Legacy Effects Research Articles

Improving the accuracy of nitrogen estimates from nonpoint source in a river catchment with multi-isotope tracers

Climate change can affect precipitation patterns, temperature, and the hydrological cycle, consequently influencing the dynamics of nitrogen (N) within aquatic ecosystems. In this study, multiple stable isotopes (15N-NO3/18O-NO3 and 2H-H2O/18O-H2O) were used to investigate the N sources and flowpath within the Bogang stream in South Korea. Within the vicinity of the stream with complex land use where various N sources were present, four end-members (rainfall, soil, sewage, and livestock) were sampled and examined. Consequently, spatial-temporal variations of the N sources were observed dependent on the type of land use. During the dry season, sewage accounted for the dominant N source, ranging from 62.2 % to 80.2 %. In contrast, nonpoint sources increased significantly across most sites during the wet season (10.3–41.6 % for soil; 6.3–35.2 % for livestock) compared to the dry season (7.7–28.5 % for soil; 6–13.2 % for livestock). However, sewage (78.7 %) remains dominant, representing the largest ratio at the site downstream of the wastewater treatment plant during the wet season. This ratio showed a notable difference from the calculated N loading ratio of 52.2 %, especially for livestock. This suggests that a significant potential for N legacy effects, given that groundwater flow is likely to be the primary hydrological pathway delivering N to rivers. This study will help to develop water resource management strategies by understanding how the interaction between N sources and hydrological process responds to climate change within sub-basins.

Cover crops improve soil structure and change organic carbon distribution in macroaggregate fractions

Abstract. Soil structure is sensitive to intensive soil management. It can be ameliorated by a reduction in soil cultivation and stimulation of plant and microbial mediators for aggregate formation, with the latter being a prerequisite and measure for soil quality. Cover crops (CCs) are part of an integrated approach to stabilize or improve soil quality. Thereby, the incorporation of diverse CC mixtures is hypothesized to increase the positive effects of CC applications. This study entailed an investigation of the legacy effect of CCs on soil aggregates after three crop rotations in the second main crop (winter wheat) after the last CC treatment. Four CCs (mustard, phacelia, clover, and oat) cultivated in pure stands and with a fallow treatment were compared to a mixture of the four CC species (Mix4) and a highly diverse 12-plant-species mixture (Mix12) in a long-term field experiment in Germany. The organic carbon (OC) distribution within macroaggregate fractions (16–8, 8–4, 4–2, 2–1, and <1 mm) and their aggregate stability were measured by dry- and wet-sieving methods, and the mean weight diameter (MWD) was calculated from water-stable aggregates. The results showed that, compared to the fallow, all CCs increased the MWD between 10 % and 19 % in soil under the following main crop. The average MWD increase over the fallow was slightly higher for CC mixtures (16 %) than for single CCs (12 %). Most of the OC (67.9 % on average) was stored in the <1 mm aggregate fraction, highest in the topsoil and decreasing with soil depth. The intermediate fractions (8–4 mm, 4–2 mm, 2–1 mm) stored 8.5 %, 10.5 %, and 11.0 % of the total OC, while 2.1 % was stored in the 16–8 mm fraction. Higher MWD improvement at the 20–30 cm depth also indicates additional benefits from a reduction in the cultivation depth. Structural equation modelling (SEM) suggests that single CCs were more likely to increase OC storage in small macroaggregates <1 mm, while CC mixtures were more likely to increase OC in the largest fraction (8–16 mm). Different individual CC species or mixtures exhibited varying involvement in the formation of different aggregate fractions. We provide evidence that litter quality, root morphology, and rhizosphere input, which affect microbial mediators of aggregate formation, might be the main reasons for the observed differences between CC treatments. Cover crops are valuable multifunctional tools for sustainable soil management. Here, we showed that they contribute to structure amelioration in arable soils. Increasing the functional diversity of plant species in CC mixtures could be a strategy to further enhance the positive effects of CCs in agroecosystems.

