Stands Of Different Ages Research Articles

Dynamics of soil respiration at different stages of pyrogenic restoration succession with different-aged burns in Evenkia as an example

An analysis of CO2 emissions and soil microbiological activity has been performed in larch stands of different ages that developed on cryogenic soils and represent different stages of post-fire succession. An abrupt increase in the soil emissions of CO2 (by more than 2 times) in young stands (15–30 years old), as well as a decrease of soil-respiration rate at the later stages of pyrogenic successions because of the restoration of the moss-lichen cover and the closure of the stand canopy was seen. Intraseasonal and interannual variations of soil CO2 fluxes were also revealed; however, their dynamics was largely determined by the local conditions.

Small Mammal Community of Forest Stands in Drahanská vrchovina Upland (Czech Republic)

In the years 2006–2011 was studied community of small terrestrial mammals in the Drahanská vrchovina Upland. There were compared four stands of different age and tree species composition (30 years old spruce stand; 105 years old spruce forest; 125 years old mixed stand, and 40 years old beech stand). Totally 276 individuals of small terrestrial mammals were trapped and analyzed. The vast majority of cases were Apodemus flavicollis (163), Clethrionomys glareolus (81 specimen), and Apodemus sylvaticus (28). Besides previous species has been confirmed Sorex araneus (2) and Microtus arvalis (1). At all sites the most numerous species was A. flavicollis. Changes in species abundance were synchronized not only among themselves, but also in comparison to southern Moravia. The smallest amplitude and thus the smallest variation showed a population of mammals in old mixed forest. The highest population densities were found in younger spruce stand. The highest biodiversity according to all aspects except the number of species has been found among spruce stands.

Fungi occurring in forests injured by industrial air pollutants in Silesia and Cracow Industrial Regions. I. An attempt to estimate the occurrence of Lophodermium pinastri (Schrad.) Chev. from signs on pine needles in the litter

An investigation was carried out on the occurrence of the fungus <i>Lophodermium pinastri</i> (Schrad.) Chév. in pine stands and which were in highly industrialized areas with a high level of toxic air pollutants. The basis for estimating the occurrence were the signs of this pathogen on dead pine needles in the litter. In all 57 thousand needles from 57 pine stands of different age were analysed.

The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands.

Floods control greenhouse gas (GHG) emissions in floodplains; however, there is a lack of data on the impact of short-term events on emissions. We studied the short-term effect of changing groundwater (GW) depth on the emission of (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in two riparian grey alder (Alnus incana) stands of different age in Kambja, southern Estonia, using the opaque static chamber (five replicates in each site) and gas chromatography methods. The average carbon and total nitrogen content in the soil of the old alder (OA) stand was significantly higher than in the young alder (YA) stand. In both stands, one part was chosen for water table manipulation (Manip) and another remained unchanged with a stable and deeper GW table. Groundwater table manipulation (flooding) significantly increases CH4 emission (average: YA-Dry 468, YA-Manip 8,374, OA-Dry 468, OA-Manip 4,187 μg C m(-2) h(-1)) and decreases both CO2 (average: OA-Dry 138, OA-Manip 80 mg C m(-2) h(-1)) and N2O emissions (average: OA-Dry 23.1, OA-Manip 11.8 μg N m(-2) h(-1)) in OA sites. There was no significant difference in CO2 and CH4 emissions between the OA and YA sites, whereas in OA sites with higher N concentration in the soil, the N2O emission was significantly higher than at the YA sites. The relative CO2 and CH4 emissions (the soil C stock-related share of gaseous losses) were higher in manipulated plots showing the highest values in the YA-Manip plot (0.03 and 0.0030 % C day(-1), respectively). The soil N stock-related N2O emission was very low achieving 0.000019 % N day(-1) in the OA-Dry plot. Methane emission shows a negative correlation with GW, whereas the 20 cm depth is a significant limit below which most of the produced CH4 is oxidized. In terms of CO2 and N2O, the deeper GW table significantly increases emission. In riparian zones of headwater streams, the short-term floods (e.g. those driven by extreme climate events) may significantly enhance methane emission whereas the long-term lowering of the groundwater table is a more important initiator of N2O fluxes from riparian gley soils than flood pulses.

