Carbon : nitrogen stoichiometry in forest ecosystems during stand development

In order to understand the ecological adaptations of primates to survive in temperate forests, we need to know the general patterns of plant phenology in temperate and tropical forests. Comparative analyses have been employed to investigate general trends in the seasonality and abundance of fruit and young leaves in tropical and temperate forests. Previous studies have shown that (1) fruit fall biomass in temperate forest is lower than in tropical forest, (2) non-fleshy species, in particular acorns, comprise the majority of the fruit biomass in temperate forest, (3) the duration of the fruiting season is shorter in temperate forest, and (4) the fruiting peak occurs in autumn in most temperate forests. Through our comparative analyses of the fruiting and flushing phenology between Asian temperate and tropical forests, we revealed that (1) fruiting is more annually periodic (the pattern in oneyear is similar to that seen in the next year) in temperate forest in terms of the number of fruiting species or trees, (2) there is no consistent difference in interannual variations in fruiting between temperate and tropical forests, although some oak-dominated temperate forests exhibit extremely large interannual variations in fruiting, (3) the timing of the flushing peak is predictable (in spring and early summer), and (4) the duration of the flushing season is shorter. The flushing season in temperate forests (17-28% of that in tropical forests) was quite limited, even compared to the fruiting season (68%). These results imply that temperate primates need to survive a long period of scarcity of young leaves and fruits, but the timing is predictable. Therefore, a dependence on low-quality foods, such as mature leaves, buds, bark, and lichens, would be indispensable for temperate primates. Due to the high predictability of the timing of fruiting and flushing in temperate forests, fat accumulation during the fruit-abundant period and fat metabolization during the subsequent fruit-scarce period can be an effective strategy to survive the lean period (winter).

