Ecology History Research Articles

Towards Biocultural Conservation of Chilean Palm Landscapes: Expanding Perspectives from Historical Ecology

The Chilean palm (Jubaea chilensis) is an endangered and culturally important species from central Chile. We studied the Ocoa palm landscape (OPL), which is currently part of a protected area that harbors the largest Chilean palm population where local peasant practices have been excluded and conflict with biodiversity conservation strategies. We explored how human–landscape relationships over time have shaped present conditions and the implications for biocultural conservation. Methods included a review of archaeobotanical and historical records, and a qualitative study focused on local peasants’ perspectives. We reported the uses of J. chilensis and the OPL since pre-Hispanic times. For the last 400 years, these uses have involved important differences between landowners and local peasants in terms of power dynamics, access to the land, and intensity of use. The current palm landscape structure directly responds to past human activities, such as palm felling and agriculture. Also, we explain peasant practices linked to the OPL as ways of resisting cultural homogenization and marginalization associated with reductive conservation approaches and other presses and pulses. Chilean palm conservation can be improved by considering ecological legacies to inform future conservation strategies and adding a biocultural approach that respectfully integrates local peasant knowledge systems and worldviews.

Avian seed dispersal out of the forests: A view through the lens of Pleistocene landscapes

Abstract Recent evidence supports that, prior to the impact of modern humans, the temperate zone of Europe was not dominated by a closed continuous forest, but consisted of heterogeneous landscapes with grasslands, light woodlands and forests. Until the late Pleistocene, this region held a diverse community of megaherbivores that maintained the open and semi‐open vegetation through grazing and browsing. This new baseline is congruent with the fact that many European woody species are light‐demanding and fail to regenerate in the shaded interiors of temperate forests. Notably, most of these species are dispersed by frugivorous and seed‐caching animals, mostly birds. Nowadays, avian seed dispersers play a key role for the connectivity and expansion of woodland patches in fragmented anthropogenic landscapes. Indeed, avian seed dispersal within and across the deforested matrix is the norm rather than the exception. Here, I reflect on the current patterns of avian seed dispersal in the fragmented anthropogenic landscapes of Europe from a Pleistocene perspective. The aim of this exercise is to discuss linkages between past and present landscapes, seeking an historical understanding of the high spatial complementarity of avian seed dispersal in and out of the forests. Synthesis: I conclude that the spatial patterns of avian seed dispersal in anthropogenic landscapes are congruent with an ecological and evolutionary history with open and semi‐open habitats created and maintained by megaherbivores (ecological memory). By shaping the environmental conditions for millions of years, megaherbivores would have created selective pressures on animals and plants for life in landscape mosaics with forests and open habitats (niche construction). Finally, I discuss differences in landscape patterns today and in the Pleistocene, as well as the generality of these ideas to other biogeographical regions.

Charcoal morphotypes as indicators of fire fuel types and fire events along eight centuries in east‐central Mexico

ABSTRACTThe study of fire and charcoal production in tropical mesophytic ecosystems provides valuable insights into the ecological and climatic history of these systems. The diverse vegetation produces charcoal in various forms and sizes, which influences its dispersion and provides key information about fire dynamics. In this study, we used an approximately 850‐year sedimentary charcoal record extracted from Lake Atezca in east‐central Mexico to reconstruct the history of fire activity, including frequency and intensity. We present innovative information on charcoal morphotypes to interpret fire regimes, identify the types of vegetation burned and analyze human impact. The results reveal a shift in fire regimes during the Spanish Conquest, transitioning from local‐scale burning associated with intensive wood burning for indigenous agriculture to regional‐scale burning characterized by the burning of herbs and grasses linked to the expansion of extensive livestock grazing. This transition is reflected in the decrease of wood charcoal and the increase of smaller particles, as well as in the rise in titanium in the sediments, indicating greater landscape alteration. The evolution of fire regimes in Lake Atezca was driven primarily by human activities since pre‐Hispanic times, although climatic factors, such as severe droughts, may have also influenced fire activity.

