**3. Natural and anthropogenic disturbance**

All habitats are exposed to an ecological succession and to natural disturbances, namely volcanic eruptions, or tropical cyclones, that significantly alter the animal and plant populations. As defined by Pickett, disturbance is "a change in the minimal structure of an object caused by a factor external to the level of interest" [20].

#### *Conserving Endemic Plant Species in Oceanic Island's Protected Areas DOI: http://dx.doi.org/10.5772/intechopen.100571*

Oceanic islands are also subject to numerous disruptive events such as hurricanes, high winds, heavy rains, high pressure systems, earthquakes, volcanic eruptions, tsunamis, extreme tides, the introduction of exotic species and human activities. These have mechanical, physiological, or biotic impacts that can last for years. In fact, because most oceanic islands are small and located in harsh environments, these disturbance events tend to have more severe consequences on oceanic islands than on continental land masses [1].

In addition to these natural disturbances, humans have had a profound impact on biodiversity, altering the composition and functioning of ecosystems. These events are of the utmost importance for the survival of wild habitats and the viability of populations.

After a disturbance event, when the number of individuals falls below a specific threshold, the species loses genetic diversity, which reduces its ability to adapt to change and therefore increases the risk of extinction. Island endemic species are usually very localised and have small numbers of individuals, which makes them highly vulnerable to disturbance and therefore to extinction [21].

### **3.1 Biological invasions**

With human settlement on oceanic islands new species were introduced as farm stock, crops, for fibres or furs, domestic animals, pets, sports, or solely as ornamentals [22, 23]. Other species, however, were introduced due to military operations, international trade, and globalisation, either ship cargoes, ballast water, shipwrecks, which unintentionally transported these exotic species to the island, whether plants or animals (**Figure 3**) [24]. More recent invasions drivers are climate change, land-use change providing new habits, pollution, and the positive interaction among non-native species, a process known as invasion meltdown [25, 26].

#### **Figure 3.**

*Invasive alien mammals: top right: mouse (*Mus muscullus*) native to south Asia is invasive worldwide; top centre: rabbit (*Oryctolagus cuniculus*) native to Europe; top right: feral goat (*Capra hircus*); bottom left: wild boar (*Sus scrofa*) native to Eurasia and Africa; bottom centre: red deer (*Cervus elaphus*) native to Europe; bottom right: grey-squirrel (*Sciurus carolinensis*) native to America.*

An introduced species is a species that (1) owing to human activity colonises a new area where it was not previously present, (2) is remotely dispersed with a wide geographic discontinuity, and (3) becomes naturalised by perpetuation of new generations without human intervention [27]. Luckily, most introduced species do not become established, due to mortality during translocation, unsuitable environmental conditions and biotic resistance exerted by the host community [28].

Nevertheless, once established, it can become a new invasive alien species (IAS) when it has an undesirable effect on the native ecosystems. The ecological and economic impact of IAS may be after the invader is well established and have wide range, and then the damage may be extremely severe. IAS are responsible for altering the ecosystem functioning, modifying native species richness and abundance, and increasing the risk of extinction, breaking down biogeographic realms, affecting the genetic biological diversity, changing the phylogenetic diversity across communities, and modifying the trophic networks, as well as disturbing human health and/or socioeconomic values at the individual, population, or community level [25, 29–31]. "Habitat transformers" species, which cause changes in ecosystem nutrient cycling at microbial or higher plant levels [32] and "ecosystem engineer" species, which are landscape modifier species [33], are particularly dangerous for they are strongly competitive IAS with the ability to alter environmental conditions, being a major contributor to species diversity loss. As such, IAS alter the composition of plant and animal communities, and also interfere with other ecosystem processes such as nutrient cycling, hydrological cycles, and primary productivity [34].