PDF HTML阅读 XML下载 导出引用 引用提醒 中国东部南北样带典型针叶林土壤酶活性分布格局 DOI: 10.5846/stxb201309272377 作者: 作者单位: 中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院大学,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31070435,31290222,31290221);国家重点基础研究发展计划项目(2012CB417103,2010CB833502);中国科学院地理科学与资源研究所"秉维"优秀青年人才基金(2011RC202);中国科学院战略性先导科技专项(XDA05050600) Pattern of enzyme activities of typical coniferous forest soils along the North-South Transect of Eastern China Author: Affiliation: Institute of Geographic Sciences and Natural Resources Research,,University of Chinese Academy of Sciences,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取中国东部南北样带不同气候区(寒温带、温带和亚热带)的针叶林作为研究对象,分析了多酚氧化酶、过氧化物酶、几丁质酶以及β-葡萄糖苷酶活性的变化。结果表明,土壤溶解性有机碳(DOC)、微生物生物量碳(MBC)、微生物生物量氮(MBN)含量从北到南依次减小,寒温带显著高于亚热带;土壤pH值在3个气候区差异显著,温带最高,亚热带最低。分解木质素的多酚氧化酶和过氧化物酶活性不存在显著性差异;而与氮循环密切相关的几丁质酶活性表现为温带显著高于寒温带和亚热带;与碳循环密切的β-葡萄糖苷酶活性在温带最高,并显著高于亚热带地区。逐步回归分析表明,土壤MBN与pH值影响土壤几丁质酶活性,而土壤β-葡萄糖苷酶活性主要受pH的控制。研究认为,在中国东部南北样带针叶林中,土壤几丁质酶和β-葡萄糖苷酶活性存在显著性差异,而pH与MBN可能是影响土壤酶活性的主要因素。 Abstract:Soil organic carbon (SOC) is the largest terrestrial pool of carbon, and the amount of carbon in soils represents about two thirds of total ecosystem. Therefore, any change in the size and turnover rate of SOC pools will potentially alter the atmospheric CO2 concentration and the subsequent global climate. Soil enzymes are involved in a series of catalyzing reactions and play pivotal roles in litter and soil organic matter decomposition as well as nutrient cycling in terrestrial ecosystems. Soil enzyme activity can be used as a proxy for plant and microbial substrate availability, the interference between soil ecosystem and external environment, and microbial community structure and metabolic capabilities. Therefore, the determination of soil enzyme activities is a powerful tool for understanding soil carbon and nitrogen biogeochemical processes and their responses to climate change. Soil enzyme activity has been a frontier of forest ecology research and has been widespread concern. Unfortunately, most of the studies to date have been limited to a single forest biome or a single forest site, and few studies concern the pattern and controlling factors of soil enzyme activity at a terrestrial transect scale. North-South Transect of Eastern China (NSTEC) is the fifteenth standard transect established by International Geosphere-Biosphere Program (IGBP) in 2005 and is mainly driven by heat, followed by precipitation. It covers almost all forest types from boreal forest to tropical rain forest, which provides an ideal tool to investigate the pattern and environmental control of soil enzyme activities in the boreal, temperate and tropical forest biomes. In the past decade, many studies were conducted to measure the main factors affecting the pattern of SOC storage and soil-atmosphere exchange of greenhouse gases in the typical forests along the NSTEC. However, little information is available on the pattern of soil enzyme activities involved in soil carbon and nitrogen cycles and they relate to soil microbial biomass at a large spatial scale. In this study, the typical coniferous forests distributed in the cold-temperate, temperate and subtropical climatic zones were selected along the NSTEC. The activities of polyphenol oxidase, peroxidase, chitinase and β-glucosaccharase, soil dissolved organic carbon (DOC), microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) as well as soil pH in the three coniferous forest soils were measured. The results showed that soil DOC, MBC, and MBN contents tended to decrease from north to south, and they were higher in the cold-temperate forest soils than in the subtropical forest soils. There was a significant difference in the soil pH values among the three coniferous forests, following the order cold-temperate > temperate > subtropical forests. Also, no significant differences were found in the soil polyphenol oxidase and peroxidase activities among the three typical coniferous forests. In contrast, the soil chitinase activity involved in soil nitrogen cycle was significantly higher in the temperate forest than in the cold-temperate and subtropical forests, and the soil β-glucosaccharase activity in the temperate forest was also significantly higher than that of the subtropical forest. Stepwise regression analysis showed that the soil chitinase activity was closely associated with soil MBN content and soil pH value, and the soil β-glucosaccharase activity was significantly and positively related to soil pH value. Our results suggest that soil cellulose- and chitin-degrading enzymes (i.e., chintinase and β-glucosaccharase) sensitively respond to climate zone. Soil MBN content and pH value are the main factors controlling soil enzyme activities of coniferous forests along the NSTEC. 参考文献 相似文献 引证文献

Ecological developments during Holocene age and high atmospheric depositions since industrialization have changed the N dynamics of temperate forest ecosystems. A number of different parameters are used to indicate whether the forests are N‐saturated or not, most common among them is the occurrence of nitrates in the seepage water below the rooting zone. The use of different definitions to describe N saturation implies that the N status of ecosystems is not always appropriately assessed. Data on N dynamics from 53 different German forests were used to classify various development states of forest ecosystems according to the forest ecosystem theory proposed by Ulrich for which N balances of input – (output plus plant N increment) were used. Those systems where N output equals N input minus plant N increment are described as (quasi‐) Steady State Type. Those forests where N output does not equal N input minus plant N increment as in a ‘transient state.’ Forests of the transient state may lose nitrogen from the soil (Degradation Type) or gain nitrogen [e.g., from atmospheric depositions (Accumulation Type)]. Forest ecosystems may occur in four different N states: (a) (quasi‐) Steady State Type with mull type humus, (b) Degradation Type with mull type humus, (c) Accumulation Type with moder type humus, and (d) (quasi‐) Steady State Type with moder type humus. Forests with the (quasi‐) steady state with mull type humus in the forest floor (n= 8) have high‐soil pH values, high N retention by plant increment, high N contents in the mineral soils, and have not undergone large changes in the N status. Forests of the Degradation Type lose nitrogen from the mineral soil (currently degradation is occurring on one site). Most forests that have moder or mor type humus and low‐soil pH values, and low N contents in the mineral soil have gone through the transient state of organic matter loss in the mineral soils. They accumulate organic matter in the forest floor (accumulation phase, currently 21 sites are accumulating 6–21 kg N ha−1 yr−1) or have reached a new (quasi‐) steady state with moder/mor type humus (n= 15). N retention in the accumulation phase has significantly increased in soil with N deposition (r2= 0.38), soil acidity (considering thickness of the forest floor as indices of soil acidity,r2= 0.43) and acid deposition (sulfate deposition,r2= 0.39). Retention of N (4–20 kg N ha−1 yr−1) by trees decreased and of soils increased with a decrease in the availability of base cations indicating the important role of trees for N retention in less acid soils and those of soils in more acid soils. Ecosystem theory could be successfully applied on the current data to understand the dynamics of N in temperate forest ecosystems.

