Theory and Methodology of Ecosystem Engineering

Ecosystems engineering is specially designed for study and management of ecosystems. Its theory and method-ology are mainly derivcd from systems ecology and systems engineering An ecosystem is a biologically functional entityconsisting of organisms, environmental factors and their interactional mechanisms which are naturally or artificially ar-ranged with their approytiate functions in the system and also subordinaled to the dynamics of the whole ecosystem If an ecosystem is broken or disintegrated into independent or isolated parts. its structural and functional entity will be greatly modified or even completely destroyed Yet without participation of organisms including human beings, a system is not anecosystem. Within an ecosystem, all life, production and social activities are directly or indirectly rclated to the energy flowand material exchange In fact. energy is a driving force for material exchange and material is the carrier of energy flowTherefore, an ecosystem can be logically recognized as an energy system Its components. structure, function. production,quality and benefits can be expressed, calculated and modelled in terms of energy. Ecoboundary theory is also used in thediscussion of pathways of energy flow. As being applied to agrolioresty management, envirommental conservation and com-munity social service which are all complicated ecosystems, ecosystem engineering requires a series of programming meas-ures such as investigation, decision-making, planning, simulating, design, establishment, management, evaluation and reno-vation so that an appropriate ecosystem with stable structure, ellective function and high productivity can be established forits expected economic, ecological and social benefits.

A Review of the Engineering Role of Burrowing Animals: Implication of Chinese Pangolin as an Ecosystem Engineer

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.

Diversity patterns of cushion plants on the Qinghai-Tibet Plateau:A basic study for future conservation efforts on alpine ecosystems

The Qinghai-Tibet Plateau(QTP)is an important cushion plant hotspot.However,the distribution of cushion plants on the QTP is unknown,as are the factors that drive cushion plant distribution,limiting our understanding of the evolution of cushion species in the region.In this study,we assessed spatial patterns of total cushion plant diversity(including taxonomic and phylogenetic)over the entire QTP and compared patterns of diversity of cushion plants with different typologies(i.e.,compact vs.loose).We also examined how these patterns were related to climatic features.Our results indicate that the southern QTP hosts the highest total cushion plant richness,especially in the south-central Hengduan Mountains subregion.The total number of cushion species declines from south to north and from southeast to northwest.Compact cushion plants exhibit similar patterns as the total cushion plant richness,whereas loose cushion plants show random distribution.Cushion plant phylogenetic diversity showed a similar pattern as that of the total cushion plant richness.In addition,cushion plant phylogenetic community structure was clustered in the eastern and southwestern QTP,whereas random or overdispersed in other areas.Climatic features represented by annual energy and water trends,seasonality and extreme environmental factors,had significant effects on cushion plant diversity patterns but limited effects on the phylogenetic community structure,suggesting that climatic features indeed promote the formation of cushion plants.Because cushion plants play vital roles in alpine ecosystems,our findings not only promote our understanding of the evolution and formation of alpine cushion plant diversity but also provide an indispensable foundation for future studies on cushion plant functions and thus alpine ecosystem sustainability in the entire QTP region.

Impact of great gerbils(Rhombomys opimus) on desert plant communities

Great gerbil（Rhombomys opimus） colonies, with bare soil and herbaceous plants, are conspicuous to the background environment throughout their range area. In order to quantify the engineer role of great gerbils, we investigated the plant communities of 20 active colonies in the Junggar Basin, Xinjiang, China. In areas without disturbance, desert plant communities were dominated by the shrubs with low level species richness. In burrow areas and surrounding intermediate areas, which were disturbed by great gerbils, the shrubs were suppressed with the decrease of vegetation cover and aboveground biomass. As a result, ＂niche gaps＂ were created in disturbed areas and worked as a refuge for herbaceous annuals and perennials. So the existence of great gerbils increased the overall species richness of the desert. Furthermore, herbaceous annuals and perennials are the major food source for great gerbils in spring, indicating that great gerbils have a mutually beneficial relationship with herbaceous plants.

Invasion syndromes:hypotheses on relationships among invasive species attributes and characteristics of invaded sites

