Ecosystems最新文献

Ecosystems are interconnected, and ecological processes frequently transcend the physical boundaries that define them. Fluxes of energy, matter, and organisms not only form important ecosystem processes within but also between ecosystems. However, the role of biological drivers in simultaneously supporting multiple ecosystem processes at the interface between aquatic and terrestrial ecosystems (that is, aquatic-terrestrial ecosystem processes) remains poorly understood, both locally and across regions. To assess the relative importance of riparian forests, detritus consumers and leaf litter mixing on different ecosystem processes of freshwater detrital food webs, we used leaf litter bags to subsidise local terrestrial leaf litter to forested and non-forested headwater stream sites in a temperate and tropical region. We also manipulated macroinvertebrate access and the composition of leaf litter mixtures. We measured three key aquatic-terrestrial ecosystem processes: biomass accrual of aquatic fungi, nitrogen loss, and decomposition rates of local leaf litter. Across both temperate and tropical streams, ecosystem multifunctionality, that is, the simultaneous sustaining of these processes, was positively associated with macroinvertebrates and riparian forests but not with leaf litter mixing. Especially leaf litter nitrogen loss and decomposition rates were consistently higher when macroinvertebrates had access across all leaf litter species. Decomposition rates were also positively associated with the other ecosystem processes. These findings highlight consistent, cross-regional effects of riparian forests and macroinvertebrate detritivores on freshwater detrital food webs. In a rapidly changing world, understanding ecosystem processes in headwater streams demands a holistic view that transcends ecosystem borders and incorporates cross-ecosystem interactions.

Supplementary information: The online version contains supplementary material available at 10.1007/s10021-025-01024-0.

The coniferous forests of the Western Cordillera are particularly affected by recent increases in wildfire extent and severity. After fire, conifer establishment and growth rates are influenced by a wide range of ecological drivers. Understanding the relative influence of ecological drivers on conifer recovery is crucial when modeling landscape dynamics. Past research has examined a wide variety of ecological drivers; however, syntheses of these drivers are rare. This systematic review focuses on forest recovery pathways, which have distinct variability in spatial and temporal measures of conifer establishment and growth. From studies examined, we extracted whether the study identified a recovery pathway and whether field or satellite spectral methods were used. Spectral methods were the most common method to determine the 84 extracted pathways. Among pathways identified, conifer self-replacement was the most common, but the second most common was state change, wherein the forest transitions in landcover type. We also investigated how recovery varied relative to different ecological drivers. Among the > 1000 drivers considered, pre-fire composition and post-fire moisture had consistent positive associations with all recovery metrics, while the association with other drivers varied by metric (stem density versus composition) and/or method (field versus spectral). Our review outlines key gaps for future research, including (1) the accuracy of spectral monitoring to capture structural growth trends, such as stem densities over time, and (2) how the effects of ecological drivers vary across scales, such as post-fire shrub cover at local versus landscape levels. Overall, fusing spectral and field data across spatiotemporal scales improves our understanding of post-wildfire recovery and dynamics, as well as our ability to anticipate the impacts of changing climate and wildfire conditions on recovering forests.

Supplementary information: The online version contains supplementary material available at 10.1007/s10021-025-01029-9.

Small coastal watersheds (< 10,000 km²) can play a large role in forming biogeochemical linkages between land and sea, yet the spatial heterogeneity of small watershed ecosystems is poorly understood due to sparse observations in many regions. In this study, we examined the spatial heterogeneity of water quality exported from diverse watersheds in two rainforest fjordland complexes. Samples were collected about monthly for a year from the outlets of 56 watersheds spanning from high mountains to low islands. Many (20) water quality properties varied significantly across six previously established watershed types defined by 12 easily computed geospatial variables. For example, organic matter concentrations ranged from very low in a Glacierized Mountains watershed type (1.2 ± 0.1 mg L^-1 DOC; 28.5 ± 4.6 µg L^-1 DON) to very high (15.1 ± 1.0 mg L^-1 DOC; 215.6 ± 20.4 µg L^-1 DON) in a Rain Lowlands type. Along this gradient, the dominant form of dissolved nitrogen switched from inorganic to organic and the dominant form of phosphorous switched from particulate to dissolved. Watershed type alone explained 67% of the variance in the first principal component of water quality (PC1) representing 20 water properties. Although underlying causes were likely complex, a great deal of spatial variation in water quality (for example, 91% of PC1) was predicted by simple measures of topography and climate (for example, elevation and mean annual precipitation). The physiographic structure of the coastal land mass appears to enable a complex mosaic of watershed ecosystems, which may affect meta-ecosystem function at the coastal margin.

Supplementary information: The online version contains supplementary material available at 10.1007/s10021-025-00964-x.

