Native Hardwood Research Articles

Influence of Mine Soil Properties on White Oak Seedling Growth: A Proposed Mine Soil Classification Model

Abstract Appalachian landowners are becoming increasingly interested in restoring native hardwood forest on reclaimed mined land. Trees are usually planted in topsoil substitutes consisting of blasted rock strata, and reforestation attempts using native hardwoods are often unsuccessful due to adverse soil properties. The purpose of this study was to determine which mine soil properties most influence white oak (Quercus alba L.) seedling growth, and to test whether these properties are reflected adequately in a proposed mine soil classification model developed for application in field assessments of mine soil suitability for reforestation. Seventy-two 3-year-old white oaks were randomly selected across a reclaimed site in southwestern Virginia that varied greatly in spoil/site properties. Tree height was measured and soil samples adjacent to each tree were analyzed for physical, chemical, and biological properties. Our proposed mined land classification model used rock type, compaction, and slope aspect as mapping criteria. Tree height, ranging from 15.2 to 125.0 cm, was regressed against mine soil and site properties. Mapping units were not well correlated with differences in tree height. Microbial biomass, pH, exchangeable potassium, extractable inorganic nitrogen, texture, aspect, and extractable phosphorous accounted for 52% of the variability in tree growth. The regression model shows that white oaks were most successful on northeast-facing aspects, in slightly acidic, sandy loam, fertile mine soils that are conducive to microbial activity. Nutrient availability, although found to be highly influential on tree growth, was not adequately represented in the classification model. We recommend that pH be included as a classification criterion, because it was correlated with all nutrient variables in the regression model.

Assessing the potential of native tree species for carbon sequestration forestry in Northeast China

Although the native forests of China are exceptionally diverse, only a small number of tree species have been widely utilized in forest plantations and reforestation efforts. We used dendrochronological sampling methods to assess the potential growth and carbon sequestration of native tree species in Jilin Province, Northeast China. Trees were sampled in and near the Changbaishan Biosphere Reserve, with samples encompassing old-growth, disturbed forest, and plantations. To approximate conditions for planted trees, sampling focused on trees with exposed crowns (dominant and co-dominant individuals). A log-linear relationship was found between diameter increment and tree diameter, with a linear decrease in increment with increasing local basal area; no significant differences in these patterns between plantations and natural stands were detected for two commonly planted species ( Pinus koraiensis and Larix olgensis). A growth model that incorporates observed feedbacks with individual tree size and local basal area (in conjunction with allometric models for tree biomass), was used to project stand-level biomass increment. Predicted growth trajectories were then linked to the carbon process model InTEC to provide estimates of carbon sequestration potential. Results indicate substantial differences among species, and suggest that certain native hardwoods (in particular Fraxinus mandshurica and Phellodendron amurense), have high potential for use in carbon forestry applications. Increased use of native hardwoods in carbon forestry in China is likely to have additional benefits in terms of economic diversification and enhanced provision of “ecosystem services”, including biodiversity protection.

English

The goal of many landowners who own reclaimed mined land is to restore the diverse mixed mesophytic forest for environmental, economic, and cultural reasons. However, native hardwoods tend to grow poorly on mined sites due to their physical, chemical and biological mine spoil properties. A 4 x 2 x 3 factorial greenhouse experiment was conducted with one-year-old seedlings. We examined the suitability of four growth media: forest topsoil (FT), weathered sandstone (WS), unweathered sandstone (US), and unweathered shale (UH), as well as the effects of inoculation with topsoil (none verses inoculated), on the growth of three native hardwood species: Fraxinus americana, Q. rubra, and L. tulipifera. Tree growth, foliar nutrients, and soil properties were measured and characterized. The WS was the mine spoil material most conducive to growth for F. americana and Q. rubra. L. tulipifera did not respond to any treatments. Foliar nutrient analysis indicated that adequate nutrition of Q. rubra was independent of spoil type (p = 0.49), F. americana was somewhat dependent on spoil type for nutrient uptake (p =<0.0001), and L. tulipifera was highly dependent, (p < 0.0001). Topsoil inoculation significantly increased growth on the UH spoil type, but not the US or WS spoil types. Topsoil inoculation significantly increased the number of herbaceous plants growing in the pots and improved foliar nutrient indices in F. americana and L. tulipifera. Many properties, such as pH, microbial activity, and water availability of the WS more closely approximated the control soil than the sandstone or shale. The results of this study show that trees are sensitive to spoil type and that certain spoil types should be selected during the reclamation process. Topsoil inoculation should also be considered as it may increase tree growth on some spoil materials, improve tree nutrition and help return the diverse native plant population that was present prior to mining.

