Mixed Broadleaf Research Articles

Medium-term transformation of Chernozems under broadleaf forests in the temperate climate of south-east Poland

Water erosion, accelerated in sloped landscapes by intense cultivation (ploughing), can rapidly degrade humus-rich topsoil horizons of chernozemic soils, leading to an irreversible loss of the most valuable soil resources, in particular in areas with relict Chernozems/Phaeozems. An afforestation can effectively control erosion rates, but dense canopy forests are commonly listed among factors that support the transformation of Chernozems into Luvisols/Retisols. A comparison of the morphology and physico-chemical properties of adjacent arable and forest soils was carried out in four catenas located in the patches of relict chernozemic soils in the loess belt of south-east Poland. An analysis has evidenced that mixed broadleaf forests have generated during the 200–300-year-long period (an approximate time since afforestation of the sites under study) topsoil acidification (by approximately 1–1.5 grade compared to adjacent arable soils), base cations leaching (below 10 cmol(+) kg−1), decrease of soil organic carbon pools (by 15–35% in the soil column of 0–50 cm) and clay depletion (by ca. 4%). The subsurface Bt (argic) horizons have developed in all afforested and some of arable soil profiles. However, all studied forest soils preserved the mollic or chernic horizons and in most cases retained the same reference soil group as adjacent arable soils (Chernozem or Phaeozem). It means that even in temperate humid climate as in south-east Poland, mixed broadleaf forests, consisting of tree species known with little acidifying impact on soil, may not rapidly degrade Chernozems. The observed evidence of physicochemical and morphological transformation is apparently weaker than the reported soil destruction caused by water erosion and justifies the controlled afforestation of the relict Chernozems and Phaeozems as a means of their preservation against rapid loss.

The influence of local environmental factors in southwestern Poland on the abundance of Ixodes ricinus and prevalence of infection with Borrelia burgdorferi s.l. and B. miyamotoi.

Ticks are important ectoparasites and vectors of pathogens that cause disease in humans and animals. The natural habitat of Ixodes ricinus ticks is forests, which are convenient habitats to search for hosts, including reservoir hosts, and therefore can be an important habitat source of tick-borne pathogens. The aim of the study was to assess the usefulness of detailed forest habitat-type maps to estimate the tick-borne risk at a local scale (Lower Silesia, SW Poland). For the purposes of estimating tick abundance, we used the land cover maps available from the Forest Data Bank. For I. ricinus collection, nine sites located in three forest habitat types were chosen: broadleaf forest, mixed broadleaf and coniferous forest and coniferous forest. Ticks were collected once a month from April to June 2018 and 2019 using the standard flagging method. At each of the nine sites, ticks were collected in four plots, of 100 m2 each. Tick abundance was analysed using general linear mixed models (GLMM). A total of 2196 (10.1/100 m2) ticks were collected, including 2093 Ixodes ricinus (95.3%; 9.6/100 m2), 46 Dermacentor reticulatus (2.1%; 0.2/100 m2) and 57 Haemaphysalis concinna (2.6%; 0.3/100 m2). Among the collected I. ricinus were 589 larvae (28.1%; 2.7/100 m2), 1261 nymphs (60.3%; 5.8/100 m2), 128 females (6.1%; 0.6/100 m2) and 115 males (5.5%; 0.5/100 m2). We found a highly significant effect of forest habitat type on the density of ticks for broadleaf forest (coefficient = 1.87267, p-value = 2.79e - 07). Additionally, a significant influence of air temperature and relative humidity on the abundance of ticks was observed. During spring, the peak activity of I. ricinus was recorded in May and June. For DNA amplification of Borrelia burgdorferi s.l., a nested PCR method was used. Out of 494 I. ricinus, 83 (16.8%) were positive for Borrelia spp. The RFLP method showed the occurrence of five species including four belonging to the B. burgdorferi s.l. complex: B. afzelii (30.1%), B. garinii (38.6%), B. valaisiana (2.4%) and B. lusitaniae (18.1%). Furthermore, B. miyamotoi (9.6%), a species belonging to bacteria that cause relapsing fever as well as co-infection of B. miyamotoi/B.lusitaniae (1.2%) were found. The differences in the infection level of Borrelia spp. between broadleaf forest and mixed broadleaf and coniferous forest were statistically significant.