As wildfire regimes shift, resource managers are concerned about potential threats to aquatic ecosystems and the species they support, especially fishes. However, predicting fish responses can be challenging because wildfires affect aquatic ecosystems via multiple pathways. Application of whole-ecosystem approaches, such as food web modeling, can act as heuristic tools that offer valuable insights that account for these different mechanisms. We applied a dynamic food web simulation model that mechanistically linked stream trophic dynamics to the myriad effects that wildfires can have on aquatic and riparian ecosystems at a local stream reach-scale. We simulated how wildfires of different severity may influence short- (months to years) and long-term (years to decades) periphyton, aquatic invertebrate, and fish biomass dynamics in forested headwater streams of the western Pacific Northwest (USA). In many cases, wildfire increased modeled periphyton, invertebrate, and fish biomass over both short- and long-time periods. However, modeled responses varied extensively in their direction (that is, positive or negative), magnitude, and duration depending on fire severity, time since fire, and trophic level. The shapes of these response trajectories were especially sensitive to predicted wildfire effects on water temperature, canopy cover, riparian shading, and instream turbidity. Model simulations suggest a single fire could result in a wide range of aquatic ecosystem responses, especially in watersheds with mixed burn severity. Our analysis highlights the utility of whole-ecosystem approaches, like food web modeling, as heuristic tools for improving our understanding of the mechanisms linking fire, food webs, and fish and for identifying contexts where fires could have deleterious impacts on fishes.

Supplementary information: The online version contains supplementary material available at 10.1007/s10021-024-00955-4.

Anoxia in lakes has intensified in recent decades, threatening ecosystem functioning. Yet, the mechanisms driving long-term trends in anoxia intensity and duration are complex, especially in managed ecosystems, where field data are limited. Using a 50-year dataset from a lake affected by both eutrophication and restoration measures, we examined annual oxygen dynamics, assessing the effect of external drivers, such as climate warming and hypolimnetic withdrawal effectiveness, and of in-lake processes influencing anoxia. Breakpoint analysis revealed a major ecosystem regime shift around 1996, reversing the earlier recovery trend. Between 1972 and 1996, both the anoxic factor and hypolimnetic total phosphorus concentrations declined, but both rose significantly afterward, with phosphorus concentrations eventually exceeding pre-restoration levels, despite declining watershed inputs. This reversal coincided with a marked increase in thermal stratification duration, which likely intensified deoxygenation by limiting oxygen renewal in the hypolimnion. Our results also show that higher anoxia levels in 1 year significantly reinforced anoxia in the following year, suggesting a self-sustaining feedback mechanism. In addition, our results provide evidence that anaerobic mineralization is important to this feedback, accumulating reduced compounds that further enhance deoxygenation. Despite management efforts, the intensification of internal phosphorus loading and the accumulation of reduced substances have progressively diminished the effectiveness of the cost-effective hypolimnetic withdrawal system implemented since 1970. Our findings demonstrate how the emergence of reinforcing feedbacks, linking oxygen depletion, internal phosphorus release, and climate-driven stratification, can undermine traditional restoration strategies. This highlights the urgent need for adaptive management that explicitly addresses these interacting mechanisms among oxygen dynamics, nutrient cycling, and climate warming.

Supplementary information: The online version contains supplementary material available at 10.1007/s10021-025-01003-5.

Fire is the major forest disturbance in Siberian larch (Larix spp.) ecosystems, which occupy 20% of the boreal forest biome and are underlain by large, temperature-protected stocks of soil carbon. Fire is necessary for the persistence of larch forests, but fire can also alter forest stand composition and structure, with important implications for permafrost and carbon and albedo climate feedbacks. Long-term records show that burned area has increased in Siberian larch forests over the past several decades, and extreme climate conditions in recent years have led to record burned areas. Such increases in burn area have the potential to restructure larch ecosystems, yet the fire regime in this remote region is not well understood. Here, we investigated how landscape position, geographic climate variation, and interannual climate variability from 2001 to 2020 affected total burn area, the number of fires, and fire size in Siberian larch forests. The number of fires was positively correlated with metrics of drought (for example, vapor pressure deficit), while fire size was negatively correlated with precipitation in the previous year. Spatial variation in fire size was primarily controlled by landscape position, with larger fires occurring in relatively flat, low-elevation areas with high levels of soil organic carbon. Given that climate change is increasing both vapor pressure deficit and precipitation across the region, our results suggest that future climate change could result in more but smaller fires. Additionally, increasing variability in precipitation could lead to unprecedented extremes in fire size, with future burned area dependent on the magnitude and timing of concurrent increases in temperature and precipitation.

