Debate In Ecology Research Articles

On maintenance and metabolisms in soil microbial communities

Biochemistry is an essential yet undervalued aspect of soil ecology, especially when analyzing soil C cycling. We assume, based on tradition, intuition or hope, that the complexity of biochemistry is confined to the microscopic world, and can be ignored when dealing with whole soil systems. This opinion paper draws attention to patterns caused by basic biochemical processes that permeate the world of ecosystem processes. From these patterns, we can estimate activities of the biochemical reactions of the central C metabolic network and gain insights into the ecophysiology of microbial biosynthesis, growth, and maintenance energy requirements: important components of Carbon Use Efficiency (CUE). We show that glucose is processed via the Embden-Meyerhof-Parnas glycolysis in one soil, but via Pentose Phosphate or Entner-Doudoroff pathways in two other soils. However, notwithstanding this metabolic diversity, glucose use efficiency is high and thus substrate use for maintenance energy and overflow respiration is low in these soils. These results contradict current dogma, based on four decades of debate in soil ecology, that the maintenance energy demand in soil communities is a quantitative important, although variable, component of soil community energy metabolism. We identify three main shortcomings in our current understanding of substrate use efficiency: 1) in numeric and conceptual models, we lack appreciation of the strategies that microbes employ to quickly reduce energy needs in response to starvation; 2) in order to understand variation in CUE, we need to improve our understanding of the processes of exudation (including all changes in allocation of C from the cell soluble to insoluble fraction and extracellular environment) and microbial turnover; and 3) whether tracer experiments can be used to measure the long-term substrate use efficiency of soil microbial communities depends critically on the ability and speed with which non-growing cells take up tracer substrates and metabolism activates and subsequently de-activates in response to starvation, as well as on how cellular activities scale to the community level. To move the field of soil ecology forward, future research must consider the details of microbial ecophysiology and develop new tools that enable direct measurement of microbial functioning in intact soils. We submit that 13C metabolic flux analysis is one of those new tools.

ORGANISMIC AND CONTINUUM VIEWS OF PLANT COMMUNITY, THE CENTENNIAL DEBATE OF ECOLOGY

It is a note to make young ecologists in India and other developing countries familiar with an important and exciting debate in ecology. Social factors have frequently influenced the course of scientific development, and this aspect may interest even to a scientist of other disciplines.

General Introduction to Environmental Humanities in India The Ecocritical Discourse in Hindu Literature

The article offers a general overview of the ecological debate and Environmental Humanities in India. After an introduction on the legacy of Gandhian ecological thought and contemporary literature, the essay focuses on the most discussed themes of the Indian classical tradition, with particular references to sacred texts (Vedas, Puranas, the epics). The sum of this knowledge is placed on the recursive perspective of Indian time: as yugas change, new structures of social life arise, reformulating society and its environment in a more holistic and sustainable way. This would be possible without ever denying the responsibility we all have in maintaining that personal empathy towards the environment that is reflected in Indian classical texts.

Is forest regeneration good for biodiversity? Exploring the social dimensions of an apparently ecological debate

Forest regeneration is a major land-use change in European uplands, and whether or not this is a desirable change for biodiversity is disputed. While this debate seems to be largely situated in the field of natural sciences, this paper aims to also examine its social dimensions. To do so, we adopt a comparative discourse analysis with four cases of protected areas in France, Spain, and Scotland. We draw on a conceptual framework highlighting both the ecological and social factors underpinning the construction of environmental discourses. It notably emphasises the role of interests, ideas and institutions, and the power dynamics underpinning discourse-coalitions. We show how diverging discourses emerged, gained ground, coalesced and competed differently in different contexts, explaining the adoption of seemingly opposite discourses by protected area authorities. These findings reaffirm the need to conceive environmental governance as an on-going deliberative process in order to achieve environmental justice.

Soil microbial diversity\u2013biomass relationships are driven by soil carbon content across global biomes

The relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity–biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.

