No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Identifying habitat modification by Chinese pangolin in subtropical forests of southern China
Abstract
The excavation of Chinese pangolin ( Manis pentadactyla ) is expected to alter habitat heterogeneity and thus affect the functioning and structure of forest ecosystems. In this study, the bioturbation of Chinese pangolin on forest soils in three regions (Heping, Tianjingshan, and Wuqinzhang) across Guangdong province was quantified. Overall, a mean of 2.66 m ³ ·ha ⁻¹ and 83.1 m ² ·ha ⁻¹ of burrows and bare mounds, respectively, was excavated by Chinese pangolin; the disturbed soils had significantly lower water content and P, C, available N concentrations, but higher bulk density, pH, and microbial abundance than those undisturbed soils. The unevenness of habitat heterogeneity improvement was mainly ascribed to the stronger soil disturbance caused in resting burrows by pangolins. Patterns of altering habitat heterogeneity were site‐specific, with high‐intensity soil disturbance occurring most in shrubs, meadows, steep habitats at high elevations, and mountain tops in Heping, while in broad‐leaved, coniferous and mixed coniferous and broad‐leaved forests away from human settlements in Tianjingshan and upper mountains at high elevations far away from roads and human settlements in Wuqinzhang. Road networks are the main interference for the burrow distribution in Heping and Wuqinzhang and should be programmed.
... The Chinese pangolin (Manis pentadactyla Linnaeus, 1758) is one of the four extant pangolin species in Asia, distributed across South Asia, Southeast Asia, and East Asia, including Hainan Island and Taiwan (Corlett, 2007;Wu et al., 2020). As an ecological engineer, the Chinese pangolin significantly influences habitat heterogeneity, impacting the structure and function of forest ecosystems (Sun et al., 2024a). Over recent decades, its population has declined drastically due to poaching for traditional medicines, dietary supplements, leather products, and decorative items (Challender et al., 2014;Shirley et al., 2023). ...
... As obligate myrmecophagous mammals, Chinese pangolins almost exclusively prey on ants and termites, often excavating burrows to access soil-inhabiting prey (Sun et al., 2020a;Chao et al., 2020). Consequently, pangolin burrows are typically classified as either resting (or resident) or feeding burrows (Sun et al., 2021b(Sun et al., , 2024aSabin et al., 2024). However, pangolins may also excavate burrows for multiple reasons. ...
The Chinese pangolin Manis pentadactyla, a burrowing mammal, relies on burrows for foraging, shelter, and rearing its young. Pangolin burrows are typically classified as either resting (or resident) or feeding burrows. Resting burrows, in particular, are crucial for the pangolin’s survival, offering shelter, protection, and stability for the pangolin, especially during colder months and breeding seasons. Consequently, understanding the characteristics and usage patterns of resting burrows is critical for effective in-situ and ex-situ conservation efforts. This study assessed the density of resting burrows using sign surveys along line transects in a fragmented agricultural landscape. Additionally, radio telemetry was employed to specifically locate and characterize the resting burrows of seven Chinese pangolins (1 male and 6 females), as well as to analyze their usage patterns. The results revealed a burrow density of 110.8 per ha, with no significant variation across different environments. However, Chinese pangolins preferred resting burrows in areas with minimal human disturbance. Over tracking periods ranging from 52 to 327 days, female pangolins used between 12 and 32 resting burrows, while a single male pangolin used 48 resting burrows. Pangolins occupied individual burrows for up to 10 days during colder months and breeding seasons. Notably, resting burrows were frequently shared among individuals. Activity patterns showed that pangolins typically exited their burrows between 6:00 PM and 12:00 AM and entered their burrows between 10:00 PM and 4:00 AM. To conclude the findings:1) burrow count, while useful for identifying pangolin presence, is not a suitable quantitative indicator of population density. 2) Most resting burrows had compacted soil at the entrance, which could be mistaken for old or inactive burrows in other studies. 3) Resting burrows function as permanent structures that are reused across seasons instead of seasonal adaptations. 4) Preserving low-disturbance habitats will be critical for ensuring sufficient resting burrow sites, thereby supporting the long-term viability of pangolin populations. These results provide valuable insights into the usage patterns of resting burrows, thus enriching the understanding of pangolin behavior, ecological requirements and conservation strategies for this endangered species.
... The soil heaps around these burrows were smaller, consisting of fine and loose soil resulting from superficial digging activity, whereas the resting burrows featured more circular entrances and larger soil heaps that contained a mix of fine and coarse particles, reflecting the varied soil layers excavated during construction. The soil around resting burrows also appeared more compact due to repeated use and the need for structural stability (Sun et al. 2025). The opening diameter of each burrow was measured using a measuring tape, whereas the GPS location of the burrows was recorded using a handheld Garmin GPS Map 60 CSx. ...
Chinese pangolins are found from lowlands to mid‐hills in Nepal and are increasingly vulnerable to extinction due to extensive illegal trade and habitat fragmentation, particularly outside the protected areas network. The information about their ecological preferences in human‐dominated landscapes beyond protected areas is essential for effective habitat management and conservation. This study aimed to assess the density and characteristics of Chinese pangolin burrows, and analyze the key ecological and anthropogenic factors influencing their burrow occurrence in Katari municipality, Udayapur District, Eastern Nepal. We employed a total of 52 strip transects, each of 500 m long and 20 m wide, divided into two 250‐m sections on either side of the main transect and spaced 200 m apart to examine the pangolin burrows. We recorded a total of 124 active burrows and 114 inactive burrows, with a density of 2.38 active burrows per hectare. A higher number of burrows (80.25%) were recorded in the forest habitat, suggesting a discrepancy in burrow distribution across the study area. The majority of the burrows were distributed at 601–800 m above sea level (33.61%), 35°–45° slope (53.78%), and 0%–25% canopy cover (52.94%). The Welch Two‐Sample t‐test suggested that there was a significant difference in the burrow opening diameter between feeding and resting burrows. Among the 15 pre‐determined ecological parameters measured during the study, a generalized linear mixed model (GLMM) identified 9 ecological parameters as significant variables influencing the Chinese pangolin burrow occurrence in the study area. These were elevation, habitat type, canopy cover, livestock grazing, anthropogenic disturbance, presence or absence of fire, and nearest distance to water sources, roads, and settlements. Long‐term habitat management plans and strategies are recommended, with an emphasis on minimizing anthropogenic disturbances both in forest and farmland areas, and proper preservation of nearby water sources.
The burrow microhabitats created by burrowing mammals, as a hotspot for biodiversity distribution in ecosystems, provide multiple critical resources for many other sympatric species. However, the cascading effects of burrow resources on sympatric animal community assemblages and interspecific interactions are largely unknown. During 2020–2023, we monitored 184 Chinese pangolin ( Manis pentadactyla ) burrows using camera traps to reveal the burrow utilization patterns of commensal species. We totally recorded up to 57 species, with 19 mammal species, 32 bird species, and 1 reptile species recorded in the burrows revisited by Chinese pangolin, with 19 mammal species and 25 bird species in the non‐revisited burrows. Among them, most bird species as peripheral species primarily utilize soil mounds while most mammal species as burrow‐used species utilize burrow tunnels. The structure of animal communities in the burrows revisited by Chinese pangolins is more complex than that in the burrows not revisited. Furthermore, the positive correlation between community species in pangolin‐revisited burrows is also stronger. Our results demonstrate that the presence and repeated visitation by Chinese pangolins could enhance positive interactions (i.e., the emergence of one species promotes the emergence of another) among species that utilize the burrow resources (particularly, burrow‐used species). Our study provides the first evidence that the ecological role of the Chinese pangolin and its associated burrow microhabitats in promoting the coexistence of burrowing commensals and the restoration of Chinese pangolin populations may potentially contribute to the restoration of local biodiversity and ecological processes.