Estimation of Aboveground Vegetation Water Storage in Natural Forests in Jiuzhaigou National Nature Reserve of China Using Machine Learning and the Combination of Landsat 8 and Sentinel-2 Data

Aboveground vegetation water storage (AVWS) is a fundamental ecological parameter of terrestrial ecosystems which participates in plant metabolism, nutrient and sugar transport, and maintains the integrity of the hydraulic system of the plant. The Jiuzhaigou National Nature Reserve (JNNR) is located in the Eastern Tibet Plateau and it is very sensitive to climate change. However, a regional estimate of the AVWS based on observations is still lacking in the JNNR and improving the model accuracy in such mountainous areas is challenging. Therefore, in this study, we combined the Landsat 8 and Sentinel-2 data to estimate AVWS using multivariate adaptive regression splines (MARS), random forest (RF) and extreme gradient boosting (XGBoost) with the linkage of 54 field observations in the JNNR. The results showed that AVWS varied among different forest types. The coniferous forests had the highest AVWS (212.29 ± 84.43 Mg ha−1), followed by mixed forests (166.29 ± 72.73 Mg ha−1) and broadleaf forests (142.60 ± 46.36 Mg ha−1). The average AVWS was 171.2 Mg ha−1. Regardless of the modelling approaches, both Sentinel-2 and Landsat 8 successfully estimated AVWS separately. Prediction accuracy of AVWS was improved by combining Landsat 8 and Sentinel-2 images. Among the three machine learning approaches, the XGBoost model performed best with a model efficiency of 0.57 and root mean square error of 48 Mg ha−1. Predicted AVWS using XGBoost showed a strong spatial pattern of across the study area. The total AVWS was 5.24 × 106 Mg with 67.2% coming from conifer forests. The results highlight the potential of improving the accuracy of AVWS estimation by integrating different optical images and using machine learning approaches in mountainous areas.

Using canopy height model derived from UAV imagery as an auxiliary for spectral data to estimate the canopy cover of mixed broadleaf forests.

Canopy cover is an important structural trait that is frequently used in forest inventories to assess sustainability as well as many other important aspects of forest stands. Remote sensing data is more effective and suitable for canopy cover estimating than traditional field measurements such as sample plots, especially at broad scales. Measurement and mapping this attribute in fine-scale is a difficult task. Aerial imagery using unmanned aerial vehicle (UAV) has been recognized as an excellent tool to estimate canopy attributes. In this study, we compared the potential of using digital hemispherical photography (DHP), digital cover photography (DCP), UAV RGB data, and canopy height model (CHM) for estimation of canopy cover of mix broad-leaved forest on seven different stands. The canopy cover was measured from two digital canopy photographic methods, including DHP (as the reference method) and DCP. The stand orthophotos were segmented using a multi-resolution image segmentation method. Afterward, the classification in two classes of the canopy cover and the non-canopy cover was conducted using minimum distance classification to estimate canopy cover. The CHM layer was generated based on the SfM algorithm and utilized in the canopy cover estimation in each stand as auxiliary data. The results showed a slight improvement when we used the CHM as auxiliary data. Overall, the results showed that the efficiency of the ground digital canopy photographic methods (zenith view) in multi-storied and dense forests is the lowest. In return, our method for digital aerial canopy photography (object-based canopy segmentation and classification) is simple, quick, efficient, and cost-effective.

Rubuskaznowskii (Rosaceae), a new bramble species from south-central Poland.

Based on field research in south-central Poland, supplemented with a review of herbarium materials, we identified a stable bramble biotype with a range large enough (190 km distance between the outermost stands) to be described as a new regional agamic species, Rubuskaznowskiisp.nov. It belongs to the series Subthyrsoidei(sect. Corylifolii). Although R.kaznowskii has a unique combination of features, it can be potentially mistaken for R.gothicus. It differs from the latter species in many aspects, including: pruinose primocanes, denser indumentum of the abaxial leaf surface, and more curved prickles on the petiole. R.kaznowskii has mainly been observed on rusty soils, in habitats of mixed coniferous and mixed broadleaf forests, usually in sunny places, along forest margins and roads, in clearings and roadside thickets.