TC Boyle’s “Politics of Nature”

This paper offers a Latourian reading of T.C. Boyle’s novel When the Killing’s Done. It shows that the novel satirizes contemporary ecological debates and stages the cultural wars of our current ecological culture. It also demonstrates, however, that the novel does not merely point out the impasse of our current ecologies: its fiction intuitively diagnoses the contemporary “crisis of purity” in modern environmental politics and points us towards the kind of entangled ecologies sketched by Latour and other recent thinkers. Like Latour’s reinvention of a more hybrid and entangled “politics of nature,” Boyle’s novel allows us to reimagine a complex and contaminated new ecology, away from the purifications of our contemporary “NaturPolitiks”.

Species abundance is jointly determined by functional traits and negative density dependence in a subtropical forest in southern China

Abstract Aims The factors affecting species abundance are a subject of ongoing debates in community ecology. Empirical studies have demonstrated that tree abundance is affected by plant functional traits and negative density dependence (NDD). However, few studies have focused on the combined effects of NDD and plant functional traits on species abundance. Methods In this study, we used tree functional traits and two census data from a 50-ha forest dynamic plot in the Heishiding (HSD) Nature Reserve to explore the combined effects of functional traits and NDD on species abundance. Using hierarchical Bayesian models, we analyzed how neighbor densities affected the survival of saplings from 130 species and extracted posterior means of the coefficients to represent NDD. The structural equation modeling (SEM) analysis was then applied to investigate the causal relationships among species functional traits, NDD and species abundance. Important Findings SEM showed that tree functional traits, including specific leaf area (SLA), leaf area (LA), leaf dry matter content (LDMC), leaf N content (LNC), maximum electron transport rate (ETRmax) and conspecific adult negative density dependence (CNDDadult), together explained 20% of the total variation in tree abundance. Specifically, SLA affected tree abundance both directly and indirectly via CNDDadult, with a totally negative influence on abundance. LDMC and LNC had only indirect effects mediated by CNDDadult on tree abundance. ETRmax and LA had directly negative effects on abundance, but their direct connections with CNDDadult were not observed. In addition, CNDDadult was negatively correlated with species abundance, indicating that abundant species are under stronger NDD. Among these investigated traits, SLA contributed the most to the variation in CNDDadult and abundance. We argued that our findings of trait–CNDDadult–abundance relationships can improve our understanding of the determinants of species commonness and rarity in forests.

Data collected by fruit body‐ and DNA‐based survey methods yield consistent species‐to‐species association networks in wood‐inhabiting fungal communities

Inferring interspecific interactions indirectly from community data is of central interest in community ecology. Data on species communities can be surveyed using different methods, each of which may differ in the amount and type of species detected, and thus produce varying information on interaction networks. Since fruit bodies reflect only a fraction of the wood‐inhabiting fungal diversity, there is an ongoing debate in fungal ecology on whether fruit body‐based surveys are a valid method for studying fungal community dynamics compared to surveys based on DNA metabarcoding. In this paper, we focus on species‐to‐species associations and ask whether the associations inferred from data collected by fruit‐body surveys reflect the ones found from data collected by DNA‐based surveys. We estimate and compare the association networks resulting from different survey methods using a joint species distribution model. We recorded both raw and residual associations that respectively do not and do correct for the influence of the abiotic predictors when estimating the species‐to‐species associations. The analyses of the DNA data yielded a larger number of species‐to‐species associations than the analyses of the fruit body‐based data as expected. Yet, we estimated unique associations also from the fruit‐body data. Our results show that the directions of estimated residual associations were consistent between the data types, whereas the raw associations were much less consistent, highlighting the need to account for the influence of relevant environmental covariates when estimating association networks. We conclude that even though DNA‐based survey methods are more informative about the total number of interacting species, fruit‐body surveys are also an adequate method for inferring association networks in wood‐inhabiting fungi. Since the DNA and fruit‐body data carry on complementary information on fungal communities, the most comprehensive insights are obtained by combining the two survey methods.