Detecting the Olympic tourism legacy: a data-driven approach

ABSTRACT This research applies a data-driven approach for identifying changes in time series to model the Olympic tourism legacy. Measuring potential legacy effects from mega-sporting events has been problematic in prior research. Issues revolve around how to measure tourism, how to control for pre-existing trends, and how to account for extraneous events affecting tourism unrelated to the Olympics. Most problematic for analytical models is determining when the tourism legacy begins and what is the functional form of the tourism legacy. Many of these issues interact and can confound results leading to erroneous conclusions. The seminal methodology developed by Tsay [(1988). Outliers, level shifts, and variance changes in time series. Journal of Forecasting, 7(1), 1–20] requires no prior assumption about the timing or functional forms of the outliers, therefore solving these issues and provides a framework that can be used when analysing mega-sporting event legacies. Using this methodology, the research finds limited support for a short-term Olympic tourism legacy and no support for a long-term tourism legacy.

Effects of climate trends and variability on tree health responses in the Black Sea and Mediterranean forests of Türkiye

To adapt forest ecosystems and forest management to climate change, it is essential to know which forest regions and which tree species are resilient to climate variability and which ones are possibly affected most by past and anticipated future changes. In this contribution, for the main forest regions of Türkiye and six tree species, recent climate variability and trends were quantified and statistically correlated to record tree defoliation and vitality. Climate variables considered are maximum temperature (Tmax), minimum temperature (Tmin), mean temperature (Tmean), and total precipitation (Prcp), which are compared to forest health responses recorded as part of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) on 277 plots across forests along the Black Sea and Mediterranean regions. In addition, long-term data on satellite measurements of the normalized difference vegetation index (NDVI) were extracted for the same 277 plots for the period 2008–2020. Firstly, 30 years (1991–2020) of reanalysis of climate variables from ECMWF were extracted for all plots; secondly, individual correlations and cross-correlations of climate variables and tree health and vitality were computed for the period 2008–2020 (significance level of 95%) for the four most dominant species from the Black Sea forests (F. orientalis, Q. cerris, P. sylvestris, P. orientalis) and two species from Mediterranean forests (P. brutia and C. libani). Temperature showed a stronger effect on most species than precipitation. Finally, time-lagged correlations were analyzed for seven-time lags (significance level of 95%) to evaluate legacy effect. The analysis revealed that different tree species from the two regions show different responses to climate variables. Species in the Mediterranean region are more resistant to droughts and climatic variations. Legacy effects of defoliation and NDVI have lasted for at least 2 years.

The role of rewilding in mitigating hydrological extremes: State of the evidence

AbstractLandscape rewilding has the potential to help mitigate hydrological extremes by allowing natural processes to function. Our systematic review assessed the evidence base for rewilding‐driven mitigation of high and low flows. The review uncovers a lack of research directly addressing rewilding, but highlights research in analogue contexts which can, with caution, indicate the nature of change. There is a lack of before‐after studies that enable deeper examination of temporal trajectories and legacy effects, and a lack of research on the scrub and shrubland habitats common in rewilding projects. Over twice as much evidence is available for high flows compared to low flows, and fewer than one third of studies address high and low flows simultaneously, limiting our understanding of co‐benefits and contrasting effects. Flow magnitude variables are better represented within the literature than flow timing variables, and there is greater emphasis on modeling for high flows, and on direct measurement for low flows. Most high flow studies report a mitigating effect, but with variability in the magnitude of effect, and some exceptions. The nature of change for low flows is more complex and suggests a higher potential for increased low flow risks associated with certain trajectories but is based on a very narrow evidence base. We recommend that future research aims to: capture effects on both high and low flow extremes for a given type of change; analyze both magnitude and timing characteristics of flow extremes; and examine temporal trajectories (before and after data) ideally using a full before‐after‐control‐impact design.This article is categorized under: Human Water > Value of Water Science of Water > Hydrological Processes Science of Water > Water Extremes Water and Life > Conservation, Management, and Awareness

Environmental change legacies attenuate disturbance response of desert soil microbiome and multifunctionality