Assessment of the Structure and Diversity of Latvian Acer platanoides Populations Using Cross-Species Nuclear Microsatellite Markers

Abstract Acer platanoides L. (Norway maple) is the most widespread native maple species in Europe, with a distribution from south and central Europe to northern Europe and Scandinavia. Acer platanoides is widespread throughout the territory of Latvia, and is mainly found in mixed broadleaf and conifer stands. The genetic diversity and differentiation of Latvian A. platanoides populations was analysed. Sampled populations were located throughout the territory of Latvia, and were selected to represent a range of ecological conditions, with differing levels of anthropogenic impact. A total of 496 individuals from 21 populations were analysed with eight microsatellite markers, which were developed from related Acer species. The obtained molecular data revealed a moderate level of polymorphism, and the analysed Latvian A. platanoides populations were moderately differentiated. This study provides an initial assessment of the genetic diversity and differentiation of Latvian A. platanoides populations, and is also one of the first reports of the analysis of A. platanoides populations using microsatellite markers. The results can be utilised to define A. platanoides genetic resource stands to ensure conservation of a wide range of germplasm.

Identification of drought-tolerant tree species through climate sensitivity analysis of radial growth in Central European mixed broadleaf forests

Climate warming and a rise in evaporative demand expose forests to increasing stress, challenging silvicultural planning in many temperate forest regions. As some major timber species are drought susceptible, the choice of native broadleaf minor timbers with assumed higher drought tolerance is a promising alternative option. However, their growth performance and vitality in a warmer and drier climate are not well known. We studied tree-ring chronologies of the Central European minor timbers Acer platanoides L., Fraxinus excelsior L., and Tilia cordata Mill. in comparison to the widely planted Quercus petraea Matt. Liebl in different mixed stands along a precipitation gradient in Central Germany and analyzed the sensitivity of radial growth to climatic drivers and severe drought events with the aim to compare the species’ drought tolerance. While growth responded in all four species positively to summer (or spring) precipitation and negatively to higher summer temperature and climatic aridity, climate sensitivity of growth decreased in the period 1967–2016, proving non-stationarity. Superposed epoch analysis revealed larger growth reduction during severe drought in the diffuse-porous species (A. platanoides, T. cordata) than the ring-porous species (Q. petraea, F. excelsior), but resilience was high in all species. Moreover, none of the species showed negative growth trends with recent climate warming, and drought sensitivity was not higher at drier sites, suggesting a considerable acclimation and adaptation potential to increasing drought stress. As all four species proved to be fairly drought tolerant, they deserve broader consideration in silvicultural concepts targeted at adapting production forests to climate warming.

Measuring the social performance of forest management

Forests produce several types of benefits to both forest landowners and society. The social benefit of private forestry is equal to private benefit plus positive externalities minus negative externalities. This study developed alternative metrics for the evaluation of the social benefit of forest management. Forest management was assessed in terms of five criteria: economic, socio-cultural, environmental and ecological performance and the resilience of the forest ecosystem. Each criterion was described with three numerical indicators. Alternative performance indices were calculated from the indicator values using methods developed for multi-criteria decision making. It was concluded that indices based on the multiplicative Cobb–Douglas utility function might be the most recommendable when forestry should produce a balanced combination of different ecosystem services. When the indices were used to compare alternative silvicultural systems in terms of their social performance, continuous cover management was ranked better than even-aged management. The performance of even-aged management improved when it aimed at increasing the share of mixed stands and broadleaf species. Maximizing net present value (NPV) with a 1% discount rate led to better social performance than maximizing NPV with a 4% discount rate.

