Danish forest development during the last 3000 years reconstructed from regional pollen data

Most present Danish forest types are a direct result of recent silvicultural practice. We use fossil pollen data converted into estimates of tree abundance to map the development of forest types during the last 3000 radioearbon yr. The forest types were clusters in an artificial neural network based on all available European Holocene pollen data. Diverse deciduous forest types found 3000 yr ago were replaced by less diverse Fagus -dominated types over a period of 2000 yr. The present day map contained many new combinations of tree species, dominated by Picea and Pinus. The association between the increase in non-forest communities and establishment of Fagus suggests that anthropogenic activity has accelerated the loss of species-rich deciduous forest with abundant .Alnus, Corylus, Quercus and Tilia. We conclude that the natural forest composition of Denmark would be deciduous forest today with a significant presence of Fugus sylvatica. Recent forest development has created a break in compositional continuity with the past that is unnatural and has posed problems for forest-dependent biota.     

Impact on lake development of changed agricultural watershed exploitation during the last three centuries

The history of the development of Lake Hejrede Sø (Denmark) and the related history of the watershed management were studied based on analyses of macrofossil content, chemical composition and Clostridium perfringens content in sediment cores. Depth-age relations of ecological changes were established through Pb²¹⁰ analyses, and a systematic search for written sources describing the watershed history was carried out.Lake Hejrede Sø used to be a humic, acid but relatively clearwater lake with an extensive submersed vegetation. Owing to deforestation and reclamation of bogs and meadows, the accumulation of nutrients in these ecotones vanished. Subsequently, in early 1800 the lake developed into a clearwater alkaline lake, and later became more eutrophic which resulted in the decline of the submersed vegetation. At the time the annual sediment phosphorus accumulation increased more than twofold, and influx of mineral matter increased drastically. In mid-1900, submersed vegetation had disappeared. The Clostridium perfringens analysis and the historical evidence show that no sewage was discharged to the lake until mid-1900, which implies that changed agricultural watershed exploitation and ecotone reclamation during the 19th century was the cause of the increased nutrient influx, and the deterioration of the lake.Written historical sources confirm the palaeolimnological interpretations and describe the agricultural practices responsible for the development.     

Late quaternary dynamics of pollen influx at mineral lake,Washington

Pollen influx analysis at Mineral Lake, Washington, indicates that immediately south of the Puget Lobe of the Fraser Glaciation, tundra was a characteristic vegetation until 16,300 years ago. Invasion ofPinus contorta began 17,500 years B.P., and boreal climax conifers (Abies, Picea andTsuga mertensiana), 16,300, but was temporarily interrupted by the Vashon advance (14,500–14,000 yr B.P.).Pseudotsuga menziesii began to grow in population 10,750 years ago, and woodland was established within a time span of 1,000 years. Modern lowland coniferous forests began to form 7,000 years ago. Logistic analysis of pollen abundance changes show that the intrinsic growth rate,r (yr⁻¹), of pioneer species (e.g. 0.024–0.026 inPteridium aquilinum) is higher than that of climax species (e.g. 0.003 inThuja plicata).P. menziesii, a subclimax species, shows an intermediater value (0.013) between these two ecologically different taxa. The absoluter value ofP. contorta (−0.011) is only slightly lower than that ofP. menziesii, although their replacement began almost simultaneously. Thus competition between these species was intense before the inflection point ofPinus curve 10,100 years ago. At this time, forest gaps became abundantly available forPseudotsuga, as indicated by a peak of the diagnostic factor (the reciprocal of the pollen influx).     

贵州白鹇湖沉积物中孢粉记录的5.5kaB.P.以来的气候变化

通过对白鹇湖沉积物柱芯孢粉组合的剖面变化分析,在有机质14C定年基础上,探讨了白鹇湖地区过去5.5 ka calB.P.以来的植被演替和气候变化过程.研究结果表明,5500-4500 aB.P.期间,各类植被比较丰富,气候温暖湿润;4500-2750 aB.P.期间,干旱草本和蕨类植物开始出现,是气候转变过渡期;2750-1500 aB.P.期间,木本植物组合类型发生明显变化,喜湿草本减少,耐旱草本增加,气候向温凉干旱化发展;1500 aB.P.至今,木本植被和喜湿草本继续减少,中生耐旱草本和蕨类植物数量继续大幅增加,干旱化趋势明显,植被组合向典型石漠化植被组合类型发展.白鹇湖沉积物剖面孢粉组合变化表明,该地区近5000a来气候变化以温度下降、降水减少为主要趋势,并存在明显的陆地植被退化现象.研究还揭示了自然气候变化事件(如气候持续干旱)可导致喀斯特地区发生石漠化,证实了喀斯特地区生态环境具先天脆弱性.科学评估白鹇湖地区气候干旱化趋势及其生态环境影响对指导该地区科学应对气候变化具重要意义,亟待加强.     