Differential coping capacities underlie the overall resistance of temperate seagrasses to herbivory

AbstractGrazing can impart long‐lasting changes in vegetated ecosystems. How ecosystems respond to herbivory depends on the ecological and evolutionary histories of their foundational species. The overall ecosystem functioning and associated biodiversity depend on these responses but there is still little understanding on how the intensity and duration of herbivory interact and impact vegetated ecosystems. We experimentally tested in the field the responses of three seagrass species with distinct life history traits to increasing intensities of herbivory over time. Specifically, we assessed structural responses (i.e., canopy height and shoot density) to reflect the ecosystem state. Additionally, we used mechanistic models to assess induced and constitutive responses in the different seagrass species. Results show that seagrasses coped with herbivory differentially in relation to their life history traits. Posidonia oceanica (persistent species) was resistant and only registered declines in canopy height, whereas both canopy heigh and shoot density rapidly decreased for Cymodocea nodosa (intermediate‐colonizing species) and Zostera noltei (colonizing species). Seagrasses also differed in the type of structural response, with the colonizing species experiencing reductions in shoot density, and the persistent P. oceanica registering declines in canopy height. After months of exposure to cumulative herbivory, all three species showed signs of stability. Interestingly, none of the species disappeared completely even when exposed to extreme herbivory. Mechanistic models indicate that herbivory‐induced responses are a potential explanation for these patterns. This study suggests that given the long evolutionary history of herbivory, some seagrasses may be remarkably well adapted to both intense and cumulative herbivory.

Species identification of modern and archaeological shark and ray skeletal tissues using collagen peptide mass fingerprinting

IntroductionElasmobranchs, such as sharks and rays, are among the world’s most endangered vertebrates, with over 70% loss in abundance over the past 50 years due to human impacts. Zooarchaeological baselines of elasmobranch diversity, distribution, and exploitation hold great promise for contributing essential historical contexts in the assessment of contemporary patterns in their taxonomic diversity and vulnerability to human-caused extinction. Yet, the historical ecology of elasmobranchs receives relatively less archaeological attention compared to that of ray-finned fishes or marine mammals, largely due to issues of taxonomic resolution across zooarchaeological identifications.MethodsWe explore the use of Zooarchaeology by Mass Spectrometry (ZooMS) for species identification in this unstudied group, using an archaeological case study from the marine environments of the Florida Keys, a marine biodiversity hotspot that is home to an array of elasmobranch species and conservation efforts. By comparison with 39 modern reference species, we could distinguish 12 taxa within the zooarchaeological assemblage from the Clupper archaeological site (Upper Matecumbe Key) that included nine sharks, two rays and a sawfish.Results and discussionThe results indicate that, through additional complexity of the collagen peptide mass fingerprint, obtained due to the presence of the cartilaginous type II collagen, ZooMS collagen peptide mass fingerprinting provides exceptionally high taxonomic resolution in this group, yielding species-level identifications in all cases where sufficient reference material was used. This case study also highlights the added value of ZooMS for taxa that are more difficult to distinguish in zooarchaeological analyses, such as vertebrae of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) and the hammerhead sharks (Sphyrna spp.) in the Florida Keys. Therefore, the application of collagen peptide mass fingerprinting to elasmobranchs offers great potential to improve our understanding of their archaeological past and historical ecology.

Ecology and life history predict avian nest success in the global tropics

Nest predation rates critically influence avian biodiversity and evolution. In the north temperate zone, increased nest failure along edges of forest fragments is hypothesized to play a major role in the disappearance of bird species from disturbed landscapes. However, we lack comprehensive syntheses from tropical latitudes, where biodiversity is highest and increasingly threatened by habitat fragmentation and disturbance. We assembled data from five decades of field studies across the global tropics (1,112 populations of 661 species) and used phylogenetic models to evaluate proposed predictors of nest success. We found significant effects of several traits, including adult body mass and nest architecture. Contrary to results from many temperate locations, anthropogenic habitat disruption did not consistently reduce nest success; in fact, raw nest success rates were lower in large tracts of primary forest than in disturbed or fragmented landscapes. Follow-up analyses within species, using a subset of 76 species for which we had estimates of nest survival in habitats with different levels of disruption, confirmed that neither disturbance nor fragmentation significantly influenced nest success. These results suggest that nest predation alone cannot explain observed declines in avian biodiversity in tropical forest fragments, raising new questions about the demographic processes that drive extinction in the tropics.