Simple Summary
As one of only eight species of pangolin, the Chinese pangolin (Manis pentadactyla) of Nepal inhabits forests, agricultural lands, and grasslands. Its population is declining due to hunting and habitat loss, and it is listed as critically endangered. Accurate information on its habitat and diet can aid in the development of site-specific management plans. Habitat characteristics such as forest canopy cover, slopes, and distance to agricultural lands and the nearest ant nests are important factors influencing the occurrence of the Chinese pangolin. Fecal analysis revealed that the ant species Aphaenogaster symthiesii, Camponotus sp., Monomorium sp., and Pheidole sp. were the dominant prey in the Chinese pangolin’s diet. This study provides baseline information to aid Chinese pangolin conservation in Nepal.
Abstract
The Chinese pangolin (Manis pentadactyla) is a myrmecophagous, nocturnal mammal species that occurs in forests, agricultural lands, and grasslands. It is critically endangered due to illegal hunting and habitat loss. Characterizing the Chinese pangolin’s habitat and diet could improve our knowledge of the conditions necessary for species persistence; however, limited information is available. We investigated the habitat and diet of Chinese pangolins in the Chandragiri Municipality, Kathmandu, Nepal from November 2021–March 2022. We identified foraging burrows within plots established along 20 transects, collected scats opportunistically at these burrows, and used a generalized linear model to assess the site-level habitat characteristics related to burrow occurrence. We recorded 88 foraging burrows which occurred in forests with 50–75% canopy closure at 1500–1700 m elevation with 20–40° slopes. The probability of detecting a Chinese pangolin foraging burrow was greater with the increasing slope gradient and decreased with increasing distance to agricultural lands and ant nests or termite mounds. The analysis of 10 scats revealed that Aphaenogaster symthiesii, Camponotus sp., Monomorium sp., and Pheidole sp. were the dominant ant prey species; no termites were detected. Baseline data from this study could be used for ex-situ conservation and the captive breeding of Chinese pangolins as well as aiding site-specific management plans in Nepal.
Exploring the spatial distribution of land use/cover change (LUCC) and ecosystem carbon storage under future climate change scenarios can provide the scientific basis for optimizing land resource redistribution and formulating policies for sustainable socioeconomic development. We proposed a framework that integrates the patch-generating land use simulation (PLUS) model and integrated valuation of ecosystem services and tradeoffs (InVEST) model to assess the spatiotemporal dynamic changes in LUCC and ecosystem carbon storage in Guangdong based on shared socioeconomic pathways and representative concentration pathways (SSP-RCP) scenarios provided by the Coupled Model Intercomparison Project 6 (CMIP6). The future simulation results showed that the distribution patterns of LUCC were similar under SSP126 and SSP245 scenarios, but the artificial surface expanded more rapidly, and the increase in forest land slowed down under the SPP245 scenario. Conversely, under the SSP585 scenario, the sharply expanded artificial surface resulted in a continuous decrease in forest land. Under the three scenarios, population, elevation, temperature, and distance to water were the highest contributing driving factors for the growth of cultivated land, forest land, grassland, and artificial surface, respectively. By 2060, the carbon storage in terrestrial ecosystems increased from 240.89 Tg in 2020 to 247.16 Tg and 243.54 Tg under SSP126 and SSP245 scenarios, respectively, of which forest ecosystem carbon storage increased by 17.65 Tg and 15.34 Tg, respectively; while it decreased to 226.54 Tg under the SSP585 scenario, and the decreased carbon storage due to forest destruction accounted for 81.05% of the total decreased carbon storage. Overall, an important recommendation from this study is that ecosystem carbon storage can be increased by controlling population and economic growth, and balancing urban expansion and ecological conservation, as well as increasing forest land area.
Pangolins in the genus Manis are nocturnal, burrowing, insectivorous mammals listed as Critically Endangered or Endangered by the International Union for Conservation of Nature. Two species of pangolins are found in Nepal: the Chinese pangolin (Manis pentadactyla) and Indian pangolin (Manis crassicaudata). Despite having high conservation priority, little attention has been given to conservation interventions of both species of pangolins found in the Terai region (low land) of Nepal. The present study assesses habitat use and factors affecting the habitat choice of pangolins in low land (Terai), Nepal, focusing on Amritdharapani Community Forest of Chitwan district. Pangolin burrows were used as the indirect signs, and opportunistic sampling method was used to record the burrows. After the identification of all occurrence sites (burrows) in the field, random points were generated excluding the points where burrows were recorded for sampling of nonoccurrence sites. A total of thirty‐nine burrows were observed at elevations ranging from 301 to 413 masl. Burrows were frequently associated with northwest aspects, gentle slope (15°–20°), moderate canopy cover (51%–75%), red‐colored soil, and acidic soils with pH 6.5–7. The burrows were most common in areas with weak human disturbance (i.e., 1,500–1,700 m from settlements), 800–1,200 m from roads, and within 300 m from a water source and within 20 m from the nearest termitarium. Distance to settlement, distance to road, soil pH, and canopy cover were found to affect the habitat choice of pangolins in the study area. The present study assesses habitat use and factors affecting the habitat choice of pangolins in low land (Terai), Nepal. The research was focused on Amritdharapani Community Forest of Chitwan District. This study revealed distance to settlement, distance to road, soil pH, and canopy cover as major factors affecting the habitat choice of pangolins in the study area.
Nitrogen (N), phosphorus (P) and acid deposition are co‐occurring in many ecosystems, likely with complex interactive effects on litter decomposition.
Few studies have been conducted to distinguish the interactive effects of these three factors on forest litter decomposition. Thus, we performed a 5‐year litter decomposition experiment with N, P, acid addition in a temperate forest of Changbai Mountain in China, including four litter types from Pinus koraiensis, Quercus mongolica, Tilia amurensis and their mixtures.
Our results showed that acid addition consistently reduced litter decomposition rate, irrespective of nutrient addition or litter types. In contrast, N and P addition had less impact on litter decomposition. Litter decomposition rate linearly reduced with decreasing soil pH, but positively increased with soil N availability. No relationship was found between soil P availability and litter decomposition. Soil enzyme activity played a key role in regulating litter decomposition response, such as acid phosphatase, xylosidase, N‐cacetyl‐b‐D‐glucosaminidase and α‐1,4 glucosidase. Besides, low‐quality litter (i.e. high C concentration, C:N and C:P ratio) amplified the negative effect of soil acidification on litter decomposition.
This study suggests that soil acidification consistently decelerates litter decomposition in temperate forests, which is independent of soil nutrient availability and litter types. The intensifying soil acidification with continuous N deposition in the future will greatly reduce litter nutrient return to soil, increasing the risk of multiple soil nutrient limitation.
A free Plain Language Summary can be found within the Supporting Information of this article.
Ecosystem engineers are organisms that alter the distribution of resources in the environment by creating, modifying, maintaining and/or destroying the habitat. They can affect the structure and function of the whole ecosystem furthermore. Burrowing engineers are an important group in ecosystem engineers as they play a critical role in soil translocation and habitat creation in various types of environment.However, few researchers have systematically summarized and analyzed the studies of burrowing engineers. We reviewing the existing ecological studies of burrowing engineer about their interaction with habitat through five directions: (1) soil turnover; (2)changing soil physicochemical properties; (3) changing plant community structure; (4) providing limited resources for commensal animals;and/or (5) affecting animal communities. The Chinese pangolin (Manis pentadactyla) is a typical example of burrowing mammals, in part (5), we focus on the interspecific relationships among burrow commensal species of Chinese pangolin. The engineering effects vary with environmental gradient, literature indicates that burrowing engineer play a stronger role in habitat transformation in the tropical and subtropical areas.The most common experiment method is comparative measurements (include different spatial and temporal scale),manipulative experiment is relatively few. We found that most of the engineering effects had positive feedback to the local ecosystem, increased plant abundance and resilience, increased biodiversity and consequently improved ecosystem functioning. With the global background of dramatic climate change and biodiversity loss in recent decades, we recommend future studies should improving knowledge of long-term engineering effects on population scale and landscape scale, exploring ecological cascades through trophic and engineering pathways, to better understand the attribute of the burrowing behavior of engineers to restore ecosystems and habitat creation. The review is presented as an aid to systematically expound the engineering effect of burrowing animals in the ecosystem, and provided new ideas and advice for planning and implementing conservation management.
