Nutrient limitation on terrestrial plant growth--modeling the interaction between nitrogen and phosphorus

Growth of plants in terrestrial ecosystems is often limited by the availability of nitrogen (N) or phosphorous (P) Liebig's law of the minimum states that the nutrient in least supply relative to the plant's requirement will limit the plant's growth. An alternative to the law of the minimum is the multiple limitation hypothesis (MLH) which states that plants adjust their growth patterns such that they are limited by several resources simultaneously. We use a simple model of plant growth and nutrient uptake to explore the consequences for the plant's relative growth rate of letting plants invest differentially in N and P uptake. We find a smooth transition between limiting elements, in contrast to the strict transition in Liebig's law of the minimum. At N : P supply ratios where the two elements simultaneously limit growth, an increase in either of the nutrients will increase the growth rate because more resources can be allocated towards the limiting element, as suggested by the multiple limitation hypothesis. However, the further the supply ratio deviates from these supply rates, the more the plants will follow the law of the minimum. Liebig's law of the minimum will in many cases be a useful first-order approximation.     

Stoichiometric food quality and herbivore dynamics

Herbivores may grow with nutrient or energy limitation, depending on food abundance and the chemical composition of their food. We present a model that describes herbivore growth as a continuous function of two limiting factors. This function uses the synthesizing unit concept, has the hyperbolic Monod model as a limiting case, and has the same number of parameters as the Monod model coupled to Liebig's discontinuous minimum rule. We use the model to explore nutrient-limited herbivore growth in a closed system with algae, Daphnia and phosphorus as the limiting nutrient. Phosphorus in algae may substantially influence Daphnia growth. This influence changes over time and is most pronounced when algae and Daphnia populations fluctuate strongly. Relative to classic models that only consider food quantity as a determinant of Daphnia growth, our model shows richer dynamical behaviour. In addition to the standard positive equilibrium, which may be stable or unstable depending on nutrient availability, a new positive equilibrium may arise in our model when mortality rates are relatively high. This equilibrium is unstable and reduces the likelihood of long-term persistence of Daphnia in the system.     

The concept of multiple-nutrient-limited growth of microorganisms and its application in biotechnological processes

The "law of the minimum" (Liebig's law) states that usually one nutrient restricts the maximum quantity of biomass that can be produced within a system, whereas all other nutrients are in excess. This general rule has been applied also to the growth of microorganisms, e.g., by adjusting the relative concentrations of the individual nutrients in growth media such that one of them, in the case of heterotrophic microbes, usually the carbon source, determines the maximum cell density that can be obtained in a culture. However, experimental data demonstrated that growth of microbial cultures can be limited simultaneously by two or more nutrients. These authors reported that during growth of bacteria and yeasts at a constant dilution rate in the chemostat, three distinct growth regimes were recognised as a function of the C:N ratio in the inflowing medium: (1) a clearly carbon-limited regime with the nitrogen source in excess, (2) a transition ("double-nutrient-limited") growth regime where both the carbon and the nitrogen source were below the detection limit, and (3) a clearly nitrogen-limited growth regime with the carbon source in excess. Subsequent calculations suggested that the extension and position of this double-nutrient-limited zone should be strongly dependent on the imposed growth rate: Whereas it is very narrow at high growth rates it should become very broad during slow growth. This pattern as a function of growth rate has now been confirmed for a number of different organisms. In industrial processes, microbial growth is always in some way controlled by the limited availability of nutrients, and limitation of specific nutrients is frequently used to force microbial cultures into a productive physiological state. This article will discuss what the consequences of multiple-nutrient-limited growth are for industrial processes and how the concept might be applied. Specific examples will be given that demonstrate the advantages and the potential of multiple nutrient-limited growth conditions for industrial production processes.     