Indigenous use and conservation of harbor seals (Phoca vitulina) at Yakutat, Alaska since the sixteenth century

Sustainable Indigenous resource use reflects balance between animal populations and levels of human consumption, influenced by natural cycles of faunal abundance, community size and subsistence needs, procurement technologies, and the requirements of trade or commodity production. Sustainability is “epiphenomenal” when animal populations are preserved, and community needs met, without deliberate measures to prevent overharvesting. Alternatively, Indigenous conservation—cultural practices that moderate use of a resource to prevent its depletion—may play a determinative role. In this study from the Tlingit community of Yakutat, Alaska in the Northwest Coast cultural region, we interweave Indigenous and scientific perspectives to trace the use and conservation of harbor seals (Phoca vitulina) from before Western contact through the Russian and American colonial periods to the present. Harbor seals, which concentrate in large numbers at a summer ice floe rookery near Hubbard Glacier, are the community's most important subsistence food and a key to its culture and history. The Smithsonian Institution and Yakutat Tlingit Tribe undertook collaborative research in historical ecology and archaeology in 2011–2014 including oral interviews with elders and subsistence providers, excavations at sealing sites, archaeofaunal analysis, historical and archival research, and consideration of climate cycles and biological regime shifts that influence the harbor seal population in the Gulf of Alaska. We compare technologies and hunting practices before and after Western contact, estimate harvest levels in different periods, and evaluate the effectiveness of traditional conservation practices that included hunting quotas enforced by clan leaders and the seasonal delay of hunting with firearms to prevent abandonment of the rookery by the seal herd.

Unveiling Thrips (Thysanoptera) as Nature's Unsung Pollinators: A Survey From Obligatory Thripophily to Thrips as Supplementary Pollinators

ABSTRACTThrips are minute, paraneopteran insects with diverse ecological histories and plant associations, encompassing herbivory, fungivory, pollination and predation. They are typically not widely adored insects as many species are regarded to be destructive crop pests and vectors of crop diseases. Nevertheless, certain thrips play a significant role in pollination as they traverse from flower to flower with pollen attached to their bodies. However, most studies on relationships between flowering plants and pollinators have overlooked the prevalence and association of thrips with flowers, and the pollination services were often incorrectly attributed to wind, bees or other agents. This is primarily due to the minute size and cryptic behaviour of thrips, their limited range of movement and minimal structural modifications to carry and disperse pollen. In recent times, the involvement of thrips in pollination was investigated by many researchers and their role was established partly or fully in several angiosperm families. Their role in pollination through specialised thripophily, as minor or secondary pollinators, or via ambophily is well‐established now. The present paper reviews the evidence of pollen transfer by thrips, obligate and nonobligate pollination relationships between plants and pollinator thrips, evolutionary aspects of thripophily, morphological and physiological adaptations in thrips and floral syndromes associated with thripophily.

Can Current Grazing Practices Preserve Biodiversity in Semi-natural Pastures? A Study of the Historical Ecology of Swedish Infield Pastures

In order to preserve the biodiversity and cultural heritage in semi-natural pastures, it is important to manage each type of pasture in a way that resembles the historical land use that has shaped the ecosystem. We monitored the grazing regime in 28 pastures in Sweden from 1987 to 2012, and compared their management with the historical grazing regimes. The studied pastures, as well as a majority of the remaining high nature value pastures in Sweden, are located in historical infield areas, where grazing was determined by the system of fencing and use of meadows and arable fields, the so-called cultivation system. Using various sources, we compiled information about the major Swedish cultivation systems and interpreted their significance for the grazing regime. Historical grazing regimes are characterized by frequent late grazing and interannual variations in grazing period and grazing pressure. In contrast, the current grazing is rather intense through the entire summer and with little between-year variation. Also, the grazing in the 1980’s and 1990’s was considerably more varied and less intense than it is today. A pronounced shift in pasture management took place in the late 1990’s, and interviews with the farmers show that the shift was mainly caused by the criteria for agri-environment subsidies. Interviews also show that the subsidies have been important for continued use of the semi-natural pastures. We claim that the differences between current and historical grazing regimes constitute a severe threat to pasture biodiversity, and that it is urgent to adjust the eligibility criteria for agri-environment payments.

Towards biocultural realism: Connecting conservation with historical ecology and common sense. A European perspective.

