Development Of Forest Ecosystems Research Articles

Above- and belowground ecosystem biomass and carbon pools in an age-sequence of temperate pine plantation forests

We assessed the successional development of above- and belowground ecosystem biomass and carbon (C) pools in an age-sequence of four White pine ( Pinus strobus L.) plantation stands (2-, 15-, 30-, and 65-years-old) in Southern Ontario, Canada. Biomass and C stocks of above- and belowground live and dead tree biomass, understorey and forest ground vegetation, forest floor C (LFH-layer), and woody debris were determined from plot-level inventories and destructive tree sampling. Small root biomass (<5 mm) and mineral soil C stocks were estimated from soil cores. Aboveground tree biomass became the major ecosystem C pool with increasing age, reaching 0.5, 66, 92, and 176 t ha −1 in the 2-, 15-, 30-, and 65-year-old stands, respectively. Tree root biomass increased from 0.1 to 10, 18, 38 t ha −1 in the 2-, 15-, 30-, and 65-year-old stands, respectively, contributing considerably to the total ecosystem C in the three older stands. Forest floor C was 0.8, 7.5, 5.4, and 12.1 t C ha −1 in the 2-, 15-, 30-, and 65-year-old stands, respectively, indicating an increase during the first two decades, but no further age-effect during the later growth phase. Mineral soil C was age-independent with 37.2, 33.9, 39.1, and 36.7 t C ha −1 in the 2-, 15-, 30-, and 65-year-old stands, respectively. Aboveground ecosystem C increased with age from 3 to 40, 52, and 100 t C ha −1 in the 2-, 15-, 30-, and 65-year-old stands, respectively, due to an increase in aboveground tree biomass. Belowground ecosystem C remained similiar in the early decades after establishment with 37, 39, and 39 t C ha −1 in the 2-, 15-, and 30-year-old stands, but increased to 56 t C ha −1 in the 65-year-old stand due to an increase in root biomass. The difference in total ecosystem C between the 2- and 65-year-old stand was 116 t C ha −1. Our results highlight the importance of considering the successional development of forest ecosystem C pools, when estimating C sink potentials over their complete life cycle.

Species diversity based on vertical structure as indicators of artificial restoration for coniferous forests in Southwest China

Five indices of species richness, species diversity and species evenness were used to assess α diversity of four types of coniferous forests undergone different artificial regeneration time. The study was based on the vertical structure of forests, involving growth-forms of total plants as well as vertical layers of woody plants. The results showed that, except for the fourth layer of woody plants, the vertical structure of the four forests exhibited significant difference in terms of their species richness, species diversity and species evenness, suggesting that α species diversity index provided more detailed information and was a better index reflecting the regeneration processes in this region. It was recommended that silvicultural management of artificially regenerated forests should be strengthened to conserve the biodiversity of the forests, optimize forest structure and, in the long run, promote sustainable development of forest ecosystems.

The Use of Arthropods as Indicators of Ecosystem Integrity in Forest Management

Abstract Arthropods play vital roles in various ecosystem functions and respond acutely to habitat manipulation. Diversity and community dynamics of arthropods are strongly correlated with ecosystem functioning. Arthropod community structure reflects habitat heterogeneity, as well as development and recovery of forest ecosystems after natural and anthropogenic disturbances. Arthropod community structure also reflects the degree of fragmentation and isolation of forest ecosystems on the landscape. Arthropods are good indicators of the overall biodiversity and ecosystem integrity of forests and can be used for evaluating and designing sound ecosystem management plans.

From single fine roots to a black alder forest ecosystem: How system behaviour emerges from single component activities