Independent colimitation for carbon dioxide and inorganic phosphorus

Simultaneous limitation of plant growth by two or more nutrients is increasingly acknowledged as a common phenomenon in nature, but its cellular mechanisms are far from understood. We investigated the uptake kinetics of CO(2) and phosphorus of the algae Chlamydomonas acidophila in response to growth at limiting conditions of CO(2) and phosphorus. In addition, we fitted the data to four different Monod-type models: one assuming Liebigs Law of the minimum, one assuming that the affinity for the uptake of one nutrient is not influenced by the supply of the other (independent colimitation) and two where the uptake affinity for one nutrient depends on the supply of the other (dependent colimitation). In addition we asked whether the physiological response under colimitation differs from that under single nutrient limitation.We found no negative correlation between the affinities for uptake of the two nutrients, thereby rejecting a dependent colimitation. Kinetic data were supported by a better model fit assuming independent uptake of colimiting nutrients than when assuming Liebigs Law of the minimum or a dependent colimitation. Results show that cell nutrient homeostasis regulated nutrient acquisition which resulted in a trade-off in the maximum uptake rates of CO(2) and phosphorus, possibly driven by space limitation on the cell membrane for porters for the different nutrients. Hence, the response to colimitation deviated from that to a single nutrient limitation. In conclusion, responses to single nutrient limitation cannot be extrapolated to situations where multiple nutrients are limiting, which calls for colimitation experiments and models to properly predict growth responses to a changing natural environment. These deviations from single nutrient limitation response under colimiting conditions and independent colimitation may also hold for other nutrients in algae and in higher plants.     

Dynamics of nutrient uptake strategies: lessons from the tortoise and the hare

Many autotrophs vary their allocation to nutrient uptake in response to environmental cues, yet the dynamics of this plasticity are largely unknown. Plasticity dynamics affect the extent of single versus multiple nutrient limitation and thus have implications for plant ecology and biogeochemical cycling. Here we use a model of two essential nutrients cycling through autotrophs and the environment to determine conditions under which different plastic or fixed nutrient uptake strategies are adaptive. Our model includes environment-independent costs of being plastic, environment-dependent costs proportional to the rate of plastic change, and costs of being mismatched to the environment, the last of which is experienced by both fixed and plastic types. In equilibrium environments, environment-independent costs of being plastic select for tortoise strategies—fixed or less plastic types—provided that they are sufficiently close to co-limitation. At intermediate levels of environmental fluctuation forced by periodic nutrient inputs, more hare-like plastic strategies prevail because they remain near co-limitation. However, the fastest is not necessarily the best. The most adaptive strategy is an intermediate level of plasticity that keeps pace with environmental fluctuations, but is not faster. At high levels of environmental fluctuation, the environment-dependent cost of changing rapidly to keep pace with the environment becomes prohibitive and tortoise strategies again dominate. The existence and location of these thresholds depend on plasticity costs and rate, which are largely unknown empirically. These results suggest that the expectations for single nutrient limitation versus co-limitation and therefore biogeochemical cycling and autotroph community dynamics depend on environmental heterogeneity and plasticity costs.     

Nitrogen Limitation of Pond Ecosystems on the Plains of Eastern Colorado

Primary production in freshwater ecosystems is often limited by the availability of phosphorus (P), nitrogen (N), or a combination of both (NP co-limitation). While N fixation via heterocystous cyanobacteria can supply additional N, no comparable mechanism for P exists; hence P is commonly considered to be the predominant and ultimate limiting nutrient in freshwater ecosystems. However, N limitation can be maintained if P is supplied in stoichiometric excess of N (including N fixation). The main objective of this study was to examine patterns in nutrient limitation across a series of 21 vernal ponds in Eastern Colorado where high P fluxes are common. Across all ponds, water column dissolved inorganic N steadily decreased throughout the growth season due to biological demand while total dissolved P remained stable. The water column dissolved inorganic N to total dissolved P ratios suggested a transition from NP co-limitation to N limitation across the growth season. Periphyton and phytoplankton %C was strongly correlated with %N while %P was assimilated in excess of %N and %C in many ponds. Similarly, in nutrient addition bottle assays algae responded more strongly to N additions (11 out of 18 water bodies) than P additions (2 out of 18 water bodies) and responded most strongly when N and P were added in concert (12 out of 18 water bodies). Of the ponds that responded to nutrient addition, 92% exhibited some sort of N limitation while less than 8% were limited by P alone. Despite multiple lines of evidence for N limitation or NP co-limitation, N fixation rates were uniformly low across most ponds, most likely due to inhibition by water column nitrate. Within this set of 18 water bodies, N limitation or NP co-limitation is widespread due to the combination high anthropogenic P inputs and constrained N fixation rates.     

