Interlinking climate change with waterenergy-food nexus and related ecosystem processes in California case studies

Global climate change creates critical challenges with increasing temperature,reducing snowpack,and changing precipitation for water,energy,and food,as well as ecosystem processes at regional scales.Ecosystem services provide life support,goods,and natural resources from water,energy,and food,as well as the environments.There are knowledge gaps from the lack of conceptual framework and practices to interlink major climate change drivers of water resources with water-energy-food nexus and related ecosystem processes.This paper provided an overview of research background,developed a conceptual framework to bridge these knowledge gaps,summarized California case studies for practices in cross sector ecosystem services,and identified future research needs.In this conceptual framework,climate change drivers of changing temperature,snowpack,and precipitation are interlinked with life cycles in water,energy,food,and related key elements in ecosystem processes.Case studies in California indicated climate change affected variation in increasing temperature and changing hydrology at the regional scales.A large variation in average energy intensity values was also estimated from ground water and federal,state,and local water supplies both within each hydrological region and among the ten hydrological regions in California.The increased regional temperature,changes in snowpack and precipitation,and increased water stresses from drought can reduce ecosystem services and affect the water and energy nexus and agricultural food production,as well as fish and wildlife habitats in the Sacramento-San Joaquin Delta(Delta)and Central Valley watersheds.Regional decisions and practices in integrated management of water,energy,food,and related ecosystem processes are essential to adapt and mitigate global climate change impacts at the regional scales.Science and policy support for interdisciplinary research are critical to develop the database and tools for comprehensive analysis to fill knowledge gaps and address ecosystem service complexity,the related natural resource investment,and integrated planning needs.

A field experimental study on the impact of Acer platanoides,an urban tree invader,on forest ecosystem processes in North America

Background:Invasive species affect community dynamics and ecosystem functions,but the mechanisms of their impacts are poorly understood.Hypotheses on invasion impact range from Superior Competitor to Novel Function,from Enemy Escape to Microbial Mediation.In this study,we examined the effects of an urban tree invader,Acer platanoides(Norway maple,NM),on a mesic deciduous forest in contrast to its native congener Acer rubrum(red maple,RM)with a split-plot design experiment.A total of 720 maple seedlings were transplanted to 72 plots under 24 trees of three canopy types.The three experimental treatments were removal of resource competition at above-and belowground and removal of leaf-litter effect.Soil moisture and nitrogen-related microbial activities were followed for each plot.Results:We found that partial canopy removal increased canopy openness and light transmission to the forest floor,but to a greater extent under NM than under RM trees.NM seedlings were more shade tolerant than RM seedlings in height growth.During the reciprocal transplantation in the mixed forest,biomass accumulation of NM seedlings under RM trees were twice as much as under NM,while that of RM seedlings under NM trees was 23.5%less than under RM.Soil net nitrification and relative nitrification were significantly higher,but mineralization rate was much lower under NM than under RM trees,which would lead to faster N leaching and lower N availability in the soil.Plots with litter removal had significantly higher seedling mortality due to herbivory by the end of 2 years,especially for NM seedlings under NM trees.Trenching enhanced soil water availability but there was no difference among canopy types.Conclusions:Our results demonstrated that invasion of NM not only altered forest canopy structure but also changed herbivory rate for seedlings and N dynamics in the soils.NM seedlings were more shade tolerant under NM canopies than RM seedlings and were more protected by NM litter under NM canopies than under RM canopies.These altered biotic and abiotic environments will likely facilitate further invasion of NM in the forests,hence positive feedbacks,and make it an increasingly serious tree invader in North America.