Tree species dynamics and disturbance in three Swedish boreal forest stands during the last two thousand years

Abstract. Data from three forest stands for the past 2000 yr show how the shade-intolerant species Pinus sylvestris and Betula pubescens maintain significant populations in the Swedish boreal landscape. Age structure data from a northern stand close to the range limits of Picea abies and Pinus complement a local pollen diagram, and reveal cyclic population fluctuations which can be related to periods of climatic stress and fire. Pollen data from two southern stands show that high fire frequencies in the past prevented the expansion of Picea populations. Reduction of the fire frequency during the last 200 yr has favoured Picea. A long time perspective reveals the population dynamics of long-lived species and indicates the controlling factors. Such knowledge permits assessment of the current status and likely future of forest stands.     

Quantitative changes of forest landscapes over the last century across Italy

A key topic in landscape ecology and vegetation science is the quantitative analysis of changes in forest cover over time, through the use of geomatics monitoring tools. Ecologists and landscape researchers are pointing out that a full understanding of ecosystems and landscapes should be based on the analysis of their functioning over long time series. Under this perspective, a long-term historical reconstruction of forest cover is essential. This study has aimed at examining the long-term dynamics of forest landscapes in Italy, over the last century, using recent remote-sensing based map (2012) and an accurate historical map (1936). A forest-non forest approach has been followed by the computation of a variety of landscape metrics using two analysis tools, with the final objective of quantifying changes in forest cover patterns and in the composition of specific landscape elements. Results show that forest landscape structure has significantly changed across Italy, resulting in a general trend of decreasing fragmentation and patchiness, mainly through enlargement of existing forest patches, which have also assumed a more geometrically regular shape. In relative terms, the greatest expansion of forest areas has occurred mainly in lowland districts characterised by the highest level of human pressure in the country.     

Representation of tundra vegetation by pollen in lake sediments of northern Alaska

Aim To understand better the representation of arctic tundra vegetation by pollen data, we analysed pollen assemblages and pollen accumulation rates (PARs) in the surface sediments of lakes. Location Modern sediment samples were collected from seventy‐eight lakes located in the Arctic Foothills and Arctic Coastal Plain regions of northern Alaska. Methods For seventy of the lakes, we analysed pollen and spores in the upper 2 cm of the sediment and calculated the relative abundance of each taxon (pollen percentages). For eleven of the lakes, we used ²¹⁰Pb analysis to determine sediment accumulation rates, and analysed pollen in the upper 10–15 cm of the sediment to estimate modern PARs. Using a detailed land‐cover map of northern Alaska, we assigned each study site to one of five tundra types: moist dwarf‐shrub tussock‐graminoid tundra (DST), moist graminoid prostrate‐shrub tundra (PST) (coastal and inland types), low‐shrub tundra (LST) and wet graminoid tundra (WGT). Results Mapped pollen percentages and multivariate comparison of the pollen data using discriminant analysis show that pollen assemblages vary along the main north–south vegetational and climatic gradients. On the Arctic Coastal Plain where climate is cold and dry, graminoid‐dominated PST and WGT sites were characterized by high percentages of Cyperaceae and Poaceae pollen. In the Arctic Foothills where climate is warmer and wetter, shrub‐dominated DST, PST and LST were characterized by high percentages of Alnus and Betula pollen. Small‐scale variations in tundra vegetation related to edaphic variability are also represented by the pollen data. Discriminant analysis demonstrated that DST sites could be distinguished from foothills PST sites based on their higher percentages of Ericales and Rubus chamaemorus pollen, and coastal PST sites could be distinguished from WGT sites based on their higher percentages of Artemisia. PARs appear to reflect variations in overall vegetation cover, although the small number of samples limits our understanding of these patterns. For coastal sites, PARs were higher for PST than WGT, whereas in the Arctic Foothills, PARs were highest in LST, intermediate in DST, and lowest in PST. Main conclusion Modern pollen data from northern Alaska reflect patterns of tundra vegetation related to both regional‐scale climatic gradients and landscape‐scale edaphic heterogeneity.     