Resorption of nitrogen, phosphorus and potassium from leaves of lucerne stands of different ages

Nutrient resorption from the senesced to the green leaves can help a plant re-use elements, thus improving adaptability and persistence. How the resorption of nitrogen (N), phosphorus (P) and potassium (K) varies among differently aged lucerne (Medicago sativa) stands and how they correlate to their stoichiometry in the leaves and soil remain uncertain. This study aimed to analyze the resorption efficiencies (REs) of N, P and K and their possible correlations with stoichiometric ratios in the plant and soil. The concentrations of plant N, P and K and soil N, P, K and carbon (C) were measured under lucerne stands established in different years, and stoichiometric ratios and REs were calculated. The relationships of REs with stoichiometric ratios were analyzed. The nitrogen resorption efficiency (NRE) was quite variable among the different stands and tended to rise and then drop with stand age, ranging from 4.6 to 33.7 % with an average of 16.2 %. The phosphorus resorption efficiency (PRE) tended to increase with stand age, ranging from 11.1 to 38.3 % with an average of 27.3 %. The potassium resorption efficiency (KRE) increased with stand age, ranging from 21.0 to 49.8 % with an average of 36.9 %. The KRE was generally highest, followed by the PRE, and the NRE was lowest. Leaf N:P and N:K generally decreased and then increased with stand age, while the K:P increased and then decreased. In the green leaves, total N concentration increased significantly with NRE and PRE, and total P concentration rose significantly with PRE, while in the senesced leaves, total N concentration decreased significantly with NRE and KRE. The N:P in the green leaves decreased significantly with PRE and the K:P in the senesced leaves dropped with NRE. Furthermore, the REs decreased with total soil nutrition status if there was any correlation. The REs increased significantly with soil ammonium N concentration, while the NRE decreased significantly with soil nitrate N concentration. In addition, soil available P concentration at most depths led to significant increases in NRE and KRE. However, the REs were rarely influenced by stoichiometric ratios of soil N, P, K and C. The NRE rose and then dropped, and the PRE and KRE both increased with stand age. Leaf N:P and N:K generally decreased and then increased with stand age, while K:P increased and then decreased. The concentrations of N, P and K increased in the green leaves and decreased in the senesced leaves with REs if there was any correlation. The REs decreased with total soil nutrition status if there was any correlation. However, the REs hardly changed with stoichiometric ratios in the leaves and soil under differently aged lucerne stands. There appear to be no correlations between REs and element stoichiometries.

Infestação de Mimosa gemmulata Barneby em áreas entretalhões de eucalipto de cerrado em sucessão secundária

Observam-se no Brasil extensos plantios de eucalipto, sobretudo no Estado de Minas Gerais, que possui essa cultura como atividade rentável em áreas marginais. Visando reduzir os efeitos da colheita florestal sobre a vegetação nativa e seleção de algumas espécies como o angiquinho (Mimosa gemmulata Barneby), objetivouse com este trabalho avaliar a sucessão secundária em povoamentos de eucalipto de diferentes idades e manejo após a exploração, comparando-a por meio da composição florística e estrutura horizontal e vertical da vegetação arbustivo-arbórea, com fragmentos de Cerrado. O trabalho foi realizado em área representativa do referido bioma no Vale do Jequitinhonha. Foram calculados os parâmetros fitossociológicos e os índices de diversidade e da similaridade em ambientes com recuperação inicial e avançada, com e sem eucalipto. O controle foi o Cerrado sentido restrito. Foram amostrados 42 famílias, 99 gêneros, 150 espécies e 1268 indivíduos. O estudo da composição florística e dos parâmetros fitossociológicos indicou a existência de famílias, gêneros e espécies de grande relevância na área que são típicos do bioma Cerrado. A remoção do eucalipto na regeneração inicial não afetou a diversidade nesses ambientes. Contudo, a remoção do eucalipto no estádio avançado promoveu redução da diversidade, permitindo a colonização pela espécie pioneira Mimosa gemmulata Barneby. No entanto, a manutenção do eucalipto na recuperação avançada resultou em maiores valores de diversidade e demais atributos estruturais. Os resultados deste estudo subsidiarão as práticas de manejo a serem adotadas em áreas similares, visando à manutenção da diversidade biológica nos locais de reestabelecimento de corredores de biodiversidade entre áreas cultivadas.