Saproxylic beetles in tropical and temperate forests – A standardized comparison of vertical stratification patterns

Forest liming is a management tool that has and continues to be used extensively across northern Europe to counteract acidification processes from anthropogenic sulfur and nitrogen (N) deposition. In this study, we quantified how liming affects soil organic carbon (SOC) stocks and attempt to disentangle the mechanisms responsible for the often-contrasting processes that regulate net soil carbon (C) fluxes. Using a paired-plot experimental design we compared SOC stocks in limed plots with adjacent unlimed control plots at 28 experimental sites to 60-cm soil depth in mature broadleaf and coniferous forests across Germany. Historical soil data from a subset of the paired experiment plots was analyzed to assess how SOC stocks in both control and limed plots had changed between 1990 and 2019. Overall, we found that forest floor C stocks have been accumulating over time, particularly in the control plots. Liming however largely offsets this organic layer buildup, which means that nutrients remain mobile and are not bound in soil organic matter complexes. Results from the paired plot analysis showed that forest floor C stocks were significantly lower in limed plots than the control ( 34 %, 8.4 ± 1.7 Mg C ha-1), but did not significantly affect SOC stocks in the mineral soil, when all sites are pooled together. In the forest floor layers, SOC stocks exhibited an exponential decrease with increasing pH, highlighting how lime-induced improvements in the biochemical environment stimulate organic matter (OM) decomposition. Nevertheless, for both forest floor and mineral soils, the magnitude and direction of the belowground C changes hinged directly on the inherent site characteristics, namely, forest type (conifer versus broadleaf), soil pH, soil texture and the soil SOC stocks. On the other hand, SOC stock decreases were often offset by other processes that fostered C accumulation, such as improved forest productivity or increased carbon stabilization, which correspondingly translated to an overall variable response by SOC stocks, particularly in the mineral soil. Lastly, we measured soil carbon dioxide (CO2) and soil methane (CH4) flux immediately after a re-liming event at three of the experimental sites. Here, we found that (1) liming doubles CH4 uptake in the long-term, (2) highlighted that soil organic matter mineralization processes respond quickly to liming, though the duration and size of the CO2 flush varied between sites, and (3) lime-derived CO2 contributed very little to total CO2 emissions over the measurement period.