How an Aggressive Weedy Invader Displaces Native Trees

How an Aggressive Weedy Invader Displaces Native Trees

The Effect of Forest Type on Benthic Macroinvertebrate Structure and Ecological Function in a Pine Plantation in the North Carolina Piedmont

We examined the impact of small-scale commercial forestry on the structure and function of 6 headwater streams in the North Carolina Piedmont. During 2001–2003 terrestrial organic matter inputs, temperature, macroinvertebrate community composition and tolerance, leaf breakdown rate, and food web structure were quantified for 2 streams draining mature stands of managed loblolly pine, 2 streams draining mature hardwood forests, and 2 streams draining 3-year-old clear cuts, which had been replanted with loblolly pine. Streams in the clear-cuts and pine plantations were bordered by a 15 m hardwood buffer. Despite differences in watershed land-use, there were no significant differences in the organic matter supply or temperature between streams draining different forest types. However, algal biomass was significantly higher in clear-cut sites than forested sites, and was also higher in hardwood sites than pine sites. Streams draining the clear-cut sites contained lower macroinvertebrate richness and diversity, and fewer intolerant species, than streams draining pine and hardwood stands. Despite the differences in macroinvertebrates community composition, there was no difference among forest types in leaf-pack breakdown rates. Analysis of δ15N and δ13C natural abundance of functional feeding group indicated that the shredders and predators collected from streams draining clear-cuts had a δ15N value that was enriched relative to the macroinvertebrates of streams draining pine and hardwood forests. This difference in δ15N signature appears to be the result of the incorporation of riparian grass species in the clear-cuts, which have a higher δ15N, into the diet of shredders. Pine sites had similar food webs to natural hardwood sites. Our results suggest that clear-cutting changes both the trophic dynamics and macroinvertebrate composition of low-order Piedmont streams in North Carolina despite the presence of hardwood buffers. However, large differences were not found between older pine and hardwood stands, indicating rapid recovery following re-growth of forest vegetation, when hardwood buffer strips were present.

Effects of silvicultural treatments on survival and growth of trees planted on reclaimed mine lands in the Appalachians

Reforestation of reclaimed surface mined lands in the Appalachian coal producing region is difficult because most sites have dense ground covers, compacted soils, and unfavorable soil chemical properties. This study evaluated the effects of a range of silvicultural treatments on the survival and growth of different tree species planted on reclaimed coal mines in the Appalachians. Three sites were selected for study, one each in Ohio (OH), West Virginia (WV), and Virginia (VA). At each site, plots were planted with three species: (1) hybrid poplar; (2) white pine; and (3) a native hardwood mix. A gradient of silvicultural treatments designed to improve survival and growth of seedlings was applied: (1) weed control only; (2) weed control plus tillage; and (3) weed control plus tillage plus fertilization. First year survival and growth varied among the three sites and the species planted. In Virginia where the minesoil was developed from oxidized sandstone, survival and growth was better than at the sites in West Virginia and Ohio where siltstone and shale derived minesoils dominated the sites. Hardwood survival across treatments was 80%, 85% and 50% for the sites in Virginia, West Virginia, and Ohio, while white pine survival was 27%, 41%, and 58%, and hybrid poplar survival was 37%, 41%, and 72%, respectively. Growth of hybrid poplar increased in response to increasing silvicultural inputs while growth of white pine and the native hardwoods were generally not affected by the silvicultural treatments applied. Hybrid poplar height and diameter growth were superior to the other species. Height growth of this species was 127 cm during the first year in the most intensive treatment at the site in Virginia. In comparison, the greatest height growth of white pine and hardwood was 9 cm and 8 cm, respectively. Detailed measurements of above- and below-ground biomass and tissue nutrient concentrations were made on the hybrid poplar at the site in West Virginia. Hybrid poplar biomass increased from 16 g to 104 g from the least intensive to the most intensive silvicultural treatment for this site. The weed control + tillage + fertilization treatment improved the foliar nutrition compared to the other treatments. The survival and growth of hybrid poplar on these sites suggest that this species may be well suited for reforesting reclaimed mined land in the Appalachians.