Abstract Deserts are predicted to be one of the ecosystems most vulnerable to global climate change, with dramatic fluctuations of temperature and water, even over the span of a single day. These previous disturbances could influence the response of the soil microbiome and its functions to subsequent disturbances, which is known as legacy effect. However, how legacy effects shape the response of soil microbiome and its functions to environmental fluctuations (e.g. temperature and water availability) in desert ecosystems remains to be investigated. Here, we firstly exposed desert soils to drought, freezing or their combination, and then followed by a second disturbance, resulting in a temporally full factorial treatment. We found that environmental change legacies affected the response of soil multifunctionality, microbial abundance and richness to second drought and freezing, except for eukaryotic richness. Initial disturbances caused legacy effects on microbial composition and weakened their responses to later disturbances, and these effects were stronger for prokaryotes than eukaryotes. The attenuated response to later disturbances is largely due to that almost half of the taxa affected by the earlier disturbances were also affected by the second disturbances. The phylogenetic depth of these responses varied minimally among the types of disturbances but were more conserved for negative responses, indicating a result of historical adaptation. Moreover, the altered community composition was associated with functional changes in the disturbed soils. These findings will improve our understanding of the mechanisms underlying the legacy impacts of multiple environmental disturbances on desert microbial communities and strengthen our ability to develop management strategies for protection prior to disturbance events. Read the free Plain Language Summary for this article on the Journal blog.

Short‐ and long‐term legacies of carbon sequestration, and nutrient burial in floodplain wetlands of agricultural and forested catchments, Indiana, United States

AbstractSoil organic carbon (C) sequestration and nitrogen (N) and phosphorus (P) burial were measured in two floodplain wetlands' soils of the West Fork of the White River watershed (Indiana, United States) whose catchments differed in land use to better understand how land use practices affect wetland C and nutrient retention. The catchment of one floodplain, Upper West Fork, is dominated by row crop agriculture (61%) whereas the second catchment, Beanblossom Creek, is mostly forested (85%). Soils (0–30 cm) of the two floodplain wetlands had similar bulk density (1.23 g/cm3). Soil organic C and N were low in both floodplains but the percent organic C and N was two times greater (3.3% C, 0.22% N) in the agricultural floodplain than in the floodplain in the forested catchment (1.5% C, 0.14% N). Soil P was three times greater in the agricultural (1100 μg/g) than in the forested floodplain (350 μg/g). Recent soil accretion based on 137Cs which provides a historical record since 1964 (60 years), was two times greater in the agricultural floodplain (2.2 mm/year) than in the forested catchment (1.0 mm/year). Sediment deposition (2500 g/m2/year), C sequestration (90 g/m2/year), and N burial (7.5 g/m2/year) were three times greater in the agricultural floodplain and P burial was seven times greater (3.0 vs. 0.41 g/m2/year). Long‐term measurements (100 years) based on 210Pb did not show large differences in C sequestration and N burial between the two floodplains though soil accretion and sediment deposition were greater in the forested floodplain. We attribute these higher rates to greater erosion in the watershed before 1950 when the catchment had more agricultural land and before instruction on best management practices to reduce soil erosion. These findings confirm previously published studies that show that P enrichment and accumulation in floodplain soils represent legacy effects of agricultural land use in the catchment.

Persistent greening against drying in northeast Asian semiarid grasslands: Asymmetrical responses of direct and legacy effects to intensified drought

Despite experiencing a decadal shift towards drought conditions at the end of the 20th century, semiarid grasslands in northeast Asia (NEA) exhibited an evident greening trend from 1982 to 2020. However, the mechanism behind this phenomenon remains unclear. Hence, we analysed the interdecadal changes in vegetation response to drought on the basis of the standardised precipitation evapotranspiration index (SPEI) and Global Inventory Modelling and Mapping Studies LAI4g datasets, with an emphasis on the differences between direct and legacy effects (as measured by resilience), to explore the mechanism of persistent grassland greening. Results revealed that during the post-drought shift period (2000–2020), the sudden decrease in the water content of the intermediate soil layer triggered an intensified vegetation response to drought. Specifically, although direct effects and resilience were amplified, they exhibited asymmetric changes. Resilience was stronger than direct effects, and this difference increased with increasing drought (drought recovery) levels. These combined effects may account for persistent greening against intensified drying in the semiarid grasslands in NEA. Given the projected exacerbation of future droughts, this study holds notable importance for comprehending the long-term change dynamics of dryland ecosystems.