Based on empirical findings in a natural black alder ecosystem in Northern Germany we developed an individual based model that integrates components of a black alder ecosystem interacting on different levels of organisation. The factors determining seasonal fine root biomass development of forest ecosystems are not yet fully understood. We used an object oriented model approach to investigate this complex matter for black alder trees. Processes like growth, storage, respiration, transport, nutrient mineralisation and uptake as well as interactions among these factors are described on the level of functionally differentiated plant organs (fine roots, coarse roots, stem, branches, leaves) and soil units. The object structure of the model is determined by spatial relations between plant modules as well as between plant modules and their local environment modules. As results of model application we found that (i) on the organ level, spatio-temporal plasticity of (root) growth allocation is related to spatio-temporal variation of resource availability, (ii) on the plant level, balanced root:shoot growth appears in response to variation of available resources light and nutrients, (iii) on the population level, tree stand development (population structure, self-thinning) resulted from coexistence and competition between plant individuals. For the understanding of the root compartment it seems relevant that the model implementation of local scale fine root dynamics is consistent with a self-organised large scale spatial heterogeneity of fine root activity pattern. On the other hand, fine-root dynamics cannot be explained as a result of autonomous dynamics. A reference to above-ground processes is a necessary condition and the overall plant seems to act as an integrator providing boundary conditions for local activity pattern. At the same time fine-root characteristics are of some importance for properties on hierarchically higher levels, e.g. co-existence in a tree population or element cycling in the ecosystem. As a conclusion, modelling of the spatio-temporal dynamics of tree root systems appears as a paradigmatic example of scale and organisation level integrating processes.

14C measurement of soil in post-mining landscapes

The formation and development of new soil organic matter under extreme soil conditions was investigated in the Lusatian lignite mining district. In order to assess the development of forest ecosystems the pedogenesis (soil development) was studied, especially the contribution of soil organic matter formed during the decomposition of plant residues and the significance of lignite inherent to the parent substrate.To determine the depth gradient of soil organic matter accumulation a differentiation between lignite derived (14C “free”) and recent carbon in the mine spoil was necessary. This was performed by AMS 14C measurement of the total organic carbon TOC (lignite derived and recent organic matter) of the soil. For TOC extraction a suitable preparation method was used. The calculation for obtaining the soil organic matter and lignite content is discussed and results of different study sites are presented. It is shown that 14C measurements of soil samples by AMS is a very helpful tool to evaluate the accumulation of recently formed organic carbon and to differentiate this carbon pool from the geogenic, i.e. lignite derived organic carbon supply in post-mining soils.

14C measurement of soil in post-mining landscapes

The formation and development of new soil organic matter under extreme soil conditions was investigated in the Lusatian lignite mining district. In order to assess the development of forest ecosystems the pedogenesis (soil development) was studied, especially the contribution of soil organic matter formed during the decomposition of plant residues and the significance of lignite inherent to the parent substrate. To determine the depth gradient of soil organic matter accumulation a differentiation between lignite derived ( 14 C “free”) and recent carbon in the mine spoil was necessary. This was performed by AMS 14 C measurement of the total organic carbon TOC (lignite derived and recent organic matter) of the soil. For TOC extraction a suitable preparation method was used. The calculation for obtaining the soil organic matter and lignite content is discussed and results of different study sites are presented. It is shown that 14 C measurements of soil samples by AMS is a very helpful tool to evaluate the accumulation of recently formed organic carbon and to differentiate this carbon pool from the geogenic, i.e. lignite derived organic carbon supply in post-mining soils.

Stem number development and potential stand density in unthinned even-aged &lt;I&gt;Azadirachta indica&lt;/I&gt; plantations in Gujarat, India

SUMMARY Growth modelling is an essential prerequisite for evaluating the consequences of a particular management action on the future development of forest ecosystem and is a central theme of forest management. Growth models are not available for many indigenous species in India and such information, particularly for neem, is very rare. In this paper equations have been developed to estimate potential stand density and to model the natural decline of trees in pure even-aged stands of neem. Relationships have been developed between the quadratic mean diameter and number of stems per ha and parameters of this relationship have been used to produce a limiting line. Two different models were applied on the data to model the natural decrease of stem numbers in the stands and performed equally well.

Landscape planning for a rural ecosystem: case study of a resettlement area for residents from land submerged by the Three Gorges Reservoir, China

The goals of landscape planning are multiple for rural ecosystems of the resettlement area in the Hubei Province of China. They relate to the types, diversity and patterns of the ecosystems, and to the conservation of ecosystem functions and biodiversity. We were interested in the improvement of socio-economic conditions, and the promotion of the development of farmland ecosystems and natural forest ecosystems. The landscape planning took into account the conservation and the restoration of forestlands, and the reconstructions of farmlands, towns and villages. The areas of towns and villages were assigned by trade-off analysis balancing ecological, economic and social benefits. The spatial pattern of used lands was designed by a multi-criteria optimal spatial planning, resulting in the strengthening of some primary ecosystem functions. In the resettlement area forests will expand to a matrix, and cropland patches together with tree fences will form patch-corridor systems. Significant ecological, economic and social benefits can be derived from this landscape pattern.