Herbivorous animals can mitigate unfavourable ratios of energy and material supplies by enhancing nutrient recycling

Recent evidence shows that high supply ratios of light and nutrients limit planktonic herbivore growth by lowering the nutritional quality of algae. Over longer time scales, however, grazers may ameliorate this effect by their impact on nutrient cycling. We examine this possibility using two species of the herbivorous zooplankter Daphnia and its algal prey under different light intensities and low phosphorus supply in laboratory microcosms. At high light, Daphnia biomass was limited for a substantial period because of low P content of algal cells. However, a gradual increase in Daphnia density eventually improved food quality through grazing and nutrient cycling and via a novel process involving positive density dependence. Competitive exclusion of one of the two Daphnia species occurred under low light but not under high light when algae were nutritionally unsuitable. Such stoichiometrically mediated interactions among herbivorous animals may represent important mechanisms that affect community structure and material flows in ecosystems.     

Nutrient co-limitation of primary producer communities

Synergistic interactions between multiple limiting resources are common, highlighting the importance of co-limitation as a constraint on primary production. Our concept of resource limitation has shifted over the past two decades from an earlier paradigm of single-resource limitation towards concepts of co-limitation by multiple resources, which are predicted by various theories. Herein, we summarise multiple-resource limitation responses in plant communities using a dataset of 641 studies that applied factorial addition of nitrogen (N) and phosphorus (P) in freshwater, marine and terrestrial systems. We found that more than half of the studies displayed some type of synergistic response to N and P addition. We found support for strict definitions of co-limitation in 28% of the studies: i.e. community biomass responded to only combined N and P addition, or to both N and P when added separately. Our results highlight the importance of interactions between N and P in regulating primary producer community biomass and point to the need for future studies that address the multiple mechanisms that could lead to different types of co-limitation.     

Bacterivorous grazers facilitate organic matter decomposition: a stoichiometric modeling approach

There is widespread empirical evidence that protist grazing on bacteria reduces bacterial abundances but increases bacteria-mediated decomposition of organic matter. This paradox has been noted repeatedly in the microbiology literature but lacks a generally accepted mechanistic explanation. To explain this paradox quantitatively, we develop a bacteria-grazer model of organic matter decomposition that incorporates protozoa-driven nutrient recycling and stoichiometry. Unlike previous efforts, the current model includes explicit limitation, via Liebig's law of minimum, by two possible factors, nutrient and carbon densities, as well as their relative ratios in bacteria and grazers. Our model shows two principal results: (1) when the environment is carbon limiting, organic matter can always be decomposed completely, regardless of the presence/absence of grazers; (2) when the environment is nutrient (such as nitrogen) limiting, it is possible for organic matter to be completely decomposed in the presence, but not absence, of grazers. Grazers facilitate decomposition by releasing nutrients back into the environment, which would otherwise be limiting, while preying upon bacteria. Model analysis reveals that facilitation of organic matter decomposition by grazers is positively related to the stoichiometric difference between bacteria and grazers. In addition, we predict the existence of an optimal density range of introduced grazers, which maximally facilitate the decomposition of organic matter in a fixed time period. This optimal range reflects a trade-off between grazer-induced nutrient recycling and grazer-induced mortality of bacteria.     

Nutrient recycling by two phosphorus-rich grazing catfish: the potential for phosphorus-limitation of fish growth

In ecosystems where excretion by fish is a major flux of nutrients, the nitrogen (N) to phosphorus (P) ratio released by fish can be important in shaping patterns of algal biomass, community composition, primary production, and nutrient limitation. Demand for N and P as well as energy influences N/P excretion ratios and has broad implications in ecosystems where nutrient recycling by fishes is substantial. Bioenergetics and stoichiometric models predict that natural fish populations are generally energy-limited and therefore N/P recycling by fishes is relatively invariant. Yet, the potential for P limitation of growth has not been examined in herbivorous fishes, which are common in many aquatic habitats. We examined N/P excretion ratios and P demand in two P-rich herbivorous catfishes of the family Loricariidae, Ancistrus triradiatus (hereafter Ancistrus) and Chaetostoma milesi (hereafter Chaetostoma). Both fishes are common grazers in the Andean piedmont region of Venezuela where we conducted this study. Mass balance (MB) models indicate that these fishes have a high P demand. In fact, our Ancistrus’ P MB model predicted negative P excretion rates, indicating that Ancistrus did not consume enough P to meet its P demand for growth. Direct measurement of excretion rates showed positive, but very low P excretion rates and high N/P excretion ratios for both taxa. To obtain measured P excretion rates of Ancistrus from the MB model, gross growth efficiency must be reduced by 90%. Our results suggest that growth rates of both of these herbivorous and P-rich fish are likely P-limited. If P limitation of growth is common among herbivorous fish populations, herbivorous fishes recycle likely at high N/P ratios and act to diminish the quality of their food.     

