Conservation Biodiversity in Arid Areas: A Review

Abstract

Drylands cover a vast area, and biodiversity conservation in these regions represents a major challenge. A bibliometric study of published research highlighted several key aspects, including publication types, research fields, years of publication, contributing countries, institutions, languages, journals, publishers, authors, and frequently used keywords. The analysis also included plants related to biodiversity conservation in arid areas, animals related to biodiversity conservation in arid areas, and causes of biodiversity decline in arid regions, effects of biodiversity loss in these regions, and restoration methods aimed at improving biodiversity conservation in arid areas. A total of 947 publications were identified, starting from 1994, authored by researchers from 99 countries, primarily from Australia, the USA, China, Spain, and South Africa, and published in 345 journals, with the most prominent being Journal of Arid Environments, Biodiversity and Conservation, and Biological Conservation. The most commonly appearing keywords included biodiversity, conservation, diversity, vegetation, and patterns, with recent years showing an increased use of terms related to the causes and effects of aridification: climate change, land use, and ecosystem services. The causes of biodiversity loss in drylands are primarily linked to human activities and climatic changes, while the effects impact the entire ecosystem. Methods to improve biodiversity include traditional agroforestry systems, tree plantations and other plant species, grazing management, and other approaches. Combined actions among stakeholders and ecologically appropriate nature-based solutions are also recommended. Improvements in conservation biodiversity in arid areas are very important also for achieving the sustainability goals in these areas. However, numerous aspects of this topic remain to be studied in greater detail.

1. Introduction

Covering around 41% of the planet’s land area, drylands provide essential support for over 2 billion people (one-third of the human population in 2000) and exhibit unique characteristics related to native plant life, carbon cycling, climatic conditions, and land utilization [1,2,3]. These regions serve as habitats for rare and endemic species and provide forage for wildlife. While resilient to limited and variable water availability [4], drylands face growing threats from human activities [5] and climate change. Challenges include extended droughts, higher temperatures, shifting moisture patterns, frequent fires, and intensified land use [6,7]. These pressures lead to severe social and environmental impacts, some of which may be irreversible [8,9,10]. The accelerating decline of biodiversity within arid environments has emerged as a pressing environmental issue of our time [11].

Plant diversity, an essential element of terrestrial ecosystems, reflects both species composition and community structure, contributing to ecosystem stability [12]. Increasingly impacted by changing climate patterns, it remains highly vulnerable to abiotic stresses, especially in delicate arid environments [13]. Declining plant diversity can disrupt ecosystems, diminish biological resources, degrade environments, reduce productivity, and trigger food crises [14].

Advances in computer technology have made quantitative reviews, such as bibliometric analysis, a powerful tool for systematically and transparently reviewing large volumes of research [15,16]. This approach offers insights into publication trends, keyword evolution, dominant disciplines, leading journals, and contributing institutions and authors [17,18]. Bibliometric analysis also uncovers connections between published research and developing trends in scientific studies [19,20].

Unlike traditional narrative reviews, bibliometric studies provide a more quantitative approach with reduced subjectivity [16]. In an era of overwhelming information and rapidly growing publications [21,22], this method is crucial for generating systematic conclusions [17,23,24]. It is often referred to as “the science of science” when evaluating progress in specific fields.

There are a few published bibliometric review articles addressing topics such as the relationship between biodiversity and ecosystem functioning [25], biodiversity offsetting [26] and disparities in knowledge production and distribution regarding biodiversity conservation in Tanzania [27]. Specifically related to arid areas, there are also some bibliometric studies, including research trends on the deserts of Northern China [28], the use of agronanotechnology in Mexico’s arid regions [29], and assessments of land degradation in drylands utilizing remote sensing technology [30].

The clustering technique is a specific feature of software programs designed to analyze and identify key research directions within a given topic. This method relies on querying a specific database, such as Web of Science (WOS) or Google Scholar, and selecting a set of works based on a given topic to form the primary dataset. Each selected work is then linked to others within the dataset based on citation relationships or co-authorship connections. These relationships are typically represented in a simplified form as a graph (https://en.wikipedia.org/wiki/Graph_theory, access date: 12 January 2025).