Climate-lake interactions recorded in varved sediments from a Swedish boreal forest lake

A 1100-year long record of lake ecosystem response to climate and catchment change with precise chronological control is reported. Diatom and pollen assemblages of an annually laminated (varved) sediment from a northern Swedish lake (Kassjön, Våsterbotten) were used as records of lake diatom communities and catchment vegetation. These data were compared with summer temperature estimates based on tree-ring records of the same geographical area to identify the effects of climate change and catchment disturbance on diatom assemblages in the lake. In a canonical ordination, 23% of the variability in the total diatom assemblages for the period AD1040–1804 was accounted for by changes in pollen data which reflect agricultural development in the catchment. Diatom species richness, however, exhibited a stronger relationship with summer temperature and, significantly, declined with the lower temperatures associated with the Little Ice Age minimum (early 17th century). Summer temperature accounted for 23% of the variability in diatom species richness 20 years later. The mechanism behind this time-lag is unclear, but may be related to catchment-mediated effects, given recent evidence for lags in the response of boreal-forest vegetation regeneration cycles to climatic variability. These results suggest that climate-related effects on lakes occurring over medium timescales can be resolved in lake sediments. Moreover, it is possible to identify these effects despite cultural-related signals, but as the latter become more extreme in the late 20th century the climate signal is obscured.     

Modern pollen and stomate deposition in lake surface sediments from across the treeline on the Kola Peninsula, Russia

We sampled and analyzed surface sediments from 31 lakes along a latitudinal transect crossing the coniferous treeline on the Kola Peninsula, Russia. The major vegetation zones along the transect were tundra, birch-forest tundra, pine-forest tundra, and forest. The results indicate that the major vegetation types in our study area have distinct pollen spectra. Sum-of-squares cluster analysis and principal components analysis (PCA) groupings of pollen sites correspond to the major vegetation zones. PCA ordination of taxa indicates that the first axis separates taxa typical of the forest zone (Pinus, Picea) from taxa typical of tundra and forest-tundra zones (Polypodiaceae, Ericaceae, and Betula). The current position of the coniferous treeline, defined in our region by Pinus sylvestris, occurs roughly where Pinus pollen values reach 35% or greater. Arboreal pollen (AP)/non-arboreal pollen (NAP) ratios were calculated for each site and plotted against geographic distance along the transect. AP/NAP ratios of 7 or greater are found within pine-forest tundra and forest vegetation zones. Pinus stomates (dispersed stomatal guard cells) are absent from sites north of the coniferous treeline and all but two samples from the forested sites contain stomates. Stomate concentrations among the samples are highly variable and range from 10 to 458 per ml and positively correlate with the changing Pinus pollen values.     

Environmental change in the Colombian subandean forest belt from 8 pollen records: the last 50 kyr

We present a reconstruction of forest history and climatic change based on 11 pollen records from eight sites, all located in the lower montane forest belt of the northern Andes in Colombia. We compared records from the Popayán area in southern Colobia, Timbio (1750 m), Genagra (1750 m) and Pitalito (1300 m) and the new Piagua (1700 m) record with the records from Lusitania (1500 m), Libano (1820 m), Pedro Palo (2000 m) and Ubaqué (2000 m) from Central Colombia. The changes of the altitudinal position of the lower/upper montane (= subandean/Andean, S/At) forest belt transition were used to estimate temperature change for the last 50 kyr. We infer a Last Glacial Maximum (LGM) temperature drop of 6°–7°C at 1700 m, and a steeper LGM lapse rate of 0.76°C/100 m compared to today (ca. 0.6°C/100 m). Around 50 uncal. kyr B.P. the temperature at 1700 m was ca. 3°C lower than today. Until 20 uncal. kyr B.P. the temperature oscillated and gradually decreased. During the LGM, temperature was down to ca. 6°–7°C lower than today. After the LGM, temperature increased and ca. 14 uncal. kyr B.P. it was 2°–3°C lower than today (S/At at ca. 1800 m, 500 m below present elevation; Susacá interstadial). An unquantified cooling (Ciega stadial) followed. During ca. 12.3–11.7 uncal. kyr B.P. the S/At shifted upslope to 2100 m indicating a temperature of 1°–2°C cooler than today (Guantiva interstadial). From 11.7–10.9 uncal. kyr B.P. the S/At was at 1800 m indicating that the temperature was ca. 3°C lower than today and wet conditions prevailed (partly coinciding with the El Abra stadial). The period 10.9–9 uncal. kyr B.P. was also cool, but drier. During 9–7.5 uncal. kyr B.P. temperature was ca. 1°C warmer relative to today (mid Holocene hypsithermal). During the last 5 kyr the presence of cultivated plants demonstates human colonization of the lower montane zone in Colombia. Received June 14, 2000 / Accepted December 19, 2000     