In this perspective, we present and discuss four major causes of the worldwide nature conservation failure: 1) ideologies based on nature-culture dualism, 2) the bias prioritising forests in conservation, 3) the illusory objectiveness of selected biological indicators, and 4) the mismanagement of rural agricultural landscapes. All of these relate to ignorance of historical ecology and neglect of the role past plays in shaping landscapes and fostering biodiversity. These led to a false anthropology focussed on the broader human economy (including agriculture) as the absolute culprit of biodiversity loss. It is believed, therefore, that biodiversity preservation depends on conservation policies and actions providing protection against human activities, such as farming. In this way, nature conservation has been detached from the rich experiences of long and fruitful coexistence of people with other elements of nature. The bio-cultural legacy includes biodiversity-rich rural landscapes, whose habitats are often either neglected or wrongly interpreted as "remnants of natural ecosystems". Consequently, conservation efforts are frequently ineffective or worse still, counter-effective. In the face of policies favouring subsidised intensive agribusiness at the cost of destroying smallholder family farming, even expensive conservation projects are usually nothing more than a "fig leaf" to cover failure. We advocate re-focussing of conservation planning to put more emphasis on landscapes' historical ecology responsible for their bio-cultural diversity. It implies the need for new principles in policies necessary to secure the economic and cultural sovereignty of local socio-ecological systems responsible for the world's bio-cultural diversity.

Shape variability and morphological discrimination of haptoral attachment structures in Urocleidoides spp. Mizelle et Price, 1964 (Monogenea: Dactylogyridae) parasitizing fish from neotropical rivers in southern Mexico

The morphology of attachment organs in Monogenea is an essential source of evidence for taxonomic assessments and understanding of ecology and evolutionary history. It has been demonstrated that geometric morphometry analysis of the haptoral attachment organs provides rich and precise information about monogeneans morphology. In this study, we consider three monogenean species of Urocleidoides, U. simonae, U. vaginoclaustrum, U. vaginoclaustroides, and the incertae sedis species U. strombicirrus that parasitize fish of the Poeciliidae, Profundulidae and Characidae in neotropical rivers in southern Mexico. We aimed to identify new morphological characteristics that can be used to describe these populations with greater certainty and to test whether these characteristics present geographic variation. Anchor shape data (n = 69) were generated using geometric morphometric methods. We discriminated species using principal components and canonical variate analysis of shape data. Our results showed that there was discernible interspecific variation. The four species contributed four new morphological characteristics: anchor point length, short versus long anchor roots, elongated versus wide anchor shape, and the relative length of inner versus outer roots. Intraspecific variation was relatively low compared to interspecific anchor shape variation in Urocleidoides spp. These new morphological characteristics may also be useful for delimiting other similar species in Monogenea.

Enhancing biodiversity: historical ecology and biogeography of the Santa Catalina Island ground squirrel, Otospermophilus beecheyi nesioticus.

People have influenced Earth's biodiversity for millennia, including numerous introductions of domestic and wild species to islands. Here, we explore the origins and ecology of the Santa Catalina Island ground squirrel (SCIGS; Otospermophilus beecheyi nesioticus), one of only five endemic terrestrial mammals found on California's Santa Catalina Island. We synthesized all records of archaeological/palaeontological SCIGS, conducted radiocarbon dating and stable isotope analysis of the potentially earliest SCIGS remains and performed genetic analysis of modern SCIGS. Squirrels were not identified in island palaeontological deposits, but at least 12 island archaeological sites contain SCIGS bones, including some that are butchered or burned. All directly dated SCIGS bones are Late Holocene in age and younger than approximately 1290 cal BP. The first mitochondrial genome for modern Otospermophilus beecheyi and 15 modern SCIGS mitogenomes document at least one introduction of squirrels. Stable isotope data indicate variable SCIGS diets and potential subsidies from marine environments to terrestrial plants consumed by some individuals. We cannot rule out a natural overwater dispersal, but the earliest SCIGS remains post-date the earliest evidence for people by several millennia and, along with other lines of evidence, support a human-assisted translocation of squirrels during the Late Holocene. These data illustrate the important role of Indigenous people in shaping and enhancing island biodiversity and ecology around the world.

Influenza A Viruses in the Swine Population: Ecology and Geographical Distribution.

Despite the efforts of practical medicine and virology, influenza viruses remain the most important pathogens affecting human and animal health. Swine are exposed to infection with all types of influenza A, B, C, and D viruses. Influenza viruses have low pathogenicity for swine, but in the case of co-infection with other pathogens, the outcome can be much more serious, even fatal. Having a high zoonotic potential, swine play an important role in the ecology and spread of influenza to humans. In this study, we review the state of the scientific literature on the zoonotic spread of swine influenza A viruses among humans, their circulation in swine populations worldwide, reverse zoonosis from humans to swine, and their role in interspecies transmission. The analysis covers a long period to trace the ecology and evolutionary history of influenza A viruses in swine. The following databases were used to search the literature: Scopus, Web of Science, Google Scholar, and PubMed. In this review, 314 papers are considered: n = 107 from Asia, n = 93 from the U.S., n = 86 from Europe, n = 20 from Africa, and n = 8 from Australia. According to the date of publication, they are conditionally divided into three groups: contemporary, released from 2011 to the present (n = 121); 2000-2010 (n = 108); and 1919-1999 (n = 85).