The critically endangered Chinese pangolin (Manis pentadactyla) is thought to be one of the most threatened species in mainland China; however, little is known about its distribution and population status. We collected information from primary literature, grey literature, interviews, personal communication, news reports, and camera trap photographs obtained between July 2010 and June 2020 to improve our understanding of Chinese pangolin distribution and status in mainland China. In total, 157 observations representing 170 individuals were obtained from eight provinces: Anhui, Zhejiang, Jiangxi, Fujian, Guangdong, Guangxi, Yunnan, and Hainan. In these observations, the sex of 17 females and 20 males were known. There were at least nine females with pups (one that became pregnant again) and one pregnant female. Eight other observations were suspected to be of Chinese pangolins. Although our findings do not adequately represent the current status and distribution of Chinese pangolins, they provide valuable information and suggest that the species still exists in parts of China and still has reproductive capacity. However, there is no denying that Chinese pangolins are scarce in many areas of mainland China where they used to occur naturally. Based on threats to pangolin populations and our findings, we suggest conservation measures including: establishing reserves or protected areas, targeted public education in communities near pangolin populations, strengthening domestic dog controls, posting speed limit signs and wildlife access warning signs on critical sections of road, and constructing steps in aqueduct walls to allow wildlife to escape. Actions taken around roads and aqueducts could both reduce mortality and improve habitat connectivity. These recommendations can improve pangolin protection efforts in mainland China.
Dicranopteris is an ancient and widespread genus of ferns in pantropical regions. Some species of the genus can form dense thickets, and dominate the understory, which are common and key species in tropical and subtropical ecosystems. However, they were mostly cut or burned in forest management because of forming dense thickets which were considered to interfere with forest regeneration and succession. In the current review, we argue that the Dicranopteris species which are able to rapidly colonize barren areas may contribute to ecosystem recovery, resistance to environmental stress, and succession control. Rapid colonization involves prolific spore production, rapid clonal growth, the generation of high surface cover, and the ability to fill gaps; stress resistance includes resistance to abiotic stress, and the ability to reduce soil erosion from rainfall, alien species invasion, and soil contamination and toxicity; and succession facilitation consists of carbon and nutrient sequestration in soil, moderation of the microclimate, alteration of the soil microbial and faunal communities, and determination of which plant species to be established in the next successional stage. All of these ecosystem functions may be beneficial to ecosystem resilience. We expect that the distribution of Dicranopteris will expand in response to global warming, changes in precipitation patterns, increases in soil pollution, deforestation, and land degradation. We recommend that Dicranopteris, as a pioneer fern and a valuable component of tropical and subtropical ecosystems, needs more attention in future research and better management practices to promote forest regeneration and succession.
The Indian pangolin (Manis crassicaudata) is the only member of order “Pholidota” occurring in Pakistan, is threatened by the rampant trade of the species, and has been listed as “Endangered” since 2014. The current study investigated the occupancy, habitat suitability and habitat preference of pangolin in the Potohar Plateau and Azad Jammu & Kashmir. A Single-season model was used to analyze the data in PRESENCE software to document occupancy of species. The presence/absence data for 240 grids with 10 sampling occasions (2400 survey plots) and 45 missing observations analyzed this model. The data collected from sampling plots along with environmental layers (including; elevation, slope, land cover, distance to nearest settlement,) and bioclimatic layers (including annual mean temperature and precipitation) were processed to generate habitat suitability maps in MaxEnt software. To document habitat preference, we stratified the habitat of Indian pangolin into three different habitat types use; forests, agricultural lands and grasslands. Estimated naïve occupancy was 0.3167 whereas detection probability was estimated as 0.32 ± 0.03(SE), which suggests 32% of the study area is occupied by the Indian Pangolin. The MaxEnt analysis showed that out of 26872.52 km² area available to Indian pangolin, 1674 km² (6.2%) was highly suitable habitat, followed by 3851.7 km² (14.3%) suitable habitat, 8438.3 km² (31.4%) less suitable habitat and 12908.2 km² (48%) not suitable habitat, although lack of signs does not necessarily equate to lack of habitat suitability and hunting pressure and other factors, independent of habitat suitability, can strongly influence occupancy. The Jackknife test of variable contribution, revealed that elevation was the most important predictor variable as measured by the gain produced by a one-variable model, followed by, average temperature, settlement, land class, slope and aspect. Among three different types of habitats studied, forest was found to be more preferred, followed by agricultural land habitat whereas grassland was used least by the species.
Pangolins are highly-threatened due to illegal hunting and poaching, and by the loss, degradation, and fragmentation of their habitats. In Nepal, effective conservation actions for pangolins are scarce due to limited information on the distribution of pangolins in many areas of the country. To identify the nationwide distribution of pangolins in Nepal, and assess the environmental variables associated with their habitat, we conducted an extensive literature review to collate data from previous studies, canvassed information from key informant interviews and expert opinion, and conducted transect surveys and sign surveys. The occurrence of pangolins was recorded based on sightings and indirect signs (such as burrows, digs, tracks, and scats) along 115 belt transects of 500-m length with a fixed width of 50-m, and habitat parameters were surveyed using 347 quadrats of 10 m*10 m. Pangolin presence was confirmed from 61 out of 75 districts from the eastern to the far western parts of the country. The highest frequency of burrows (74%) was observed in the forested habitat constituting brown soil with medium texture (0.02–2 mm) within an elevation range of 500–1500 m above sea level. Logistic regression suggested that the occurrence of pangolin was highly influenced by ground cover and canopy cover of 50–75%, litter depth, and the distance to termite mounds and roads. We used 4136 occurrence GPS points of pangolin burrows that were compiled and collected from the literature review and field surveys in order to predict the potential habitat distribution of pangolin using maximum entropy algorithm (MaxEnt 3.4.1). The model predicted 15.2% (22,393 km²) of the total land of Nepal as potentially suitable habitat for pangolin, with 38.3% (8574 km²) of potential habitat in the eastern region, followed by 37.6% (8432 km²) in the central and 24.1% (5,387 km²) in the western regions. The results of this study present a national baseline for pangolin distribution and serve as an important document for developing and executing conservation actions and management plans for the long-term conservation of pangolins in Nepal.
Tropical forest fragmentation results in habitat and biodiversity loss and increased carbon emissions. Here, we link an increased likelihood of tropical forest loss to decreasing fragment size, particularly in primary forests. The relationship holds for protected areas, albeit with half the rate of loss compared with all fragments. The fact that disturbance increases as primary forest fragment size decreases reflects higher land use pressures and improved access for resource extraction and/or conversion in smaller fragments. Large remaining forest fragments are found in the Amazon and Congo Basins and Insular Southeast Asia, with the majority of large extent/low loss fragments located in the Amazon. Tropical areas without large fragments, including Central America, West Africa, and mainland Southeast Asia, have higher loss within and outside of protected areas. Results illustrate the need for rigorous land use planning, management, and enforcement in maintaining large tropical forest fragments and restoring regions of advanced fragmentation.
Conservation strategies based on charismatic flagship species, such as tigers, lions, and elephants, successfully attract funding from individuals and corporate donors. However, critics of this species-focused approach argue it wastes resources and often does not benefit broader biodiversity. If true, then the best way of raising conservation funds excludes the best way of spending it. Here we show that this conundrum can be resolved, and that the flagship species approach does not impede cost-effective conservation. Through a tailored prioritization approach, we identify places containing flagship species while also maximizing global biodiversity representation (based on 19,616 terrestrial and freshwater species). We then compare these results to scenarios that only maximized biodiversity representation, and demonstrate that our flagship-based approach achieves 79−89% of our objective. This provides strong evidence that prudently selected flagships can both raise funds for conservation and help target where these resources are best spent to conserve biodiversity. Conservation actions focused on flagship species are effective at raising funds and awareness. Here, McGowan et al. show that prioritizing areas for conservation based on the presence of flagship species results in the selection of areas with ~ 79-89% of the total species that would be selected by maximizing biodiversity representation only.