Corticosterone in territorial male Swainson’s Thrushes varies in relation to forest age but not vegetation cover

Glucocorticoids are thought to be related to habitat quality and may provide information about the relative health of individuals. We used a model selection approach to test whether plasma glucocorticoid levels of the Swainson's thrush (Catharus ustulatus) were associated with two attributes that may reflect breeding habitat quality in coniferous plantation forests: stand age and vegetation cover. For baseline corticosterone, the top model included stand age with limited support for models that included vegetation cover. Mean baseline corticosterone for terri- torial male thrushes sampled in mature stands was 78.2 % higher than territorial males sampled in early seral stands. For handling-induced corticosterone, there was limited separation among candidate models, and only one model, containing stand age and Julian day, was better supported than the null model. Despite previous research that has shown hardwood cover is an important component of breeding habitat quality for thrushes, our investigation found limited evidence that vegetation cover was associ- ated with either baseline or handling-induced corticoste- rone levels. Given that early seral and mature conifer forests are characterized by markedly different habitat features, we hypothesize that the observed differences in baseline corticosterone represent either reduced fitness of male thrushes in mature stands or an adaptive adjustment of glucocorticoid levels to match local environmental conditions that equalize fitness across stands of different ages.

The armoured mite fauna (Acari: Oribatida) from a long-term study in the Scots pine forest of the Northern Vidzeme Biosphere Reserve, Latvia

In 1992-2012, a considerable amount of soil micro-arthropods has been collected annually as a part of a project of the National Long-Term Ecological Research Network of Latvia at the Mazsalaca Scots Pine forest sites of the North Vidzeme Biosphere Reserve. Until now, the data on oribatid species have not been published. This paper presents a list of oribatid species collected during 21 years of ongoing research in three pine stands of different age. The faunistic records refer to 84 species (including 17 species new to the fauna of Latvia), 1 subspecies, 1 form, 5 morphospecies and 18 unidentified taxa. The most dominant and most frequent oribatid species are Oppiella (Oppiella) nova, Tectocepheus velatus velatus and Suctobelbella falcata.

Wood-inhabiting fungi on pedunculate oak coarse woody debris in relation to substratum quantity and forest age

Wood-inhabiting fungi on pedunculate oak (<em>Quercus robur</em>) coarse woody debris (CWD) was investigated in 50 plots of 0.1 ha in oak stands of different ages in Lithuania. In maturing stands (50-120 years) the average volume of oak CWD was 4.7 m<sup>3</sup>/ha, and in mature stands (over 120 years) – 13.9 m3/ha. Both in maturing and mature stands, the greatest fraction of CWD consisted of fallen oak branches (81 % and 84 % respectively), whereas fallen trunks comprised about 10 % of the total units of CWD. In total 1350 records of 203 species (49 ascomycetes and 154 basidiomycetes) were collected during 2 years of investigation. Species richness and abundance increased significantly with the increase of volume and abundance of CWD. Higher species richness was detected in mature stands than in maturing ones. Wood-inhabiting species composition varied greatly at stand scale, and one third of all detected species occurred only in one plot. Red-listed fungi were found only in mature stands. We conclude that, even in managed oak stands, oak CWD maintains a rather diverse species composition of ascomycetes and basidiomycetes. However, the current practice of forestry in Lithuania of removing dying or dead wood of large volume, e.g. standing and fallen trunks, reduce the distribution of highly specialized, usually rare, and endangered fungi.

Effect of hydrologic regime and forest age on Collembola in riparian forests

The principal objective of the study was to assess factors of primary importance for collembolan community variability measured in riparian forest stands of different age after traditional clear cutting within natural and altered hydrologic regimes. The study was conducted in the Ukrainian part of the Latorica river floodplain where the largest stands of the highly protected medio-European Querco—Ulmetum minoris fluvial forests can be found. Six oak forest stands were investigated on the river floodplain: three in a natural section (inside levee) of the floodplain, which have their original features preserved with periodical inundation, and three in a section separated by a flood control embankment (outside levee) and subjected to serious damage by drainage. In each section the three stands sampled were represented by different ages regenerated with clear-cutting (>3 years, >8 years and >112 years).Differences in hydrologic regimes were central to identification of a predictable and explainable percentage of variation in species composition of Collembola communities in fluvial forests. The hydrologic regime factor was correlated with the basic structural attributes of collembolan communities, such as abundance, species richness and some ecological traits. Season accounted for a higher degree of variation in collembolan communities than did the age of forest stands. We conclude that differences in hydrologic regime are of much higher importance in structuring collembolan communities in riparian forests than are the ages of stands.