Considering the clustering technique, there are multiple ways to establish connections within the dataset. These connections may be based on author affiliations within research groups or citation relationships between selected articles. The first type of connection enables the assessment of Total Link Strength, while the second type evaluates the Links attribute.

An essential aspect of clustering analysis is the evaluation of an article’s Total Link Strength. As commonly known, two standard attributes measure an article’s impact weight: the Links attribute and the Total Link Strength attribute. The Links attribute indicates the number of connections an article has with other articles, while Total Link Strength measures the overall strength of these connections based on co-authorship links.

For example, in co-authorship networks, the Links attribute represents the number of co-authorship connections a researcher has. Meanwhile, the Total Link Strength attribute reflects the overall weight of co-authorship links between a researcher and others in the field. This distinction helps identify key research teams working in a specific area, while the Links attribute assesses scientific influence on research output.

This study aims to identify and analyze global research trends on biodiversity conservation in arid areas through bibliometric analysis; determine key themes and contributors by assessing publication types, research fields, leading journals, authors, and countries; examine the causes and effects of biodiversity loss in arid regions based on a systematic review of published studies; evaluate conservation and restoration methods applied in arid areas, including agroforestry, tree plantations, grazing management, and nature-based solutions.

By integrating bibliometric analysis with a classical review, this study offers a comprehensive overview of biodiversity conservation research in drylands, serving as a valuable resource for researchers, policymakers, and conservation practitioners. Given the rapid expansion of research on biodiversity in arid areas, there is an urgent need for a comprehensive review that consolidates and synthesizes existing findings. Current studies on biodiversity loss, conservation efforts, and ecological management in drylands are scattered across multiple disciplines. A systematic review is necessary to identify key research trends, highlight knowledge gaps, and provide a foundation for future studies.

2. Materials and Methods

The first part of the article involved a bibliometric study to analyze global research data on conservation biodiversity in arid areas from 1994 to 2023. An analysis of studies examining the link between biodiversity and ecosystem functions of arid environments was conducted using the Science Citation Index Expanded (SCI-E) within the Web of Science Core Collection, covering the years 1994 to 2023.

The search, conducted in SCI-E, used the terms “TS = conservation biodiversity in arid areas (955 documents) OR conservation biodiversity in drylands” (211 documents) limiting results to articles (852 articles). After excluding unrelated records, 947 relevant publications were identified. The criteria used for screening included the following: Inclusion Criteria: articles from the Web of Science (WoS) database, specifically from the Science Citation Index Expanded (SCI-E); research related to “conservation biodiversity in arid areas OR conservation biodiversity in drylands.”; and only peer-reviewed journal articles. Exclusion Criteria: conference proceedings, articles with unclear origins, unrelated studies, and duplicate records were excluded. These criteria were determined before screening, ensuring a more systematic and reproducible review process. Retrieved literature was downloaded in batches of at least 500 documents in Txt format, which were collected and stored as “download” files for categorization and analysis. The study examined ten key aspects: (1) publication types, (2) research fields, (3) publication years, (4) contributing countries, (5) affiliated institutions, (6) primary language, (7) scientific journals, (8) publishing entities, (9) leading authors, and (10) key terms.

Data processing utilized Web of Science Core tools [31], complemented by Excel [32] and Geochart [33]. Map visualization and cluster analysis were performed using VOSviewer version 1.6.20 [34]. We performed an initial screening of the collected data, excluding conference presentations, articles with unclear origins, those unrelated to the specific topic, and duplicate records. The bibliometric analysis aimed to identify prominent themes and key contributors and provide insights into the articles, authors, and journals focusing on this subject.

The second part of the study applied a classic review approach, involving an in-depth examination of 90 published articles. Additionally, Google Scholar was used to review these articles and to identify other relevant articles for discussion, including those not strictly related to the selected keywords. The findings on biodiversity in arid regions were categorized into five main result areas: plants related to biodiversity conservation in arid regions, animals related to biodiversity conservation in arid regions, causes of biodiversity decline in arid regions, effects of biodiversity loss in arid regions, and restoration methods for improving biodiversity conservation in arid regions.