Anthropogenic activities have driven many wildlife species towards extinction. Among these species, the geographic distributions of many are poorly documented, which can limit the effectiveness of conservation. The critically endangered Chinese pangolin (Manis pentadactyla) is experiencing population decline throughout its range due to land-use changes and illegal trade for food and traditional medicine. Using distribution records and maximum entropy modeling, we predicted the potential distribution of the Chinese pangolin across Nepal. Most suitable potential habitats of the Chinese pangolin occurred in forest areas of the mid-hill region in central and eastern Nepal, followed by cultivated land. Almost all potential suitable habitats of the Chinese pangolin occurred outside of protected areas, and most of them were encroached upon by cultivated land, human settlements, and infrastructure developments. The results from this study provide baseline information on the potential suitable habitats of the Chinese pangolin in Nepal, which helps to develop site- and species-specific management plans and to identify priority areas to minimize the current threats to the pangolin and enhance the stewardship of species conservation.
Ecosystem engineers are species that have a role in creating and maintaining certain habitat traits that are important for other species. Burrowing species do this by creating subterranean refugia from predation and thermal extremes, but also providing foraging opportunities through soil movement and by increasing local landscape heterogeneity. In this study, we used camera traps to monitor the burrows of greater bilbies (Macrotis lagotis), a vulnerable Australian marsupial, in an area subject to frequent disturbance by fire. We tested the hypothesis that bilby burrows provide refuge for other species and therefore their presence increases biodiversity. In total, 45 taxa – 22 bird, 16 reptile and 7 mammal taxa – were recorded interacting with 127 burrows across 7 sites. Species richness was greater at burrows compared with vegetation away from burrows, while abundance was no different. There was no difference in species assemblage for bilby burrows that were actively maintained by bilbies compared with abandoned burrows, although there was more activity at bilby maintained burrows. A wildfire allowed us to test the ad hoc hypothesis that the use of bilby burrows was greater when vegetation cover was removed by fire. We recorded significant differences in species assemblage interacting with burrows after fire, although overall species richness and abundance did not change. The response of individual species was variable; for example, burrows provide a refuge for smaller species (such as mice and small reptiles), and may therefore protect them from the effects of fire. Where they persist, bilbies provide an important ecosystem engineering service, as their burrows support a broad range of species. Further reduction in the distribution of the bilby is therefore likely to have a flow‐on effect on biodiversity, impacting species that use their burrows for refuge.
Aim
Organisms that disturb the soil while foraging or creating shelter (ecosystem engineers) can have profound effects on ecosystems. Soil ejecta from these disturbances can enhance surface nutrients and the resulting depressions accrue organic matter and develop into biological hotspots. Here, we describe a global meta‐analysis of studies that assessed the impacts of vertebrate soil disturbance on both biotic and abiotic components of ecosystems.
Location
Global land surface.
Time period
1941–2016.
Major taxa studied
Vertebrates.
Methods
After conducting a systematic literature search, we quantitatively synthesized the findings of 149 published studies that compared disturbed and undisturbed surfaces. Our meta‐analysis included 64 engineer species, primarily comprised of rodents and a subset of other mammals.
Results
We found that vertebrate soil disturbance significantly enhanced soil nitrogen (by 77%) and phosphorus (35%), and the productivity (32%) and recruitment (32%) of vascular plants. Disturbances had a greater cover of bare soil (126%) than undisturbed controls, and higher abundances of secondary vertebrates (1,233%), that use pre‐constructed burrows as shelter and foraging grounds. Soil disturbance significantly reduced water run‐off (63%) and the abundance of biocrusts (82%). Soil disturbance effects generally intensified with increasing aridity, and the magnitude of soil disturbance effects was not moderated by the area of the disturbance. Disturbances older than 12 months were more distinct from the surrounding matrix than fresh disturbances. The phylogeny of engineers was unrelated to their ecosystem effects, indicating that the same functionality could readily evolve in different taxa.
Main conclusions
In general, disturbances become localized patches of elevated functioning, providing strong evidence that vertebrate engineers, especially those in drylands, are an important source of environmental heterogeneity.
Many small- and medium-sized mammals dig for their food. This activity potentially affects soil condition and fertility. Digging is well developed especially in Australian mammals, many of which have recently become rare or extinct. We measured the effects of digging by mammals on soil in a Tasmanian temperate dry sclerophyll forest with an intact mammal community. The density of diggings was 5812 ha⁻¹, affecting 11% of the forest floor. Diggings were created at a rate of around 3113 diggings ha⁻¹ yr⁻¹, disturbing 6.5% of the forest floor and displacing 7.1 m³ ha⁻¹ of soil annually. Most diggings were made by eastern bettongs (Bettongia gaimardi) and short-beaked echidnas (Tachyglossus aculeatus). Many (approx. 30%) fresh diggings consisted of re-excavations of old diggings. Novel diggings displaced 5 m³ ha yr⁻¹ of soil. Diggings acted as traps for organic matter and sites for the formation of new soil, which had higher fertility and moisture content and lower hardness than undisturbed topsoil. These effects on soil fertility and structure were strongest in habitats with dry and poor soil. Creation of fine-scaled heterogeneity by mammals, and amelioration of dry and infertile soil, is a valuable ecosystem service that could be restored by reintroduction of digging mammals to habitats from which they have declined or gone extinct.
The Indian pangolin (Manis crassicaudata) is under threat due to hunting for local consumption and illegal trafficking of scales and meat. The dearth of scientific studies on the ecology of the M. crassicaudata has impaired accurate assessments of its conservation needs. This study investigated the habitat preference and burrow characteristics of M. crassicaudata in a tropical lowland rainforest in southwest Sri Lanka. A total of 75 burrows (54 feeding burrows and 21 resting burrows) of M. crassicaudata in four different habitat types i.e. secondary forest, Pine-dominated forest, rubber cultivations and tea-dominated home gardens bordering forest were observed using fixed-width transects in order to characterize resting and feeding burrows of this species. The highest density of resting burrows was recorded from the secondary forest (4ha⁻¹), followed by rubber cultivations (2.5ha⁻¹) while no resting burrows were recorded in the Pine-dominated forest and the tea-dominated home gardens bordering forest. Feeding burrows were more abundant in the Pine-dominated forest (5.7ha⁻¹). The burrow depth, burrow opening height, and width were significantly larger in resting burrows compared to feeding burrows. Resting burrows were located at higher elevations (75-100m) with moderately high slopes (45⁰−60⁰), dense canopy cover (>75%) and away from human habitation. Feeding burrows showed a greater variability in terms of associated environmental features. The study further revealed that Indian pangolins exclusively prefer habitats with rocks and boulders under which they dig resting burrows while the location of feeding burrows largely overlaps with the distribution of prey species. The resting burrow design consisted of a bending tunnel that initially slopes downward and then gradually inclines at an angle between 20 and 30⁰, leading to the resting chamber. Our study highlights the importance of conserving fragmented secondary natural forests in changing landscapes of the southwest lowlands of Sri Lanka as these habitats appear to be critical to sustaining populations of M. crassicaudata.
Protecting biodiversity against the impacts of climate change requires effective conservation strategies that safeguard species at risk of extinction¹. Microrefugia allowed populations to survive adverse climatic conditions in the past2,3, but their potential to reduce extinction risk from anthropogenic warming is poorly understood3–5, hindering our capacity to develop robust in situ measures to adapt conservation to climate change⁶. Here, we show that microclimatic heterogeneity has strongly buffered species against regional extirpations linked to recent climate change. Using more than five million distribution records for 430 climate-threatened and range-declining species, population losses across England are found to be reduced in areas where topography generated greater variation in the microclimate. The buffering effect of topographic microclimates was strongest for those species adversely affected by warming and in areas that experienced the highest levels of warming: in such conditions, extirpation risk was reduced by 22% for plants and by 9% for insects. Our results indicate the critical role of topographic variation in creating microrefugia, and provide empirical evidence that microclimatic heterogeneity can substantially reduce extinction risk from climate change.
Biodiversity is being threatened by human activities worldwide. Inside protected areas, anthropogenic
activities are mostly under control. However, outside protected areas, threatened or endangered species still
need protection, and identification of a species’ habitat requirements is essential for conservation planning. We
gathered information on habitat characteristics of and anthropogenic threats to the Chinese pangolin (Manis
pentadactyla), a critically endangered species for which such baseline data are scarce. We found closed-canopy forest nearest water sources at an altitude from 555 to 1,740 m to be suitable habitat for Chinese pangolins. Forest fires, livestock grazing, distance to nearest footpath, and distance to nearest household were negatively associated with presence of Chinese pangolins. To protect the Chinese pangolin outside of the reserve system, we recommend public awareness programs and campaigns to protect habitat in addition to directly protecting this species against hunting and trading.