Large contribution of soil N2O emission to the global warming potential of a large-scale oil palm plantation despite changing from conventional to reduced management practices

Abstract. Conventional management of oil palm plantations, involving high fertilization rate and herbicide application, results in high yield but with large soil greenhouse gas (GHG) emissions. This study aimed to assess a practical alternative to conventional management, namely reduced fertilization with mechanical weeding, to decrease soil GHG emissions without sacrificing production. We established a full factorial experiment with two fertilization rates (conventional and reduced fertilization, equal to nutrients exported via fruit harvest) and two weeding methods (herbicide and mechanical), each with four replicate plots, since 2016 in a ≥ 15-year-old, large-scale oil palm plantation in Indonesia. Soil CO2, N2O, and CH4 fluxes were measured during 2019–2020, and yield was measured during 2017–2020. Fresh fruit yield (30 ± 1 Mgha-1yr-1) and soil GHG fluxes did not differ among treatments (P≥ 0.11), implying legacy effects of over a decade of conventional management prior to the start of the experiment. Annual soil GHG fluxes were 5.5 ± 0.2 Mg CO2-C ha−1 yr−1, 3.6 ± 0.7 kg N2O-N ha−1 yr−1, and −1.5 ± 0.1 kg CH4-C ha−1 yr−1 across treatments. The palm circle, where fertilizers are commonly applied, covered 18 % of the plantation area but accounted for 79 % of soil N2O emission. The net primary production of this oil palm plantation was 17 150 ± 260 kgCha-1yr-1, but 62 % of this was removed by fruit harvest. The global warming potential of this planation was 3010 ± 750 kgCO2eqha-1yr-1, of which 55 % was contributed by soil N2O emission and only < 2 % offset by the soil CH4 sink.

Seismically induced hillslope disturbance, sediment connectivity and mass wasting: Insights from the 2008 Wenchuan earthquake

A mega-earthquake in a mountainous region can trigger thousands of landslides. Subsequently, these loose co-seismic materials will experience the erosion-transport-sediment process. This process is closely associated with a series of cascading hazards, such as landslides, debris flows and floods. The disturbance and legacy effects of earthquakes have become the focus of attention for post-earthquake reconstruction and disaster mitigation. By combining the modeling of seismic-induced landslide magnitude with an analysis of the coseismic material sediment connectivity and transfer processes, we assessed the impacts of the 2008 Wenchuan earthquake on the mass balance and subsequent geohazard activities. The 2008 Wenchuan earthquake produced 22,785 Mt of deposit storage, 37.9 % of which (∼8636 Mt) is connected to the channels and prone to erosion and transfer by hydrodynamic forces, and the remaining 62.1 % (∼14,149 Mt) was deposited on hillslopes far from the channel network and contributed little to the sediment dynamics. Long-term field observations found a causal relationship between decreasing surface erosion rate and gradual healing of co-seismic deposits due to coarsening by progressive removal of fine grains. We evaluated the residence time of fine-grained (<0.25 mm) landslide materials using the post-earthquake sediment evacuation rate and identified three stages regarding the enhanced erosion and surface mass wasting after the 2008 Wenchuan earthquake, namely, the high activity period (within 40.6 ± 5.4 years), the low activity period (40.6 ± 5.4–107.1 ± 14.2 years), and the steady period (after 107.1 ± 14.2 years). This has important implications for the hazard assessment of landslides and debris flows in understanding and modeling the post-seismic geohazard evolution over multiple timescales.

Legacy effects of crop sequencing on biomass and their variability on farmers' fields in Finland are shaped by weather, farm conditions and rationales for land use