Captive Breeding Reveals Insights Into the Ecology and Reproductive Biology of 11 Little-Known Malagasy Frog Species.

Amphibians are facing an extinction crisis, with ex situ programs increasingly being used as a tool for their conservation. However, conservation efforts are often limited because we do not understand the ecological, behavioral, and life history traits of many amphibian species. Here, we report on the seasonal breeding patterns, egg-laying behavior, clutch size, and development of 11 frog species maintained at a conservation breeding facility in Andasibe, Madagascar. The frogs exhibited diverse breeding strategies aligned with life history theory. Counting the eggs in 1239 egg masses across these 11 species, we found endotrophic microhylids and terrestrial-breeding species had the smallest clutch size yet completed metamorphosis quickly, whereas species that laid eggs above or in water with exotrophic larvae had larger clutch sizes and took longer to develop. Most reproduction in captivity occurred during the warm, rainy season and followed seasonal patterns in temperature variation. Yet, Mantidactylus betsileanus bred throughout the year, and Heterixalus betsileo required additional environmental stimuli to trigger reproduction. Notably, we confirmed that Gephyromantis mitsinjo lays eggs on land with tadpoles developing terrestrially within jelly, a behavior previously theorized but which until now remained unobserved. Such observations show how captive breeding programs can be used to gain valuable data on the life history traits of species that are otherwise challenging to observe in nature. Our findings can be used to assess threats to closely related species, helping inform conservation efforts in a country harboring exceptional amphibian species richness and endemism.

Designing fit‐for‐purpose monitoring – A case study of a cryptic songbird

AbstractMonitoring threatened species is essential for understanding their conservation needs and developing effective recovery strategies. However, designing and implementing monitoring programs can be challenging in resource‐constrained environments, where conservation practitioners must balance the need for detailed information with limited resources. We present a case study focusing on the design of a range‐wide monitoring program for the Endangered rufous scrub‐bird (Atrichornis rufescens) in the mountain forests of eastern Australia. We first developed a ‘wish list’ of monitoring questions and then trialed the methods needed for answering them using sequence of pilot studies. We implemented a phased approach comprising (i) a study of whether individuals could be identified by their songs, (ii) identification of a ‘core range’ using species distribution models to refine the search area, and (iii) a trial of the efficacy of a preferred feasible monitoring approach. We offer a practical pathway for designing question‐driven monitoring programs for threatened species. Our study highlights the importance of clarifying explicit monitoring goals and tailoring methods to suit species' ecological and life history characteristics. By following this systematic approach, conservation efforts can obtain valuable information for effective management, even with limited resources and prevailing uncertainty about species ecology.

The Functional Comparison of Eukaryotic Proteomes: Implications for Choosing an Appropriate Model Organism to Probe Human Biology.

Phenotypic differences between species are, in significant part, determined by their proteomic diversity. The link between proteomic and phenotypic diversity can be best understood in the context of the various pathways and biological processes in which proteins participate. While the conservation pattern for individual proteins across species is expected to follow the phylogenetic relationships among the species, the diversity patterns of individual pathways may not: certain pathways may be much more conserved among distantly related species than two closely related species, owing to the ecological histories of the species. Thus, a pathway-centric analysis of proteome conservation and diversity has important implications for the appropriate choice of a model organism when investigating specific aspects of human biology. Exploiting the complete genome sequences and protein-coding gene annotations, here we perform a comprehensive gene-set-centric analysis of proteomic diversity between humans and 54 eukaryotic organisms, resulting in a catalog of organisms that are most similar to humans in terms of specific pathways, processes, expression patterns, and diseases. We corroborate our findings using species-specific mass spectrometry data.Our analysis provides a general framework to identify conserved and unique pathways in a group of organisms and a resource to prioritize appropriate model systems to study a specific biological system in a reference organism such as humans.