The methodology we have used is succinctly presented in Figure 1.

3. Results

3.1. A Bibliometric Review

We have inventoried 947 publications on this topic. Most of them are articles (852 articles, namely 90% of the total publications), followed by 53 reviews (6%), 33 proceedings papers (3%), and 9 book chapters (1%), (Figure 2).

Figure 2 illustrates the overwhelming dominance of articles compared to other types of publications, such as conference proceedings. This aspect is particularly interesting as it demonstrates the preference of researchers to publish their findings in high-ranking scientific journals, ensuring more effective communication of their results. The ratio of articles to other types of publications is approximately the same as in other research fields.

In Figure 2a,b, a histogram represents the distribution of articles across research domains. The analysis reveals that the Environmental Sciences and Ecology category accounts for over 50% of the total publications, while related fields such as Biodiversity Conservation and Plant Sciences show an exponentially decreasing representation. This trend is particularly intriguing as an exponential distribution generally characterizes natural and random processes, suggesting the potential for Shannon-type modeling in this context.

The first article addressing this subject appeared in a distinguished academic journal in 1994. Starting with this year up to the present (90 articles were published up until now, in 2024), the number of articles has increased, reaching 70–90 articles per year (Figure 2c).

Figure 2c illustrates the evolution of publications over time in this research area. A clear upward trend is observed, and among all the analytical models tested, the linear interpolation function provided the best fit, with an R² value of 0.8549. This suggests that the dynamics of scientific output in this field follow a linear growth model.

There is not a big difference between authors who have published the largest number of articles regarding this subject. However, the first places are occupied by Luke Kelly (10 articles), Andrew Bennett and Michael Clarke (each with 9 articles), and Dale Nimmo (8 articles).

Next, we can identify the leading research teams and authors who have conducted studies and published findings on biodiversity in arid regions. This allows for the identification of countries that have made significant scientific contributions.

Researchers from 99 countries on 5 continents have contributed to articles on this topic (Figure 2d). The most represented countries are Australia (174 articles), USA (158 articles), China (130 articles), Spain (94 articles), and South Africa (79 articles).

This analysis further supports the idea of classifying countries based on their scientific output in this field during the studied period.

Contributors from 99 nations across 5 continents have authored research on this topic (Figure 3). The most frequently represented countries are Australia (174 articles), the USA (158 articles), China (130 articles), Spain (94 articles), and South Africa (79 articles).

Among the 58 research areas in which we can frame the analyzed research papers, the most important ones are Environmental sciences and Ecology (590 articles), Biodiversity Conservation (228 articles), and Plant Sciences (91 articles) (Figure 3).

The most influential institutions producing research in this field include the Chinese Academy of Sciences (58 articles), Consejo Superior de Investigaciones Científicas (33 articles), University of the Chinese Academy of Sciences (31 articles), Consejo Nacional de Investigaciones Científicas (28 articles), and University of Cape Town (24 articles).

A significant portion of research (903 papers) is published in English, followed by Spanish (13 articles), Portuguese (4 articles), German, and Arabic (1 article).

Studies on this subject have appeared in 345 different journals, with the largest number of contributions from the Journal of Arid Environments (39 articles), Biodiversity and Conservation (37 articles), and Biological Conservation (24 articles). However, when assessing Total Link Strength, the top three identified are Biological Conservation, Biodiversity and Conservation, and Journal of Applied Ecology (

Table 1. Leading academic journals publishing research on the subject of biodiversity conservation in arid areas.

Crt. No.	Journal	Documents	Citations	Total Link Strength
1	Biological Conservation	24	1813	37
2	Biodiversity and Conservation	37	916	28
3	Journal of Applied Ecology	15	681	27
4	Diversity and Distributions	18	631	23
5	Conservation Biology	11	1213	21
6	Journal of Arid Environments	39	814	17
7	Rangeland Journal	19	300	15
8	Plos One	15	282	14
9	Landscape and Urban Planning	6	258	13
10	Ecological Application	10	1146	12
11	Ecological Indicators	19	441	12
12	Land	13	143	12
13	Journal of Biogeography	11	1016	11
14	Science of the Total Environment	15	312	11
15	Diversity	12	108	9

).