Creating dynamic yield tables for forest estate modelling

Summary Forestry Tasmania is a Government Business Enterprise that administers a land base of 1.5 million ha. The land base is a diverse mix of reserved and production native forests, and hardwood and softwood plantations. Forestry Tasmania has a legislated requirement to make available a minimum of 300 000 m3 of high quality eucalypt sawlogs per annum. In the future, eucalypt plantations will have an important role in meeting this requirement. This paper discusses recent advances in using plantation yield tables at Forestry Tasmania. There are significant advantages in generating yield tables dynamically, particularly for the strategic modelling of wood production. Traditional static tables require a separate table for each possible combination of forest stratum and silvicultural action, leading to proliferation of the tables. A dynamic yield table, on the other hand, does not constrain the choice of silvicultural action or allocation of forest yield to strata: it is a compact and efficient representation of the underlying biometric equations. Forestry Tasmania's forest estate modelling tool is Remsoft's Spatial Planning System, including Woodstock. This system provides the option of supplying growth equations in a Windows Dynamic Link Library (DLL), which is called when the system executes. Up to a thousand parameters can be passed between Woodstock and the DLL, and so almost unlimited sophistication can be embodied within the DLL. Woodstock is written in Delphi, and ideally the DLL should be written in the same language. Forestry Tasmania, however, already had growth models coded in Visual Basic, and so was faced with the dilemma of rewriting the existing models in Delphi, or constructing an interface that allowed compatibility between the two languages. The latter option was chosen and has been successful.

Coarse woody debris in Australian forest ecosystems: A review

Abstract Coarse woody debris (CWD) is the standing and fallen dead wood in a forest and serves an important role in ecosystem functioning. There have been several studies that include estimates of CWD in Australian forests but little synthesis of these results. This paper presents findings from a literature review of CWD and fine litter quantities. Estimates of forest‐floor CWD, snags and litter from the literature are presented for woodland, rainforest, open forest and tall open forest, pine plantation and native hardwood plantation. Mean mass of forest floor CWD in Australian native forests ranged from 19 t ha−1 in woodland to 134 t ha−1 in tall open forest. These values were generally within the range of those observed for similar ecosystems in other parts of the world. Quantities in tall open forests were found to be considerably higher than those observed for hardwood forests in North America, and more similar to the amounts reported for coniferous forests with large sized trees on the west coast of the USA and Canada. Mean proportion of total above‐ground biomass as forest floor CWD was approximately 18% in open forests, 16% in tall open forests, 13% in rainforests, and 4% in eucalypt plantations. CWD can be high in exotic pine plantations when there are considerable quantities of residue from previous native forest stands. Mean snag biomass in Australian forests was generally lower than the US mean for snags in conifer forests and higher than hardwood forest. These results are of value for studies of carbon and nutrient stocks and dynamics, habitat values and fire hazards.

Effects of groundnut stover or Bermudagrass hay supplementation to doe kids on winter hardwood range