Settlement Patterns and Built Environment at the Archaeological Site of Yalahau, Yucatan

ABSTRACT The Parque Estatal de Yalahau Project is a multidisciplinary effort combining archaeology, paleoecology, and historical ecology. The initial analysis focuses on settlement patterns within the Protected Natural Area of Parque Estatal de Yalahau-Yucatan, Mexico. The research uses a conceptual framework integrating humans, non-human species, and geological/climatic forces into a holistic, historical landscape approach, where humans shaped and symbolically interpreted their surroundings, leaving tangible impacts. The study situates findings within the Maya region, contributing to the growing recognition that the ancient Maya shaped sustainable landscapes rather than degrading the environment. The discussion centers on three key aspects of the Prehispanic Yalahau landscape: 1) settlement patterns in wetlands; 2) Maya environmental engineering and the absence of water stress; and, 3) landscape as an expression of sociopolitical strategy. The Yalahau site demonstrates how the Maya thoughtfully blended urban spaces with plants, animal ecologies, and water resources, reflecting deep social understanding of terrain and wetlands.

Ancient Fishing Strategies for the Extinct Thicktail Chub (Gila crassicauda) in the Sacramento-San Joaquin Delta

ABSTRACT Now extinct, Thicktail chub (Gila crassicauda) was endemic to central California and was a key component of local fisheries before the 1800s. Little is known about their biology, behavior, ecology, or role in precontact Native American fisheries. Archaeological sites contain large numbers of thicktail chub bones and represent a key source of data to fill our considerable gap in knowledge. We developed regression equations to convert thicktail chub skeletal elements to estimates of standard length (SL). Bones from two contemporaneous precontact Late Period (ca 700 -200 cal BP) sites, CA-CCO-138, and CA-CCO-647, in the Sacramento-San Joaquin Delta, show that precontact thicktail chub achieved a maximum standard length (SL) of 306 mm. Bone size distributions suggest spearing was the most likely capture technique, likely during a spring-summer nearshore fishery. The results contribute vital information to thicktail chub historical ecology and their key role in precontact Indigenous fisheries.

Testing for allocation strategies and evolutionary tradeoffs in the bivalve shell

ABSTRACT Tradeoffs are a fundamental aspect of evolution, such that organismal morphologies often reflect a combination of developmental constraints and functional requirements. The net result is a striking variety of allocation strategies—where and how resources are shunted into aspects of the body plan to meet these competing demands. The bivalve shell records aspects of the animal's allocation strategies as the relative investment in the carbonate valves and the internal soft parts, generally reflected by the volume of the internal cavity. The carbonate volume can be further partitioned among different components of the shell, including the sculptural elements thought to evolve partly under ecological controls. Assuming there are general limits to energy acquisition, bivalve individuals may show different allocations between the volumes of the inner cavity and shell, and possibly for the sculpture. Using 3D scans of 385 valves representing 339 extant marine species occurring in the Florida Keys, USA, we find a variety of allocation strategies but that tradeoffs in shell construction are uncommon. Instead, species with relatively high allocations to their shell thickness also have prominent sculpture, suggesting a structural relationship. Neither outer shell mineralogy nor microstructure appears to partition the tradeoff space, suggesting varied pathways to the fabrication of both convergent and divergent shell forms. Framing new morphological and physiological analyses of bivalves by allocation strategies recorded in their well-fossilized shells opens new opportunities for understanding an under-studied, macroevolutionary dynamic: how tradeoffs have shaped the class's 500 million-year evolutionary and ecological history.

Cycles, Breakthroughs, and Histories of Ecological Change: 1949 or 1972?

These reflections on Stevan Harrell’s An Ecological History of Modern China evaluate the book in relation to existing historiography of the ecological transformations that have accompanied China’s development since the founding of the People’s Republic of China (PRC). After outlining the theoretical underpinnings of Harrell’s history of modern China as a “system of social-ecological systems” and his revisionist periodization of PRC history in terms of the “adaptive cycle,” the commentary contrasts Harrell’s central arguments with those advanced in earlier studies. Interpretative differences relate to whether 1949 constituted a watershed in China’s ecological history or a continuation of longer-term environmental trends, and the significance of the PRC’s acquisition of technology for synthetic fertilizer plants after rapprochement with the United States in 1972 in making it possible for China to replenish its nutrient-depleted soils, increase agricultural productivity, and overcome environmental constraints that limited economic growth. Despite bringing unprecedented economic prosperity, as Harrell shows, that growth has decreased ecological resilience and increased vulnerability. The commentary concludes by asking how Harrell’s arguments might be reconciled with alternative understandings of modern China’s ecological and environmental history.