Table 1 presents the distribution of scientific output in relation to the most representative journals publishing articles on biodiversity conservation in arid regions. The table includes evaluations of the Total Link Strength attribute, which measures the overall strength of co-authorship connections between a researcher and other collaborators. For example, in Table 1, the first journal shows a high number of citations accumulated across a set of documents, reflecting the effectiveness of research teams and the extent of their co-authorship networks. If all 1813 citations were evenly distributed among 24 articles, each would receive an average of 74 citations, with the number of connections expected to be half as many.

In Figure 4, a tree diagram illustrates the leading journals involved in scientific production on this topic, ranked according to Total Link Strength. The relationships between these journals are mapped based on their citation connections and collaboration networks.

For further illustration, Figure 5 presents statistical analyses of publications from 1994 to 2025 in the Biodiversity and Conservation Journal.

In Figure 5a, a histogram displays the number of articles published during this period. The distribution follows a bimodal pattern, with two peaks: one between 2003 and 2009 and the other from 2018 to 2021. The first peak correlates with climate change discussions (https://www.ipcc.ch/report/ar5/syr/, access date: 13 Jan 2025), while the second corresponds to the COVID-19 pandemic period.

Figure 5b,c show histograms representing the distribution of citation counts from the Web of Science Core Collection and all Web of Science databases. A normal, exponentially decreasing trend is observed where articles with high citation counts are notably fewer.

Additionally, Figure 5d features a box-plot diagram illustrating citation variation by publication year in this journal. An ANOVA analysis reveals a statistically significant variation (p < 0.02) in citation counts over time, suggesting that research topics experience periods of heightened interest.

Similarly, Figure 6 presents statistical analyses of publications from 1994 to 2025 in the Journal of Arid Environments. In Figure 6a, a histogram displays the number of articles published, showing a trimodal distribution with three peaks: 2003–2005, 2014–2017, and 2019–2021. The most recent peak coincides with the COVID-19 pandemic, particularly concerning its impact on agriculture and production.

Figure 6b,c depicts histograms illustrating the citation distribution from the Web of Science Core Collection and all Web of Science databases. As in the previous case, the distribution follows a normal, exponentially decreasing pattern, with fewer highly cited articles.

Finally, Figure 6d presents a box-plot diagram showing citation variation by publication year in this journal. An ANOVA analysis indicates a statistically significant variation (p < 0.0001) in citation counts over time, reinforcing the idea that scientific interest in certain topics fluctuates over the years.

Among the 120 publishers who have published articles on this subject, the most prominent publishers include Elsevier (199 articles), Wiley (181 articles), and Springer Nature (155).

In the published articles, the most frequently used keywords are biodiversity, conservation, diversity, vegetation, and patterns (

Table 2. The most commonly appearing keywords in studies related to conservation of biodiversity in arid areas.

Crt. No.	Keyword	Occurrences	Total Link Strength
1	biodiversity	435	1290
2	conservation	356	1078
3	diversity	146	511
4	vegetation	131	446
5	patterns	113	385
6	species richness	85	346
7	management	99	338
8	impacts	69	235
9	climate change	72	219
10	protected areas	71	218
11	communities	61	201
12	land use	49	194
13	habitat	52	193
14	biodiversity conservation	66	182
15	dynamics	54	182
16	ecology	49	181

).

Keywords can be categorized into three primary clusters, with the first containing climate change, degradation, desert, desertification, drought, dynamics, ecosystem services, impact, land use, restoration, soil, and vegetation; the second including abundance, biodiversity conservation, ecology, forest, fragmentation, habitat, and richness; and the third including areas, classification, endemism, landscape, patterns, and plant diversity (Figure 7).

The evolution of keyword usage over time is as follows: during 2015–2016, terms such as endemism, biogeography, areas, and communities were prevalent; in 2016–2018, the focus shifted to disturbance, diversity, ecosystem, vegetation, and patterns; while in 2018–2019, keywords like impacts, climate change, land use, and ecosystem services became dominant (Figure 8).