Goats in north-central Texas raised on rangeland often face winter forage quantity and quality deficits that may be mitigated by feeding hay or stover. Groundnut ( Arachis hypogea) stover (8% CP, 35% ADF, 43% NDF and 8% acid detergent lignin (ADL) DM basis) and bermudagrass ( Cynodon dactylon) hay (12% CP, 33% ADF, 73% NDF, and 5% ADL DM basis) were tested at Stephenville, Texas as 0.0, 0.5, or 2.0% BW supplement/substitution diets on 18 kg Boer X Spanish doe kids browsing native hardwoods (8 ha −1). Both hay and stover were fed ad libitum in a traditional feedlot, using a complete formulated feed ration as a control. Trials ran for 10 weeks from January to March in 2003 (134 mm rainfall) and in 2004 (182 mm rainfall). Goats receiving 0.5% and 2% BW bermudagrass or 2% BW groundnut stover had greater ADG than those in the control and 0.5% BW groundnut paddocks ( P < 0.05). Goats fed complete ration in the drylot had greater ( P < 0.05) ADG than those eating either hay or stover ad libitum. Bermudagrass hay rejected by goats in the hardwood trial was 20% lower in CP, 7% greater in NDF, 8% greater in ADF, and 9% greater in ADL than the original fed hay; groundnut stover refusals were 21% lower in CP, 12% greater in NDF, 19% greater in ADF, and 20% greater in ADL concentration than the stover when fed. Supplementing goats on hardwood range with bermudagrass hay or groundnut stover may improve ADG when browse is scarce or of poor quality.

Kraft pulping of Drimys winteri wood chips biotreated with Ganoderma australe

AbstractDrimys winteri, a native hardwood from Chile, presents some interesting characteristics that make it suitable for the pulp and paper industry. In this work, the potential of D winteri for the conventional kraft and biokraft pulp production was evaluated. For biokraft pulping, wood chips were biotreated with the white‐rot fungus Ganoderma australe. During the biotreatment, a selective pattern of biodelignification was observed and the wood chips biotreated for 15, 30 and 45 days were submitted to kraft cooking. At low cooking severity (H‐factor below 1500 h−1, 15% active alkali and 25% sulfidity), all biopulps presented lower kappa numbers than control pulps and approximately the same screened pulp yield. Biopulps were easily refined in a PFI mill, requiring less PFI revolutions to achieve the same fibrillation degree. The strength properties of the biopulps were similar to those of the control pulps. Copyright © 2005 Society of Chemical Industry

English

There is increasing interest among eastern U. S. landowners and coal operators in restoring mined land to native hardwood forests. Establishing a mix of native hardwood tree species simultaneously with erosion control ground covers is difficult. The purpose of this study was to test the response of hardwood species to three levels of ground cover control using an herbicide. Treatments were control (90% ground cover), spot spray around trees (50% cover), and broadcast spray (10% cover). Survival of oak species was generally greater when spot sprayed, but survival of ash, maple, poplar and white pine was unaffected. Tree biomass of most species was greater on spot sprayed plots. Trees on broadcast sprayed plots were damaged by herbicide drift rendering this treatment less effective. Overall stocking on spot sprayed plots was 67%, which met the stocking performance standard when 700 trees/acre were planted. A Forestland Reclamation Approach, which includes ground cover management, is needed for successful native hardwood reforestation.

English

Landowners in the Appalachian region are becoming increasingly interested in restoring the native hardwood forest on mined land after reclamation. Trees are usually planted in topsoil substitutes consisting of blasted rock strata from the geologic profile. Reforestation attempts using native hardwoods have often been unsuccessful due to the highly variable nature of the physical, chemical, and biological properties of mine spoils. The purpose of this study was to determine which mine soil properties most influence white oak seedling growth, and to test whether or not these properties are adequately reflected in a preliminary mine soil classification model. Seventy-two 3-yr-old white oak trees were randomly selected across a reclaimed site in southwestern Virginia that varied greatly in spoil type and site properties. Tree height was measured and soil samples were taken to a 40 cm depth at the base of each tree and analyzed for physical, chemical, and biological properties hypothesized to influence tree growth. Tree height and biomass, which ranged from 15 to 125 cm, and 0.24 to 190.03 g, respectively, were regressed against mine soil and site properties. Potassium, size of microbial populations, extractable nitrogen, pH, soil texture, aspect, and phosphorous accounted for over 52% of the variability in tree growth. This study indicates that white oaks are most successful growing on east-facing aspects, in slightly-acidic, sandy loam textured, fertile mine soils that are conducive to soil microbial activity. These results suggest that sandstone rock types with suitable chemical properties should be selected for topsoil substitutes when native hardwood restoration is the desired post-mining land use.