Mammal burrowing plays an important role in soil translocation and habitat creation in many environments. As a consequence, many burrowing mammals have at some point been studied in an ecosystem engineering context. From a geomorphological point of view, one of the focus areas of burrowing mammal research is on the amount of soil that is excavated and the rate at which this happens. As such, reviews exist on the volumes and rates of sediment removal by burrowing mammals in specific environments or for specific groups of species. Here, a standardised comparison of mammal burrowing across a broad range of burrowing mammal species and environments is provided, focussing on both burrow volume and excavation rate. Through an ISI Web of Science-based literature search, articles presenting estimates of burrow volumes and/or excavation rate were identified. Relationships between species body size and burrow volume/excavation rate were explored and the influence of sociality and method of burrow volume estimation were assessed. The results show that, although larger species construct larger burrows, it is the smaller species that remove more sediment per unit time at larger, site-level spatial scales. Burrow volume estimates are, however, independent of species sociality (solitary versus group-living) and method of burrow volume estimation (excavation-based versus mound-based). These results not only confirm previously established relationships between species body size and burrow volume, but, more importantly, they also add to this, by exploring larger scale impacts of burrowing mammals along a body size gradient.
To assess the overall threat status of wild vertebrates in China, the Ministry of Environmental Protection, allied with the Chinese Academy of Sciences, initiated a program compiling a China Biodiversity Red List —Vertebrates in 2013. Through this program, we compiled a Red List of China’s Vertebrates using three documents as reference: (1) IUCN Red List Categories and Criteria (Version 3.1) (IUCN, 2012a); (2) Guidelines for Using the IUCN Red List Categories and Criteria (Version 8.1) (IUCN Standards and Petitions Subcommittee, 2010); and (3) Guidelines for Application of IUCN Red List Criteria at Regional and National Levels (Version 4.0) (IUCN, 2012b). We applied the following IUCN categories, i.e. Extinct (EX), Extinct in the Wild (EW), Regionally Extinct (RE), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), and Data Deficient (DD), to describe the status of vertebrates in China. The information for assessing Red List of China’s Vertebrates was mainly collected from specimens, literature and experts. Specimen data were collected from museums located at the Chinese Academy of Sciences and other universities as well as local natural history museums. Based on the specimen data collected, we analyzed the data using GIS to gain information about the extent of occurrence and area of occupancy of each vertebrate species evaluated, which provided fundamental data for the assessment. In addition to specimen data, literature review provided the main information for this assessment, in reference to new species, species distribution, ecology, conservation, and resource utilization. Furthermore, expert consultation was another important assessment method. Experts are familiar with latest status of the species they study. By referring to literature and field experience, the experts provided sufficient and updated information of relevant species, including the taxonomic definition, population size and trends, habitat conditions, threats, utilization, and conservation information. The deadline for information collection was March 31, 2015. The mammalian inventory system in the assessment followed the system of China’s Mammal Diversity (Jiang et al, 2015), including 673 species of mammals, among which 150 endemic species were assessed. The inventory systems of birds, reptiles and amphilbians followed that in Zheng (2011), Cai et al (2015) and Fei et al (2012), respectively. The assessment of the Red List of China’s Vertebrates included the following steps: information collection, database establishment, formation of an advisory committee, core experts group, and working group, and establishment of a pool of corresponding experts. Members of the advisory committee consisted of Academician Yiyu Chen (from the Endangered Species Scientific Commission of the People’s Republic of China), Academician Yaping Zhang (from the Chinese Academy of Sciences), Academician Jianming Jin (from the Ministry of Environmental Protection), Academician Jianzhang Ma (from Northeast Forestry University) and Academician Guangmei Zheng (from Beijing Normal University). The advisory commission oversaw assessment progress. Five working groups, one core expert group and corresponding expert teams of mammals, birds, reptiles, amphibians and continental fishes were formed. The core expert group assisted each working group in determining the evaluation method, criteria, and verified species data. The working groups were responsible for implementing the assessment plan as specified, including data collection and organization, initial assessment of red listed species, contacting experts by correspondence, and compiling evaluation results. The core experts discussed and reviewed the species’ living status. The working groups gathered advisory experts across the nation and formed an advisory expert pool. The advisory experts participated in the Red List evaluation by correspondence or at review meetings. After the review, we finished assessing each species using unified standards, including scientific name, Chinese name, family name, Chinese family name, status assessed, and IUCN criteria. On May 6, 2015, the Red List of China’s Vertebrates passed an evaluation jointly held by the Ministry of Environmental Protection of the People’s Republic of China and the Chinese Academy of Sciences. The Red List was officially released in the form of the 32nd Announcement of the Ministry of Environmental Protection of the People’s Republic of China and the Chinese Academy of Sciences on May 23, 2015. Detailed information and analyses of the results of the Red List can be found in Jiang ZG et al (2016), Zhang et al (2016), Cai et al (2016), Jiang JP et al (2016) and Cao et al (2016). This paper contains the Red List of China’s Vertebrates including that of mammals, birds, reptiles, amphibians and continental fishes. The references cited in this data paper can be found at the website www.biodiversity-science.net/ fileup/PDF/2016076-1.pdf.
Top predators can provide fundamental ecosystem services such as nutrient cycling, and their impact can be even greater in environments with low nutrients and productivity, such as Arctic tundra. We estimated the effects of Arctic fox (Vulpes lagopus) denning on soil nutrient dynamics and vegetation production near Churchill, Manitoba in June and August 2014. Soils from fox dens contained higher nutrient levels in June (71% more inorganic nitrogen, 1195% more extractable phosphorous) and in August (242% more inorganic nitrogen, 191% more extractable phosphorous) than adjacent control sites. Inorganic nitrogen levels decreased from June to August on both dens and controls, whereas extractable phosphorous increased. Pup production the previous year, which should enhance nutrient deposition (from urine, feces, and decomposing prey), did not affect soil nutrient concentrations, suggesting the impact of Arctic foxes persists >1 year. Dens supported 2.8 times greater vegetation biomass in August, but δ(15)N values in sea lyme grass (Leymus mollis) were unaffected by denning. By concentrating nutrients on dens Arctic foxes enhance nutrient cycling as an ecosystem service and thus engineer Arctic ecosystems on local scales. The enhanced productivity in patches on the landscape could subsequently affect plant diversity and the dispersion of herbivores on the tundra.
Pangolins belong to the least studied burrowing mammals whose information on distribution and ecology is still scarce in Nepal. Their distribution was studied in the Nagarjun forest of Shivapuri Nagarjun National Park (SNNP) during April 2013. We surveyed 700×60 m 2 strip transects for indirect data collection, 140 quadrates of 10×10 m 2 were used for vegetation analysis. Total 235 burrows were recorded which were not uniform in distribution. Burrows were mostly distributed in the habitat dominanat by Schima wallichii, Castonopsis tribuloides, Castonopsis indica and Betula alnoides with canopy cover between 25-50% in brown soil and in northwest aspect in the elevation range between 1450-1550 m. Chi-square test revealed that there was a significant difference in the distribution of burrows according to different transects, altitude, aspects, soil, vegetation and crown cover. Wilcoxon test revealed there was a significant difference in the burrows dimension distributed in red and brown soil. Fresh burrows density was found to be 0.8333 burrows per hectare.