3.2. A Classical Review

3.2.1. Plants Related to Biodiversity Conservation in Arid Areas

Numerous plant species have been studied together with biodiversity in arid areas (

Table 3. Plants species found in articles published on conservation of biodiversity in arid areas.

Crt. No.	Species	Significance of Species	Geographical Area	Cited by
1	Acacia reficiens Wawra	invasive species	Kenya	David et al., 2020 [35]
2	Agave aurea Brandegee	endemic species	Baja California Peninsula, USA	Klimova et al., 2024 [36]
3	Alhagi sparsifolia Shap.	species adapted to drought	Worldwide	Tariq et al., 2022 [37]
4	Boswellia dalzielii Hutch.	keystone species	Burkina Faso	Sabo et al., 2023 [38]
5	Commiphora sp.	endemic species	Yemen, India	La Montagna et al., 2023, [39]; Kulloli et al., 2013, [40]
6	Faidherbia albida (Delile) A. Chev	keystone species	Ghana	Akpalu et al., 2022 [41]
7	Glycyrrhiza uralensis Fischer	endangered species	North China	Zhang et al., 2010 [42]
8	Hordeum vulgare L.	keystone species	Worldwide	Visioni et al., 2023 [43]
9	Linaria nigricans Lange	endangered species	Spain	Penas et al., 2011 [44]
10	Opuntia stricta Haw.	invasive species	Kenya	Muthoka et al., 2021 [45]
11	Phoenix pusilla Gaertn.	endemic species	India	Kinhal et al., 2010 [46]
12	Piliostigma thonningii (Schumach.) Milne-Redh.	indigenous species	Ethiopia	Hailemariam et al., 2021 [47]
13	Primula boveana Decne. ex Duby	one of the rarest and threatened plants worldwide	Egipt	Abdelaal et al., 2020 [48]
14	Prosipis cineraria (L.) Druce (Ghaf)	dominant species in hot subdesert areas worldwide	United Arab Emirates, Western Asia	Kalarikkal et al., 2022, [49]; Baibout et al., 2022, [50]
15	Prosopis juliflora (Swartz) DC.	invasive species	Southwestern Iran	Amiri et al., 2022 [51]
16	Quercus sp.	native species	Iran	Sadeghi et al., 2024 [52]
17	Rosa arabica Crép.	endemic species	Southern Sinai, Egypt	Omar and Elgamal, 2021 [53]
18	shrub species (Chuquiraga avellanedae, Schinus johnstonii and Larrea divaricata)	native plants	The Monte, Argentina	Martinez et al., 2021 [54]
19	Stipa tenacissima L.	the species playing an important ecological role in arid and semiarid ecosystems	Tunisia	Ben Mariem and Chaieb, 2017 [55]
20	Tamarix ramosissima Ledeb.	an invader species of arid and semi-arid environments	Argentina	Natale et al., 2010 [56]
21	Vachellia (Acacia) tortilis (Forskk.) and Vachellia stuhlmannii (Taub.)	ecologically and economically important plant species in the African savanna ecosystem	Africa	Nkosi, 2024 [57]

).

3.2.2. Animals Related to Biodiversity Conservation in Arid Areas

Animals are widespread, even in arid areas. Because of this, numerous animal species have been studied in these areas (

Table 4. Animal species found in articles published on conservation of biodiversity in arid areas.