CONTEXTThe legacy effect of a previous crop on a subsequent crop in rotation is a valuable and often underutilized ecosystem service which can provide benefits when designing cropping systems, especially in the case of cereal-based land use. OBJECTIVETo support future diversification of crop sequencing in Finland, this study was carried out with the aims to identify the variation in the pre-crop values of relevant crop combinations in farmers' fields in Finland, depending on the weather and farm conditions. METHODSWe used a method developed to estimate on-farm realized pre-crop value from Sentinel − 2 images available annually for 120,174–711,828 field parcels in Finland during 2016–2020 (the total number of observations was >1,818,000). RESULTS AND CONCLUSIONSBoth the weather and farming conditions explained the variation in the pre-crop values, which might range from positive to negative. For example, a higher mean temperature and fewer rainy days during the growing season of a previous crop often reduced the legacy effects of crop sequencing, however, this was dependent on the crop choices. A higher number of rainy days and elevated temperatures during the subsequent crop's season often increased the pre-crop value, while prolonged droughts in either of the growing seasons tended to reduce these. The farmers' current land use did not support the realization of pre-crop value – especially in the case of potential benefits provided by grasslands for croplands. SIGNIFICANCEThis study highlights the challenges that weather variation and complexity of the production systems may cause for a farmer when aiming to identify the impacts of crop sequencing on yields, ecosystem services, and farm economy. Hence, there is an evident need to develop a decision support system that recognizes regional farming systems, available crop choices, crop management, weather conditions, and the farmers' rationale concerning decision making.

Legacy effects of preceding crops improve flue-cured tobacco productivity in southwest China by optimizing soil structure, nutrients, and microbial interactions

Legacy effects of preceding crops improve flue-cured tobacco productivity in southwest China by optimizing soil structure, nutrients, and microbial interactions

Forest management and former land use have no effect on soil fungal diversity in uneven-aged mountain high forests

Key messageMetabarcoding analysis of soil fungal communities in French mountain forests revealed that harvesting intensity, time since last harvest and former land use had no effect on fungal community composition compared to key abiotic factors. Low-intensity management in these uneven-aged mountain forests therefore has limited effects on soil fungal community composition which is mainly driven by elevation and edaphic properties.ContextPast and current human activities are known to affect forest biodiversity. However, the effects of former land use and forest management have been studied much more extensively on higher plants than on fungi.AimsOur objectives were to assess the effects of harvesting intensity, duration since last harvest and former land use on soil fungal communities in uneven-aged mountain high forests.MethodsOn the basis of historical land-use maps drawn between 1862 and 1864 and on historical forest management archives, we selected 62 sites in the French Alps with contrasting land-use histories (ancient forests, which were already forested on historical maps vs recent forests, which have recovered following abandonment of pastures) and different durations since last harvest (from 1 to over 50 years). We carried out soil sampling and assessed fungal diversity by metabarcoding analysis. We analysed soil fungal molecular operational taxonomic units (MOTU) diversity as a whole and for the main lifestyle groups (such as wood saprotrophic or ectomycorrhizal fungi) using multiple linear regressions on Shannon’s diversity index and fungal taxonomic composition using canonical correlation analysis.ResultsWe found no significant effect of harvesting intensity, time since last harvest or land-use history on total fungal MOTU diversity, fungal lifestyle diversity or taxonomic composition. In contrast, we observed significant effects of elevation, pH, organic carbon and available phosphorus content on the taxonomic and functional composition of soil fungal communities.ConclusionsThe structure of soil fungal communities (i.e. diversity and species composition) was mainly determined by elevation and edaphic factors, indicating a high-context dependency, as previously found in similar studies. Our study in mountain forests shows that recent forests established on former pastures had no legacy effect on soil conditions and fungal communities, in contrast to previous results in lowland areas, where recent forests were mainly established on former cropland. Uneven-aged forest management had no effect on fungal diversity, in contrast to previous results observed in even-aged high forests.

Invasions eliminate the legacy effects of substrate history on microbial nitrogen cycling

AbstractChanges in substrate quality driven by climate, land use, or other forms of global change may represent a strong selective force on microbial communities. Invasion of new taxa into a community through dispersal, evolution, or recolonization could impact the outcome of this environmental selection. Here, we simulated substrate change with a trait‐based model of microbial litter decomposition (DEMENTpy) to assess the legacy effects of past substrate quality and the impact of selection by a new substrate on community decomposition activity. Simulations were run with different levels of invasion, including invasion from communities long‐adapted to the new substrate. Legacy effects were evident with substrate change for native communities differing in composition. Protein was the only substrate that exerted a strong enough selective force to affect community composition. Legacy effects disappeared when invaders came from substrates similar to the new substrate. Together, our simulations demonstrate that substrate quality changes associated with global change can lead to legacy effects on substrate degradation. In decomposing plant litter, such legacy effects can occur if substrate inputs shift to higher protein content and if invasion is low.