Cloud forest dynamics in the Mexican neotropics during the last 1300 years

Key questions for understanding the resilience and variability of Mexican Neotropical cloud forest assemblages in current and future climate change include: How have human disturbances and climate change affected the dynamics of the cloud forest assemblage? What are the predominant processes responsible for its present day composition and distribution? Are the current conservation strategies for the cloud forest in accordance with preserving its natural variability through time? In this study, the temporal dynamics of the cloud forest in west‐central Mexico over the last ～1300 years were reconstructed using palaeoecological techniques. These included analyses of fossil pollen, microfossil charcoal, and sediment geochemistry. Results indicated that a cloud forest assemblage has been the predominant vegetation type in this region over the last ～1300 years. During this time, however, there have been changes in the vegetation with an apparent expansion of cloud forest from ～832 to 620 cal years bp and a decline from 1200 to 832 cal years bp . Climate change (intervals of aridity) and human disturbances through anthropogenic burning appear to have been the main factors influencing the dynamics of this cloud forest. The spatial heterogeneity reported for high‐altitude forests in this region, in concert with high beta diversity, appears to be a manifestation of the high temporal variability in species composition for these forests. Greater turnover in cloud forest taxa occurred during intervals of increased humidity and is probably representative of a higher temporal competition for resources among the cloud forest taxa. The present results support the current protection scheme for cloud forests in west‐central Mexico where areas are kept in exclusion zones to avoid timber extraction, grazing, and agriculture; this will maintain diversity within these forests, even if there are only a few individuals per species, and enable the forests to retain some resilience to current and future climate change.     

Carbon balances in US croplands during the last two decades of the twentieth century

Carbon (C) added to soil as organic matter in crop residues and carbon emitted to the atmosphere as CO₂ in soil respiration are key determinants of the C balance in cropland ecosystems. We used complete and comprehensive county-level yields and area data to estimate and analyze the spatial and temporal variability of regional and national scale residue C inputs, net primary productivity (NPP), and C stocks in US croplands from 1982 to 1997. Annual residue C inputs were highest in the North Central and Central and Northern Plains regions that comprise ~70% of US cropland. Average residue C inputs ranged from 1.8 (Delta States) to 3.0 (North Central region) Mg?C?ha^?1?year^?1, and average NPP ranged from 3.1 (Delta States) to 5.4 (Far West region) Mg?C?ha^?1?year^?1. Residue C inputs tended to be inversely proportional to the mean growing season temperature. A quadratic relationship incorporating the growing season mean temperature and total precipitation closely predicted the variation in residue C inputs in the North Central region and Central and Northern Plains. We analyzed the soil C balance using the crop residue database and the Introductory Carbon Balance regional Model (ICBMr). Soil C stocks (0–20?cm) on permanent cropland ranged between 3.07 and 3.1?Pg during the study period, with an average increase of ~4?Tg?C?year^?1, during the 1990s. Interannual variability in soil C stocks ranged from 0 to 20?Tg?C (across a mean C stock of 3.08?±?0.01?Pg) during the study period; interannual variability in residue C inputs varied between 1 and 43?Tg C (across a mean input of 220?±?19?Tg). Such interannual variation has implications for national estimates of CO₂ emissions from cropland soils needed for implementation of greenhouse gas (GHG) mitigation strategies involving agriculture.     

A comparison of sedimentary DNA and pollen from lake sediments in recording vegetation composition at the Siberian treeline