As invasion science accepts that there is no single causal factor for biological invasion, the identification of groups of traits that are often associated, or ＂syndromes＂, is a logical move forward. Invasion syndromes are proposed to identify suites of site conditions （biotic and environmental） that render a site vulnerable to invasion by different types of invaders. This paper proposed four invasion syndromes which relate invader attributes （competitive ability, niche construction, phenotypic plasticity, and phenological niche separation） to the biotic characteristics （biodiversity and enemies） and environmental conditions （resource abundance and fluctuation） of invaded sites. The four invasion syndromes described in this paper are a development of hypotheses of how the many factors that influence species invasion might be associated. Invasion Syndrome 1 proposes that sites with relatively high resource abundance and high diversity should be vulnerable to invasion by species with high competitive ability. Invasion Syndrome 2 hypothesizes that sites with relatively low resource abundance and low diversity should be vulnerable to invasion by species with niche construction ability. Invasion Syndrome 3 postulates that sites with moderate or fluctuating resources and moderate diversity should be vulnerable to invasion by species with high phenotypic plasticity. Invasion Syndrome 4 hypothesizes that species introduced into a site where it has phenological niche separation from natives will not have to contend with interference from the biotic community at a site （diversity or natural enemies） and may invade where ever site environmental conditions suit its life history. Further work is needed to support, contradict, or refine these hypotheses and almost certainly will identify more invasion syndromes.

The African Elephant (<i>Loxodonta africana</i>): Mini-Review of an Endangered Species

Humankind is responsible for conditioning the distribution of species, including the African elephant. From its great physical form to its fascinating social behaviour, Loxodonta africana can trigger an admiration in some and be undervalued by others, often ending up being a victim of human activities. Increasingly, the apparent impossibility of the coexistence of these two species represents a problem for the conservation of the large African mammal. Here it was reviewed the published bibliography about the African savannah elephant (L. africana), between July 2015 and December 2019. The Web of Science (WoS) database enabled the search for the words “Loxodonta africana”. From this research, we obtained 310 articles, 149 of them were analysed. Elephants have characteristics that define its uniqueness that are constantly reported, such as: its cognition and extraordinary memory, factors that influence its movements and its distribution, its specific vocalization and the strong dependence on social connections. Threats to the conservation of the species and the urgency of interventions are also an important subject of discussion. Poaching for ivory represents a major obstacle on conservation and has been drastically reducing the number of elephant populations and causing future consequences for those who thrive. Law enforcement in reducing/prohibit poaching has proven to be insufficient, so there is an urgent need to combat the demand for ivory. Also, it is necessary to bypass the conflict, promote tolerance and enable cohabitation. We believe that educating human populations to better understand the species may be the difference to guarantee a future for the species. Conservationists may be the enablers of these educational actions, however, to make the difference, it is necessary to know the species in detail. Mastering knowledge in these behavioural areas will contribute to improve mitigation strategies, which could make the difference to guarantee a future for the species.

Functional-trait ecology of the plateau pika Ochotona curzoniae in the Qinghai-Tibetan Plateau ecosystem

Understanding a species’functional traits allows for a directed and productive perspective on the role a species plays in nature,and thus its relative importance to conservation planning.The functionaltrait ecology of the plateau pika Ochotona curzoniae is examined to better understand the resilience and sustainability of the high alpine grasslands of the Qinghai-Tibetan Plateau(QTP).The key functional traits of plateau pikas are their abundance and behavior of digging extensive burrow systems.Plateau pikas have been poisoned over a significant part of their original geographic distribution across the QTP,allowing comparison of ecological communities with and without pikas.Nearly all mammalian and avian carnivores,most of which are obligate predators on pikas,have been lost in regions where pikas have been poisoned.Most endemic birds on the QTP nest in pika burrows;when pikas are poisoned,burrows collapse,and these birds are greatly reduced in number.Due to the biopedturbation resulting from their burrows,regional plant species richness is higher in areas with pikas than without.The presence of pika burrows allows higher rates of infiltration during heavy monsoon rains compared to poisoned areas,possibly mitigating runoff and the potential for serious downslope erosion and flooding.Thus,the functional traits of plateau pikas enhance native biodiversity and other important ecosystem functions;these traits are irreplaceable.As plateau pikas are not natural colonizers,active reintroduction programs are needed to restore pikas to areas from which they have been poisoned to restore the important functional ecological traits of pikas.

Environmentally applied nucleic acids and proteins for purposes of engineering changes to genes and other genetic material

In this article we summarize the development of vehicles for penetrating living cells,tissue and organisms with nucleic acids(DNA and RNA)and proteins that damage or repair DNA.The purpose in doing so is to provide an assessment of the potential for these technologies to unintentionally cause harm to human health or the environment or to be retasked with an intention to cause harm.Two new types of biological-molecule-based products are being developed for use in medicine,agriculture and food production or preservation.The first type are genetically modified organisms,such as those that express bio-pesticides.They produce molecules and that are difficult to alter at scale after release.Products of this type are usually evaluated by both food and environmental regulators.The second type comprises topical chemical or physical agents.Most of these are in pre-commercial testing phase.Topically applied products use nucleic acids and/or proteins wherein the active biological is transferred by contact,ingestion or inhalation.From a survey of the research and patent literature we suggest that chemical formulations and physical manipulations that can be used to ferry nucleic acid and protein cargo into cells,tissues or organisms could be assembled de novo or repurposed from existing commercial products and loaded with proteins and/or nucleic acids designed using publicly available genome sequences.Biological actives may evade risk assessment and regulatory review because they are often excluded from the category of hazardous chemicals and are actively being excluded as agents of genetic modifi-cation.This emerging gap in oversight could lead to either dual use appropriation or unintended harm to human health or the environment.