Extreme events as ecosystems drivers： Ecological consequences of anomalous Southern Hemisphere weather patterns during the 2001/2002 austral spring-summer

The frequency and severity of extreme events associated with global change are both forecast to increase with a concomitant increase expected in perturbations and disruptions of fundamental processes at ecosystem, community and population scales, with potentially catastrophic consequences. Extreme events should thus be viewed as ecosystem drivers, rather than as short term deviations from a perceived ＇norm＇. To illustrate this, we examined the impacts associated with the extraordinary weather pattern of the austral spring/summer of 2001/2002, and find that patterns of ocean-atmosphere interactions appear linked to a suite of extreme events in Antarctica and more widely across the Southern Hemisphere. In the Antarctic, the extreme events appear related to particular ecological impacts, including the substantial reduction in breeding success of Ade1ie penguins at sites in the Antarctic Peninsula as well as for Adelie penguin and snow petrel colonies in East Antarctica, and the creation of new benthic habitats associated with the disintegration of the Larsen B Ice Shelf. Other major impacts occurred in marine and terrestrial ecosystems at temperate and tropical latitudes. The suite of impacts demonstrates that ecological consequences of extreme events are manifested at fundamental levels in ecosystem processes and produce long-term, persistent effects relative to the short-term durations of the events. Changes in the rates of primary productivity, species mortality, community structure and inter-specific interactions, and changes in trophodynamics were observed as a consequence of the conditions during the 2001/2002 summer. Lasting potential consequences include reaching or exceeding tipping points, trophic cascades and regime shifts.

Linking molecular deadwood-inhabiting fungal diversity and community dynamics to ecosystem functions and processes in Central European forests

Fungi play vital roles in the decomposition of deadwood due to their secretion of various enzymes that break down plant cell-wall complexes.The compositions of woodinhabiting fungal(WIF)communities change over the course of the decomposition process as the remaining mass of wood decreases and both abiotic and biotic conditions of the wood significantly change.It is currently not resolved which substrate-related factors govern these changes in WIF communities and whether such changes influence the deadwood decomposition rate.Here we report a study on fungal richness and community structure in deadwood of Norway spruce and European beech in temperate forest ecosystems using 454 pyrosequencing.Our aims were to disentangle the factors that correspond to WIF community composition and to investigate the links between fungal richness,taxonomically-resolved fungal identity,and microbial-mediated ecosystem functions and processes by analyzing physico-chemical wood properties,lignin-modifying enzyme activities and wood decomposition rates.Unlike fungal richness,we found significant differences in community structure between deadwood of different tree species.The composition of WIF communities was related to the physico-chemical properties of the deadwood substrates.Decomposition rates and the activities of ligninmodifying enzymes were controlled by the succession of the fungal communities and competition scenarios rather than fungal OTU richness.Our results provide further insights into links between fungal community structure and microbialmediated ecosystem functions and processes.

National Forest Inventories capture the multifunctionality of managed forests in Germany

Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.

Spatial analysis of plant detritus processing in a Mediterranean River type: the case of the River Tirso Basin, Sardinia, Italy

The river continuum concept represents the most general framework addressing the spatial variation of both structure and function in river ecosystems. In the Mediterranean ecoregion, summer drought events and dams constitute the main sources of local disturbance to the structure and functioning of river ecosystems occurring in the river basin. In this study, we analysed patterns of spatial variation of detritus processing in a 7th order river of the Mediterranean ecoregion(River Tirso, Sardinia-Italy) and in three 4th order sub-basins which were exposed to different summer drought pressures. The study was carried out on Phragmites australis and Alnus glutinosa leaf detritus at 31 field sites in seasonal field experiment Detritus processing rates were higher for Alnus glutinosa than for Phragmites australis plant detritus. Processing rates of Alnus glutinosa leaves varied among seasons and study sites from 0.006 d -1 to 0.189 d -1 and those of Phragmites australis leaves ranged from 0.0008 d -1 to 0.102 d -1, with the lowest values occurring at sites exposed to summer drought. Seasons and sites accounted for a significant proportion of such variability. Alder detritus decay rates generally decreased with increasing stream order, while reed detritus decay rates generally increased on the same spatial gradient. Summer drought events affected these spatial patterns of variation by influencing significantly the decay rates of both plant detritus. The comparisons among and within sub-basins showed strong negative influence of summer drought on detritus processing rates. Similarly, in the entire River Tirso basin decay rates were always lower at disturbed than at undisturbed sites for each stream order; decay rates of reed detritus remained lower at those sites even after the end of the disturbance events, while alder decay rates recovered rapidly from the summer drought perturbations. The different recovery of the processing rates of the two leaves could also explain the different patterns of spatial variation observed between the two leaves.