The religious vision of nature in the light of Laudato Si’: An interreligious reading between Islam and Christianity

The environmental crisis is undoubtedly one of the most critical and urgent problems of our times. Many people are raising their voices in support of nature to build a better future for humanity and for our planet. In this article, the authors explore the specific contribution that Christianity and Islam can offer in this debate and how religions can help bring back into the ecological discourse the element of the sacred that abandoned the reflection about nature since the advent of the Enlightenment. Moving from the spiritual dimension of nature in the light of Pope Francis’s 2015 encyclical on ecology Laudato Si’ , the authors argue that the current ecological crisis can represent an opportunity for a renewed encounter among religions, bringing together the ethical and the spiritual, recovering the element of communion between human beings and nature that points to something beyond themselves. The authors present the Laudato Si’ as a universal invitation and a space for encounter between world religions that puts at its heart love as a guiding principle and animating force of a much-needed ecological, spiritual and anthropological conversion. Contribution: This article focuses on the spiritual dimension of nature in Pope Francis’s 2015 encyclical letter Laudato Si ’. The authors argue that the document with its emphasis on love represents a platform for dialogue between Christianity and Islam by bringing back the element of the sacred in the current ecological debate.

Ecological niche models display nonlinear relationships with abundance and demographic performance across the latitudinal distribution of Astragalus utahensis (Fabaceae).

The potential for ecological niche models (ENMs) to accurately predict species' abundance and demographic performance throughout their geographic distributions remains a topic of substantial debate in ecology and biogeography. Few studies simultaneously examine the relationship between ENM predictions of environmental suitability and both a species' abundance and its demographic performance, particularly across its entire geographic distribution. Yet, studies of this type are essential for understanding the extent to which ENMs are a viable tool for identifying areas that may promote high abundance or performance of a species or how species might respond to future climate conditions. In this study, we used an ensemble ecological niche model to predict climatic suitability for the perennial forb Astragalus utahensis across its geographic distribution. We then examined relationships between projected climatic suitability and field‐based measures of abundance, demographic performance, and forecasted stochastic population growth (λs). Predicted climatic suitability showed a J‐shaped relationship with A. utahensis abundance, where low‐abundance populations were associated with low‐to‐intermediate suitability scores and abundance increased sharply in areas of high predicted climatic suitability. A similar relationship existed between climatic suitability and λs from the center to the northern edge of the latitudinal distribution. Patterns such as these, where density or demographic performance only increases appreciably beyond some threshold of climatic suitability, support the contention that ENM‐predicted climatic suitability does not necessarily represent a reliable predictor of abundance or performance across large geographic regions.

Dynamics of a predator–prey model with generalized Holling type functional response and mutual interference

Mutual interference and prey refuge are important drivers of predator–prey dynamics. The “exponent” or degree of mutual interference has been under much debate in theoretical ecology. In the present work, we investigate the interplay of the mutual interference exponent, and prey refuge, on the behavior of a predator–prey model with a generalized Holling type functional response — considering in particular the “non-smooth” case. This model can also be used to model an infectious disease where a susceptible population, moves to an infected class, after being infected by the disease. We investigate dynamical properties of the system and derive conditions for the occurrence of saddle–node, transcritical and Hopf-bifurcations. A sufficient condition for finite time extinction of the prey species has also been derived. In addition, we investigate the effect of a prey refuge on the population dynamics of the model and derive conditions such that the prey refuge would yield persistence of the population. We provide additional verification of our analytical results via numerical simulations. Our findings are in accordance with classical experimental results in ecology (Gause, 1934), that show that extinction of predator and prey populations is possible in a finite time period — but that bringing in refuge can effectively yield persistence.

“We dredge because it doesn’t work”: urban political ecology and the uneven geographies of sediment metabolism

ABSTRACT As shipping companies deploy increasingly larger ships, urban ports around the world must build and maintain new infrastructure to accommodate these vessels. One subaqueous component of these urban infrastructures is the dredged fairways in port and river bottoms through which ships pass. This paper examines the urban political ecological significance of these fairways, framing the movement, governance, and politics of dredging as sediment metabolism. With an emphasis on understanding how the dredging industry produces a range of uneven geographies, the paper situates sediment metabolism in a series of current debates in urban political ecology regarding the metabolic rift, methodological cityism, and anticolonial metabolisms using case studies from multiple sites of dredging activity, especially the North Sea region and Aotearoa/New Zealand.

