutrition. Soil δ15N values were highest and most variable at WRD 2 (6.2‰) compared to all other sites (irrigated woodland 3.1‰, undisturbed woodland 2.5‰, WRD 1 0.9‰). This may indicate that N-turnover and nitrification was greatest at WRD 2 leading to greater 15N enrichment of soil N. At all sites, Acacia species were nodulated and putatively fixing N2. With the exception of WRD 2 where leaf δ15N of Acacia species averaged 0.9‰, Acacia species had 15N depleted values characteristic of species that receive N derived from N2 fixation (−0.8 to −0.6‰).

Observations of the Photosynthetic Physiology of Tree Species within the C3 Monocotyledon Genus Pandanus, and Comparison with Dicotyledon C3 Tree Species

Photosynthetic characteristics of tree species from the tropical C3 monocotyledon genus Pandanus were compared with C3 dicotyledon species growing in similar environments. The Pandanus species had similar maximum photosynthetic rates (Amax) to dicotyledon tree species in leaves from both sun and shaded environments when Amax was expressed on an area basis. Because of the low specific leaf area of the schlerophyllous leaves of the Pandanus compared to the dicotyledon species, the similarity in Amax was no longer evident when Amax was expressed on a dry-weight basis. Leaf dark respiration rates of the Pandanus on a leaf area and weight basis were generally lower than the shade-intolerant dicotyledons and similar to the shade-tolerant dicotyledon species. Low dark respiration rates and low specific leaf area of the Pandanus may be important characteristics for growth and survival in environments where resource levels are low and the likelihood of tissue damage is high.

Tree productivity and successional status in Québec northern hardwoods

Few studies have sought to understand the growth characteristics of tree species in order to explain the observed patterns of succession. This study seeks to determine the successional status of hardwood species in a secondary succession, to analyze their productivity and to examine the existing relationships between these two aspects. The age, production and biomass of 3273 stems were estimated in 34 stands distributed along a stand age gradient in south-western Québec. The successional status of a species was determined by comparing its abundance with stand age in a contingency table. Linear regressions of the logarithm of the age of trees with the logarithm of the aerial biomass (log [B]), the logarithm of the net primary production (log[NPP]) and the relative biomass increment (NNP/B) were established for each species. An analysis of covariance allowed the separation of statistically different species regression curves. Sugar maple (Acer saccharumMarsh.), American beech (Fagus grandifoliaEhrh.) and eastern hemlock (Tsuga canadensis[L.] Carr.) are indicator species of old stands; bitternut hickory (Carya cordiformis[Wang.] K. Koch), white ash (Fraxinus americanaL.), butternut (Juglans cinereaL.), black cherry (Prunus serotinaEhrh.), white elm (Ulmus americanaL.) and red elm (Ulmus rubraMühl.) are mostly found in young stands. Ironwood (Ostrya virginiana[Mill.] K. Koch) is a ubiquitous species, found in stands of all ages. Analysis of the relationships between tree age and B, NPP and NPP/B revealed that the more a species is capable of rapidly increasing its biomass at a young age, the less it is able to sustain this growth with increasing age. This growth trade-off relationships ordered species along a gradient of productivity patterns closely linked to the observed stand age gradient.

Models of forest dynamics based on roles of tree species

A linkage between the two major modeling approaches to forest dynamics, transition Markovian models and jabowa-foret type simulators, is generated by developing a compact model of forest dynamics. This patch transition model utilizes functional roles instead of species. The roles or types are based on the regeneration and mortality characteristics of tree species; specifically, the requirements of canopy gaps for regeneration and the capacity to create canopy gaps upon death. A gap-size plot can be assigned to each of a set of states defined according to dominance of one of the roles. Transition probabilities among these states and mean holding times in each transition lead to semi-Markovian analytical calculations of the stationary state probabilities. Forest dynamics, as the proportions of total canopy space occupied by each role in a collection of gap-size plots, can be analyzed and simulated using a chain of first-order differential equations to emulate the distributed time-delays. Additional fixed time-delays in the transition of every pair of states is also included to account for long latencies. In addition to simplifying the simulations, the resulting model can also utilize available results of the theory of semi-Markov processes; and therefore, can provide analytical guidance to the simulations, the feasibility of direct exploration of hypothesis and the possibility of fast computation from closed-form solutions and formulae. These advantages can especially be useful in the simulation of landscape dynamics and species-rich tropical forests.

96/03293 - Photosynthetic characteristics of tropical tree species with special references to palms

96/03293 - Photosynthetic characteristics of tropical tree species with special references to palms