Dietrich Hertel

Georg August University of Göttingen · Plant Ecology and Ecosystems Research

Introduction Ferns constitute the second largest group of vascular plants. Previous studies have shown that the diversity and composition of fern communities are influenced by resource availability and water stress, among other factors. However, little is known about the influence of these environmental factors on their biotic interactions, especia...

Cyclic di-adenosine monophosphate (c-di-AMP) is a second messenger involved in diverse metabolic processes including osmolyte uptake, cell wall homeostasis, as well as antibiotic and heat resistance. This study investigates the role of the c-di-AMP receptor protein DarA in the osmotic stress response in Bacillus subtilis. Through a series of experi...

Fine roots are multifunctional organs that may change function with ageing or root branching events from primarily absorptive to resource transport and storage functions. It is not well understood, how fine root branching patterns and related root functional differentiation along the longitudinal root axis change with soil chemical and physical con...

Recent hot droughts have caused tree vitality decline and increased mortality in many forest regions on earth. Most of Central Europe's important timber species have suffered from the extreme 2018/2019 hot drought, confronting foresters with difficult questions about the choice of more drought- and heat-resistant tree species. We compared the growt...

To increase the resilience of forests to drought and other hazards, foresters are increasingly planting mixed stands. This requires knowledge about the drought response of tree species in pure- and mixed-culture neighborhoods. In addition, drought frequently interacts with continued atmospheric nitrogen (N) deposition. To disentangle these factors...

Key message In mixed combinations, the negative impact of water reduction and N addition is mitigated for F. sylvatica, but not for conifers. Insight into the responses of trees in mixed and monospecific cultivation to water scarcity and nitrogen (N) excess is necessary to recommend suitable tree mixtures for future European forests. Our aim was to...

Background The establishment of mycorrhizal relationships between a fungus and a plant typically enhances nutrient and water uptake for the latter while securing a carbon source for the fungus. However, under a particular set of environmental conditions, such as low availability of light and abundant nutrients in the soil, the resources invested in...

Background Nutrient cycle in tropical forests is mainly driven by litter fall amounts and by litter decay due to litter physical and chemical properties. Apart from differences in site conditions, different successional stages of tropical rainforests may influence nutrient inputs to the soil via differences in litter fall and decay. Methods We stu...

Fine roots are multifunctional organs that may change function with ageing or root branching events from primarily absorptive to resource transport and storage functions. It not well understood, how fine root branching patterns and related root functional differentiation along the root axis change with soil chemical and physical conditions. We exam...

Niche theory fundamentally contributed to the understanding of animal diversity. However, in soil, the diversity of animals seems enigmatic since the soil is a rather homogeneous habitat, and soil animals are often generalist feeders. A new approach to understand soil animal diversity is the use of ecological stoichiometry. The elemental compositio...

Tropical forests are threatened by anthropogenic activities such as conversion into agricultural land, logging and fires. Land-use change and disturbance affect ecosystems not only aboveground, but also belowground including the ecosystems' carbon and nitrogen cycle. We studied the impact of different types of land-use change (intensive and traditi...

Despite the crucial role of fine roots for water and nutrient uptake, soil biological activity and ecosystem carbon cycling, the response of root dynamics to rapidly advancing land-use change in the tropics is still poorly understood. To address this uncertainty, we investigated the consequences of tropical forest conversion to intensively managed...

Forest soils have been recognized as important reservoirs of older stable carbon (C) in the biosphere and thus play a key role in the global C cycle. While much research has addressed the consequences of forest conversion and forest use on soil organic carbon (SOC) stocks, some controversies remain as to whether primary forest soils store significa...

In India, short-rotation plantations have increasingly been promoted over the last decades in response to altered forest management policy and increased wood demand. Understanding how short-rotation forest species coordinate fast growth with water demand and carbon investment will help improving management decisions. We investigated the intra-speci...

1In India, short-rotation plantations have increasingly been promoted over the last decades in 2 response to altered forest management policy and increased wood demand. Understanding how 3 short-rotation forest species coordinate fast growth with water demand and carbon investment 4 will help improving management decisions. 5

Many experiments have shown that biodiversity enhances ecosystem functioning. However, we have little understanding of how environmental heterogeneity shapes the effect of diversity on ecosystem functioning and to what extent this diversity effect is mediated by variation in species richness or species turnover. This knowledge is crucial to scaling...

Farmland tree cultivation is considered an important option for enhancing wood production. In South India, the native leaf-deciduous tree species Melia dubia is popular for short-rotation plantations. Across a rainfall gradient from 420 to 2170 mm year-1 , we studied 186 farmland wood-lots between one and nine years in age. The objectives were to i...