Beyond the Ruins of Embobut

The Embobut Forest, western Kenya, can be described as an entanglement of ruins. These ruins are the materialisation of a series of contested ecological debates and political decisions pivoting on the questions of conservation and community rights to land that have resulted in the violent dislocation of local Sengwer and Marakwet communities. In the first instance, this paper aims to contextualise these debates by offering an analytic focus on the process of ruination in order to offer a more nuanced narrative of landscape modification and changing human lives over the past century. Subsequently, I look beyond processes of ruination and towards notions of transformation, in an attempt expound how Embobut has not become a static world of passive ruins but rather is constantly changing as novel forms of dwelling and new ecological relationships continue to unfold in a manner not envisaged by conservation policy.

A half century of Holistic Management: what does the evidence reveal?

Holistic Management (HM) is a decision-making framework based on triple bottom line thinking and a proactive approach to managing complexity. Primarily associated with an approach to managing livestock, it has spurred long running and still unresolved debates in rangeland ecology and management. Less studied are the social, cultural, and psychological aspects of HM, which may hold the key to successful ecological outcomes. In this article, we describe the main tenets of HM as conceived by wildlife biologist Allan Savory and address the longstanding and unresolved controversy over its legitimacy. We then provide a meta-analysis that not only provides an up-to-date review of the multidisciplinary evidence and ongoing arguments about HM, but also provides a novel explanation for the controversy—that it is grounded in epistemic differences between disciplines associated with agricultural science that rule out any chance of resolution. We conclude that the way to resolve the controversy over HM is to research, in partnership with ranchers, rangeland social-ecological systems in more holistic, integrated ways. This can account for the full range of human experience, co-produce new knowledge, and contribute to social-ecological transformation.

The Centenary of the Russian Revolution and Permanent Counterrevolution

In my paper, I analyse the distant consequences of Russian Revolution of 1917 in the twentieth and twenty-first centuries. They can be traced even now. I also study the ideological opposition of Soviet–Russian and international socialism vs. Western capitalism through the prism of revolutionary–counterrevolutionary struggle in both Soviet and post-Soviet times. In view of persistent economic and mental crisis of modern Western capitalism, it is high time to revise our understanding of the achievements of planned economy that was characteristic for the Russian Revolution and the former Soviet Union. These achievements are important in the situation of the global systemic crisis of the Western neoliberal ideological model, especially for ecological socialism and healthy democratic debates / decision-making.

The Earth Mourns: Interconnectedness of Yahweh, People and Land in Jeremiah 23:10 and 15

ABSTRACT According to Jeremiah 23:10 the land mourns because of the unethical behaviour of the religious leaders in Judean society. The example set by these leaders gives leeway to the people of Judah to follow suit. The article discusses the relationship between the actions of people in society and the effect of their behaviour on the land. I depart from the assumption that this reciprocal relational reliance is the result of a particular worldview in which there exists interconnectedness of the divine, the people relating to this divine entity and the land allotted to them. The view argued is that Jeremiah 23:10 reflects a particular worldview consisting of the conceptual structures HOLY/COMMON and PURE/IMPURE. Besides discussing the issue of the relationship between the divine, the people and the land in 23:10 and 15, I make some suggestions relevant to the ecological debate in society. Keywords: Mourn; land; unethical behaviour; curse; worldview; Jeremiah 23:10; adultery; evil

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang, Northwest China

The association between biodiversity and belowground biomass (BGB) remains a central debate in ecology. In this study, we compared the variations in species richness (SR) and BGB as well as their interaction in the top (0–20 cm), middle (20–50 cm) and deep (50–100 cm) soil depths among 8 grassland types (lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients (elevation, energy condition (annual mean temperature (AMT) and potential evapotranspiration (PET)), and mean annual precipitation (MAP)) based on a 2011–2013 survey of 379 sites in Xinjiang, Northwest China. The SR and BGB varied among the grassland types. The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths. The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition; however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths. The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth. Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition. These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.