Can the impacts of invasive African Olive on native Cumberland Plain Woodland plants be mitigated through bioinoculation?

SummaryInvasive plants often impact the abiotic and biotic conditions of the ecosystems they invade. These impacts can persist after the removal of the invader as legacy effects that may hamper restoration. We assessed whether the invasion of Cumberland Plain Woodland in Australia by African Olive impacts the performance of native species through legacy effects. We also tested whether the addition of soil inocula from uninvaded Cumberland Plain Woodland and rhizosphere soils can mitigate the effects of invaded soils on native plant performance. To do this, we grew four native Cumberland Plain Woodland species (Australian Indigo, Climbing Saltbush, Hickory Wattle, Wedge‐leaf Hop‐bush) in mesocosms containing either uninvaded Cumberland Plain Woodland soil, African Olive‐invaded Cumberland Plain Woodland soil or invaded Cumberland Plain Woodland soil inoculated with uninvaded or native rhizosphere soil. We found invaded soils to not consistently impact the growth of the Cumberland Plain Woodland species studied. In invaded soil, Hickory Wattle produced lower above and belowground biomass, Climbing Saltbush produced lower belowground biomass and Australian Indigo had a lower root to shoot ratio compared to plants grown in Cumberland Plain Woodland soil. The nodulation of Australian Indigo did not differ between soil treatments, while that of Hickory Wattle responded positively to inoculation. Our results suggest that the addition of native soil biota may improve the outcomes of ecological restoration projects on a species‐specific basis.

The legacy effect and urban management planning driving changes in Urban Green Spaces land use in Haikou city, Hainan province: a comprehensive analysis

The legacy effect and urban management planning driving changes in Urban Green Spaces land use in Haikou city, Hainan province: a comprehensive analysis

Impacts of sequential salinity and heat stress are recovery time-specific in freshwater crustacean, Daphnia pulicaria

Stressors can interact to affect animal fitness, but we have limited knowledge about how temporal variation in stressors may impact their combined effect. This limits our ability to predict the outcomes of pollutants and future dynamic environmental changes. Elevated salinity in freshwater ecosystems has been observed worldwide. Meanwhile, heatwaves have become more frequent and intensified as an outcome of climate change. These two stressors can jointly affect organisms; however, their interaction has rarely been explored in the context of freshwater ecosystems. We conducted lab experiments using Daphnia pulicaria, a key species in lakes, to investigate how elevated salinity and heatwave conditions collectively affect freshwater organisms. We also monitored the impacts of various recovery times between the two stressors. Daphnia physiological conditions (metabolic rate, Na+-K+-ATPase (NKA) activity, and lipid peroxidation level) and life history traits (survival, fecundity, and growth) in response to salt stress as well as mortality in heat treatment were examined. We found that Daphnia responded to elevated salinity by upregulating NKA activity and increasing metabolic rate, causing a high lipid peroxidation level. Survival, fecundity, and growth were all negatively affected by this stressor. These impacts on physiological conditions and life history traits persisted for a few days after the end of the exposure. Heat treatments caused mortality in Daphnia, which increased with rising temperature. Results also showed that individuals that experienced salt exposure were more susceptible to subsequent heat stress, but this effect decreased with increasing recovery time between stressors. Findings from this work suggest that the legacy effects from a previous stressor can reduce individual resistance to a subsequent stressor, adding great difficulties to the prediction of outcomes of multiple stressors. Our work also demonstrates that cross-tolerance/susceptibility and the associated mechanisms remain unclear, necessitating further investigation.