Increased Benthic Algal Primary Production in Response to the Invasive Zebra Mussel (Dreissena polymorpha) in a Productive Ecosystem,Oneida Lake,New York

Increased water clarity associated with zebra mussel （Dreissena polymorpha） populations may favor benthic algal primary production in freshwater systems previously dominated by pelagic phytoplankton production. While zebra mussel-mediated water clarity effects on benthic primary production have been implicated in published reports, few production estimates are available. This study estimates benthic primary production in Oneida Lake, NY before and after zebra mussel invasion （1992）, using measured photosynthetic parameters （P^Bmax, α^β and β） from sampled benthic algal communities. In the summers of 2003 and 2004, primary production was measured as O2 evolution from algal communities on hard （cobble） and soft （sediment） substrate from several depths. We also backcast estimates of benthic primary production from measurements of light penetration since 1975. Estimates of whole-lake epipelic and epilithic algal primary production showed a significant （4%） increase and exhibited significantly less interannual variability subsequent to the establishment of zebra mussels. We applied our model to two lakes of differing trophic status; the model significantly overestimated benthic primary production in a hypereutrophic lake, but there was no significant difference between the actual and predicted primary production values in the oligotrophic lake. The hypereutrophic lake had higher zebra mussel densities than Oneida （224 vs. 41 per sample respectively）. Though total community respiration （measured in total darkness） was factored into our model predictions of production, our model may need modification when heterotrophic respiration is a large portion of total community metabolism.

Ecological role of the giant root-rat(Tachyoryctes macrocephalus)in the Afroalpine ecosystem

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation.This is the case for the giant root-rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains,Ethiopia.We studied the impact of root-rats on various ecosystem features within a 3.5-ha study locality dominated by Alchemilla pasture,which represents an optimal habitat for this species,in 2 periods of a year.The root-rats altered plant species composition,reducing the dominant forb,Alchemilla abyssinica,while enhancing Salvia merjame and a few other species,and reduced vegetation cover,but not the fresh plant biomass.Where burrows were abandoned by root-rats,other rodents took them over and A.abyssinica increased again.Root-rat burrowing created small-scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments.Less compacted soil tended to be rich in nutrients,including carbon,nitrogen and phosphorus,which likely affected the plant growth on sites where the vegetation has been reduced as a result of root-rat foraging and burrowing.

Burrowing Richardson's ground squirrels affect plant seedling assemblages via environmental but not seed bank changes

In grassland ecosystems,burrowing mammals create disturbances,providing habitat for animal species and increasing plant community diversity.We investigated whether seedling assemblages on Richardson's ground squirrel Urocitellus richardsonii mounds result from seed rearrangement or environmental changes that favor germination of certain species over others.To test whether ground squirrels rearrange the seed bank by burrowing,we compared seed compositions among mounds,burrows,and undisturbed soil.To test whether ground squirrels change environmental conditions,we compared soil nitrate and bare ground cover on and off mounds.We also compared seedlings that germinated on mounds with seedlings that germinated on artificial disturbances from which we removed aboveground vegetation.Soil nitrate and bare ground cover were significantly higher on mounds than artificial disturbances.While seed richness and abundance did not differ among mounds,burrows,and undisturbed soil,seedling richness was reduced on mounds relative to artificial disturbances.Burrowing disturbance favors seedlings that can capitalize on bare ground availability but are less able to immobilize nitrate,as opposed to perennial species that immobilize more nitrate but take longer to establish.Our results suggest that Richardson's ground squirrels act as ecosystem engineers,although future research following succession on ground squirrel mounds is necessary to understand how they influence plant communities past the seedling stage.

枯死灌木斑块对退化旱地生态系统的调节作用

A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev.The most impacted shrub species is the Noaea mucronata(Forssk.)Asch.and Schweinf.In a four-year study,we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces,suggesting that the dead shrub patches encompass improved micro-habitats.However,unexpectedly,the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces.At the same time,soil quality in the dead shrub patches was higher than that in the inter-patch spaces.Therefore,it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water,supporting increased herbaceous productivity.For explaining the discrepancy between herbaceous vegetation and soil-water,we formulated a conceptual framework,which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem.We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died.The dead shrub patches encompass a unique form of ecosystem engineering.The study highlights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.