Accordingly, IAS may have severe negative impacts on oceanic islands because these ecosystems are species-poor and have few highly competitive species [30]. IAS impacts on islands are intensified through the interaction with other global change threats, including over-exploitation of natural resources, agricultural intensification, urban development, and climate change, exacerbating some invasions, and facilitating others, escalating the impact and the extent of IAS [35]. Currently, IAS may be the main cause for ecological disintegration globally, and thus the early detection, rapid action in eradication and good planning is of utmost importance, mainly on islands or other limited habitats [23].

#### **3.2 Climate change**

Climate change poses serious risks for human and natural systems. Species are shifting their geographic ranges and altering the numbers of individuals in their populations, variations in seasonal activities, migration patterns and interactions between different species are also occurring in response to ongoing climate change. The impact from recent climate-related extremes, such as heat waves, floods, droughts, cyclones, and fires, reveal significant vulnerability and risk of many ecosystems, some irreversible. To make matters worse, carbon stored in the terrestrial biosphere in peatlands, permafrost, and forests, among others, may be lost to the atmosphere, exacerbating ecosystem degradation. Furthermore, the sea level rise projected for the 21st century and beyond will have an enormous impact on coastal systems, islands, and low-lying areas, which will suffer adverse impacts such as submergence, flooding and coastal erosion. These impacts will be extremely severe on low-lying developing countries and small island states [36].

Due to climate change, the intensity and frequency of wildfires is also increasing [37]. Besides the noticeable economic impact, heat dramatically disturbs soil surface, often causes a decrease in diversity and abundance of soil biota, and strongly increases the risk of erosion by wind and water [38]. These effects depend upon fire severity, and some fire regimes are beneficial to ecosystems. These are controlled by

#### *Conserving Endemic Plant Species in Oceanic Island's Protected Areas DOI: http://dx.doi.org/10.5772/intechopen.100571*

environmental factors such as amount, nature, and moisture of live and dead fuel, air temperature and humidity, wind speed, and topography of the site [39, 40]. Due to climate change, induced wildfires are becoming more frequent and are more aggressive and, thus, have frequently severe negative impact on the vegetation and on sensitive species.

Islands are particularly vulnerable to climate change disturbance, owing to the vulnerability of island endemic plants, due to habitat loss and interactions with introduced species [41]. The IAS may benefit from climatic change, as they are opportunistic, very competitive species, thus less vulnerable due to their adaptability to new environments [42]. Manes et al. [41] study stated a 100% risk of extinction for island ecosystem due to climate change and a risk of extinction 3 and 10 times higher for endemic than native and introduced species, respectively.

As such it is expected a decline of endemic plants in oceanic islands, a degradation of mangroves, wetlands, and seagrass around small islands, a degradation of groundwater and freshwater ecosystems due to saline intrusion, a spread of warm water species into the Mediterranean, namely IAS, among many other negative impacts attributed to climatic change [36].

Steffen et al. [43] postulate that the Anthropocene' era is rapidly approaching levels of human-induced greenhouse gases that are approaching critical levels. When reaching an irreversible threshold, the devastating consequences will be irreparable for the distributions of species and in the composition of biological communities. Many of these impacts may already be permanent.

#### **3.3 Tourism and recreation**

Disregarding the impact of the pandemic Tourism and Leisure are among the fastest growing economic activities of recent decades [44]. Yet, touristic activities are well known by their negative consequences, being responsible, for instance, for greenhouse gas emissions [45], high patterns of visitor consumption and waste generation [46], for plant damage, including vegetation removal and changes in land cover and land use [47], tourists trampling and spreading weeds and pathogens, and altering fire regimes [17, 48]. Tourists also often pick flowers, threatening the more charismatic species [49]. Tourism, thus, have negative impact in the wildlife, health, physiology, reproduction rate, and behaviour of the wild species [45, 50–53], prompting the decline of sensitive plants, while favouring the growth of resistant species, frequently opportunistic and exotic ones [49].

Thus, tourism is frequently an unsustainable activity not complying with the UNWTO definition of sustainable tourism as "tourism that takes full account of its current and future economic, social and environmental impacts, addressing the needs of visitors, the industry, the environment and host communities" [54].