English

Restoring mined land to native forest after surface mining could provide short- and long-term financial, environmental, and societal benefits. This study was conducted to test establishment procedures for short- and long-rotation tree species that consider (i) tree and ground cover compatibility, (ii) seeding versus hand-planting of certain short-rotation hardwood species (sycamore, green ash and tulip poplar), (iii) performance toward bond release, (iv) stocking among species and species types, and (v) the influence of spoil type, grading intensity, and site factors on tree performance. Reforestation treatments including natural invasion, direct seeding, and planting of nurse trees, softwoods and hardwoods were established on ten 2-ha recently-mined sites in Virginia, West Virginia, and Kentucky. A broad gradient in spoil type, degree of compaction, and ground cover amount occurred across the 10 sites. Natural invasion was negligible (7 trees/ha), and direct seeding of nurse and softwood species produced only 353 trees/ha. Planted softwoods (sycamore, green ash, red maple) had the highest stocking level (907-930 trees/ha), while planted hardwoods (oaks, sugar maple, white ash) survived with 783-865 trees/ha. Stocking levels of the commercially- valuable long-rotation hardwoods were significantly less then short-rotation softwoods. Stocking was influenced by groundcover competition, mine spoil density, and slope. None of the reforestation treatments were sufficiently stocked to meet state bond release criteria. Better mine soil conditions and less competitive ground covers are needed to ensure adequate stocking of native hardwoods.

English

The Appalachian coalfields occur largely under rugged mountains covered by native hardwood forests. These forests, soils, and bedrock are removed by the surface mining process. Surface mines are not typically reclaimed to a managed forest land-use, but are often seeded with non-native grasses and legumes, or with pines, black locust, and shrubs for unmanaged forest land. Surface mining and reclamation techniques since the passage of the Surface Mining Control and Reclamation Act of 1977 (SMCRA) create highly compacted mine soils with high coarse fragment content, low organic matter, and high pH, which inhibits native forest reestablishment. The purpose of this study was to develop a forest site quality classification model to advise landowners on the production potential and feasibility of reforesting their mined lands with white pine (Pinus strobus L.). Ten selected physical, chemical, and site properties were assessed and a model was developed using variables that were the most highly correlated with the growth of 10- to 18-year-old white pines established on post- SMCRA surface-mined sites. A model with soil pH, texture, density, and rooting depth variables yielded a coefficient of determination of 0.71. Sufficiency curves were used in a productivity index (PI) model to classify reclaimed surface-mined land into one of five forest site quality classes (FSQC). A site index (SI50 = dominant tree height at age 50) for white pine was estimated for each class, and this measure of productivity may be used to aid in management decisions regarding reforestation of surface mines in the Appalachian coalfields.

Establishment and growth of native hardwood and conifer seedlings underplanted in thinned Douglas-fir stands

Five conifers and two hardwoods native to the Pacific Northwest were planted under four overstory densities of 30-year-old plantations of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) in the Oregon Coast Range, USA. Stand treatments were unthinned (547 trees ha −1), narrow thin (252 trees ha −1), wide thin (138 trees ha −1), and very wide thin (72 trees ha −1). Conditions in the unthinned stands were lethal to both hardwoods and conifers. Eighth-year survival in thinned stands ranged from 87 to 94% for conifer species and 61 to 94% for hardwood species. Eighth-year mean heights of conifer species ranged from 2.6 to 5.4 m. On the basis of size and damage incurred during the study, we ranked conifer species in decreasing order of suitability for underplanting as western hemlock (Tsuga heterophylla (Raf.) Sarg.), Sitka spruce (Picea sitchensis (Bong.) Carr. ), Douglas-fir, grand fir (Abies grandis (Dougl. ex D. Don) Lindl. ), and western redcedar (Thuja plicata Donn ex D. Don ). Eighth-year mean height of red alder ( Alnus rubra (Bong.)) was 7.7 m in thinned stands. Heavy and repeated browse (mostly from elk, Cervus elaphus) on bigleaf maple ( Acer macrophyllum Pursh) and to a lesser degree on western redcedar led us to conclude that these species may be unsuitable for underplanting unless they can be adequately protected. The other five conifer species and red alder suffered little damage during the study and are all viable choices for underplanting where diversity enhancement is an objective. Major findings from this study are (1) underplanting was successful (good survival and size) when the overstory canopy was thinned to wide or very wide spacings and available light was markedly increased; (2) fast growth of planted seedlings such as red alder, western hemlock, and Sitka spruce can enhance stand structure early in the development of thinned stands; (3) the level of thinning intensity affects light availability in the understory and will determine the vitality and longevity of underplanted seedlings; and (4) animal damage, mostly from elk browse and antler rubbing, varied by species and by size of seedlings but can be so serious as to limit the choice of seedlings.