Multiple nutrients and herbivores interact to govern diversity,productivity, composition,and infection in a successional grassland

In spite of increasing awareness that interactions between herbivory and the supply rates of multiple nutrients control biodiversity, ecosystem functions and ecosystem services in ecological communities, few experimental studies have concurrently examined the independent and joint effects of multiple nutrients and mammalian consumers on these responses in natural systems. Here we quantify the independent and interactive effects of multiple concurrent changes to resources and consumers in an invaded annual grassland community in California. In a two‐year study using thirty‐seven 400‐m² plots, we examine interactions among four nutrient treatments (N, P, K and micronutrients) and a keystone herbivore (pocket gopher Thomomys bottae) on four plant community outcomes: 1) plant diversity, 2) functional group composition, 3) net biomass production, an important ecosystem function, and 4) infection risk by a group of viral pathogens shared by crop and non‐crop grasses (barley and cereal yellow dwarf viruses), an important regulating ecosystem service. We found that grassland biodiversity and infection risk were controlled by nutrient identity and supply ratio whereas nutrients interacted strongly with consumers to control grassland composition and net primary productivity. The most important insights arising from this multi‐factor experiment are that net biomass production increased with phosphorus or nitrogen supply; however, when gophers were present, nitrogen caused no net effect on biomass production. In addition, infection risk was driven by phosphorus, nitrogen and micronutrient supply. Infection in a sentinel host increased strongly with the addition of micronutrients or phosphorus; however, infection declined with increasing N/P supply ratio, indicating stoichiometric control of infection risk. Finally, in spite of manipulating multiple factors, plant species richness declined with nitrogen, alone. The importance of higher‐order interactions demonstrates that a multi‐factor approach is critical for effective predictions in a world in which anthropogenic activities are simultaneously changing herbivore abundance and the relative supply of many nutrients.     

When microbes and consumers determine the limiting nutrient of autotrophs: a theoretical analysis

Ecological stoichiometry postulates that differential nutrient recycling of elements such as nitrogen and phosphorus by consumers can shift the element that limits plant growth. However, this hypothesis has so far considered the effect of consumers, mostly herbivores, out of their food-web context. Microbial decomposers are important components of food webs, and might prove as important as consumers in changing the availability of elements for plants. In this theoretical study, we investigate how decomposers determine the nutrient that limits plants, both by feeding on nutrients and organic carbon released by plants and consumers, and by being fed upon by omnivorous consumers. We show that decomposers can greatly alter the relative availability of nutrients for plants. The type of limiting nutrient promoted by decomposers depends on their own elemental composition and, when applicable, on their ingestion by consumers. Our results highlight the limitations of previous stoichiometric theories of plant nutrient limitation control, which often ignored trophic levels other than plants and herbivores. They also suggest that detrital chains play an important role in determining plant nutrient limitation in many ecosystems.     

Feeding by omnivores increases food available to consumers

Consumers are usually thought of as negatively affecting producers, but they can affect them positively by releasing nutrients (nutrient regeneration). The net effects of consumers on producers should depend on the balance between the effects of consumption and nutrient regeneration. In aquatic habitats, nutrient regeneration by consumers may increase microbial activity on leaf detritus as well as algal production, which in turn may stimulate further nutrient release and benefit herbivores or detritivores by increasing food quantity or quality. Omnivores can regenerate nutrients from animals, algae and detritus, creating diverse nutrient pathways. Many tadpoles are omnivores, and their nutrient regeneration may be important in aquatic food webs. To reveal the nutrient pathways created by tadpoles and examine whether omnivorous tadpoles can have positive effects on producers and consumers, we experimentally examined the effects of nutrient regeneration by three densities of tadpoles on primary producers, leaf litter, and other consumers in tank mesocosms. Tadpole exclosures were placed inside each mesocosm, allowing us to separate direct consumption effects from indirect nutrient regeneration effects. Nutrient regeneration caused by the herbivorous and carnivorous feeding activities of tadpoles positively affected rates of production of benthic algae, phytoplankton, and herbivorous benthic chironomid larvae, and rates of mineralization of leaf litter. The increased production of benthic algae and chironomid larvae was consumed by the tadpoles themselves, leaving no net change in the standing biomass of these resources. Our experiment thus demonstrated that omnivores created complicated nutrient pathways and accelerated rates of primary production and growth rates of other consumers, leading to increased rates of food availability to the omnivores themselves. Interactions of this nature may be common in many systems and could strongly moderate the effects of consumers on their resources and each other.     