A Crown Morphology-Based Approach to Individual Tree Detection in Subtropical Mixed Broadleaf Urban Forests Using UAV LiDAR Data

Owing to the complex forest structure and large variation in crown size, individual tree detection in subtropical mixed broadleaf forests in urban scenes is a great challenge. Unmanned aerial vehicle (UAV) light detection and ranging (LiDAR) is a powerful tool for individual tree detection due to its ability to acquire high density point cloud that can reveal three-dimensional crown structure. Tree detection based on a local maximum (LM) filter, which is applied on a canopy height model (CHM) generated from LiDAR data, is a popular method due to its simplicity. However, it is difficult to determine the optimal LM filter window size and prior knowledge is usually needed to estimate the window size. In this paper, a novel tree detection approach based on crown morphology information is proposed. In the approach, LMs are firstly extracted using a LM filter whose window size is determined by the minimum crown size and then the crown morphology is identified based on local Gi* statistics to filter out LMs caused by surface irregularities contained in CHM. The LMs retained in the final results represent treetops. The approach was applied on two test sites characterized by different forest structures using UAV LiDAR data. The sensitivity of the approach to parameter setting was analyzed and rules for parameter setting were proposed. On the first test site characterized by irregular tree distribution and large variation in crown size, the detection rate and F-score derived by using the optimal combination of parameter values were 72.9% and 73.7%, respectively. On the second test site characterized by regular tree distribution and relatively small variation in crown size, the detection rate and F-score were 87.2% and 93.2%, respectively. In comparison with a variable-size window tree detection algorithm, both detection rates and F-score values of the proposed approach were higher.

Tree species composition and nutrient availability affect soil microbial diversity and composition across forest types in subtropical China

Soil microorganisms represent a significant component of terrestrial biodiversity and play a critical role in myriad ecological processes. The conversion of native forests to tree plantations is a major contributor to biodiversity loss on a global scale; however, our understanding of the influences of forest type conversion on soil microbial diversity and community composition remains unclear. Here we sampled twelve spatially interspersed stands of native mixed broadleaf forests, broadleaf-dominated (50–70% broadleaf trees), bamboo-dominated (20–40% broadleaf trees), and pure bamboo forests in subtropical China, to examine the effects of forest type conversion on soil bacterial and fungal diversity and composition. We found that the tree species richness, stand basal area, and soil carbon to nitrogen ratio decreased, while the total soil phosphorus increased from the native broadleaf forests to pure bamboo forests. Bacterial and fungal operational taxonomic units (OTUs) across the three soil depths increased significantly from 760 and 243 in native broadleaf to 795 and 336 in pure bamboo forests, respectively. However, neither bacterial nor fungal richness differed significantly among forest types at the phylum level. Across forest types, both bacterial and fungal OTU richness increased with the bamboo proportion and decreased with the soil carbon and nitrogen ratio. The fungal OTU richness also increased with the soil phosphorus content; however, neither bacterial nor fungal richness was affected by the tree species richness or stand basal area. Both bacterial and fungal community compositions changed with forest type and soil depth, with their compositional overlap from native broadleaf forests decreasing consistently with the bamboo proportion and soil phosphorus. Overall, our results provide insights into the importance of overstory tree composition and the availability of soil nutrients in affecting soil microbial diversity and composition, while providing management guidance for the inclusion of soil microbial diversity in forest conservation and management.

A comparison of the baseflow recession constant (K) between a Japanese cypress and mixed-broadleaf forest via six estimation methods

The baseflow recession constant (K) is known to be a versatile parameter used in forecasting low flows, flow-frequency analyses, improving regional models, and other various hydrological analyses. This study took place in Inuyama city, Aichi prefecture, central Japan, where K for two catchments of differing vegetation [Japanese cypress (CF), 2.42 ha; mixed-broadleaf (MB), 2.08 ha] were produced via six estimation methods and compared. Water level was recorded by dataloggers (converted to daily discharge) and rainfall, by raingauges. Over 5 years (May 2013–April 2018), 18 baseflow recession events were qualified for analysis from which K were calculated. Overall, K in CF (0.969) was marginally higher than in MB (0.955), which translates to lower water depletion in CF possibly due to lower transpiration. In each catchment, K did not differ significantly between the growth and dormant period. Root mean square error (RMSE) is lower and less variable in CF than in MB. Reproducing baseflow using season-specific K values did not show any clear reduction in RMSE; hence, the complexity is not justified. In general, all K-estimators performed well (low RMSE) and can be used. Out of six K-estimators, two have relatively higher standard deviation (SD) and will underestimate baseflow especially when the K was produced from short (< 6 days) baseflow recession limbs. Others reproduce unbiased baseflow but have relatively higher SD and RMSE. None of the estimators were unusable, but two estimators that have the lowest SD and least bias were recommended.