Reliable information on past and present vegetation is important to project future changes, especially for rapidly transitioning areas such as the boreal treeline. To study past vegetation, pollen analysis is common, while current vegetation is usually assessed by field surveys. Application of detailed sedimentary DNA (sedDNA) records has the potential to enhance our understanding of vegetation changes, but studies systematically investigating the power of this proxy are rare to date. This study compares sedDNA metabarcoding and pollen records from surface sediments of 31 lakes along a north–south gradient of increasing forest cover in northern Siberia (Taymyr peninsula) with data from field surveys in the surroundings of the lakes. sedDNA metabarcoding recorded 114 plant taxa, about half of them to species level, while pollen analyses identified 43 taxa, both exceeding the 31 taxa found by vegetation field surveys. Increasing Larix percentages from north to south were consistently recorded by all three methods and principal component analyses based on percentage data of vegetation surveys and DNA sequences separated tundra from forested sites. Comparisons of the ordinations using procrustes and protest analyses show a significant fit among all compared pairs of records. Despite similarities of sedDNA and pollen records, certain idiosyncrasies, such as high percentages of Alnus and Betula in all pollen and high percentages of Salix in all sedDNA spectra, are observable. Our results from the tundra to single‐tree tundra transition zone show that sedDNA analyses perform better than pollen in recording site‐specific richness (i.e., presence/absence of taxa in the vicinity of the lake) and perform as well as pollen in tracing vegetation composition.     

林隙干扰对森林生态系统的影响

林隙干扰通过改变森林微生境异质性和群落演替进程,对森林物种组成、林分结构和系统功能产生重要影响.本研究评述了有关林隙干扰对森林生态系统影响的最新研究进展,从物种生物学特性和环境因素两个方面分析了林隙干扰对森林物种组成变化的影响规律,基于群落组件和群落架构阐述了林隙干扰对森林结构的作用关系,梳理了林隙干扰对森林生态系统功...     

How drought events during the last century have impacted biomass carbon in Amazonian rainforests

During the last two decades, inventory data show that droughts have reduced biomass carbon sink of the Amazon forest by causing mortality to exceed growth. However, process-based models have struggled to include drought-induced responses of growth and mortality and have not been evaluated against plot data. A process-based model, ORCHIDEE-CAN-NHA, including forest demography with tree cohorts, plant hydraulic architecture and drought-induced tree mortality, was applied over Amazonia rainforests forced by gridded climate fields and rising CO₂ from 1901 to 2019. The model reproduced the decelerating signal of net carbon sink and drought sensitivity of aboveground biomass (AGB) growth and mortality observed at forest plots across selected Amazon intact forests for 2005 and 2010. We predicted a larger mortality rate and a more negative sensitivity of the net carbon sink during the 2015/16 El Niño compared with the former droughts. 2015/16 was indeed the most severe drought since 1901 regarding both AGB loss and area experiencing a severe carbon loss. We found that even if climate change did increase mortality, elevated CO₂ contributed to balance the biomass mortality, since CO₂-induced stomatal closure reduces transpiration, thus, offsets increased transpiration from CO₂-induced higher foliage area.     

Impact of changing wood demand,climate and land use on European forest resources and carbon stocks during the 21st century

We used the European Forest Information Scenario Model (EFISCEN) to project the development of forest resources for 15 European countries from 2000 to 2100 under a broad range of climate scenarios, which were based on the a1fi, a2, b1 and b2 storylines of the Special Report on Emissions Scenarios of the Intergovernmental Panel on Climate Change. Each climate scenario was associated with consistent land-use change and wood demand assumptions. Climate change-induced growth changes were incorporated into the calculations by scaling inventory-based stem growth in EFISCEN by net primary productivity estimated from the Lund–Potsdam–Jena dynamic global vegetation model. The impact of changes in wood demand, climate and forest area were studied separately, and in combination, in order to assess their respective effects. For all climate scenarios under consideration, climate change resulted in increased forest growth, especially in Northern Europe. In Southern Europe, higher precipitation in spring and the projected increased water-use efficiency in response to rising atmospheric CO₂ concentrations mitigated the effects of increasing summer drought. Climate change enhanced carbon sequestration in tree biomass. The climate change-induced increase in tree growth led to a faster increase in growing stocks compared with the simulation using current climate. As productivity decreased in higher stocked forests, the positive impact of climate change began to level off during the second half of the 21st century in the scenarios where wood demand was low. Afforestation measures had the potential to increase growing stock and annual increment; however, large areas were needed to obtain notable effects. Despite noticeable differences in the growth response between the climate scenarios, changes in wood demand proved to be the crucial driving force in forest resource development. Tree carbon stocks increased by 33–114% between 2000 and 2100 when only changes in wood demand were regarded. Climate change added another 23–31% increase, while changes in forest area accounted for an additional increase of 2–40%. Our results highlight potential future pathways of forest resource development resulting from different scenarios of wood demand, land use and climate changes, and stress the importance of resource utilization in the European forest carbon balance.     