The presence of tourists in Protected Areas is especially sensitive, for the number of visitors in a protected area increase the number of exotic species on site, since visitors increase propagule pressure and disturbance [28]. More disturbed habitats create open space that may allow IAS to establish and, thus, offer invaders an edge against native species [24].

Yet, due to the dependence on a healthy and safe environment, a social change seems to be arising within tourists and policymakers, increasingly seeking more environmentally friendly practices and tourism activities, through the development of nature-based tourism and ecotourism [55, 56]. In fact, more sustainable tourism activities are increasingly supporting wildlife conservation and local populations welfare are becoming a reality in many countries with pristine ecosystems and charismatic species [57–59].

#### **3.4 Agriculture, and deforestation**

Agriculture is intensifying at global level, and this trend will continue in the next years, to meet the growing human population needs. This agriculture expansion will bring ecosystem simplification, loss of ecosystem services, and species extinctions [60]. The agricultural spreading could have major impacts on biodiversity hotspots, as these are areas where there is significant population growth, often poor and with a low development index, where there is an increasing pressure to produce food and promote economic growth through the commercial use of natural resources [61]. In fact, many tropical protected areas, are suffering forest loss through agricultural intrusion, often to grow palm trees for biofuels, being a cheap source of oil [62].

Forest loss has also been occurring through legal or illegal logging, conversion to small-scale agriculture, and larger-scale commercial plantations, namely in the Amazon, Africa, and Asia, but also in small tropical islands, such as New Britain [63]. At the community level, large trees contribute extensively to ecosystem functioning and provide key habitats for biodiversity [64]. Logging is known to degrade forest structure, creating gaps, removing soil, and fostering the proliferation of IAS [65].

#### **3.5 Urbanisation**

Human population has more than doubled since 1950 and for the next half century there should be a continued rapid growth in the least developed regions [66]. This massive growth in human population has serious consequences for natural habitats, with increasing pollution, the spread of IAS, carbon emissions and the consumption and destruction of natural resources, resulting in the change of many of the last remaining wild spaces on the planet [67]. Therefore, fewer world ecosystems are away from human pressure, and many are experiencing biodiversity loss and ecosystem degradation due to the construction of infrastructures, for vehicles, for the industry, for hydraulic and harbour set-ups, hydroelectric infrastructures, among others, with severe impacts on many ecosystems and species. Roads, for example, open new opportunities for habitat fragmentation, fires, logging, and land speculation [68, 69]. The rapid proliferation of roads will also strongly influence the footprint of agriculture. Thus, wild regions, parks and protected areas, relics of intact habitat within biodiversity hotspots, such as islands, are among the environments where roads and other infrastructure should be limited, allowing the conservation of such habitats and species [68, 70].

Besides the roads, the building of infrastructures for urban expansion, tourism, or for other economic activities, has, evidently, direct impact in the vegetation clearance, to open the area. However, beyond the immediate impact on the vegetation, such infrastructures have a long-term impact, due to habitat fragmentation, the changes caused on the soil hydrology, pollution runoff, and as already mentioned, as a corridor for the introduction of pathogens and IAS [71, 72].

#### **4. Conservation measures**

Protected areas (PAs) are the main pillar of conservation activities and are therefore the first integrated approach for the conservation of biodiversity and ecosystem services worldwide [73]. Acknowledging the worldwide recognition of the importance of the PAs as a tool for the economic, social, and scientific importance, and for their role in environmental well-being, the total PA has increased

#### *Conserving Endemic Plant Species in Oceanic Island's Protected Areas DOI: http://dx.doi.org/10.5772/intechopen.100571*

tenfold from 1959 until 2016, from roughly 2 Mkm2 to almost 20 Mkm2 , corresponding to 202,467 total PAs. In 2014 around 17% of the world island biomes were protected, mainly temperate (23%) and polar ecosystems (17.5%), while less than 13% of tropical islands were protected, where endemism is higher [74]. Also, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services report [36] and the recent Global Biodiversity Outlook [75] noted some interesting progress in the conservation and sustainable use of biodiversity in PAs.