DIVERSITY, DISTRIBUTION AND ECOLOGY OF BOLETOID MUSHROOMS FROM GARHWAL HIMALAYA, UTTARAKHAND

The present investigation was carried out in different mixed broadleaf and coniferous forests of Garhwal Himalaya. Major associates trees are Quercus, Rhododendron, Betula, Pinus, Cedrus and Cupressus in the explored forest. The specimens were collected from these forests between July 2000 to September 2004, in the elevation range of 1600–3000 m above sea level from districts Chamoli, Pauri, Rudraprayag and Tehri. As a result of an extensive field survey and microscopic study in laboratory, 7 genera spread over into 35 taxa belonging to 3 families (Boletaceae, Gyroporaceae and Suillaceae) were identified. Of these, 7 taxa were known to be edible and consumed in various parts of Garhwal region.

A comparison of hydrological characteristics between a cypress and mixed-broadleaf forest: Implication on water resource and floods

Broadleaf or conifer forest? – an ongoing dilemma as regards water resource and flood prevention. Although conifer trees use less water and are hydrophobic, existing studies at the watershed scale have shown varying results due to variability in meteorological conditions and forestry practices. In this study, two adjacent headwater catchments [2.42 ha cypress (CF); 2.08 ha mixed-broadleaf (MB)] were gauged. The study area in central Japan has a warm temperate climate with high annual rainfall and typhoons. Daily discharge (n = 1398) and storm event hydrographs (n = 242) were compared between CF and MB and discussed in light of water availability and storm event runoff characteristics. Overall water yield in CF was 6.4% lower than in MB but this was caused by lower streamflow on high discharge periods (30% frequency); thus, may not adversely affect municipal/agricultural water supply. For 70% of the time including during dry periods, water yield was higher in CF. This agrees with the principle that conifers use less water than broadleaf trees – even at the forested catchment scale. Discharge in the CF stream is also less variable than that in the MB stream. During storm events, the CF stream has higher flashiness (shorter response time to rainfall and higher peak discharge) than the MB stream; but in larger storms (≳70 mm), the MB stream may have higher peak discharge. Our data demonstrates that a well-managed plantation forest does not necessarily have inferior hydrological function compared to a natural broadleaf forest, which differs from the stereotype. Frequencies of high and low flows as well as runoff characteristics were also presented in hopes of promoting better forestry decisions when considering water demand and existing stormwater drainage infrastructures.

Carbon Storage of Woody Debris of Evergreen Broadleaf Forests in Mid-Subtropical Region of China

To better understand the effect of forest succession on carbon storage of woody debris (WD), carbon stock and allocation of evergreen broadleaf forest, a major zonal forest in subtropical China was investigated. Three forest types were sampled, pine (Pinus massoniana) forest (PF), pine and broadleaf mixed forest (MF) and evergreen broadleaf forest (BF). The amount of woody debris (WD) biomass was between 1.26–8.82 Mg · hm–2, under the following order: PF &lt; MF &lt; BF, showed a trend of increase gradually with the succession. Coarse woody debris (CWD) carbon content varies with tree species and its decomposition level, with the improvement of CWD decomposition level, gradually reduce its carbon content. The woody debris carbon storage of PF, MF, and BF were 0.62 Mg · hm–2, 1.75 Mg · hm–2 and 3.78 Mg · hm–2, respectively, corresponded to the tree carbon storage 0.73%, 1.83% and 2.92%.