NITROGEN STORAGE AND CYCLING IN OLD- AND SECOND-GROWTH NORTHERN HARDWOOD FORESTS

Ecosystem retention of N is mediated by interactions among plant, soil, and microbial processes. These are likely to change with forest ecosystem development as living plant biomass accumulation slows and detrital biomass increases. We investigated linkages among N storage, N cycling processes, and N leaching losses in a study of replicate mid- successional (80-yr-old) and late-successional (uneven-aged old-growth). northern hardwood forests in the western upper peninsula of Michigan, USA. Our study tested hypotheses that detrital biomass and microbial immobilization of N function as larger N sinks and corre- spond to greater N retention in old-growth compared to maturing second-growth forests. Aboveground living and detrital biomass pools were greater in old-growth compared to second-growth forest, a difference due largely to coarse woody debris (CWD). The total amount of N in detrital pools was significantly greater in old-growth than second-growth forests. We also found more rapid rates of microbial N immobilization in old-growth forests than in second-growth forests. In situ net N mineralization ranged widely among individual stands and did not differ between old- and second-growth forests. Nitrogen (organic + inorganic) leaching did not differ significantly between old-growth and second-growth forests, and was substantially lower than wet deposition inputs. Nitrate leaching losses were significantly related to soil NO3- pools, litterfall N flux, and fine root biomass across both old- and second-growth forest stands. We conclude that CWD and microbial N uptake and turnover are greater N sinks in old-growth than in second-growth forests. This apparent N sink was not the primary factor influencing N leaching loss, however. Patterns of N dynamics among individual forest ecosystems indicate that N losses correspond to net rates of N mineralization and to litterfall N flux (indicators of plant N cycling), which are independent of forest age, biomass pools, and gross N transformations at the successional stages that we compared.

Disturbances and structural development of natural forest ecosystems with silvicultural implications, using Douglas-fir forests as an example

Forest managers need a comprehensive scientific understanding of natural stand development processes when designing silvicultural systems that integrate ecological and economic objectives, including a better appreciation of the nature of disturbance regimes and the biological legacies, such as live trees, snags, and logs, that they leave behind. Most conceptual forest development models do not incorporate current knowledge of the: (1) complexity of structures (including spatial patterns) and developmental processes; (2) duration of development in long-lived forests; (3) complex spatial patterns of stands that develop in later stages of seres; and particularly (4) the role of disturbances in creating structural legacies that become key elements of the post-disturbance stands. We elaborate on existing models for stand structural development using natural stand development of the Douglas-fir—western hemlock sere in the Pacific Northwest as our primary example; most of the principles are broadly applicable while some processes (e.g. role of epicormic branches) are related to specific species. We discuss the use of principles from disturbance ecology and natural stand development to create silvicultural approaches that are more aligned with natural processes. Such approaches provide for a greater abundance of standing dead and down wood and large old trees, perhaps reducing short-term commercial productivity but ultimately enhancing wildlife habitat, biodiversity, and ecosystem function, including soil protection and nutrient retention.

Populations of ectomycorrhizal Laccaria amethystina and Xerocomus spp. show contrasting colonization patterns in a mixed forest.

• The knowledge of temporal and spatial structure of populations of ectomycorrhizal fungi, together with the origin and maintenance of their genetic variation, is critical to understanding how populations of these fungi establish, evolve and disappear at different stages of development of forest ecosystems. • Identification and spatial delimitation of genets in populations of the ectomycorrhizal basidiomycetes, Laccaria amethystina, Xerocomus chrysenteron and X. pruinatus were inferred from the polymorphism of two codominant genetic loci, the nuclear rDNA internal transcribed spacers (ITS) and intergenic spacers (IGS), and anonymous dominant RAPD markers from basidiocarps collected in a mixed mature forest in the fungal reserve of La Chanéaz (Switzerland). • The L. amethystina population showed numerous small, short lifespan genets; most closely spaced basidiocarps were genetically unique. Our results confirmed that sexual spore propagation is important in the life history of L. amethystina in undisturbed mature forests. By contrast, we found a single genet for each of the boletoid species colonizing a nearby plot indicating that clonal growth dominated. • In La Chanéaz forest, the intrinsic biological features of the investigated species appear to play a higher role in colonization strategy than the features of local habitat.