Crt. No.	Species/Group of Species	Significance of Species	Geographical Area	Cited by
	Invertebrates
1	ground-dwelling arthropods	keystone species	Gobi desert, China	Li et al., 2013 [58]
2	desert pallid bee (Centris pallida)	native species	arid landscapes Spanning the southwestern United States and northwestern Mexico	Cruz et al., 2024 [59]
3	darkling beetles	keystone species	Patagonia, Argentina	Cheli et al., 2021 [60]
4	Tenebrionidae	keystone species	China; Patagonia, Argentina;	Li et al., 2022 [61]; Cheli et al., 2013 [62]
5	Cephalota deserticoloides	endemic species	Southeast Iberian, Spain	Herrera-Russert et al., 2021 [63]
6	Anopheles sp.	keystone species	Caatinga, Brazil	Marteis et al., 2015 [64]
7	trapdoor spider	keystone species	Southern Australia	Rix et al., 2017 [65]
8	spiders	keystone species	Pacific Northwest, USA	Smith, DiCarlo and DeBano, 2021 [66]
9	scorpions	keystone species	Egypt	Lira et al., 2023 [67]
10	ants	keystone species	Sonoran Desert, Mexico; Karnataka, India	Bestelmeyer and Schooley, 1999 [68]; Begum et al., 2021 [69]
11	epigean insects	keystone species	Pingüino de Humboldt National Reserve in Chile	Pizarro-Araya et al., 2014 [70]
12	wild cockroaches Moluchia brevipennis	endemic species	Chile	Schapheer et al., 2017 [71]
13	Butterfly (general)	keystone species	Arizona, USA	Rowe et al., 2023 [72]
14	melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe.	keystone species	Northern China	Wang et al., 2007 [73]
	Vertebrates
	Fish
15	fish (general)	keystone species	Mexico	Contreras-B et al., 2014 [74]
16	Nile tilapia, Oreochromis niloticus	invasive species	Southeastern Arabian Peninsula	Esmaeili et al., 2023 [75]
	Amphibians
17	amphibian (general)	keystone species	West Sahara-Sahel; Hidalgo, Mexico	Sampaio et al., 2021 [76]; Roth-Monzón et al., 2018 [77]
	Reptiles
18	reptiles (general)	keystone species	Souss-Massa National Park, Marocco; Oman	Elbahi et al., 2023 [78]; Carranza et al., 2018 [79]
19	gecko (Gehyra variegata)	native species	Australia	Duckett et al., 2013 [80]
20	Pristurus rupestris rupestris	keystone species	Arabia	Garcia-Porta et al., 2017 [81]
21	snail (general)	keystone species	Australia	Rossini et al., 2017 [82]
22	Moorish tortoise (Testudo graeca soussensis)	protected species	Marocco	Lagarde et al., 2012 [83]
	Birds
23	birds (general)	keystone species	Quitobaquito Springs, Arizona, USA; South Africa; northeastern Brazil	Flesch et al., 2023 [84]; Githaiga-Mwicigi et al., 2002 [85]; Alves et al., 2013 [86]
24	Otus scops	endangered species	Alicante, Spain	Martinez et al., 2007 [87]
25	Neotis nuba	endangered species	Niger	Crego et al., 2023 [88]
	Mammals
26	large mammals	keystone species	Central Asia	Berger et al., 2013 [89]
27	small mammals	keystone species	Australia, the dry Andes of northwestern Argentina	Pedler et al., 2016 [90]; Urquizo et al., 2022 [91]
28	Bats (general)	keystone species	World, the southern Judean plains of Israel	Lison et al., 2020 [92]; Kahnonitch et al., 2018 [93]
29	Rodent (general)	keystone species	Mexico	Acosta and Fernandez, 2015 [94]
30	pale field-rat (Rattus tunneyi)	native species	Edel Land, Shark Bay, Western Australia	O’Neill et al., 2021 [95]
31	Ludwig’s bustard Neotis ludwigii	endemic species	South Africa	Evans, 2023 [96]
32	Kangaroo	native species	Queensland, Australia	McAlpine et al., 1999 [97]
33	Dasyurus hallucatus	endangered species	Australia	Dunlop et al., 2017 [98]
34	fox (Vulpes vulpes)	keystone species	Australia, Sahara	Sheldon et al., 2023 [99]; Karssene, 2017 [100]
35	dingoe	native species	Australia	Tatler et al., 2019 [101]
36	Andean Cat (Leopardus jacobita)	endangered species	Central Andes of Chile	Zapararte et al., 2022 [102]

).

3.2.3. Causes of Biodiversity Decline in Arid Regions

Some authors highlight that climate fluctuations and human interventions serve as major factors influencing vegetation cover changes, with their effects on plant dynamics differing across regions [103]. Additionally, the expansion of human activities, such as large-scale agricultural reclamation and inefficient water use, also play a significant role [104].