Effects of sediment disturbance by the heart urchin &lt;i&gt;Echinocardium cordatum&lt;/i&gt; on the sediment–seawater solute exchange: An exclusion experiment

&lt;p&gt;Spatangoid heart urchins are dominant bioturbators in marine soft-sediment ecosystems worldwide. Their repeated sediment reworking prevents biogeochemical sediment stratification and colonization by other species, with implications for sedimentary reaction processes that affect the local sediment–seawater solute exchange. Here, we used a simple exclusion experiment to investigate how a subtidal &lt;italic&gt;Echinocardium cordatum&lt;/italic&gt; population (18.2 ± 6.7 individuals m&lt;sup&gt;−2&lt;/sup&gt;), foraging at an individual speed of ~45 cm per day affects the sediment–seawater solute exchange. To do so, we removed all heart urchins from eight one-meter-diameter areas of the 10-m deep seafloor of Man O'War Bay, Hauraki Gulf, New Zealand, and prevented recolonization and thus sediment reworking for 56 days. Subsequently, we measured the sediment–seawater exchange of O&lt;sub&gt;2&lt;/sub&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;–&lt;/sup&gt;, NO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;–&lt;/sup&gt;, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, and N&lt;sub&gt;2&lt;/sub&gt; both within and outside the exclusion areas, under light or dark conditions, and found no difference. The absence of a legacy effect of foraging &lt;italic&gt;E. cordatum&lt;/italic&gt; after their removal suggests that, at least in this habitat, their influence on the sediment–seawater solute exchange may be limited to sediment being displaced in the immediate surrounding of the urchin. This unexpected result underlines the importance of evaluating the influence of bioturbators on the sediment–seawater solute exchange in the context of local environmental conditions, animal behavior, and population characteristics.&lt;/p&gt;

Resilience and response: Unveiling the impacts of extreme droughts on forests through integrated dendrochronological and remote sensing analyses

Extreme droughts are anticipated to have detrimental impacts on forest ecosystems, especially in water-limited regions, due to the influence of climate change. However, considerable uncertainty remains regarding the patterns in species-specific responses to extreme droughts. Here, we conducted a study integrating dendrochronology and remote sensing methods to investigate the mosaic-distributed maple-oak (native) natural forests and poplar plantations (introduced) in the Horqin Sandy Land, Northeast China. We assessed the impacts of extreme droughts on tree performances by measuring interannual variations in radial growth and vegetation index. The results showed that precipitation and self-calibrated palmer drought severity index (scPDSI) are the major factors influencing tree-ring width index (RWI) and normalized difference vegetation index (NDVI). The severe droughts between 2000 and 2004 resulted in reduced RWI in the three studied tree species as well as led to NDVI reductions in both the maple-oak natural forests and the poplar plantations. The RWI reached the nadir during the 2000–2004 severe droughts and remained at low levels two years after the severe drought, creating a legacy effect. In contrast to the lack of significant correlation between RWI and scPDSI, NDVI exhibited a significant positive correlation with scPDSI indicating the greater sensitivity of canopy performance to droughts than radial growth. Furthermore, interspecific differences in RWI and NDVI responses were observed, with the fast-growing poplar species experiencing a more significant RWI decrease and more negative NDVI anomaly during severe droughts than native species, highlighting the species-specific trade-offs between drought resilience and growth rate. This study emphasizes the importance of combining tree-level radial growth with landscape-scale canopy remote sensing to understand forest resilience and response. Our study improves our understanding of forest responses to extreme drought and highlights species differences in climate responses, offering crucial insights for optimizing species selection in sustainable afforestation and forest management in water-limited regions under the influence of climate change.

Special feature on ecosystem engineers: Cross‐scale and cross‐system perspectives

Abstract Ecosystem engineers are those organisms that shape our ecosystems (directly and/or indirectly) by modulating the resource availability to other species. This definition has broadened our views of the different roles species play in their environments through a greater appreciation of organism‐mediated abiotic changes. However, the term is still under debate due to misunderstandings in its interpretation and application. One of the reasons for the source of ambiguity is the difficulty of imagining an organism that does not affect its surrounding environment in a particular way. Despite the controversy over the semantics, the concept has quickly gained acceptance as an important ecological driver of ecosystem functioning across different disciplines, most notably by expanding the original definition to include interactions among several species with ecosystem engineering capabilities. The papers compiled in this special feature outline the new path for addressing not only how to measure/monitor these complex species interactions, including those with alien ecosystem engineers, but also to integrate their impactful legacy effects in enhancing ecosystem processes. This knowledge will lead the way to integrate ecosystem engineers into future protection, management and restoration efforts. Read the free Plain Language Summary for this article on the Journal blog.