Both land use intensification and abandonment within grasslands lead to a homogenisation of vegetation structure. Therefore, specially structured microsites such as vegetation gaps with bare ground play an important role for species conservation within grasslands. Vegetation gaps are crucial for the establishment of low-competitive plant species and offer special microclimatic conditions essential for the development of the immature stages of many invertebrate species. The influence of small-scale soil disturbance in the form of mounds created by ecosystem engineers such as ants or moles on biodiversity is therefore of special scientific concern. The effects of mound-building species on plant species diversity have been extensively studied. However, knowledge on the significance of these species for the conservation of other animals is rare. In this study we analyse the importance of mounds created by the European mole (Talpa europaea) as an oviposition habitat for the small copper (Lycaena phlaeas) within Central European mesotrophic grasslands. Our study showed that host plants occurring at molehills were preferred for oviposition. Oviposition sites were characterised by an open vegetation structure with a high proportion of bare ground (with a mean coverage of about 50 %), a low cover of herbs and low-growing vegetation (mean height: 4.5 cm). Our study clearly illustrates the importance of small-scale soil disturbance for immature stages of L. phlaeas and the conservation of this species within mesotrophic grasslands. Mound-building ecosystem engineers, such as T. europaea, act as important substitutes for missing dynamics within mesotrophic grasslands by diversifying vegetation structure and creating small patches of bare soil.
Mammals that forage for food by biopedturbation can alter the biotic and abiotic characteristics of their habitat, influencing ecosystem structure and function. Bandicoots, bilbies, bettongs and potoroos are the primary digging marsupials in Australia, although most of these species have declined throughout their range. This study used a snapshot approach to estimate the soil turnover capacity of the southern brown bandicoot (Isoodon obesulus, Shaw 1797), a persisting digging Australian marsupial, at Yalgorup National Park, Western Australia. The number of southern brown bandicoots was estimated using mark–recapture techniques. To provide an index of digging activity per animal, we quantified the number of new foraging pits and bandicoot nose pokes across 18 plots within the same area. The amount of soil displaced and physical structure of foraging pits were examined from moulds of 47 fresh foraging pits. We estimated that an individual southern brown bandicoot could create ~45 foraging pits per day, displacing ~10.74 kg of soil, which extrapolates to ~3.9 tonnes of soil each year. The digging activities of the southern brown bandicoots are likely to be a critical component of soil ecosystem processes.
Through their excavations, giant armadillos (Priodontes maximus) alter their physical surroundings and create new habitats, which influence resources for at least 24 other species of vertebrates in the Brazilian Pantanal. The role of this poorly known species as an ecosystem engineer may be of high value to the community of vertebrates.
Invasive species are known to have substantial trophic effects on ecosystems and ecosystem processes. The invasion of the house mouse (Mus musculus) onto sub-Antarctic islands has had a devastating effect on plants, invertebrates, and birds with substantial changes in ecosystem functions. Less well understood, however, are the nontrophic, geomorphic effects of mice resulting from their burrowing activities. We examined the extent of burrow construction by M. musculus across an area of about 20 ha on Marion Island and the effects of burrows on water flow and sediment movement. We recorded a density of 0.59 ± 0.48 (mean ± SD) burrows m− 2, with more burrows at lower altitudes and shallower slopes, and twice the density in the solifluction risers (0.86 ± 0.54 m− 2) than the intervening terraces or treads (0.40 ± 0.51 m− 2). Most burrows were dug horizontally into the slope and tended to extend about 20 cm deep before turning. A very conservative estimate of sediment removed from burrows from this depth is 2.4 t ha− 1. However, taking into account more detailed data on burrow morphology based on excavations, actual amounts may be closer to 8.4 t ha− 1. Average soil displacement rate for a single burrow, measured over 5 days, was 0.18 kg burrow− 1 day− 1. Burrows acted as conduits for water and warmer air. Stones at burrow entrances were moved eight times farther by water (10.4 cm) than those not associated with burrows. Similarly, temperatures adjacent to burrow entrances were 4.1 °C higher than sites 10 cm away. Together our data indicate that mice are having substantial deleterious and geomorphic effects on sub-Antarctic ecosystems through their burrowing. With lower rates of mouse mortality resulting from warmer climates predicted under global climate models, we can expect an increase in damage resulting from mouse activity.
AimWhile soil microorganisms play key roles in Earth's biogeochemical cycles, methodological constraints and sparse data have hampered our ability to describe and understand the global distribution of soil microbial biomass. Here, we present a comprehensive quantification of the environmental drivers of soil microbial biomass. LocationGlobal. Methods
We used a comprehensive global dataset of georeferenced soil microbial biomass estimates and high‐resolution climatic and soil data. ResultsWe show that microbial biomass carbon (CMic) is primarily driven by moisture availability, with this single variable accounting for 34% of the global variance. For the microbial carbon‐to‐soil organic carbon ratio (CMic/COrg), soil nitrogen content was an equally important driver as moisture. In contrast, temperature was not a significant predictor of microbial biomass patterns at a global scale, while temperature likely has an indirect effect on microbial biomass by influencing rates of evapotranspiration and decomposition. As our models explain an unprecedented 50% of the global variance of CMic and CMic/COrg, we were able to leverage gridded environmental information to build the first spatially explicit global estimates of microbial biomass and quantified the global soil microbial carbon pool to equal 14.6 Pg C. Main Conclusions
Our unbiased models allowed us to build the first global spatially explicit predictions of microbial biomass. These patterns show that soil microbial biomass is not primarily driven by temperature, but instead, biomass is more heterogeneous through the effects of moisture availability and soil nutrients. Our global estimates provide important data for integration into large‐scale carbon and nutrient models that may imply a major step forward in our ability to predict the global carbon balance, now and in a future climate.
We censused and measured armadillo burrows in ten 10 m x 40 m plots in each of four habitat types at a study site in northern Florida and one in the Atlantic coastal rainforest of Brazil. The nine-banded armadillo (Dasypus novemcinctus) was the only species of armadillo found in Florida, but several additional species were present in Brazil. Burrows were more numerous but smaller in Brazil than in the U. S., probably due to the inclusion of burrows dug by the smaller congener D. septemcinctus. In Brazil, burrows were larger and more numerous in swamp and forest habitats than in grassland or disturbed areas, suggesting that D. novemcinctus is found primarily in forests and swamps while D. septemcinctus is located in the other areas. This was supported by data from sightings of live animals. In Florida, burrows were more numerous in hardwood hammocks than in wetlands, fields or upland pine areas, but burrow dimensions did not vary across habitat types. In Florida, armadillos were seen more frequently than expected in hammocks and wetlands and less frequently than expected in fields and upland pine areas. There were also age (juvenile versus adult), sex, and yearly differences in habitat use in Florida. Biomass, abundance, and species diversity of terrestrial invertebrates did not vary significantly between habitat types in Florida, suggesting that habitat associations of armadillos were not influenced by prey availability.
Structural equation modeling (SEM) is a vast field and widely used by many applied researchers in the social and behavioral sciences. Over the years, many software pack-ages for structural equation modeling have been developed, both free and commercial. However, perhaps the best state-of-the-art software packages in this field are still closed-source and/or commercial. The R package lavaan has been developed to provide applied researchers, teachers, and statisticians, a free, fully open-source, but commercial-quality package for latent variable modeling. This paper explains the aims behind the develop-ment of the package, gives an overview of its most important features, and provides some examples to illustrate how lavaan works in practice.
Burrowing species can be considered important ecosystem engineers that increase landscape heterogeneity, create subterranean shelters and provide foraging opportunities. We measured and described different aspects of giant armadillo (Priodontes maximus) excavations (size, age), and differences generated in relation to the surrounding environment (vegetation, humidity, temperature) in three sites of the Argentine Chaco Region. We used camera‐traps in two protected areas to monitor the use of burrows by other species and tested two primary and non‐mutually exclusive hypotheses: Giant armadillo burrows are used as thermal protection from temperature extremes and provide new foraging opportunities for other species. Greater litter cover and depth were recorded in giant armadillo burrows, and more bare ground in spoil piles, producing habitat heterogeneity. Burrows had higher humidity and more moderate temperatures, with lower temperatures during hot months and higher temperatures during cold months. Out of 48 vertebrate species recorded by camera‐traps, 27 taxa (17 mammals, 9 birds and one reptile) were recorded using burrows. White‐lipped peccaries (Tayassu peccari) and collared peccaries (Pecari tajacu) used burrows more frequently than other mammals. Medium‐sized carnivores such as Pampas fox (Lycalopex gymnocercus) and Geoffroy´s cat (Leopardus geoffroyii) tended to only investigate burrows, probably searching for prey. In no instances, animals other than giant armadillos were recorded staying inside burrows for more than a few seconds. Medium‐sized species interacted more frequently than large‐sized species, and smaller species used giant armadillo burrows less than larger ones, suggesting that the benefits provided by excavations to other species depend on their body weight. The probability of use of burrows decreases with time, suggesting that burrows provide a finite resource used opportunistically. Further reduction in the distribution of the giant armadillo is therefore likely to have effects on habitat heterogeneity and biodiversity, probably impacting the fitness of species that use their burrows as foraging sources. We described giant armadillo (Priodontes maximus) excavations and differences generated in relation to the surrounding environment in the Argentina Chaco Region. We tested two hypotheses, that giant armadillo burrows are used as thermal protection from temperature extremes, and that they provide new foraging opportunities for other species. Giant armadillo excavations alter vegetation, contributing to habitat heterogeneity. Their burrows present higher humidity, more moderate temperatures, and provide foraging opportunities for other species. Further reduction in the distribution of the giant armadillo is therefore likely to have effects on biodiversity, probably impacting the fitness of species that use their burrows as foraging sites.