Timber Harvesting Does Not Increase Fire Risk and Severity in Wet Eucalypt Forests of Southern Australia

AbstractLindenmayeret al. proposed that logging makes “some kinds of forests more prone to increased probability of ignition and increased fire severity.” The proposition was developed most strongly in relation to the wet eucalypt forests of south‐eastern Australia. A key argument was that logging in wet forests results in drier forests that tend to be more fire‐prone, and this argument has gained prominence both in the literature and in policy debate. We find no support for that argument from considerations of eucalypt stand development, and from reanalysis of the only Australian study cited by Lindenmayeret al. In addition, there is no evidence from recent megafires in Victoria that younger regrowth (<10 years) burnt with greater severity than older forest (>70 years); furthermore, forests in reserves (with no logging) did not burn with less severity than multiple‐use forests (with some logging). The flammability of stands of different ages can be explained in terms of stand structure and fuel accumulation, rather than as a dichotomy of regrowth stands being highly flammable but mature and old‐growth stands not highly flammable. Lack of management of fire‐adapted ecosystems carries long‐term social, economic, and environmental consequences.

The proportion of heartwood in conifer (Pinus sylvestris L., Picea abies [L.] H. Karst.) trunks and its influence on trunk wood moisture -

As the tree age increases, the formation of heartwood takes place in the central part of the tree. Since there is a large difference in the moisture content between sapwood and heartwood in conifers, the proportion of heartwood expressed in percentage is one of the most important factors influencing the average moisture of trunk wood. The aim of the research was to find out the changes in parameters of heartwood proportion and the changes in average trunk wood moisture parameters, depending on the age of the tree. To evaluate and compare the heartwood proportion in pine and spruce trunk and its moisture, sample plots were established throughout the territory of Latvia in 2011. These sample plots were established in stands of different ages (37–143 years). The total number of sample plots was 61–29 for pines with 246 sample trees and 32 sample plots for spruces with 270 sample trees. With the increase in the tree age from 60 to 140 years, the heartwood proportion increases and the average moisture content of trunk wood decreases. With an increase of the heartwood proportion in pine from 18% to 39%, the average moisture of trunk wood decreases from 108% to 86%, but with an increase of the heartwood proportion in spruce from 30% to 49%, the average moisture content of trunk wood decreases from 107% to 81%.  

Shrub encroachment shifts the bioclimatic limit between marcescent and sclerophyllous oaks along an elevation gradient in west‐central Spain

AbstractQuestions(1) Does shrub encroachment affect the regeneration of two contrasting species of oak along an elevation gradient in the west‐central Iberian Peninsula? (2) Do different nurse shrubs have any relevant species‐specific effects along the gradient? (3) Does shrub encroachment affect the location of the bioclimatic limit between these two oak species along the elevation gradient?LocationTwelve sites distributed from the Arribes del Duero plains to the Sistema Central mountains (Salamanca province, Spain).MethodsWe measured the regeneration of two contrasting oak tree species (Quercus ilex subsp. ballota Samp – sclerophyllous, Q. pyrenaica Willd – marcescent) as the relative percentage cover of seedlings and saplings (<1.3‐m high) in plots 10 m in diameter distributed in stands of different age. We fixed the bioclimatic limit at 50% relative proportion of species in each plot, i.e. whether one species was more abundant than the other in a plot. Shrub stand age was estimated by counting growth rings in the principal stems of the oldest shrubs in a plot. We fitted generalized linear mixed models to analyse the effects of elevation, specific nurse shrub and shrub stand age on regeneration and the probability of one species being more abundant than the other.ResultsThe regeneration and relative proportion of Q. ilex (sclerophyllous) decreased with elevation. Regeneration did not vary with shrub encroachment, although the relative proportion increased notably in the youngest stands. In turn, regeneration and relative proportion of Q. pyrenaica (deciduous) significantly increased towards the upper sites and mature shrub stands. We found no evidence of specific nurse shrub effects on regeneration or the probability of one species being more abundant than the other in either of the two species of oak.ConclusionsThe bioclimatic limit between the two contrasting species of oak shifted with shrub stand age along the elevation gradient. Land practices preventing shrub encroachment can thus indirectly shift this limit towards higher elevations. The effects of shrubs may be critical in resolving the climatic and land‐use effects on elevation shifts of species under changing conditions in bioclimatic transitions.