Forest ecosystem development in post-mining landscapes: a case study of the Lusatian lignite district.

The restoration of surface mining landscapes requries the (re)creation of ecosystems. In Lusatia (eastern Germany), large-scale open-cast lignite mining operations generated spoil dumps widely consisting of acidified, phytotoxic substrates. Amelioration and rehabilitation measures have been developed and applied to these substrates since the 1950s. However, it is still not clear whether these approaches are sustainable. This paper reports on collaborative research work into the ecological potential of forest ecosystem development on typical minesites in the Lusatian lignite district. At first sight, pine stands on minesites along a chronosequence comprising about 35 years did not show differences when compared with stands on non-mined sites of the general region. Furthermore, with some modification, conceptual models for flora and fauna succession in forest stands on non-mined sites seem to be applicable, at least for the early stages of forest ecosystem development. For example, soil organism abundance and activity at minesites had already reached levels typical of non-mined sites after about 20-30 years. In contrast, mine soils are very different from non-mined soils of the test region. Chemically, mine soil development is dominated by processes originating from pyrite oxidation. Geogenic, i.e. lignitic, soil organic carbon was shown to substitute for some functions of pedogenic soil organic matter. Rooting was hampered but not completely impeded in strongly acidified soil compartments. Roots and mycorrhizae are apparently able to make use of the characteristic heterogeneity of young mine soils. Considering these recent results and the knowledge accumulated during more than 30 years of research on minesite rehabilitation internationally, it can be stated that minesite restoration might be used as an ideal case study for forest ecosystem development starting at "point zero" on "terra nova".

Impact of fire behavior on postfire forest development in a homogeneous boreal landscape

Although behavior of stand-replacing wildfire has significant impacts on initial tree regeneration in the fire-prone boreal landscape, the unknown behavior of most past wildfires has precluded any evaluation of these impacts on the progressive development of late-successional forest ecosystems. In this study, the effects of fire behavior on long-term ecosystem development were evaluated by linking the banding pattern of tree density in a jack pine (Pinus banksiana Lamb.) - black spruce (Picea mariana (Mill.) BSP) forest on a flat and homogeneous landform in northern Quebec to a similar, previously documented pattern of unburned strips of tree crowns. Complex wildfire-atmosphere interactions during the spread of a 1941 stand-replacing wildfire created this pattern in stem density, most likely by differentially damaging the canopy-stored seed bank between areas of contrasting fire severity. Sites with initial differences in seedling densities have followed different recovery pathways and developed markedly different forest structures, as well as differences in species abundance. Compared with areas of severe crown fire, the present-day vegetation in areas of low crown fire severity shows a higher density of living pines in the canopy layer, higher spruce and dead pine densities in the subcanopy layer, a lower pine density in the understory layer, and a higher abundance of Cladina rangiferina (L.) and Cladina stellaris Opiz (Brodo) in the lichen mat. This close spatial connection between crown fire severity and the ecological processes driving ecosystem recovery may explain large differences in vegetation among sites in the boreal landscape.