Diverse temperate forest bird assemblages demonstrate closer correspondence to plant species composition than vegetation structure

The aggregate structure of vegetation has long provided a strong conceptual basis for understanding the ecological separation of faunal species, while correspondence with plant species composition remains largely underdeveloped and considered secondary to structure. Longstanding ecological debate on the matter has likely been sustained by statistical methods incapable of accommodating an entire species composition in the explanatory role. We used direct ordination methodologies (predictive co‐correspondence and canonical correspondence analyses) that allow the comparison of prediction levels between composition and structure for understanding avian assemblage composition in a temperate forestland in southeastern Ohio. Compositional (birds and woody plants) and structural (both vertical and horizontal dimensions) data were collected from point samples comprising a spectrum in topography and successional state. Total woody plant composition (11.22%) explained more (cross‐validatory) variation in avian species composition than structure, quantified with dense LiDAR recordings (7.35%) and field methods (6.31%). Plant composition assumed an integrative character, synthesizing aspects of environmental condition, structure, and most likely species‐specific preferences for tree and shrub species that structural indices alone could not for predicting avian species composition. These results conflict with the traditional view that structure be most influential to avian assemblage composition. Instead these results demonstrate that plant and avian assemblages are closely linked, and that plant species per se can be a powerful tool for predicting avian habitat. More importantly, in furthering ecological understanding, it is critical to consider the complex web of interacting processes that make up temperate forest ecosystems, in which composition occupies a key position.

Hysteresis and critical transitions in a coffee agroecosystem

Seeking to employ ecological principles in agricultural management, a classical ecological debate provides a useful framing. Whether ecosystems are controlled from above (predators are the limiting force over herbivores) or from below (overutilization of plant resources is the limiting force over herbivores) is a debate that has motivated much research. The dichotomous nature of the debate (above or below) has been criticized as too limiting, especially in light of contemporary appreciation of ecological complexity-control is more likely from a panoply of direct and indirect interactions. In the context of the agroecosystem, regulation is assumed to be from above and pests are controlled, a way of using ecological insights in service of an essential ecosystem service-pest control. However, this obvious resolution of the old debate does not negate the deeper appreciation of complexity-the natural enemies themselves constitute a complex system. Here we use some key concepts from complexity science to interrogate the natural functioning of pest regulation through spatially explicit dynamics of a predator and a disease operating simultaneously but distributed in space. Using the green coffee scale insect as a focal species, we argue that certain key ideas of complexity science shed light on how that system operates. In particular, a hysteretic pattern associated with distance to a keystone ant is evident.

An architectural understanding of natural sway frequencies in trees.

The relationship between form and function in trees is the subject of a longstanding debate in forest ecology and provides the basis for theories concerning forest ecosystem structure and metabolism. Trees interact with the wind in a dynamic manner and exhibit natural sway frequencies and damping processes that are important in understanding wind damage. Tree-wind dynamics are related to tree architecture, but this relationship is not well understood. We present a comprehensive view of natural sway frequencies in trees by compiling a dataset of field measurement spanning conifers and broadleaves, tropical and temperate forests. The field data show that a cantilever beam approximation adequately predicts the fundamental frequency of conifers, but not that of broadleaf trees. We also use structurally detailed tree dynamics simulations to test fundamental assumptions underpinning models of natural frequencies in trees. We model the dynamic properties of greater than 1000 trees using a finite-element approach based on accurate three-dimensional model trees derived from terrestrial laser scanning data. We show that (1) residual variation, the variation not explained by the cantilever beam approximation, in fundamental frequencies of broadleaf trees is driven by their architecture; (2) slender trees behave like a simple pendulum, with a single natural frequency dominating their motion, which makes them vulnerable to wind damage and (3) the presence of leaves decreases both the fundamental frequency and the damping ratio. These findings demonstrate the value of new three-dimensional measurements for understanding wind impacts on trees and suggest new directions for improving our understanding of tree dynamics from conifer plantations to natural forests.