Eastern white pine response to release 30 years after partial harvesting in pine mixedwood forests

Exploitive logging and wildfires during the past 150 years have created larger areas of pine mixedwood forests. A study was set up in pine mixedwood forests within the Petawawa Research Forest, near Chalk River, Ontario, Canada to investigate increasing the growth, yield and quality of eastern white pine ( Pinus strobus L). Understorey pine was released from an overstorey of mainly intolerant hardwoods by careful partial harvesting in two-storied stands. Growth and development of white pine were assessed at three stand densities (initial white pine basal areas of 7, 11.5 and 16 m 2 ha −1 in 1971) in both partially harvested and uncut control plots. A randomized design with five replicates was used. Plots were re-measured 10, 20 and 30-years after treatment. A total volume of 123 m 3 ha −1 of mainly intolerant hardwoods was harvested in 1971 from treated areas, yet total stand volumes in 2001 were similar to those in control plots. After partial harvesting, the rate of stand development was increased and much of what would have been natural hardwood mortality was used for pulpwood. The growth of the immature released white pine was increased significantly at all three initial basal areas. At the highest initial pine basal area, the periodic annual increment of pine was greatest during the 30-year period after partial harvesting. During the last decade, the annual increment of pine has declined, but in the partially harvested plots it still ranged between 6.1 and 8.3 m 3 ha −1 year −1 being highest at the medium initial pine basal area. The total increment within the control plots was very low, especially during the last decade because of high losses to mortality of both aspen and white birch. The white pine increment was lower in the control plots at about half that in the partially harvested plots. The approach investigated here allowed for the effective use of the shorter-lived intolerant hardwoods while increasing the growth and development of white pine. This method could be applied to increase pine productivity, and possibly the extent of white pine in areas where pine is less common today than in earlier times. White pine is a fire-adapted species and with the effective forest fire suppression programs of today, silvicultural techniques are needed to maintain, enhance and in some cases, restore white pine forests.

Mapping Land-Use Change and Monitoring the Impacts of Hardwood-to-Pine Conversion on the Southern Cumberland Plateau in Tennessee

Abstract Over the past two decades, forests in the southeastern United States have undergone dramatic changes as the result of urban sprawl and conversion to intensively managed pine plantations. The Cumberland Plateau, an important ecoregion in the southeastern United States, contains some of the largest remaining tracts of privately owned, native hardwood forest in North America. These ecologically important forests have been undergoing increasingly rapid rates of hardwood-to-pine conversion, much of which has gone undetected by large-scale statewide inventories. Forest conversion in Tennessee's southern Cumberland Plateau provides a case study highlighting the need for interdisciplinary and spatially explicit assessments of the impact and drivers of land-use change at smaller scales. Aerial and satellite imagery were used to create computer-generated maps of land use and forest cover for a 243 000 ha study area within a seven-county region of the southern Cumberland Plateau in Tennessee to track and do...