Effects of manual brushing on 10-year survival and growth of Douglas-fir in the mixed broadleaf – shrub complex of southern interior British Columbia

Manual brushing is used to minimize the competitive effects of paper birch (Betula papyrifera Marsh) and associated broadleaved trees on young Douglas-fir (Pseudotsuga menziesii var. glauca) in southern interior British Columbia. Effects of brushing broadleaved trees, predominantly birch, on interior Douglas-fir survival and growth were studied on four sites. Treatments were applied when plantations were five to nine years old. Through 10 years post treatment, brushing did not affect Douglas-fir survival, but increase height by 22 % and stem diameter by 31 % and the differences were greater than seen at five years. After 10 years, linear models described a declining Douglas-fir height or diameter with increasing broadleaved tree density. Boundary line analysis was used to describe maximum treatment response to broadleaved density and two distance independent competition indices for birch and broadleaves, combining either cover or density with relative heights (CRH, DRH, respectively). A negative exponential relationship was fit to 10-year Douglas-fir heights and diameters with increasing values CRH or DRH. Competition thresholds for density, CRH and DRH were not apparent. The quantile regression results indicated the 10-year response of young Douglas-fir diameter to brushing occurred primarily with the largest 55 % to 85 % of the population, CRH and DRH respectively.

Evaluation of ecosystem services in a protected mountain area: Soil organic carbon stock and biodiversity in alpine forests and grasslands

Ecosystem services (ES) evaluation is included in the environmental programs and policy strategies of protected natural areas in many countries. Alpine forests and grasslands play an important role in climate regulation but their contribution is still unknown. In this study, we estimated soil organic carbon (SOC) stocks for forest and grassland habitats by collecting samples from 87 plots in Gran Paradiso National Park (western Italian Alps). Results of the LMM show that habitat type affects SOC stock; grasslands and mixed broadleaf forests store higher SOC than mixed coniferous forests, spruce forests and larch forests. We investigate the relationships between biodiversity, SOC stock, OC stock in organic layers, soil types, forests structure and other environmental features using a canonical component analysis and a Pearson correlation matrix. The results show that biodiversity is mainly influenced by the altitude, OC stock in organic layers OH and habitats of coniferous forests. Biodiversity positively correlates to organic layers (Staphylinidae, Formicidae, Orthoptera), forests’ Shannon and evenness indices (Carabidae, Formicidae, Orthoptera, Aranea, Lepidoptera) and forests’ basal areas and stem density (Staphylinidae, Formicidae, Aranea). Further studies are needed to better investigate the relation between biodiversity and habitat features on ecosystem functions and thus on the provision of ES.

Computer Vision and Deep Learning Techniques for the Analysis of Drone-Acquired Forest Images, a Transfer Learning Study

Unmanned Aerial Vehicles (UAV) are becoming an essential tool for evaluating the status and the changes in forest ecosystems. This is especially important in Japan due to the sheer magnitude and complexity of the forest area, made up mostly of natural mixed broadleaf deciduous forests. Additionally, Deep Learning (DL) is becoming more popular for forestry applications because it allows for the inclusion of expert human knowledge into the automatic image processing pipeline. In this paper we study and quantify issues related to the use of DL with our own UAV-acquired images in forestry applications such as: the effect of Transfer Learning (TL) and the Deep Learning architecture chosen or whether a simple patch-based framework may produce results in different practical problems. We use two different Deep Learning architectures (ResNet50 and UNet), two in-house datasets (winter and coastal forest) and focus on two separate problem formalizations (Multi-Label Patch or MLP classification and semantic segmentation). Our results show that Transfer Learning is necessary to obtain satisfactory outcome in the problem of MLP classification of deciduous vs evergreen trees in the winter orthomosaic dataset (with a 9.78% improvement from no transfer learning to transfer learning from a a general-purpose dataset). We also observe a further 2.7% improvement when Transfer Learning is performed from a dataset that is closer to our type of images. Finally, we demonstrate the applicability of the patch-based framework with the ResNet50 architecture in a different and complex example: Detection of the invasive broadleaf deciduous black locust (Robinia pseudoacacia) in an evergreen coniferous black pine (Pinus thunbergii) coastal forest typical of Japan. In this case we detect images containing the invasive species with a 75% of True Positives (TP) and 9% False Positives (FP) while the detection of native trees was 95% TP and 10% FP.