Increases in the deposition of atmospheric nitrogen (N) influence N cycling in forest ecosystems and can result in negative consequences due to the leaching of nitrate into groundwaters. From December 1995 to February 1998, the Pan-European Programme for the Intensive and Continuous Monitoring of Forest Ecosystems measured forest conditions at a plot scale for conifer and broadleaf forests, including the performance of time series of soil solution chemistry. The influence of various ecosystem conditions on soil solution nitrate concentrations at these forest plots (n = 104) was then analyzed with a statistical model. Soil solution nitrate concentrations varied by season, and summer concentrations were approximately 25% higher than winter ones. Soil solution nitrate concentrations increased dramatically with throughfall (and bulk precipitation) N input for both broadleaf and conifer forests. However, at elevated levels of throughfall N input (more than 10 kg N ha−1 y−1), nitrate concentrations were higher in broadleaf than coniferous stands. This tree-specific difference was not observed in response to increased bulk precipitation N input. In coniferous stands, throughfall N input, foliage N concentration, organic layer carbon–nitrogen (C:N) ratio, and nitrate concentrations covaried. Soil solution nitrate concentrations in conifer plots were best explained by a model with throughfall N and organic layer C:N as main factors, where C:N ratio could be replaced by foliage N. The organic layer C:N ratio classes of more than 30, 25–30, and less than 25, as well as the foliage N (mg N g−1) classes of less than 13, 13–17, and more than 17, indicated low, intermediate, and high risks of nitrate leaching, respectively. In broadleaf forests, correlations between N characteristics were less pronounced, and soil solution nitrate concentrations were best explained by throughfall N and soil pH (0–10-cm depth). These results indicate that the responses of soil solution nitrate concentration to changes in N input are more pronounced in broadleaf than in coniferous forests, because in European forests broadleaf species grow on the more fertile soils.

Phosphorus( P) as a basic mineral nutrient is considered to constrain primary productivity in many tropical and subtropical forests. Soil phosphatase plays a very important role in P cycling in forest ecosystems because it catalyzes the hydrolysis of soil organic P compounds( e. g.,nucleic acids and phospholipids) into forms that are available to plants and soil microbes. Soil phosphatase activity is widely considered an effective indicator of the P demand of plants and microbes due to its ability to mediate plant and microbial nutrient acquisition from organic P compounds. In recent decades,increasing nitrogen( N) deposition due to human activity has been demonstrated to cause soil P deficiency and increase soil acid phosphomonoesterase activity( APA) in several tropical or subtropical forests. However,little is known about the effects of N deposition on soil APA in other forest types( e. g.,broadleaf forest and coniferous forest) or whether P addition may relieve soil P limitation in these forests. The present study investigated the responses of soil APA to N and P additions in a monsoon evergreen broadleaf forest( MEBF),a Pinus massoniana forest( PF),and a mixed broadleaf and pine forest( MF) in Dinghushan Mountain,Guangdong Province of southern China via a six- year fertilization experiment. The experiment used full factorial design,including four treatments: control( no fertilization),N addition( 150 kg N hm- 2a- 1),P addition( 150 kg P hm- 2a- 1),and combined N and P addition( 150 kg N hm- 2a- 1plus 150 kg P hm- 2a- 1).Each 5 m × 5 m plot was established with a surrounding buffer strip( 5 m wide). For each N and P application,NH4NO3 and Na H2PO4 solutions were applied below the canopy with a backpack sprayer,every other month from January 2007 to July 2013. In July 2013,soil samples were collected for analysis. Results showed that soil APA was significantly higher in MEBF(( 15. 83 ± 2. 46) μmol g- 1h- 1) than that in MF(( 10. 71 ± 0. 78) μmol g- 1h- 1) or PF(( 9. 12 ± 0. 38) μmol g- 1h- 1) soils,and a significant negative correlation existed between soil APA and soil available P contents in all forest types. N addition significantly increased soil APA in MEBF,while no statistical difference was found in MF or PF. P addition significantly decreased soil APA in MF and PF,but had no significant effect in MEBF. Combined N and P addition notably depressed soil APA in PF,but had no significant influence in MEBF and MF. Importantly,interactions between N and P additions were observed in MEBF. Based on our results,N deposition is expected to aggravate soil P deficiency in mature subtropical forest,while the N-induced P-limited state of these forests might be effectively relieved by P addition. In conclusion,the addition of P fertilizer may serve as an effective method for the sustainable future development of tropical and subtropical forests.