Nutrient limitation of periphyton growth in arctic lakes in south-west Greenland

Many arctic lakes are oligotrophic systems where phototrophic growth is controlled by nutrient supply. Recent anthropogenic nutrient loading is associated with biological and/or physico-chemical change in several lakes across the arctic. Shifts in nutrient limitation (nitrogen (N), phosphorus (P), or N + P) and associated effects on the growth and composition of algal communities are commonly reported. The Kangerlussuaq region of south-west Greenland forms a major lake district which is considered to receive little direct anthropogenic disturbance. However, long-range transport of pollutant N is now reaching Greenland, and it was hypothesised that a precipitation gradient from the inland ice sheet margin to the coast might also deliver increased N deposition. In situ nutrient bioassays were deployed in three lakes across the region: ice sheet margin, inland (close to Kangerlussuaq) and the coast (near Sisimiut), to determine nutrient limitation of lakes and investigate any effects of nutrients on periphyton growth and community composition. Nutrient limitation differed amongst lakes: N limitation (ice sheet margin), N and P limitation (inland) and N + P co-limitation (coast). Factors including variation in N supply, ice phenology, seasonal algal succession, community structure and physical limnology are explored as mechanisms to explain differences amongst lakes. Nutrient limitation of arctic lakes and associated ecological impacts are highly variable, even across small geographic areas. In this highly sensitive region, future environmental change scenarios carry a strong risk of significantly altering nutrient limitation; in turn, potentially severely impacting lake structure and function.     

Oligotrophication of a large,deep lake alters food quantity and quality constraints at the primary producer–consumer interface

To assess nutritional consequences associated with lake oligotrophication for aquatic consumers, we analyzed the elemental and biochemical composition of natural seston and concomitantly conducted laboratory growth experiments in which the freshwater key herbivore Daphnia was raised on natural seston of the nowadays (2008) oligotrophic Lake Constance throughout an annual cycle. Food quality mediated constraints on Daphnia performance were assessed by comparing somatic growth rates with seston characteristics (multiple regression analysis) and by manipulating the elemental and biochemical composition of natural seston experimentally (nutrient supplementation). Results were compared to similar experiments carried out previously (1997) during a mesotrophic phase of the lake. In the oligotrophic phase, particulate carbon and phosphorus concentrations were lower, fatty acid concentrations were higher, and the taxonomic composition of phytoplankton was less diverse, with a more diatom‐ and cryptophytes‐dominated community, compared to the previous mesotrophic phase. Multiple regression analysis indicated a shift from a simultaneous limitation by food quantity (in terms of carbon) and quality (i.e. α‐linolenic acid) during the mesotrophic phase to a complex multiple nutrient limitation mediated by food quantity, phosphorus, and omega‐3 fatty acids in the following oligotrophic phase. The concomitant supplementation experiments also revealed seasonal changes in multiple resource limitations, i.e. the prevalent limitation by food quantity was accompanied by a simultaneous limitation by either phosphorus or omega‐3 fatty acids, and thus confirmed and complemented the multiple regression approach. Our results indicate that seasonal and annual changes in nutrient availabilities can create complex co‐limitation scenarios consumers have to cope with, which consequently may also affect the efficiency of energy transfer in food webs.     

Evidence for extensive but variable nutrient limitation in New Zealand lakes

Nutrient limitation causes reduced growth of organisms, which can translate into far-reaching consequences for populations, communities, and ecosystems. Phosphorus (P) limitation, in particular, is associated with reductions in organismal growth because ribosomes, upon which growth depends, require abundant phosphorus to be produced. Chromosomes are also relatively rich in P, meaning that organisms with relatively high chromosome complements (e.g. polyploids) might be especially dependent on abundant environmental P. Here we address the likelihood of nutrient limitation in multiple populations of Potamopyrgus antipodarum, a New Zealand freshwater snail featuring wide ploidy variation. We found that some form of P limitation is very likely in many, but not all, populations of this snail that we surveyed. We also detected extensive across-population variation in P and nitrogen (N) content and N and P limitation and co-limitation in the algae that P. antipodarum eat. Accordingly, we then experimentally evaluated how P and N alone and together influenced growth rate in P. antipodarum. We found that response to nutrients differed by lineage and that dietary P content was more important than dietary N content as a determinant of growth rate, a trait closely tied to fitness in P. antipodarum. The widespread likelihood of (1) P limitation and (2) variation in dietary P availability across New Zealand lakes, along with (3), evidence for lineage-level variation in sensitivity to P limitation, sets the stage for the possibility that variation in nutrient availability contributes to the distribution and maintenance of ploidy variation in P. antipodarum.     