Numerous authors address the influence of human activities on biodiversity decline in arid regions [13,105]. Changes in land use also significantly contribute to this issue as land use land cover changes drastically reduce plant diversity [106,107]. Groundwater sources in semi-arid zones are experiencing increasing depletion and deterioration as a result of land use changes [108]. Furthermore, dry ecosystems are particularly susceptible to anticipated alterations in rainfall distribution [109].

Desertification refers to the long-term deterioration of dryland ecosystems caused by both climate variations and human activities. In hyper-arid deserts, human influence plays a greater role in shaping vegetation structure and plant diversity than natural soil characteristics [110].

3.2.4. Effects of Biodiversity Loss in Arid Regions

Recurrent drought and invasive plant encroachment threaten culturally significant vegetation, endanger biodiversity, and jeopardize associated traditional knowledge [111].

Connectivity among populations is critical for conserving biodiversity in drylands as water-limited environments often feature sparse habitat cover, severe fragmentation, harsh surroundings, and rapid global degradation and sustainability loss [112].

Another effect is represented by the continuously increasing presence of invasive species. Arid ecosystems are especially prone to encroachment by invasive species. Fluctuating vegetation, coupled with adaptations that promote dispersal and facilitation, enables certain alien plants to invade these fragile systems. Other authors argue that drylands face degradation due to vegetation loss, the expanding presence of invasive or undesirable species, or both [37].

3.2.5. Restoration Methods for Improving Biodiversity Conservation in Arid Areas

Traditional agroforestry systems used in various countries have proven over time to be highly effective methods for improving biodiversity conservation in arid regions. Three examples include: (1) intercropping and border cropping, also referred to as boundary or perimeter planting, which are agroforestry methods integrating irrigated cultivation of Eucalyptus camaldulensis and Tamarix aphylla alongside wheat, chickpeas (Cicer arietinum), or cluster beans (Cyamous tetragocalobe) [113]; (2) multi-crop “milpa” and “chichipera” cactus forest in Mexico [114]; and (3) olive-based agroforestry systems in Mediterranean region [115].

Trees play a crucial environmental role through efficient water conservation, maintaining soil stability, and by providing essential wildlife support. Afforestation initiatives are vital tools for mitigating climate change, conserving biodiversity, and rehabilitating arid zones [116]. Furthermore, tree species can significantly influence the diversity of native soil fauna in arid regions [117].

Using other plant species is yet another important technique. The adaptability of barley allows it to withstand diverse biotic and abiotic stresses, making it one of the few cereals capable of thriving in arid conditions [43]. Prosopis flexuosa DC (Leguminosae) is effective for quickly restoring plant cover in Argentina’s Monte Desert [118]. Similarly, Alhagi sparsifolia, a drought-tolerant legume, adapts root morphology to withstand extreme dryness, stabilizes soil under high winds, and mitigates land degradation and desertification [37].

Grazing management that balances biodiversity with productivity offers effective solutions for arid areas. For example, rotational grazing has shown promising outcomes in Australia [119]. Managed livestock grazing [120] and moderate or no grazing are important for preserving vegetation patterns, biodiversity, and ecological processes [121]. Strategies focusing on profitable and sustainable cattle grazing have also been explored [122].

Biological soil crusts (BSCs) play an essential role in arid ecosystems by retaining soil and water resources while fixing carbon and nitrogen. These crusts consist of cyanobacteria, lichens, bryophytes, and associated food webs [123]. Biocrust restoration, involving the inoculation of crust-forming organisms, offers a valuable rehabilitation method [124].

Other methods focus on water management, often the most critical factor in addressing these degradations. Some authors suggest innovative irrigation techniques, like AquaTrap [125], or the use of agricultural drainage ditches [126]. In the Thar Desert, India, conserving water has become a key strategy for preserving biodiversity [127].