Tree species is the major factor explaining C:N ratios in European forest soils

A 15N tracing study was carried out to investigate the potential gross nitrogen (N) dynamics in thirteen forest soils in Eastern China ranging from temperate to tropical zones (five coniferous forests, six deciduous broad-leaf forests, one temperate mixed forest, one evergreen broad-leaf forests ecosystems), and to identify the major controlling factors on N cycling in these forest ecosystems. The soil pH ranged from 4.3 to 7.9 and soil organic carbon (SOC) ranged from 6.6 g kg−1 to 83.0 g kg−1. The potential gross N transformation rates were quantified by 15N tracing studies where either the ammonium or nitrate pools were 15N labeled in parallel treatments. Gross mineralization rates ranged from 0.915 μg N g−1 soil day−1 to 2.718 μg N g−1 soil day−1 in the studied forest soils. The average contribution of labile organic-N (MNlab) to total gross mineralization (MNrec+MNlab) was 86% (58% to 99%), indicating that turnover of labile organic N plays a dominant role in the studied forest ecosystems. The gross mineralization rates in coniferous forest soils were significantly lower (ranging between 0.915 and 1.228 μg N g−1 soil day−1) compared to broad-leaf forest soils (ranging from 1.621 to 2.718 μg N g−1 soil day−1) (p < 0.01). Thus, the dominant vegetation may play an important role in regulating soil N mineralization. Nitrate production (nitrification) occurred via two pathways, oxidation of NH4+ and organic N the forest soils. Correlations with soil pH indicated that this is a key factor controlling the oxidation of NH4+ and organic N in theses forest ecosystems. NH4+ oxidation decreased with a decline in pH while organic N oxidation increased. The climatic conditions (e.g. moisture status) at the various sites governed the NO3−-N consumption processes (dissimilatory NO3− reduction to NH4+ (DNRA) or immobilization of NO3−). Total NO3− consumption and the proportion of total NO3− consumption to total NO3− production decreased with an increase in the drought index of ecosystems, showing that strong interactions appear to exist between climatic condition (e.g. the drought index), N mineralization and the rate of DNRA. Interactions between vegetation, climatic conditions govern internal N cycling in these forests soils.

While much is known about process level control on N2O production by nitrification and denitrification, knowledge of the environmental controls responsible for site variation in annual N2O fluxes on ecosystem level is low. Our goal was to improve existing concepts of controls on N2O fluxes. We measured N2O emission weekly or biweekly during 1 year in 11 temperate forest ecosystems using closed chambers. We identified three types of forest with different temporal emission patterns: forest with seasonal, event‐based and background emission patterns. Comparison of annual data sets from literature showed that most temperate forests had low N2O emissions throughout the year (background emission pattern) with mean annual fluxes of 0.39 ±0.27 kg N ha−1 yr−1 (n = 21). Event‐based emission patterns were observed during frost/thaw periods and after rewetting. Highest fluxes up to 72 kg N ha−1 were emitted from a drained alder forest with organic soil in 46 weeks, followed by well drained tropical and temperate forests with seasonal emission patterns and fluxes between 2 − 6 (n = 3) and 1 − 5 kg N ha−1 yr−1 (n = 4), respectively. Seasonal emission patterns were explained by combined effect of high annual precipitations; broad leave trees; amount and structure of organic upper horizon; high mineral bulk densities; and plant community. These state variables reduce gas diffusivity so that oxygen demand by microorganism and roots exceeded oxygen supply during wet and warm periods (&gt;10° C). The resultant upper mean level was about 100 μg N2O−N m−2 h−1 in both temperate and tropical forests. Annual N2O losses of the seasonal emission type were controlled by both duration and upper mean level of the periods with high emissions. We conclude that “short‐term controls” of climate determine the duration of high emissions, whereas “long‐term controls” by state variables determine the difference between background and seasonal emission types.

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.