Coupling changes of soil functional gene abundances and extracellular enzyme activities across the diagnostic horizons of agricultural Isohumosols

Soil functional microbial taxa and extracellular enzymes are involved in a variety of biogeochemical cycling processes.Although many studies have revealed the vertical change patterns of microbial communities along soil profile,the general understanding of the coupling changes in the functional gene abundances(FGAs)and extracellular enzyme activities(EEAs)in soil profiles is still limited,which hinders us from revealing soil ecosystem processes.Herein,we comparatively investigated the FGAs and EEAs in the diagnostic A,B,and C horizons of soil profiles obtained from two suborders of Isohumosols(Mollisols),Ustic and Udic Isohumosols,in Northeast China based on quantitative real-time polymerase chain reaction and standard fluorometric techniques,respectively.The distribution patterns of both FGAs and EEAs significantly distinguished by the two soil suborders and were also separated from A to C horizon.Additionally,the variations of EEAs and FGAs were greater in Udic Isohumosols compared to Ustic Isohumosols along soil profiles,and greater changes were observed in C horizon than in A horizon.Both FGAs and EEAs correspondently decreased along the soil profiles.However,when normalized by soil organic carbon,the specific EEAs significantly increased in deep soil horizons,suggesting that microorganisms will input more resources to the production of enzymes to ensure microbial nutrient requirements under resource scarcity.More importantly,we revealed that soil microbial nutrient demands were limited by carbon(C)and phosphorus(P),and the C and P limitations significantly increased along soil profiles with a greater C limitation observed in Ustic Isohumosols than in Udic Isohumosols.Overall,our findings provided solid evidence showing the links between FGAs,EEAs,and microbial nutrient limitations,which would be helpful for a better understanding of the ecosystem processes in soil profiles.

Current and near-term advances in Earth observation for ecological applications

There is an unprecedented array of new satellite technologies with capabilities for advancing our understanding of ecological processes and the changing composition of the Earth’s biosphere at scales from local plots to the whole planet.We identified 48 instruments and 13 platforms with multiple instruments that are of broad interest to the environmental sciences that either collected data in the 2000s,were recently launched,or are planned for launch in this decade.We have restricted our review to instruments that primarily observe terrestrial landscapes or coastal margins and are available under free and open data policies.We focused on imagers that passively measure wavelengths in the reflected solar and emitted thermal spectrum.The suite of instruments we describe measure land surface characteristics,including land cover,but provide a more detailed monitoring of ecosystems,plant communities,and even some species then possible from historic sensors.The newer instruments have potential to greatly improve our understanding of ecosystem functional relationships among plant traits like leaf mass area(LMA),total nitrogen content,and leaf area index(LAI).They provide new information on physiological processes related to photosynthesis,transpiration and respiration,and stress detection,including capabilities to measure key plant and soil biophysical properties.These include canopy and soil temperature and emissivity,chlorophyll fluorescence,and biogeochemical contents like photosynthetic pigments(e.g.,chlorophylls,carotenoids,and phycobiliproteins from cyanobacteria),water,cellulose,lignin,and nitrogen in foliar proteins.These data will enable us to quantify and characterize various soil properties such as iron content,several types of soil clays,organic matter,and other components.Most of these satellites are in low Earth orbit(LEO),but we include a few in geostationary orbit(GEO)because of their potential to measure plant physiological traits over diurnal periods,improving estimates of water and carbon budgets.We also include a few spaceborne active LiDAR and radar imagers designed for quantifying surface topography,changes in surface structure,and 3-dimensional canopy properties such as height,area,vertical profiles,and gap structure.We provide a description of each instrument and tables to summarize their characteristics.Lastly,we suggest instrument synergies that are likely to yield improved results when data are combined.