Although more recent reports do not include data on islands, between 2014 and 2020 the protected land and inland water ecosystems increased from 15.4% to 16.64% (with a total of 22.5 million km<sup>2</sup> and 248,113 protected areas), and the protected coastal waters and the ocean increased from about 4.5% to 7.74% (28.1 million km2 and 17,828 protected areas) [76, 77]. This growth falls within the conservation efforts tackled by the Aichi Biodiversity Targets under the Convention on Biological Diversity (CBD). Still, despite the progress in conservation and sustainable use of biodiversity, the Strategic Goal 11 has been tightly missed: "by 2020, at least 17% of terrestrial and inland water areas and 10% of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystem services" [78].

While many of the endemic species' populations are within protected areas, often these are not enough to fully protect them, because, among other problems, management quality is not satisfactory, and thus biodiversity loss has persistently continued [79]. Therefore, it seems that the extensive conservation efforts are not being successful and new approaches are needed.

Current conservation strategies are still largely based on the assumption that we live in a dynamic but slowly changing world. Such an assumption needs to be revised considering the rapid rate of climate change already experienced in recent years, which is expected to continue at this pace if not increasing, over the coming decades, forcing researchers and managers to rethink and recalibrate the conservation responses [80]. On the other hand, conservationist classical approaches are based mainly on *ex-situ* conservation of endangered species, and reintroduction measures from which they have been lost, while restoring degraded or lost ecosystems [81]. When it comes to conservation of plants, and endemic species in particular, the scenario seems even more ineffective, with plants becoming increasingly rare around the world. Successful plant conservation includes research on the species distribution and rarity. Then an efficient management plan to tackle conservation efforts, prioritisation of measures, stakeholders' interests, and training capacity are important to mitigate threats facing threatened species. To implement such plans, policy and funding are foundation stones to support continued capacity of conservation. Ultimately, the last but not the least, a deep education plan for the public, so to understand and support the importance of plants and the need for their conservation is of utmost importance to achieve efficient conservation. These are not simple or isolated actions. Coordination of plant conservation efforts is also needed to ensure that resources and expertise are used in a strategic, efficient, and effective manner [82].

### **4.1 Data collection**

Due to lack of knowledge and interest, plants are often under protected by policy, their conservation efforts are underfunded, and their importance is under cherished. To overcome such lack of information, an Important Plant Areas (IPAs) criteria system was defined, offering a pragmatic and scientifically rigorous mean of delivering these datasets, assisting the informed decision making and conservation prioritisation [83]. This database generates essential data for other databases such as

the IUCN Key Biodiversity Areas (KBAs) programme [77] producing a worldwide network of relevant information. The database, however, is still rather limited, for many countries have not yet made available the data on the distribution, rarity and threat status of plant species and their habitats, mainly in the tropical areas.

The IPA criteria, for the first time, recognises the socio-economically valuable plant species providing essential goods, such as the importance of plants as a food source, medicines, timber, fuel, materials for clothing, ornamental, social and cultural traditions, besides the vital ecosystem services [83].

The identification of the biodiversity hotspots and endemism centres, along with the assessments summarised by the IUCN red list categorisation [84] and creating global, national, and regional lists of threatened species, are, likewise, valuable tools in conservation prioritisation and planning [85]. Most countries have national agencies responsible for gathering information on native ecosystems, habitats, endemic species, PAs, in regional or national databases, fundamental information for the implementation of conservation actions.

The improvement of biological and ecological knowledge will allow to better target conservation measures.

#### **4.2 Legal protection**

Besides the legal protection at regional and national levels, there are several international cooperation treaties to tackle the threats on wildlife and nature protection. The following are some of the most important, within the plant conservation:


Although each of these international treaties stand on its own, regarding their objectives and commitments, they are inter-linked between their goals and complement each other. Each convention governing body set out specific mandates for cooperation between the biodiversity-related conventions, providing a framework for joint action of biodiversity and a foundation for sustainable development [74].