PRIMARY SUCCESSION AND FOREST DEVELOPMENT ONCOASTAL LAKE MICHIGAN SAND DUNES

Vegetation and soil properties were described across a well-dated sand-dune chronosequence bordering northern Lake Michigan to document patterns and rates of primary succession and forest ecosystem development, and to determine environmental constraints that potentially drive succession and regulate species diversity. The site experienced frequent and continuing formation of 72 shore-parallel dune ridges over the past 2375 yr. Across the chro- nosequence represented by the youngest 13 dune ridges aged 25-440 yr, there were clear patterns of species turnover and community convergence as well as successional changes in species diversity, aboveground biomass, aboveground litter production, net ecosystem produc- tion, nutrient pools, and nutrient cycling. Dune-building species were replaced by evergreen shrubs and bunchgrass within 100 yr, which in turn, were replaced by mixed pine forest within 345 yr. Plant-species richness increased to a peak in developing forest at 285 yr but thereafter decreased as early-successional species disappeared from the communities. Rates of species addition peaked between 95 and 145 yr as forest species invaded, whereas rates of species loss peaked between 345 and 440 yr as early-successional species were lost from the developing forest. Development of the forest ecosystem required ;300 yr (i.e., 145-440 years). Total eco- system carbon increased in a logistic manner to 128 Mg C/ha, with net ecosystem production peaking at 30 g C·m 22 ·yr 21 in developing forest. Aboveground biomass and O horizon mass increased to ;137 Mg/ha and ;79 Mg/ha, respectively, whereas aboveground litter production increased to 3.5 Mg·ha 21 ·yr 21 at 440 yr, but thereafter varied between 175 and 350 Mg·ha 21 ·yr 21 . Total carbon and total nitrogen in the upper 15 cm of mineral soil and O horizon accumulated to ;42 Mg/ha and ;1.36 Mg/ha, respectively. Estimated average rates of carbon and nitrogen accumulation over 440 yr of ecosystem aggradation were 23.2 g·m 22 ·yr 21 for carbon and 0.38 g·m 22 ·yr 21 for nitrogen. Because nitrogen-fixing plants are rare on the upland dune ridges, ecosystem aggradation depends largely on atmospheric nitrogen inputs. Following colonization by conifers, soil acidification resulted in rapid leaching losses of calcium and magnesium, whereas phosphorus and potassium were cycled more tightly. The dune chronosequence represents a complex gradient of changing environmental con- straints that differentially reduce the survival, growth, and reproduction of plant species. Young dune ridges near the lake shore are characterized by strong winds, sand burial and erosion, high insolation, high rates of evaporation, and low availability of nitrogen and phosphorus. These conditions ameliorate with increasing dune age as wind velocities and sand movement diminish with distance from the lake, as accumulating organic matter improves the moisture- holding capacity and nitrogen availability of the soil, and as mineral weathering mobilizes soil phosphorus. However, in developing forest, light and cationic nutrients may become limiting, and decreased light availability, cool soil temperatures, and accumulation of a thick forest floor may limit recruitment from seed for many species. These numerous potential environmental constraints suggest a considerable complexity in this ostensibly simple ecosystem.

Response Mechanisms of Birch and Poplar to Air Pollutants

The impact of air pollutants on trees has been a research interest for decades. Nevertheless, uncertainty exists about the potential effects of the pollutant concentrations occurring at present, for example, in Central Europe. This uncertainty results from an incomplete understanding of the mechanisms by which air pollutants and other environmental factors influence woody plants. This review presents examples of the mechanisms of ozone and NO2 impacts at low concentrations on birch and poplar. The question of whether the responses found in the ecophysiology and structural differentiation of the trees reflect acclimation to these pollutants rather than injury is given particular attention. An attempt to interpret the response of carbon allocation to ozone and NO2 by one explanatory model is presented. The capacity of air pollutants to change carbon allocation may affect interspecific competition and, by this, the species composition and the dynamics in the development of forest ecosystems.

Reconstruction of recent forest dynamics based on pollen analysis and micromorphological studies of young acid forest soils under Scots pine plantations

Reconstructions of vegetation development of forest ecosystems have traditionally drawn on pollen samples of thick mor-humus profiles. In The Netherlands, however, well developed acid forest soils are scarce, especially under Scots pine (Pinus sylvestris). Scots pines have been planted from ad 1800 onwards, since when an acid soil profile has developed. This paper aims to show that pollen analysis of young acid forest soils not only can be used for the reconstruction of vegetation development in forests but also, combined with micromorphological observations, reveals information about forest dynamics in terms of litter production, decomposition processes and soil development. For that purpose four sites were selected in Scots pine stands, planted between ad 1900 and ad 1940 on drift sand deposits. At each site samples for pollen analysis were obtained from the entire organic layer and the top of the mineral soil. The pollen records of young acid forest soils show a shift in pollen assemblages, caused by a change from an open heath landscape towards a closed canopy after forest plantation. Micromorphological observations by thin sections of the undisturbed acid soil profile enhanced the interpretations of the pollen records. Micromorphological studies of these forest soils revealed the presence of non-burrowing soil animals and the preservation of pollen grains in the excrements of these soil animals. The absence of soil mixing animals and the pollen preservation in soils results in a pollen stratification, representing the recent local vegetation development. Furthermore, the pollen concentration curves show the stabilization periods of drift sand. The incidental increase of the pollen concentrations in the mineral soil indicates alternations of active sand drifting and stabilization periods, while the continuous increase of pollen concentrations towards the top of the mineral soil points to the final stabilization of the drift sand by Scots pine and the development of an AE-horizon.