Although not widely used, ecosystem engineers represent a promising and sustainable tool in nature-based ecosystem management and restoration. In grassland ecosystems, a few invertebrates that engineer soils have been identified as key species regulating soil nutrients and plant communities' diversity and dynamics. Here, we assessed the role of the harvester ant Messor barbarus, an ecological engineer, in a Mediterranean dry grassland under restoration by characterising its nest environment, particularly the soil and vegetation. We found profound differences in soil physical and chemical variables and plant community structure between nests and ant-free patches in the restored grassland. Messor barbarus has improved soil fertility, driven the seed bank towards the reference grassland and significantly increased plant biomass, species richness and micro-local-hetero-geneity. As biological filters, M. barbarus has driven plant communities towards a new trajectory in the restored site. Ant patches are characterised by mesotrophic species, whereas ant-free patches are dominated by species characteristic of compacted soils. They have accelerated the ecological recovery of Mediterranean dry grassland plants by directly and indirectly facilitating their re-establishment. These results illustrate the potential key role of ants as ecological engineers for the conservation and restoration of Mediterranean grasslands.
Vulnerability to habitat fragmentation
Habitat fragmentation caused by human activities has consequences for the distribution and movement of organisms. Betts et al. present a global analysis of how exposure to habitat fragmentation affects the composition of ecological communities (see the Perspective by Hargreaves). In a dataset consisting of 4489 animal species, regions that historically experienced little disturbance tended to harbor a higher proportion of species vulnerable to fragmentation. Species in more frequently disturbed regions were more resilient. High-latitude areas historically experienced more disturbance and harbor more resilient species, which suggests that extinction has removed fragmentation-sensitive species. Thus, conservation efforts to limit fragmentation are particularly important in the tropics.
Science , this issue p. 1236 ; see also p. 1196
Digging mammals are often considered ecosystem engineers, as they affect important properties of soils and in turn nutrient exchange, vegetation dynamics and habitat quality. Returning such species, and their functions, to areas from where they have been extirpated could help restore degraded landscapes and is increasingly being trialled as a conservation tool. Studies examining the effects of digging mammals have largely been from arid and semi‐arid environments, with little known about their impacts and importance in mesic systems. To address this knowledge gap, we investigated the ecological role of a recently introduced population of eastern barred bandicoots (Perameles gunnii) on Churchill Island, Victoria, south‐eastern Australia, from which all digging mammals have been lost. We quantified the annual rate of soil turnover by estimating the number of foraging pits bandicoots created in 100‐m2 plots over a 24‐h period. Foraging pit counts could not be completed in each season, and the overall turnover estimate assumes that autumn/winter months represent turnover rates for the entire year; however, this is likely to fluctuate between seasons. Ten fresh and ten old pits were compared to paired undug control sites to quantify the effect soil disturbance had on soil hydrophobicity, moisture content and soil strength. Plots contained between zero and 64 new foraging pits each day. We estimated that an individual eastern barred bandicoot digs ~487 (95% CI = 416–526) small foraging pits per night, displacing ~13.15 kg (95% CI = 11.2–14.2 kg) of soil, equating to ~400 kg (95% CI = 341–431 kg) of soil in a winter month. Foraging pits were associated with decreased soil compaction and increased soil moisture along the foraging pit profile. Eastern barred bandicoots likely play an important role in ecosystems through their effects on soil, which adds to an increasing body of knowledge suggesting restoration of ecosystems, via the return of ecosystem engineers and their functions, holds much promise for conserving biodiversity and ecological function.
Ecosystem engineers have been widely studied for terrestrial systems, but global trends in research encompassing the range of taxa and functions have not previously been synthesised.
We reviewed contemporary understanding of engineer fauna in terrestrial habitats and assessed the methods used to document patterns and processes, asking: (a) which species act as ecosystem engineers and with whom do they interact? (b) What are the impacts of ecosystem engineers in terrestrial habitats and how are they distributed? (c) What are the primary methods used to examine engineer effects and how have these developed over time? We considered the strengths, weaknesses and gaps in knowledge related to each of these questions and suggested a conceptual framework to delineate “significant impacts” of engineering interactions for all terrestrial animals.
We collected peer‐reviewed publications examining ecosystem engineer impacts and created a database of engineer species to assess experimental approaches and any additional covariates that influenced the magnitude of engineer impacts.
One hundred and twenty‐two species from 28 orders were identified as ecosystem engineers, performing five ecological functions. Burrowing mammals were the most researched group (27%). Half of all studies occurred in dry/arid habitats. Mensurative studies comparing sites with and without engineers (80%) were more common than manipulative studies (20%). These provided a broad framework for predicting engineer impacts upon abundance and species diversity. However, the roles of confounding factors, processes driving these patterns and the consequences of experimentally adjusting variables, such as engineer density, have been neglected. True spatial and temporal replication has also been limited, particularly for emerging studies of engineer reintroductions.
Climate change and habitat modification will challenge the roles that engineers play in regulating ecosystems, and these will become important avenues for future research. We recommend future studies include simulation of engineer effects and experimental manipulation of engineer densities to determine the potential for ecological cascades through trophic and engineering pathways due to functional decline. We also recommend improving knowledge of long‐term engineering effects and replication of engineer reintroductions across landscapes to better understand how large‐scale ecological gradients alter the magnitude of engineering impacts.
Understorey vegetation comprises the majority of species diversity and contributes greatly to ecosystem functioning in boreal forests. Although patterns of understorey abundance, species diversity and composition associated with forest stand development are well researched, mechanisms driving these patterns remain largely speculative.
We sampled fire‐origin stands of varying stand ages and overstorey compositions on mesic sites of the boreal forest of Canada and used structural equation modelling (SEM) to link time since fire (stand age), light availability and heterogeneity, substrate heterogeneity and soil nitrogen to understorey vegetation cover and species diversity.
The most parsimonious model for total understorey cover showed a positive direct effect of stand age ( r = .43) and an indirect effect via mean light level (0.18) and shrub cover (−0.11), with a positive total effect (0.50); the per cent broadleaf canopy had a direct negative effect (−0.22) and an indirect effect via shrub cover (−0.11). The model for total understorey species richness showed an indirect effect of stand age via mean light (0.24), light heterogeneity (0.10) and substrate heterogeneity (0.07), with a positive total effect (0.52); per cent broadleaf canopy had an indirect effect via light heterogeneity (0.09), and substrate heterogeneity (−0.10). Soil nitrogen did not significantly influence either understorey cover or species richness. The models for vascular plants followed similar trends to those for total understorey cover and species richness; however, there was an opposite indirect effect of light heterogeneity for both cover and species richness of non‐vascular plants. Shrub cover had positive direct and negative direct and indirect effects on both vascular and non‐vascular cover and species richness.
Synthesis . Our findings indicate that understorey cover and species diversity are driven by time since disturbance, light availability as influenced by overstorey and shrub layers, but with important additional effects mediated by light and substrate heterogeneity. Non‐vascular understorey vegetation is more strongly determined by time since disturbance than vascular vegetation, and negatively affected by broadleaf tree abundance. The overall results highlight the importance of colonization, light availability and heterogeneity, substrate specialization and growth dynamics in determining successional patterns of boreal forest understorey vegetation.