Carbon sequestration potential of Rhizophora mucronata and Avicennia marina as influenced by age, season, growth and sediment characteristics in southeast coast of India

This work analysed the carbon sequestration potential in two species of mangroves (Rhizophora mucronata and Avicennia marina) along with their growth, biomass, sediment characteristics for four seasons of the year 2009–2010, in planted stands of different age (1–17.5 years) in the Vellar-Coleroon estuarine complex, India. The mangroves were recorded to store significant amount of biomass. Avicennia marina performed better to display 75 % higher rate of carbon sequestration than that in Rhizophora mucronata. This could be attributed to growth efficiency and high biomass production. For instance, Avicennia marina exhibited 2.7 fold higher girth, 24 % higher net canopy photosynthesis, 2 fold aboveground biomass (AGB), 40 % more belowground biomass (BGB) and 77.3 % higher total biomass, than R. mucronata did. Seasonally the rate of carbon sequestration was 7.3 fold higher in post-monsoon, 3.4 fold in monsoon, 73 % more in summer than that in pre-monsoon. The rate of carbon sequestration was positively correlated with age of planted site, tree height, tree diameter, net canopy photosynthesis, AGB, BGB, total biomass, carbon stock, growth efficiency, AGB/tree height tree girth, leaf area index, silt content (p < 0.01). The carbon sequestration was negatively corrected with soil temperature and clay content (p < 0.05). Mangroves were found to be a productive system and important sink of carbon in the tropical coastal zone, but increasing soil temperature due to global warming would have a negative impact on carbon sequestration potential of the mangroves.

Edaphic and environmental controls of soil respiration and related soil processes under two contrasting manuka and kanuka shrubland stands in North Island, New Zealand

The conversion of marginal pastoral land in New Zealand to higher biomass shrubland consisting of manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides var. ericoides) offers opportunity for carbon (C) sequestration, with potential co-benefits of soil erosion control. We therefore selected two areas with different soils in different climatic regions to investigate and compare soil respiration rates, methane and nitrous oxide emission profiles, and key carbon exchange processes controlling carbon sequestration. In addition, two shrubland stands of different ages were selected in each area, providing four sites in total. Regular (almost monthly) soil respiration measurements were made over a 2-year period, with less frequent methane and nitrous oxide flux measurements, and soil sampling once at the end of the study. The cooler, wetter volcanic soils had higher total organic C (6.39 ± 0.12% v. 5.51 ± 0.17%), soil C : nitrogen (N) ratios (20.55 ± 0.20 v. 18.45 ± 0.23), and slightly lower mineral N (3.30 ± 0.74 v. 4.89 ± 0.57 mg/kg) and microbial biomass C (1131 ± 108 v. 1502 ± 37 mg/kg) than the more drought-prone, stony, sedimentary soils. Mineral-N contents at all sites indicated N-limited ecosystems for allocation of below- and above-ground C. The estimated mean annual cumulative respiration rate recorded in the volcanic soil was 10.26 ± 7.45 t CO2-C/ha.year compared with 9.85 ± 8.63 t CO2-C/ha.year in the stony sedimentary soil for the 2 years of our study. Older shrubland stands had higher respiration rates than younger stands in both study areas. Methane oxidation was estimated to be higher in the volcanic soil (4.10 ± 2.13 kg CH4-C/ha.year) than the sedimentary soil sites (2.51 ± 2.48 kg CH4-C/ha.year). The measured natural background levels of nitrous oxide emissions from these shrubland soils ranged between negligible and 0.30 ± 0.20 kg N2O-N/ha.year. A strong climatic control (temperature and moisture) on gas fluxes was observed at all sites. Our sampling strategy at each of the four sites was to estimate the mean soil respiration rates (n = 25) from an 8 by 8 m sampling grid positioned into a representative location. Soil respiration rates were also measured (by additional, less frequent sampling) in two adjacent grids (1-m offset and 100-m distant grid) to test the validity of these representative mean values. The 1-m offset grid (n = 25) provided a statistically different soil respiration rate from the main grid (n = 25) in 25% of the 12 sampling events. The 100-m grid (n = 25) provided a statistically different respiration rate to the main grid in 38% of the 26 sampling events. These differences are attributed to the spatially variable and sporadic nature of gaseous emissions from soils. The grid analysis tested the prediction uncertainty and it provides evidence for strong spatial and temporal control by edaphic processes in micro-sites. A partial least-squares regression model was used to relate the 2009 annual cumulative soil respiration to site-specific edaphic characteristics, i.e. biomass, nutrient availability, porosity and bulk density, measured at the end of that year. The model explained ≥80% of the variance at three of the four sites.