Determination of nitrite in lake sediments

Abstract

An evaluation of nitrite determination in marine lake sediments has shown that spectrophotometric measurements can be in error due to light scattering by colloidal (<0.2 μm) matter in extract solutions and incomplete nitrite recovery. The scatter error can be minimised by using uncoloured extract in the reference beam but precision at low levels remains poor (RSD 25 to 100%). Recovery tests on ‘spiked’ sediment indicated that optimum retrieval (～85%) occurred with 30 minute mixing with 0.2 M NH₄Cl, using a sediment to extractant ratio of 1:30. To counter this variable, calibration based on standard addition to sample suspensions is recommended. Modified procedure proposed is suitable for measuring up to 10 μg g^?1 of nitrite N; the lake sediments tested contained <100 ng g^?1     

A modern pollen–climate calibration set based on lake sediments from the Tibetan Plateau and its application to a Late Quaternary pollen record from the Qilian Mountains

Aim Fossil pollen spectra from lake sediments on the Tibetan Plateau have been used for qualitative climate reconstruction, but no modern pollen–climate calibration set based on lake sediments is available to infer past climate quantitatively. This study aims to develop such a dataset and apply it to fossil data. Location The Tibetan Plateau, between 30 and 40° N and 87 and 103° E. Methods We collected surface sediments from 112 lakes and analysed them palynologically. The lakes span a wide range of mean annual precipitation (P_ann; 31–1022 mm), mean annual temperature (T_ann; −6.5 to 1 °C), and mean July temperature (T_July; 2.6–19.7 °C). Redundancy analysis showed that the modern pollen spectra are characteristic of their respective vegetation types and local climate. Transfer functions for P_ann, T_ann and T_July were developed with weighted averaging partial least squares. Model performance was assessed by leave-one-out cross-validation. Results The root mean square errors of prediction (RMSEP) were 104 mm (P_ann), 1.18 °C (T_ann) and 1.17 °C (T_July). The RMSEPs, when expressed as percentages of the gradient sampled, were 10.6% (P_ann), 15.7% (T_ann) and 11.9% (T_July). These low values indicate the good performance of our models. An application of the models to fossil pollen spectra covering the last c. 50 kyr yielded realistic results for Luanhaizi Lake in the Qilian Mountains on the north-eastern Tibetan Plateau (modern P_ann 480 mm; T_ann−1 °C). T_ann and P_ann values similar to present ones were reconstructed for late Marine Isotope Stage 3, with minimum values for the Last Glacial Maximum (c. 300 mm and 2 °C below present), and maximum values for the early Holocene (c. 70 mm and 0.5 °C greater than present). Main conclusions The modern pollen–climate calibration set will potentially be useful for quantitative climate reconstructions from lake-sediment pollen spectra from the Tibetan Plateau, an area of considerable climatic and biogeographical importance.     

Impact of nitrogen deposition on forest and lake food webs in nitrogen‐limited environments

Increased reactive nitrogen (N_r) deposition has raised the amount of N available to organisms and has greatly altered the transfer of energy through food webs, with major consequences for trophic dynamics. The aim of this review was to: (i) clarify the direct and indirect effects of N_r deposition on forest and lake food webs in N‐limited biomes, (ii) compare and contrast how aquatic and terrestrial systems respond to increased N_r deposition, and (iii) identify how the nutrient pathways within and between ecosystems change in response to N_r deposition. We present that N_r deposition releases primary producers from N limitation in both forest and lake ecosystems and raises plants' N content which in turn benefits herbivores with high N requirements. Such trophic effects are coupled with a general decrease in biodiversity caused by different N‐use efficiencies; slow‐growing species with low rates of N turnover are replaced by fast‐growing species with high rates of N turnover. In contrast, N_r deposition diminishes below‐ground production in forests, due to a range of mechanisms that reduce microbial biomass, and decreases lake benthic productivity by switching herbivore growth from N to phosphorus (P) limitation, and by intensifying P limitation of benthic fish. The flow of nutrients between ecosystems is expected to change with increasing N_r deposition. Due to higher litter production and more intense precipitation, more terrestrial matter will enter lakes. This will benefit bacteria and will in turn boost the microbial food web. Additionally, N_r deposition promotes emergent insects, which subsidize the terrestrial food web as prey for insectivores or by dying and decomposing on land. So far, most studies have examined N_r‐deposition effects on the food web base, whereas our review highlights that changes at the base of food webs substantially impact higher trophic levels and therefore food web structure and functioning.