To understand the impacts of reforestation on woody species composition, species diversity and community structure, seven plantation forests in dry-hot valley of the Jinsha River in Southwest China were investigated, with adjacent wastelands, natural shrub grassland and a natural forest as references. Species importance value, species richness, species heterogeneity and Sorenson similarity index between plantations and the natural forest were analyzed. Results indicated that compared to wastelands and natural shrub grassland, reforestation improved species diversity and community structure, and more forest woody species found suitable habitats in plantations. Species diversity in understory of plantations and Sorenson similarity index were significantly negatively correlated with stem density in mature plantations (26-31 years old). Higher species diversity and Sorenson similarity index existed in mature sparse plantations due to lower stem density and more tree species planted initially. In contrast, reference natural forest, with species heterogeneity of 2.28 for shrub layer, showed the highest species diversity. It would take a long time for species composition and diversity to recover through reforestation in a dry-hot valley. Therefore, it was essential to protect remnant natural forests strictly and reforest with suitable management such as lower stem density and increasing genetic diversity of trees planted.
Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).
Burrowing animals fundamentally influence the character of soils, ecosystem function, erosion, and soil management for food production and hazardous wastes. Perhaps the most important indicator of their potential impacts is the average void space created for burrow construction and maintenance per unit area per unit time. We integrated published estimates of burrow volume (m3) and excavation rates (m3 ha-1 year-1) of pocket gophers (Rodentia: Geomyidae) to assess their reliability in assessment of impacts and whether these variables are scale-dependent. Estimates were difficult to interpret and compare because research goals, assumptions, and methods varied considerably among studies, as did site conditions and reporting of results. Volume of burrows made by various species of pocket gophers averaged 0.68 m3, and averages differed significantly between species. Rate of excavation averaged 18 m3 ha-1 year-1 for Geomyidae, and it declined with increasing spatial extent of study area used to make the estimates. Counts of mounds produced the largest estimates of burrow volume and excavation rate, and injection of polyurethane foam into burrows produced low estimates. High variation in estimated rates of burrow excavation indicates the need for further research to characterize magnitude and types of impacts gophers have on natural and managed ecosystems.
Dimensions of the burrow systems of four small mammals common to southeastern Idaho (Spermophilus townsendii, Dipodomys ordii, Microtus montanus and Peromyscus maniculatus) were determined in undisturbed soils. Spermophilus constructed two distinct burrow systems: over 120 cm deep and less than 60 cm deep. The deeper systems were significantly longer and had larger volume than the shallower burrows and the systems constructed by the other species. Burrow parameters for Dipodomys were bimodal, suggesting deep and shallow burrows, but this was not demonstrated statistically. All parameters for Dipodomys burrows were similar to shallow Spermophilus burrows. Volumes of both were significantly greater than volumes for Peromyscus and Microtus. A significant portion of the variability of all parameters for Microtus and shallow Spermophilus burrows was explained by the distribution of soil particle sizes, but equations based on these were only of limited value in predicting burrow parameters.
Chinese Pangolin is nocturnal, shy, non-aggressive, solitary, strange and burrowing mammal which has received low scientific attention. Little information is known about its biology, distribution and status. In Nepal it is distributed in many districts and protected areas. The status of this mammal is decreasing in the country but there is no any research regarding its biology, status and distribution. Although, this mammal is protected nationally and internationally, it is facing too much problems due to habitat destruction and illegal trade. This article mainly focuses on the biology, status, distribution and conservation threats of this ecologically beneficial handsome creature. DOI: http://dx.doi.org/10.3126/init.v5i0.10267 The Initiation 2013 Vol.5; 164-170
The zoogeomorphological impact of burrowing animals varies in time and space as a result of the particular life history traits of the organisms involved, the patchy distribution of habitat resources, and fluctuations in population size. Such ecological complexity presents a major challenge for biogeomorphologists wishing to upscale from individuals to populations. Using a unique ecological data set for Eurasian badgers (Meles meles L.) in Wytham Woods, Oxfordshire, UK, we show that direct zoogeomorphological impact (soil displacement during sett excavation) is constrained by fluctuations in overall population size. Modeled digging rates for individual badgers (0.19–4.51 m3 yr−1) varied depending on the ecological function of the sett they are associated with, and we estimate that the whole population has displaced 304–601 ± 72 m3 of soil during the construction of 64 setts. This represents an overall excavation rate of 6.7–19.4 m3 (6.0–17.5 t) yr−1 in sett areas or 1.42–4.12 g m−2 yr−1 when averaged over the whole 424 ha woodland. As well as direct soil displacement, badger digging exposes material that is initially susceptible to erosion by water relative to undisturbed and litter-covered soils. Over time, setts become stabilized, representing unique landforms that persist in the landscape for decades to centuries.
Habitat selection by Chinese pangolin (Manis pentadactyla) in winter was studied in Dawuling Natural Reserve, Maoming City of Guangdong Province, China, from December 1999 through February 2001.The objective of this study was to determine the pangolin's habitat requirement in winter during poor environmental conditions. The dominant habitat of this Reserve was classified into 4 types, i.e. mixed coniferous and broadleaf forest (MCBF), evergreen broadleaf forest (EBF), coniferous forest (CF) and shrub forest (SF). The results showed that the ranking of vegetation types selected by pangolins in winter was MCBF > SF > EBF > CF. Pangolins preferred MCBF, and avoided CF. The environmental factors preferred by pangolins in winter were 30°-60° steep slopes, middle of slopes and bottom of slopes, sunny slopes, distance from human disturbance source exceeding 1 000 m with a minor disturbance degree, heavy (81 % - 100 %) undergrowth with good shelter conditions, moderate (760 - 1 500 m) elevation, and medium (31 % - 70 %) closure of arbor canopy. The surroundings factors avoided by pangolins were sharp slopes steeper than 60° or gentle slopes less than 30°, shady slopes, distance from human disturbance source within 1 000 m, dense (71 % - 100 %) or sparse (0 % - 30 %) closure of arbor canopy, medium or lower coverage (0 % - 50 %) of undergrowth, and the top of the slope. Pangolins preferred south-facing burrow entrances with thick cover, and avoided north-facing burrow entrances with bare or poor shelter. The thick layer of shrub and herbs growing under the tree canopy appeared to be especially important to pangolins during winter.
We measured gopher tortoises (Gopherus polyphemus) and their burrows from a population in central Florida. Burrows of most juveniles were excavated. Newly emerged hatchlings constructed burrows that had the same structure as the burrows of older juveniles. The cross-sectional shape of juvenile burrows was similar to that of adult burrows, although the latter tended to be proportionally wider. Differences in burrow shape between juveniles and adults were consistent with allometric changes in tortoise shape. Juvenile burrows had a significantly greater angle of declination than adult burrows. Regression analysis showed that relationship between carapace length and burrow width differed significantly between juveniles and adults.
In harsh, resource-limited rangelands, plants and other structures, such as animal burrows, can ameliorate extreme microclimate conditions and increase resource availability for other species. The aim of this study was to determine whether relic bilby (Macrotis lagotis) refuge burrows had the potential to contribute to a rangeland restoration program by moderating microclimate and accumulating resources. During the day, the burrows maintained significantly higher relative humidity than control microsites. At night, temperature was significantly higher and humidity was significantly lower in the burrows than the control microsites. Both temperature and humidity were also significantly less variable in the burrows. There was some overlap between burrows and control microsites in soil chemistry, but burrows were significantly higher in soil moisture, pH(CaCl2), exchangeable magnesium, exchangeable potassium, mineral nitrogen, and total cation exchange capacity, and significantly lower in bio-available aluminium. Soils in burrows contained three times more mineral nitrogen, which has been previously shown to increase plant diversity and abundance in the presence of additional moisture. These results suggest the relic bilby burrows could potentially provide more suitable habitats for the establishment and productivity of other species by moderating microclimates, accumulating nutrients and soil moisture, and ameliorating the potentially detrimental effects of bio-available aluminium.