On multiple-nutrient-limited growth of microorganisms,with special reference to dual limitation by carbon and nitrogen substrates

Simultaneous limitation of microbial growth by two or more nutrients is discussed for dual carbon/nitrogen-limited growth in continuous culture. The boundaries of the zone where double-limited growth occurs can be clearly defined from both cultivation data and cellular composition and they can be also predicted from growth yield data measured under single-substrate-limited conditions. It is demonstrated that for the two nutrients carbon and nitrogen the zone of double nutrient limitation is dependent on both the C:N ratio of the growth medium and the growth (dilution) rate. The concept on double-(carbon/nitrogen)-limited growth presented here can be extended to other binary and multiple combinations of nutrients.     

Emergence of nutrient co‐limitation through movement in stoichiometric meta‐ecosystems

Evidence that ecosystems and primary producers are limited in their productivity by multiple nutrients has caused the traditional nutrient limitation framework to include multiple limiting nutrients. The models built to mimic these responses have invoked local mechanisms at the level of the primary producers. In this paper, we explore an alternative explanation for the emergence of co‐limitation by developing a simple, stoichiometrically explicit meta‐ecosystem model with two limiting nutrients, autotrophs and herbivores. Our results show that differences in movement rates for the nutrients, autotrophs and herbivores can allow for nutrient co‐limitation in biomass response to emerge despite no local mechanisms of nutrient co‐limitation. Furthermore, our results provide an explanation to why autotrophs show positive growth responses to nutrients despite ‘nominal’ top‐down control by herbivores. These results suggest that spatial processes can be mechanisms for nutrient co‐limitation at local and regional scales, and can help explain anomalous results in the co‐limitation literature.     

Nitrogen availability limits phosphorus uptake in an intertidal macroalga

Nutrients such as nitrogen (N) and phosphorus (P) limit primary productivity, and recent anthropogenic activities are changing the availability of these nutrients, leading to alterations in the type and magnitude of nutrient limitation. Recent work highlights the potential for N and P to interact to limit primary production in terrestrial and freshwater systems. However, mechanisms underlying co-limitation are not well described. Documentation of ambient nutrient levels and tissue nutrients of the intertidal macroalga Fucus vesiculosus for 2 years in the southern Gulf of Maine, USA, indicates that N availability may be impacting the ability of F. vesiculosus to access P, despite relatively high ambient P concentrations. To experimentally validate these observations, F. vesiculosus individuals were enriched with N or P for 6 weeks, followed by an uptake experiment to examine how the interactions between these nutrients affected macroalgal N and P uptake efficiency. Results illustrate that exposure of seaweed to different nutrient regimes influenced nutrient uptake efficiency. Notably, seaweeds enriched with N displayed the highest P uptake efficiency at low, biologically relevant, P concentrations. Our results confirm that N availability may be mediating the ability of primary producers to access P. These interactions between limiting nutrients have implications for not only the growth and functioning of primary producers who rely directly on these nutrients but also the entire communities that they support.     

Bridging factorial and gradient concepts of resource co‐limitation: towards a general framework applied to consumers

Organism growth can be limited either by a single resource or by multiple resources simultaneously (co‐limitation). Efforts to characterise co‐limitation have generated two influential approaches. One approach uses limitation scenarios of factorial growth assays to distinguish specific types of co‐limitation; the other uses growth responses spanned over a continuous, multi‐dimensional resource space to characterise different types of response surfaces. Both approaches have been useful in investigating particular aspects of co‐limitation, but a synthesis is needed to stimulate development of this recent research area. We address this gap by integrating the two approaches, thereby presenting a more general framework of co‐limitation. We found that various factorial (co‐)limitation scenarios can emerge in different response surface types based on continuous availabilities of essential or substitutable resources. We tested our conceptual co‐limitation framework on data sets of published and unpublished studies examining the limitation of two herbivorous consumers in a two‐dimensional resource space. The experimental data corroborate the predictions, suggesting a general applicability of our co‐limitation framework to generalist consumers and potentially also to other organisms. The presented framework might give insight into mechanisms that underlie co‐limitation responses and thus can be a seminal starting point for evaluating co‐limitation patterns in experiments and nature.