A left-variable word over an alphabet A is a word over $A \cup \{\star \}$ whose first letter is the distinguished symbol $\star $ standing for a placeholder. The ordered variable word theorem ($\mathsf {OVW}$), also known as Carlson–Simpson’s theorem, is a tree partition theorem, stating that for every finite alphabet A and every finite coloring of the words over A, there exists a word $c_0$ and an infinite sequence of left-variable words $w_1, w_2, \dots $ such that $\{ c_0 \cdot w_1[a_1] \cdot \dots \cdot w_k[a_k] : k \in \mathbb {N}, a_1, \dots , a_k \in A \}$ is monochromatic.

In this article, we prove that $\mathsf {OVW}$ is $\Pi ^0_4$-conservative over $\mathsf {RCA}_0 + \mathsf {B}\Sigma ^0_2$. This implies in particular that $\mathsf {OVW}$ does not imply $\mathsf {ACA}_0$ over $\mathsf {RCA}_0$. This is the first principle for which the only known separation from $\mathsf {ACA}_0$ involves non-standard models.

Changing human behaviours is a key facet of addressing global environmental issues. There are many factors (i.e. determinants) that could influence whether an individual engages in pro-environmental behaviour, and understanding these determinants can improve efforts to protect and restore the natural environment. However, despite published criticism of poor survey design, there is little practical guidance on how to capture these determinants accurately in closed-answer surveys (those with predefined answer options). A recent literature review summarized behavioural determinants of pro-environmental behaviour. We build on this by providing practical insights into how 17 key pro-environmental behavioural determinants can be measured through closed-answer surveys. We reviewed 177 papers published during 2013–2023 that met the criteria for inclusion. These papers captured 624 measurements of the 17 determinants. We found seven types of question formats used, including scales (Likert scales, semantic scales and a pictorial scale), multiple-choice questions (where respondents could select either one or more answer options), binary questions and ranking questions. We then synthesized design considerations both specifically for each format and more broadly across surveys. These considerations included using validated measures, reducing cognitive burden and biases (e.g. social desirability bias, order effects, recall bias), selecting the question format (e.g. different formats of multiple-choice or binary questions) and using best practices for scale questions. The insights collected through this review provide practical advice for developing closed-answer surveys that robustly and usefully measure key determinants of pro-environmental behaviour.

Birds are often used as ecological indicators because they are widely distributed across diverse habitats and display distinct behavioural responses to environmental changes. The Endangered Grey Crowned Crane Balearica regulorum is regarded as a flagship species of Africa’s wetland and grassland habitats, both of which are undergoing substantial transformation to alternative land uses. The delayed reproductive strategies and habitat specialisation of this crane species makes them more vulnerable to extinction, but this risk is further compounded by data paucity. We employed traditional and contemporary survey methods to collect breeding metrics to calculate stage transition probabilities (i.e. egg–hatchling, hatchling–juvenile) and to identify possible macro-environmental factors that either promote or hinder their reproductive output in a key agricultural area in KwaZulu-Natal, South Africa. We found that Grey Crowned Cranes have a low hatching rate of 38.4% (95% confidence interval 29.3–48.4%) and show that this low hatching rate is exacerbated under high rainfall intensity. Multivariate analyses and multi-model inference revealed that successful nest-sites were generally associated with larger open water-bodies, greater distances from shore, and increased proximity to secondary roads, buildings, and natural grasslands. Although increased agricultural activities might promote greater foraging opportunities, the overall breeding outcomes of this species were poor in this key agricultural region. Our findings stress the urgent need for further fine-scale data collection and monitoring activities to better inform conservation strategies for this species. We also encourage future studies to focus on aspects affecting Grey Crowned Crane breeding in regions where proximity to human activities is inevitable.

Satellite remote sensing is vital for monitoring anthropogenic changes and for alerting us to escalating environmental threats. With recent technological advances, a variety of satellite-based monitoring systems are available to aid conservation practitioners. Yet, documented knowledge of who uses near-real-time satellite-based monitoring and how these technologies are applied to inform conservation decisions is sparse. Through an online survey and semi-structured interviews, we explored how developers and users leverage conservation early-warning and alert systems (CEASs) for enhanced conservation decisions. Some 167 developers and users of near-real-time fire and forest monitoring systems from 40 countries participated in this study. Globally, respondents used 66 unique CEASs. The most common applications were for education and awareness, fire/disaster management and law enforcement. Respondents primarily used CEASs to enforce land-use policies and deter illegal activities, and they perceived these tools as underutilized for incentivizing policy compliance or conservation. Respondents experienced inequities regarding system access, exposure and ability to act upon alert information. More investments in capacity-building, resources and action plans are needed to better link information to action. Implementing recommendations from this research can help us to increase the accessibility and inclusivity of CEAS applications to unlock their powerful capabilities for achieving conservation goals.

Biodiversity is in rapid decline, but the extent of loss is not well resolved for poorly known groups. We estimate the number of extinctions for Australian non-marine invertebrates since the European colonisation of the continent. Our analyses use a range of approaches, incorporate stated uncertainties and recognise explicit caveats. We use plausible bounds for the number of species, two approaches for estimating extinction rate, and Monte Carlo simulations to select combinations of projected distributions from these variables. We conclude that 9,111 (plausible bounds of 1,465 to 56,828) Australian species have become extinct over this 236-year period. These estimates dwarf the number of formally recognised extinctions of Australian invertebrates (10 species) and of the single invertebrate species listed as extinct under Australian legislation. We predict that 39–148 species will become extinct in 2024. This is inconsistent with a recent pledge by the Australian government to prevent all extinctions. This high rate of loss is largely a consequence of pervasive taxonomic biases in community concern and conservation investment. Those characteristics also make it challenging to reduce that rate of loss, as there is uncertainty about which invertebrate species are at the most risk. We outline conservation responses to reduce the likelihood of further extinctions.