Development of new forest stands after a large scale forest decline in the Krušné hory Mountains

In the Krušné hory Mountains, biomass accumulation and soil chemical status were studied in four forest stands — Picea pungens (A), Betula verrucosa (B), Picea abies (C) and Sorbus aucuparia (D) — growing in a region heavily affected by air pollution. Ages of the stands were 5, 5, 30 and 13 years respectively. Stands A and B grow on sites modified during the site preparation before planting (topsoil removing by bulldozer). Stand C represents Picea abies stands which had dominated this area before air pollution stress increased. Stand D derived from spontaneous regeneration of Sorbus aucuparia after a decline of a mature spruce stand. Total above- and below-ground biomass accumulations in stand A, B, C and D were 21.75, 43.11, 149.6 and 131.67 t · ha −1 respectively. Soil chemical status was affected to a large extent by topsoil removal in stand A and B compared to stand C and D. It is pronounced mainly in the reduced content of organic matter. Young stands of Betula verrucosa and Sorbus aucuparia are able to form close forest stands with a relatively high biomass accumulation and can thus effectively contribute to the development of new forest ecosystems in the Krušné hory.

A comparison of tree growth models

Abstract Tree growth models project the growth and development of forest ecosystems by increasing the size of each simulated tree in the forest on an annual or greater periodic basis. These models are often referred to as ‘tree models’ because they are based on the birth, growth and death of individual trees, and the characteristics of individual trees are aggregated to describe the stand. This paper distinguishes between two types of models based upon their major purpose for development and data requirements. Forest growth models are defined as those used to assess the yield of a managed forest under prescribed conditions and usually require large calibration data sets. Community dynamics models are defined as those applied to ecological questions about the feedback of environment and species characteristics on growth and yield, and have species-specific rather than site-specific data requirements. The structure and data requirements for each model type affects their regional and temporal applicability as well as their predictive value. A combination approach using the two types of models may be t the most general model of tree growth and stand development.

The impact of tree species on soil productivity.

A general discussion with a bibliography of recent literature. A reappraisal of earlier studies in Europe suggests that the dieback of 2nd-rotation coniferous plantations on poor soils was due to intensive site preparation leading to losses of soil organic matter. Afforestation, which generally increases site fertility, can be preceded by complete soil cultivation without ill effect. A strategy is proposed for silvicultural management according to the stage of ecological development of forest ecosystems. A methodology is also proposed for determining the impact of individual species on soil productivity. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Energy and Nutrient Dynamics of Forest Floors in Three Minnesota Forests

Forest floors are fundamental components of forest ecosystems in several respects. In terms of system energetics, the transfer of plant debris to the forest floor and subsequent utilization by heterotrophs is a major pathway of energy flow. Forest floors can also be regarded as nutrient pools involving input, output, mean nutrient content and turnover rates. Depending on environmental conditions, accumulated detritus can represent a significant portion of total organic matter in forest ecosystem development (Olson 1963). In addition, forest floors are significant in terms of water flux (Lowdermilk 1930; Fletcher 1952), regulation of plant reproduction (Little & Moore 1949) and fuel for fires. This report describes a comparative study of energy and nutrient dynamics in floors of three Minnesota forests. The objectives of this study were to: (i) measure rates of energy and nutrient flow into forest floors through detritus pathways; (ii) determine minimum energy storage levels and nutrient pool standing states; and (iii) estimate rates of nutrient turnover in the detritus pools.