Sorbus aucuparia regeneration in a coarse‐grained spruce forest – a landscape scale

AbstractQuestionsWhat is the spatial range of regeneration of the fleshy‐fruited tree Sorbus aucuparia (rowan) in a coarse‐grained spruce stand on a large landscape scale? Does the spatial distribution and size of stands of different ages affect the probability of rowan regeneration? What are the consequences of the dynamics of dominant coniferous tree species for the dynamics of admixture rowan?LocationA sub‐alpine spruce forest in the Tatra Mountains, Poland.MethodsWe mapped all mature rowans in a 203‐ha area and counted the rowan seedlings and saplings on a grid of evenly distributed plots. In plots, the age and diameter of trees were measured. Patches of homogenous stands were distinguished and each rowan tree and each plot was assigned to one of four stand categories: dense small‐crowned stands, dense large‐crowned stands, sparse large‐crowned stands and sparse stands near the upper forest limit. Areas above the upper forest limit formed a separate fifth category.ResultsThe distribution of rowan trees was clumped. Most of them grew in dense spruce stands up to 135 yr old and near the upper forest limit. Substantially fewer rowan trees were in sparse spruce stands of nearly 200 yr old. Seedlings and saplings occurred at high density (mean 24.8 individuals 100 m−2) only up to 40 m from trees bearing fruits, and at much lower density at longer distances. In consequence of the clumped distribution of adult trees and the short range of seed dispersal, most of the old spruce stands were outside the range of abundant regeneration of rowan.ConclusionsThe presence of fine‐ vs coarse‐grained mosaics of coniferous stands of different ages can strongly influence population processes in a rowan population on a large landscape scale. Extensive disturbances resulting in large homogenous patches of coniferous stands, the long lifespan of a single generation of spruce and spatial limitation of rowan seed dispersal seem responsible for the small contribution this broad‐leaved species makes to sub‐alpine forests. A high share of rowan can be expected in forests with fine‐grained mosaics of stands, where small patches of young and old stands are inter‐mixed, assuring delivery of seeds to stands of each category.

Contributions of detrital subsidies to aboveground spiders during secondary succession, revealed by radiocarbon and stable isotope signatures

Prey subsidies originating from detritus add nutrients and energy to arboreal communities. Measurement of this subsidy is required in the understanding of how food web dynamics respond to changes in surrounding environments. Shrub spiders are one of the key predators involved in food web coupling. We evaluate the effects of potential changes in prey availabilities during secondary succession on the contribution of subsidy from detrital food webs to shrub spiders and how different spider feeding guilds used the subsidy of prey from detrital food webs. We measured the relative importance of the subsidy for the spider feeding guilds, using the ratios of stable isotopes of C (δ(13)C), and N (δ(15)N) and C isotope discrimination (Δ(14)C). Diet age was calculated from Δ(14)C values, because old diet ages of spiders indicate that the spiders consume prey from detrital food sources. Dominant aerial prey (Diptera) had a distinctively old diet age compared with arboreal prey, which indicates that aerial prey were subsidized from detrital food webs. Sit-and-wait spiders tended to have an older diet age than active hunting spiders, which indicates that sit-and-wait spiders depended more on subsidies. Diet age varied only slightly for spiders in stands of different ages, indicating that rates at which spiders use grazing and detrital prey are probably determined more by foraging strategies and not by stand age. A dominance of sit-and-wait predators will lead to higher detrital subsidy inputs in shrub habitats. This study highlights the effect of shrub spider community structure (feeding guild composition) on the volume of the subsidy received from the detrital food web.