Planted forests of Scots pine (P. sylvestris L.) and other Pinus species extend over >1.7 million hectares in the Pleistocene lowlands of northern Germany, replacing former broadleaf forests (primarily European beech, Fagus sylvatica L.). This transformation belongs to the world’s largest broadleaf-conifer forest conversions; yet, the belowground c...

Tropical forests represent the largest store of terrestrial biomass carbon (C) on earth and contribute over-proportionally to global terrestrial net primary productivity (NPP). How climate change is affecting NPP and C allocation to tree components in forests is not well understood. This is true for tropical forests, but particularly for African tr...

The efficiency of the water transport system in trees sets physical limits to their productivity and water use. Although the coordination of carbon assimilation and hydraulic functions has long been documented, the mutual inter-relationships between wood anatomy, water use and productivity have not yet been jointly addressed in comprehensive field...

During the last decade, a paradigmatic shift regarding which processes determine the persistence of soil organic matter (SOM) took place. The interaction between microbial decomposition and association of organic matter with the soil mineral matrix has been identified as a focal point for understanding the formation of stable SOM. Using an improved...

Revealing the interactive effects of multiple environmental change drivers (water deficits, nitrogen (N) deposition, land-use change) is crucial for evaluating actual and possible future changes in forest ecosystem functioning. Here, we analyse whether and to what extent combined effects of spring and summer water deficits and variable amounts of N...

While much research has addressed the aboveground response of trees to climate warming and related water shortage, not much is known about the drought sensitivity of the fine root system, in particular of mature trees. This study investigates the response of topsoil (0–10 cm) fine root biomass (FRB), necromass (FRN), and fine root morphology of fiv...

Fine roots (≤2 mm) consume a large proportion of photosynthates and thus play a key role in the global carbon cycle, but our knowledge about fine root biomass, production, and turnover across environmental gradients is insufficient, especially in tropical ecosystems. Root system studies along elevation transects can produce valuable insights into r...

We studied the fine root system of Fagus sylvatica in six mature stands on different bedrock down to the rock surface (or to 2 m) to investigate whether (1) the stand total of fine root biomass (FRB) increases, while the fine root live:dead ratio decreases, with decreasing soil base richness, (2) specific root area (SRA) and root tip frequency incr...

The signaling nucleotide cyclic di-AMP (c-di-AMP) is the only known essential second messenger in bacteria. Recently, c-di-AMP has been identified as being essential for controlling potassium uptake in the model organism Bacillus subtilis and several other bacteria. A B. subtilis strain lacking c-di-AMP is not viable at high potassium concentration...

Agriculture and the exploitation of natural resources have transformed tropical mountain ecosystems across the world, and the consequences of these transformations for biodiversity and ecosystem functioning are largely unknown1–3. Conclusions that are derived from studies in non-mountainous areas are not suitable for predicting the effects of land-...

In high-elevation grasslands, plants can encounter periods with high air temperature while the soil remains cold, which may lead to a temporary mismatch in the physiological activity of leaves and roots. In a climate chamber experiment with graminoid species from three elevations (4400, 2400, and 250 m a.s.l.), we tested the hypothesis that soil te...

In forest ecosystems, ectomycorrhizal (ECM) fungi are important for plant growth and soil biogeochemical processes. The biochemical composition of ECM mycelium is an important fungal effect trait with consequences for its decomposition rate, and consequently on soil carbon pools and plant nutrition. Although the link between ECM fungi and leaf litt...

Despite a large body of studies investigating soil organic carbon (SOC) stocks and potential influencing factors, the impact of contrasting parent material, particularly in the subsoil, has received little attention. To reveal potential effects varying parent materials exert on SOC stocks, we investigated chemical (⁠14C content and overall chemical...

Climate change can impact forest ecosystem processes via individual tree and community responses. While the importance of land-use legacies in modulating these processes have been increasingly recognised, evidence of former land-use mediated climate-growth relationships remain rare. We analysed how differences in former land-use (i.e. forest contin...

Climate extremes are predicted to become more frequent and intense in future. Thus, understanding how trees respond to adverse climatic conditions is crucial for evaluating possible future changes in forest ecosystem functioning. Although much information about climate effects on the growth of temperate trees has been collected in recent decades, o...

Land-use intensification in the tropics plays an important role in meeting global demand for agricultural commodities but generates high environmental costs. Here, we synthesize the impacts of rainforest conversion to tree plantations of increasing management intensity on carbon stocks and dynamics. Rainforests in Sumatra converted to jungle rubber...