A natural population of Vriesea friburgensis var. paludosa was genetically and demographically characterized. Four selected enzymatic systems were used. In total, 10 allozymic loci were analysed. The proportion of polymorphic loci was 70% and the number of alleles per locus was 2.3· The mean observed and expected heterozygosities were 0.234 and 0.226, respectively. An excess of heterozygotes was revealed by the value of the fixation index (—0.035). These indices showed the presence of high levels of genetic diversity in the population studied. A demographic survey revealed almost six times more vegetative than sexually reproductive plants. Reproductive plants were found only in clusters. The genetic diversity exhibited by this population, associated with vegetative as well as sexual propagation, resulting in clusters or colonies, would allow the employment of a sustainable management strategy for species conservation as well as its exploitation as an ornamental.

The technique of excised embryos was employed to facilitate the propagation of Podophyllum emodi derived from seeds collected at the different elevation zones of Himachal Pradesh, India. Seed germination was low, irrespective of stage of seed development or zone of collection. Germination was improved significantly (89.14%) in the partially mature and mature seeds collected from alpine and temperate zones when excised embryos were cultured on basal B5 medium. Leaf emergence and plant establishment in the field was also significantly higher in the plants raised through this technique, despite hypocotyl dormancy. The technique was successfully employed for the production of plants to be reintroduced in large numbers into their habitat in the Great Himalayan National Park.

The grasslands of Central Anatolia in Türkiye, including the steppes and forest-steppes, are often mischaracterized as degraded ecosystems due to long-standing human activities, particularly agriculture and domestic grazing. However, palaeoecological evidence and recent research suggest that these grasslands are ancient, biodiversity-rich systems that have persisted through various climatic changes and disturbance regimes. This manuscript challenges the conventional view that Central Anatolian grasslands are secondary and degraded, arguing instead that they represent old-growth ecosystems that coexisted with forests as alternative biome states throughout history. We emphasize the need to re-evaluate current land management practices, particularly afforestation efforts, which may undermine the resilience of these ecosystems to climate change. By recognizing the ecological value of these old-growth grasslands and adopting a comprehensive conservation strategy, the conservation and restoration of these vital ecosystems can be improved, ensuring their resilience and biodiversity in the face of future environmental challenges.

Contrary to the common perception of hyperarid drylands as barren and lifeless, these regions are home to some of the planet’s most unique biodiversity and support over 100 million people. Despite their ecological and human significance, hyperarid drylands remain among the least studied biomes in the world. In this article, we explore how improving our understanding of hyperarid ecosystems in the Middle East can yield valuable insights applicable to other hyperarid regions. We examine how ongoing greening initiatives in the Middle East offer a unique opportunity to deepen our knowledge of dryland ecology and advocate for the establishment of a comprehensive research program in the region. This program would focus on ecosystem functionality across spatial and temporal scales, setting the stage for a global monitoring network for hyperarid drylands. Such efforts would inform conservation strategies and climate change mitigation, while also shedding light on the resilience and adaptability of hyperarid ecosystems to environmental change. Ultimately, this monitoring would guide management practices to preserve biodiversity, enhance ecosystem services and promote sustainable development in hyperarid regions worldwide.

Seahorses Hippocampus spp. are commercially and culturally important to many communities. Although seahorses are widely used in traditional medicine, as curios and as aquarium fishes in Southeast Asia, documentation on the current nature and extent of culturally motivated seahorse uses in Malaysia is lacking. To examine how ethnicity and other socio-demographic drivers shape traditional medicinal use and underlying cultural beliefs involving seahorses, we administered a questionnaire-based survey during March 2021–April 2022 to members of the general public and fishers in Malaysia. Approximately one-fifth (21.0%) of respondents reported consuming seahorses (34.4% of these used seahorses for medicinal purposes, 55.2% for other non-medicinal uses and 10.4% for both types). Consumers of seahorses were from all ethnic groups except for Indigenous groups. In the general public group, medicinal use was more common amongst the Chinese respondents, whereas in the fisher group, other uses were more common amongst the Malay respondents. Amongst the threats facing seahorses, which include overfishing, habitat destruction, bycatch and ocean plastic pollution, only bycatch was perceived as a major threat by most of the general public and fisher respondents. The relatively low prevalence of reported seahorse use amongst Malaysians is an encouraging finding from a conservation perspective. However, the high proportion of non-medicinal uses indicates the need to focus on such other uses to ensure the sustainability of seahorse use in Malaysia.

The additionality of forest conservation interventions is frequently questioned. In particular, they are often considered to be located in places where forests are not threatened, which points to the existence of location biases. Revisiting this location bias concept, we conceptually distinguish potential and effective additionality and theoretically consider how the objectives of the implementer affect the siting choice of the forest conservation interventions and their additionality. Our theoretical intuition is that the choices of the implementers are influenced by the quality of institutions. Our results show that (1) the implementer's objective and local institutions may lead the implementer to select a site with low development potential and low forest threat, and (2) the selection of a site with low development potential, which is frequently presented as a location bias, does not necessarily preclude additionality.