CROWN DELINEATION INFLUENCE ON STANDING VOLUME CALCULATIONS IN PROTECTED AREA

Abstract. The aim of this study was to evaluate the automatically determined parameters of tree crowns, which are then used in two-phase inventory method of growing stock. Research was performed in forest stands of different age, located in the Stolowe Mountains National Park (south-western Poland) where the dominant species was Norway spruce (Picea abies L.). On the test area of approximately 500 hectares, 35 sample plots were measured. On LIDAR-based Crow Height Model (CHM), in the places corresponding to the position of 500 m2 circular ground samples, automatic segmentation was carried out. The extent of the crown was associated with the height of the tree. Two variants of the assigning separate crowns in the sample were used: (1) according to the centroid position, (2) according to the location of any fragment of the crown inside the sample plot boundary. In each of the variants five series of measurements with different relative height of the range 0.65–0.8 (with a gap of 0.05) were carried out. Relationship between the volume of living trees measured on the ground and LIDAR parameters (average height of trees and tree canopy projection area) automatically measured based on CHM was determined. Multiple correlation coefficient differed depending on the location to extract coverage crowns and ranged from 0.687 to 0.788. The variant of counting of all trees with crowns or pieces inside the sample appeared to perform better. The relationship between the above-indicated characteristics was stronger after elimination of dead trees (about 0.1 for each of cases). This means that for measurements of the growing stock in forests under protection, it is necessary to improve the process of automatic segmentation of the crown, by identification and elimination of dead trees – usually present at sample plot.

Selection and interpretation of soil quality indicators for forest recovery after clearing of a tropical montane cloud forest in Mexico

Through slash-and-burn techniques, vast areas formerly occupied by tropical montane cloud forest (TMCF) in Mexico have been converted into croplands and secondary forest of different ages. Despite the dramatic changes in soil properties and processes detected during cropping and forest regeneration, no attempts have been made to develop soil quality indicators (SQI) to assist in the assessment of soil conditions during such changes. SQI are considered to be essential in evaluating plans of forest restoration or management; as such, the objectives of this study were to (i) select soil properties that can be used as SQI during forest regeneration for abandoned crop fields in a TMCF area managed under the slash-and-burn method; and (ii) examine the ecological significance of stand age for function-based interpretations of the selected SQI. To this end, the soil properties of three adjacent chronosequences in El Rincón, Sierra Norte, Southern Mexico were analyzed. Each chronosequence consisted of ordered series of five stands of different age after abandonment: a cornfield and adjacent forests of ∼15 (incipient forest), ∼45 (young forest), ∼75 (mature forest), and⩾100 (old-growth forest) years after abandonment. The soil properties of undisturbed old-growth forest stands were used as a reference. After inspection of principal component analysis results and control charts, the following soil properties were chosen as SQI in TMCF areas: soil organic carbon, pH, plant-available P, O horizon thickness and exchangeable Al3+. The selected SQI displayed different rates of change during forest regeneration. Soil organic carbon had a fast recovery rate and, therefore, a greater ability to return to its original level after disturbance. In contrast, O horizon thickness, soil pH, plant-available P, and exchangeable Al3+ showed a slow rate of change during the fallow period. SQI did not always change linearly nor improve with the age of the forest. The highest exchangeable Al3+ concentration was detected in 45-year-old forests, suggesting that at this forest age, soil become an important filter against Al3+ sensitive species, potentially affecting vegetation composition. Considering the slow recovery rate of some SQI, we estimate that fallow periods of at least 100years are required in order to reach good soil quality in TMCF ecosystems. Management practices should therefore consider the maintenance of forest of different ages spanning at least 100years in the landscape. Doing so would achieve more sustainable management practices by allowing a relatively continuous recovery of the ecosystem without prolonged interruptions of land utilization.

Long-term changes in bird community in the unmanaged post-fire eastern Québec boreal forest

Little information is available on long-term changes in bird communities following fire in the unmanaged forest. We have evaluated and compared bird species communities along two long-term chronosequences after fire (0 to >200 years post-fire) in the eastern Quebec boreal forest, which is known for its long fire-return intervals. By characterizing forest habitat in stands of different ages (time since fire), we were able to model species richness and bird community characteristics in three habitat types: mature forests, forest-edge, and open-forests. Although bird species richness did not vary greatly, our results show changes in species composition following successional stages and highlight the need to protect the forest at all stages, especially old-growth, which provides a heterogeneous environment suitable for several species. Keeping a mosaic composed of all-age, fire-disturbed forests should facilitate the conservation of bird diversity in the eastern boreal forest.