When applied to climate change-related precipitation decline, the optimal partitioning theory (OPT) predicts that plants will allocate a larger portion of carbon to root growth to enhance the capacity to access and acquire water. However, tests of OPT applied to the root system of mature trees or stands exposed to long-term drying show mixed, partl...

Saltmarsh plants are exposed to multiple stresses including tidal inundation, salinity, wave action and sediment anoxia, which require specific root system adaptations to secure sufficient resource capture and firm anchorage in a temporary toxic environment. It is well known that many saltmarsh species develop large below-ground biomass (roots and...

Organic carbon in subsoils amounts to 40–60% of the global soil carbon pool and is generally characterized by apparent turnover times of hundreds to thousands of years and an increasing spatial variability with depth. The objective of this study was to analyze the amounts and distribution of SOC and to elucidate the turnover and storage mechanisms...

Background and Aims To increase yield, cacao is planted increasingly in unshaded monocultures, replacing a more traditional cultivation under shade. We investigated how shade tree cover and species diversity affect the root system and its dynamics. Methods In a replicated study in Sulawesi (Indonesia), we studied the fine and coarse root system do...

Growth and death of fine roots represent an important carbon sink in forests. Our understanding of the patterns of fine root turnover is limited, in particular in tropical forests, despite its acknowledged importance in the global carbon cycle. We used the minirhizotron technique for studying the changes in fine root longevity and turnover along a...

The conversion of tropical rainforest to agricultural systems such as oil palm alters biodiversity across a large range of inter- acting taxa and trophic levels. Yet, it remains unclear how direct and cascading effects of land-use change simultaneously drive ecological shifts. Combining data from a multi-taxon research initiative in Sumatra, Indone...

Savanna ecosystems are increasingly pressured by climate and land-use changes, especially around populous areas such as the Mt. Kilimanjaro region. Savanna vegetation consists of grassland with isolated trees or tree groups and is therefore characterized by high spatial variation and patchiness of canopy cover and aboveground biomass. Both are majo...

Despite their importance for water uptake and transport, the xylem anatomical and hydraulic properties of tree roots have only rarely been studied in the field. We measured mean vessel diameter (D), vessel density (VD), relative vessel lumen area (lumen area per xylem area) and derived potential hydraulic conductivity (Kp) in the xylem of 197 fine-...

Potassium is the most abundant metal ion in every living cell. This ion is essential due to its requirement for the activity of the ribosome and many enzymes but also because of its role in buffering the negative charge of nucleic acids. As the external concentrations of potassium are usually low, efficient uptake and intracellular enrichment of th...

The second messenger cyclic di–adenosine monophosphate (c-di-AMP) is essential in the Gram-positive model organism Bacillus subtilis and in related pathogenic bacteria. It controls the activity of the conserved ydaO riboswitch and of several proteins involved in potassium (K+) uptake. We found that the YdaO protein was conserved among several diffe...

Low temperatures are crucial for the formation of the alpine treeline worldwide. Since soil temperature in the shade of tree canopies is lower than in open sites, it was assumed that self-shading may impair the trees’ root growth performance. While experiments with tree saplings demonstrate root growth impairment at soil temperatures below 5–7°C, f...

Background and aimsTropical alpine ecosystems are identified as the most vulnerable to global environmental change, yet despite their sensitivity they are among the least studied ecosystems in the world. Despite its important role in constraining potential changes to the carbon balance, soil nitrogen (N) turnover and plant availability in high lati...

Deforestation and land-use change are occurring on an increasing scale throughout Indonesia with profound effects on ecosystem structure and functions marked by consequences in biogeochemical cycles. This study investigates the influence of forest conversion on soil organic matter as well as the fine and coarse root system. Furthermore, the relatio...

Smallholder-dominated agricultural mosaic landscapes are highlighted as model production systems that deliver both economic and ecological goods in tropical agricultural landscapes, but trade-offs underlying current land-use dynamics are poorly known. Here, using the most comprehensive quan-tification of land-use change and associated bundles of ec...

Primer pair sequences for plants, bacteria, and archaea

Supplementary Figures 1 - 9, Supplementary Tables 1 - 5, Supplementary Note 1 and Supplementary References

Advancing our understanding of tree fine root dynamics is of high importance for tree physiology and forest biogeochemistry. In temperate broad-leaved forests, ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) tree species often are coexisting. It is not known whether EM and AM trees differ systematically in fine root dynamics and belowground re...

Rapid transformation of natural forests into other land-use systems in the lowlands of Sumatra, Indonesia, strongly reduces total aboveground biomass and affects nutrient cycling. However, the consequences of this conversion for C and N stocks of dead wood remains poorly understood particularly in natural forests and jungle rubber. This study exami...