Synthesizing Remote Sensing and Biophysical Measures to Evaluate Human–wildlife Conflicts: The Case of Wild Boar Crop Raiding in Rural China

Crop raiding by wild boars is a growing problem worldwide with potentially damaging consequences for rural dwellers’ cooperation with conservation policies. Still, limited resources inhibit continuous monitoring, and there is uncertainty about the relationship between the biophysical realities of crop raiding and humans’ perceptions and responses. By integrating data from camera traps, remote sensors, and household surveys, this study establishes an empirical model of wild boar population density that can be applied to multiple years to estimate changes in distribution over time. It also correlates historical estimates of boar population distribution with human-reported trends to support the model’s validity and assess local perceptions of crop raiding. Although the model proved useful in coniferous and bamboo forests, it is less useful in mixed broadleaf, evergreen broadleaf, and deciduous forests. Results also show alignment between perceptions of crop raiding and actual boar populations, corroborating farmers’ perceptions which are increasingly dismissed as a less reliable source of information in human–wildlife conflict research. The modeling techniques demonstrated here may provide conservation practitioners with a cost-effective way to maintain up-to-date estimates of the spatial distribution of wild boar and resultant crop raiding.

Variation in soil lignin protection mechanisms in five successional gradients of mixed broadleaf–pine forests

AbstractOver 200 yr of ecosystem succession in northeastern China, conifers have replaced broadleaf trees. Vegetation changes during forest succession may affect soil organic C (SOC) stability, which is associated with altered protection mechanisms. Lignin phenol composition, a predictor of soil organic matter variation, was assessed for macroaggregates, microaggregates, and silt–clay (SC) fractions from successional gradients in five forests aged 19 to 239 yr in the Changbai Mountains nature reserve. The large macroaggregates (4.00–8.00 and 2.00–4.00 mm) comprised 45.17 to 59.87% of bulk dry weight and 40.22 to 60.89% of SOC in the 19‐, 32‐, and 48‐yr‐old pioneer forests. However, we detected increased mass proportions and SOC contents in small macroaggregates (1.00–2.00 and 0.25–1.00 mm) in the mixed broadleaf–Korean pine (Pinus koraiensis Siebold &amp; Zucc.) forest after 122 yr. Lignin in bulk soil and aggregates in the 122‐yr‐old stand had lower acid/aldehyde ratios for the vanillyl and syringyl types than other stands, indicating less lignin decomposition. The highest C (198.20 g kg−1 soil) and lignin concentrations (6.14 mg 100 mg−1 C) were detected in the bulk soil from the 239‐yr‐old stand, where SC fraction occupied 56.18% of the C and 84.17% of the lignin content in bulk soil. Forest succession from broadleaf to a broadleaf–pine mixture shifted SOC sequestration and lignin protection from aggregates to SC fractions, along with the development of plant litter composition, fine‐root biomass and turnover, and microorganism biomass, which prompted effective long‐term SOC accumulation in successional forest communities.

Effect of spot burning of logging residues on the properties of mountain forest soils and the occurrence of ground beetles (Coleoptera, Carabidae)

We investigated the relationships between dehydrogenase activity and the physicochemical properties of mountain soils over three and five years from Norway spruce (Picea abies L. Karst) logging residue spot burning and the occurrence of epigeic carabid beetles. Six study sites were utilised, including 18 study plots (nine plots in a mixed coniferous mountain forest site and nine plots in a mixed broadleaf mountain forest site), with five replicate pitfall traps at each site located in southern Poland. Soil samples from the organic horizon were taken for pH, organic carbon, nitrogen, base cation content, acidity and dehydrogenase activity determination. Carabid beetles were monitored in weekly intervals during the period of July to August 2016. The burning of logging residues led to modified soil properties, especially the dehydrogenase activity. In all the tested variants, the activity was higher in soil samples after the burning in comparison to the control variants. We show no positive correlation between dehydrogenase activity and the number of carabid specimens. The preferences of dominant predatory hygrophilous carabids to acid habitats with weakly decomposed organic matter were proven. Simultaneously, the soil organic matter content was positively related to the carabid abundance. The significant impact of forest site conditions and the date of logging residue burning on the number of caught specimens were confirmed. In contrast, no relationships between the species richness, species diversity, mean individual biomass and spot burning effect were found. This work supports the recommendation of spruce fine woody debris utilisation by spot burning on mountain regions with rich habitats presenting moderate wet conditions and small land falls.