Identification of the Armillaria root rot pathogen in Ethiopian plantations

SummaryArmillaria root rot is a well‐known disease on a wide range of plants, world‐wide. In Ethiopia, the disease has previously been reported on Pinus spp., Coffea arabica and on various native hardwoods. The causal agent of the disease has been attributed to Armillaria mellea, a species now known to represent a complex of many different taxa. The aim of this study was to determine the extent of Armillaria root rot and the identity of the Armillaria sp. in Ethiopian plantations. As part of a plantation disease survey in 2000 and 2001, samples were collected in plantations at and around Munessa Shashemene, Wondo Genet, Jima, Mizan and Bedele, in south and south‐western Ethiopia. Basidiocarps were collected and their morphology studied. Morphological identification was confirmed by sequencing the intergenic spacer (IGS‐1) region of the ribosomal rRNA operon and comparing data with published sequences of Armillaria spp. Armillaria isolates were collected from Acacia abyssinica, Pinus patula, Cedrela odorata and Cordia alliodora trees. Sporocarps were found on stumps of native Juniperus excelsa. Basidiocarp morphology and sequence data suggested that the fungus in Ethiopia is similar to that causing disease of Pinus spp. in South Africa and previously identified as A. fuscipes. This identification was confirmed for all isolates, based on sequence data. Armillaria fuscipes is known to be common in southern Africa. Its widespread occurrence in Ethiopia suggests that it is also the major cause of Armillaria root rot in that country.

Structure and dynamics of tree populations within unsuccessful conifer plantations near the Shirakami Mountains, a snowy region of Japan

At plantations of the evergreen conifer Cryptomeria japonica (ca. 20 years old) damaged by heavy snow, the growth of planted trees, composition of colonizing native hardwoods, and successional trends of tree populations were investigated. The study site of ca. 2 km×2 km was established in 1998 within a river basin contiguous to the Shirakami Mountains which was registered as a World Natural Heritage site. This site was originally covered with old-growth forests of Fagus crenata. Twenty-one plots (each 400 m 2) were established (11 in the plantations and 10 in adjacent remnant natural forests) and a census of trees was conducted in 1998 and in 2000. During this period, the mean basal area slightly decreased from 39.8 to 38.8 m 2 ha −1 in the natural forests, In the plantations, the mean basal area increased from 15.3 to 20.3 m 2 ha −1. Only focusing on C. japonica, the value changed from 11.4 to 14.2 m 2 ha −1, which was smaller than expected in the management table for this district (14.5–22.5 m 2 ha −1 on average). The smaller basal area of the plantations had resulted from a high mortality of C. japonica. That was caused by damage from heavy snow falls during winter, especially on east-facing slopes. This was considered to have resulted from spatial variation in snow depth depending on slope aspect. Native hardwoods had colonized the resulting openings in the plantations, and increased their basal area more rapidly than the planted conifers. They presently occupy 29% of the total basal area of the plantations on average. The composition of native hardwoods differed between the natural forests and the plantations; climax species occupied a significantly larger proportion of the basal area in the natural forests (e.g., F. crenata) and pioneer species had greater importance in the plantations (e.g., Pterocarya rhoifolia, Swida controversa, Phellodendron amurense). Pioneers in the plantations tended to distribute on the east-facing slopes, probably reflecting higher number of openings created there. As the result of the natural succession, tree communities in the plantations are expected to become dominated by climax species, but it will take quite a long time.

Characterization of organic matter in rainfall, throughfall, stemflow, and streamwater from three subtropical forest ecosystems

Little is known about the characteristics of dissolved organic matter derived from precipitation, throughfall, stemflow, and streamwater in subtropical forest ecosystems. Water samples were, thus, collected from rainfall, throughfall and stemflow of a China-fir plantation, a secondary hardwood and a natural hardwood, and streams in forest ecosystems in the central part of subtropical Taiwan on March 31 and May 8, 1999. We examined pH, electrical conductivity, dissolved organic carbon, and acid-neutralizing capacity (ANC) in the samples. Furthermore, the humic polymers (MW>1000) and fulvic acids (FAs; MW>1000) were isolated from the water samples and characterized by elemental analyses and Fourier transform infrared (FTIR) spectroscopy. Results showed that the contents of carboxylic acid of both humic polymers (MW>1000) and FAs (MW>1000) contributed to the water sample ANC, ranging from 8.7 to 61.2% and 0.2 to 38.1%, respectively. FTIR and elemental analyses of isolated humic polymers (MW>1000) and FAs (MW>1000) from throughfall and stemflow had characteristics previously reported for humic substances. The study showed that throughfall and stemflow, not affected by soils, may be additional sources of humic substances.