Seasonal patterns and annual rates of N inputs, outputs, and internal cycling were determined for an old-growth mixed-conifer forest floor in the Sierra Nevada Mountains of California. Rates of net N mineralization within the forest floor, and plant N-uptake and leaching of inorganic N from the forest floor were 13, 10, and 9 kg-N ha-1 yr-1, respectively. The Mediterranean-type climate appeared to have a significant effect on N cycling within this forest, such that all N-process and flow rates showed distrinct seasonal patterns. We estimated the forest floor supplies less than one-third of the total aboveground plant N-uptake in this forest. The rate of net nitrification within the forest floor was always low (1 kg-NO3 --N ha-1 30d-1). Mean residence times for organic matter and N in the forest floor were 13 and 34 years, respectively, suggesting that this forest floor layer is a site of net N immobilization within this ecosystem. We examined the influence of the forest floor on mineral soil N dynamics by injecting small amounts of15N-enriched (NH4)2SO4 solutions into the surface mineral soil with the forest floor present (+FF) or removed (-FF). K2SO4-extractable NO3 --N, total inorganic-N, and total-N pool sizes in the mineral soil were initially increased after forest floor removal (after 4 months), but NO3 --N and total inorganic-N were not significantly different thereafter. Microbial biomass-N and K2SO4-extractable total-N pool sizes were also found to be larger in mineral soils without a forest floor after 1 and 1.3 years, respectively. Total15N-recovery was greater in the +FF treatment compared to the -FF treatment after 1-year (about 50% and 35%, respectively) but did not differ after 1.3 years (both about 35%), suggesting that the forest floor delays but does not prevent the N-loss from the surface mineral soil of this forest. We estimated using our15N data that fungal translocation from the mineral soil to the forest floor may be as large as 9 kg-N ha-1 yr-1 (similar in magnitude to other N flows in this forest), and may account for all of the observed absolute increase of N in litter during the early stages of decomposition at this site. Our results suggest that the forest floor acts both as a source and sink for N in the mineral soil.

The use of biomass from forest harvesting residues or stumps for bioenergy has been increasing in the northern European region in the last decade. The present analysis is a regional review from Nordic and UK coniferous forests, focusing on the effects of whole-tree harvesting (WTH) or whole-tree thinning (WTT) and of WTH followed by stump removal (WTH + S) on the forest floor and mineral soil, and includes a wider array of chemistry data than other existing meta-analyses. All intensified treaments led to significant decreases of soil organic carbon (SOC) stock and total N stock in the forest floor (FF), but relative responses compared with stem-only harvesting were less consistent in the topsoil (TS) and no effects were detected in the subsoil (SS). Exchangeable P was reduced in the FF and TS both after WTT and WTH, but significant changes in exchangeable Ca, K, Mg and Zn depended on soil layer and treatment. WTH significantly lowered pH and base saturation (BS) in the FF, but without apparent changes in cation exchange capacity (CEC). The only significant WTH-effects in the SS were reductions in CEC and BS. Spruce- and pine-dominated stands had comparable negative relative responses in the FF for most elements measured except Mg and for pH. Relative responses to intensified harvesting scaled positively with growing season temperature and precipitation for most variables, most strongly in FF, less in the TS, but almost never in the SS, but were negative for P and Al. The greater reduction in FF and TS for soil organic carbon after intensive harvesting decreased with time and meta-regression models predicted an average duration of 20–30 years, while many other chemical parameters generally showed linear effects for 30–45 years after intensified harvesting. Exchangeable acidity (EA), BS and pH all showed the reversed effect with time, i.e. an initial increase and then gradual decrease over 24–45 years. The subsoil never showed a significant temporal effect. Our results generally support greater reductions in nutrient concentrations, SOC and total N in forest soil after WTH compared with SOH in northern temperate and boreal forest ecosystems.

The relationships of soil total nitrogen concentrations, pools and C:N ratios with climate, vegetation types and nitrate deposition in temperate and boreal forests of eastern Canada

Composition and dynamics of dissolved carbohydrates and lignin-degradation products in two coniferous forests, N.E. Bavaria, Germany