Andean highland soils contain significant quantities of soil organic carbon (SOC); however, more efforts still need to be made to understand the processes behind the accumulation and persistence of SOC and its fractions. This study modeled SOC variables—SOC, refractory SOC (RSOC), and the ¹³C isotope composition of SOC (δ¹³C_SOC)—using machine learning (ML) algorithms in the Central Andean Highlands of Peru, where grasslands and wetlands (“bofedales”) dominate the landscape surrounded by Junin National Reserve. A total of 198 soil samples (0.3 m depth) were collected to assess SOC variables. Four ML algorithms—random forest (RF), support vector machine (SVM), artificial neural networks (ANNs), and eXtreme gradient boosting (XGB)—were used to model SOC variables using remote sensing data, land-use and land-cover (LULC, nine categories), climate topography, and sampled physical–chemical soil variables. RF was the best algorithm for SOC and δ¹³C_SOC prediction, whereas ANN was the best to model RSOC. “Bofedales” showed 2–3 times greater SOC (11.2 ± 1.60%) and RSOC (1.10 ± 0.23%) and more depleted δ¹³C_SOC (− 27.0 ± 0.44 ‰) than other LULC, which reflects high C persistent, turnover rates, and plant productivity. This highlights the importance of “bofedales” as SOC reservoirs. LULC and vegetation indices close to the near-infrared bands were the most critical environmental predictors to model C variables SOC and δ¹³C_SOC. In contrast, climatic indices were more important environmental predictors for RSOC. This study’s outcomes suggest the potential of ML methods, with a particular emphasis on RF, for mapping SOC and its fractions in the Andean highlands.

The importance of woody detritus as a source of soil organic matter is not well constrained. We quantified the recovery of ¹³C derived from isotopic-enriched sugar maple wood in various C fractions of two temperate forest soils in central New York, USA. Decay rates of small woody debris were quite rapid (k = 0.362 to 0.477 per year) and after 10 years less than 1% of the original wood mass remained in incubation bags. After six years we recovered only 0.26% (± 0.025) of the added ¹³C in the upper 5 cm of underlying soil. After 10 years this recovery declined to 0.11% (± 0.020) indicating substantial lability of retained SOC; most of this decline occurred from year 6 to 8 in the 1–5 cm depth increment, suggesting that the residue was quite stable at 10 years. The largest fraction of ¹³C was recovered in microaggregates (45%), especially those occluded within macroaggregates (30%), with a smaller proportion associated with the silt + clay fraction (20%). These proportions did not change significantly from year 6 to 10. Faster decay and higher ¹³C recovery were coincident with abundant saproxylic invertebrates from Scarabaeidae at one of the sites. We conclude that small woody debris is a minor source of stable SOC in these temperate forests (that is, less than 1% of annual SOC accumulation).

Ecosystem services (ES) in Mediterranean regions are critically affected by forest fires, which pose significant threats to human reliance on these services. This study delves into the post-fire dynamics of ES, emphasising the distinct recovery processes in seeders dominated and resprouters dominated systems. By integrating an ecosystem service capacity matrix with transition matrices, we analysed the temporal recovery patterns of ES after fire disturbances under conditions corresponding to southern France Mediterranean-Type Ecosystems. In seeders dominated environments, recovery is gradual, with services like carbon sequestration and soil quality taking up to 87 years to regain 90% of their capacity post-high-intensity fires. Conversely, resprouters dominated systems show rapid regrowth, with carbon sequestration recovering in as little as 23 years following similar disturbances. Our findings highlight the variable recovery timelines across different ES. Pollination and wild plants display remarkable resilience, with recovery times not exceeding 2 years regardless of fire severity. However, provisioning services such as game provision exhibit lower resilience, requiring up to 67 years for recovery. Cultural services, reflecting emblematic and symbolic values, demonstrate greater resilience, with recovery spanning 3 to 51 years. This study underscores the importance of understanding vegetation types and succession patterns in predicting ES recovery post-fire, offering insights into ecosystem recovery and resilience in fire-prone Mediterranean landscapes.

Soil respiration is the largest single efflux in the global carbon cycle and varies in complex ways with climate, vegetation, and soils. The suppressive effect of nitrogen (N) addition on soil respiration is well documented, but the extent to which it may be moderated by stand age or the availability of soil phosphorus (P) is not well understood. We quantified the response of soil respiration to manipulation of soil N and P availability in a full-factorial N x P fertilization experiment spanning 10 years in 13 northern hardwood forests in the White Mountains of New Hampshire, USA. We analyzed data for 2011 alone, to account for potential treatment effects unique to the first year of fertilization, and for three 3-year periods; data from each 3-year period was divided into spring, summer, and fall. Nitrogen addition consistently suppressed soil respiration by up to 14% relative to controls (p ≤ 0.01 for the main effect of N in 5 of 10 analysis periods). This response was tempered when P was also added, reducing the suppressive effect of N addition from 24 to 1% in one of the ten analysis periods (summer 2012–2014, p = 0.01 for the interaction of N and P). This interaction effect is consistent with observations of reduced foliar N and available soil N following P addition. Mid-successional stands (26–41 years old at the time of the first nutrient addition) consistently had the lowest rates of soil respiration across stand age classes (1.4–6.6 µmol CO₂ m⁻² s⁻¹), and young stands had the highest (2.5–8.5 µmol CO₂ m⁻² s⁻¹). In addition to these important effects of treatment and stand age, we observed an unexpected increase in soil respiration, which doubled in 10 years and was not explained by soil temperature patterns, nutrient additions, or increased in fine-root biomass.