4. Discussion

4.1. Existing Literature on Biodiversity in Arid Areas

Among the scientific disciplines to which these published studies are linked are, naturally, Biodiversity Conservation (also found in the used keywords), as well as general subjects connected to this topic (Environmental Science and Ecology), or domains connected to the nature of species used in fighting against the phenomenon (Plant Sciences, Forestry), and domains affected by drought (Agriculture, Zoologie). However, we must highlight the very large number of identified domains (58) that correlate with the complexity of the analyzed phenomenon.

The trend of exponential growth in published articles noted in other bibliometric studies [128,129,130,131] also applies to our studied topic. This phenomenon can be explained by three main factors: the extremely large geographic area for the spreading of arid zones, a fact that leads to the large number of countries from there the article publishers originate; a very large diversity of this subject themes (ecology, climatology, plants, animal management) that cannot be exhausted easily; and a substantial increase in the quantity of scientific journals and publications from the last decade.

The issues of biodiversity conservation and drylands are universal and can be seen in the fact that authors who have published scientific articles on this subject belong to the entire globe. However, the large majority belong to Australia (as almost the entire country (continent) is framed as dryland), USA (where 40% of the surface is considered dryland- [132], China (which contains 6.6 million km² of drylands that sustain an estimated 580 million people [133], Spain, and South Africa.

The journal featuring the highest volume of research published on this topic seems to have a name perfectly suited to the study conducted: Journal of Arid Environments. It is followed by journals dedicated to conservation measures specific to these areas, such as Biodiversity and Conservation and Biological Conservation, as well as journals with broader scientific scopes, including Science of the Total Environment, Diversity, Land, and Ecological Indicators.

A common approach for exploring thematic areas and extracting key insights across various scientific domains involves analyzing the keywords within publications. In contemporary academia, keywords serve as a crucial component associated with research outputs [134]. Keywords can be grouped in three categories: topical keywords, complimentary keywords, and diverse keywords [135]. In our case, the ranking of keywords used in the published articles begins, as expected, with biodiversity and conservation, continues with terms related to the impacted categories (vegetation, species richness), and includes the terms related to the nature of this phenomenon (impacts, management, habitat, ecology). As some authors have observed [136,137,138], an analysis of keywords reflects trends in research, and in the case of our analysis, we can observe a gradual evolution from general terms specific for the analyzed subject (endemism, biogeography, areas, communities) to complex terms that include the multitude effects of aridity (climate change, land management, and ecosystem-related services).

Some of the most frequently used keywords were ‘biodiversity’ and ‘conservation’. These core keywords are reflected almost everywhere in the classical review as the titles of its subchapters themselves include these terms.

Plants from arid areas are well adapted to the harsh climatic conditions, yet they represent remarkable biodiversity. This was also highlighted by our inventory of species cited in scientific articles published in prestigious journals. Although only 21 species are listed, it is evident that their actual number is much higher. Furthermore, many articles refer to plants in general or focus on certain classes, families, and so forth.

While arid zones may appear to have fewer animal species compared to other ecosystems (tropical forests, estuaries, mountain grasslands, etc.), they are nonetheless ecologically significant. Our investigation into the specialized literature revealed that all animal categories have been studied, and the number of species is even higher than that of plants in the same ecological zone.

From the analysis of the scientific literature, the primary drivers of biodiversity declining in arid areas have been identified as human activities and climate changes. Many authors emphasize the combined action of these factors, showing that neither one alone is the sole driver, but rather their simultaneous influence. While climate initially played a dominant role in biodiversity decline, over the last century, human activity appears to have surpassed the impact of climatic factors. The negative effects of human activities are manifold (deforestation, overgrazing, etc.), but one direct consequence is the so-called land use change.

The decline in biodiversity in arid areas has consequences for the entire ecosystem. These effects are not unique to arid zones but are more pronounced here due to the already reduced biodiversity and the extremely challenging (mainly climatic) conditions.

4.2. Restoration Strategies and Conservation Solutions

Among the restoration methods for improving conservation biodiversity in arid areas, the following were identified: agroforestry systems, tree plantations, the use of other plant species, grazing management, and other methods. It is worth emphasizing that many authors have highlighted the importance of traditional methods, used for centuries to address these issues, such as the agroforestry systems specific to certain regions.

Introducing trees into arid regions is often proposed as a strategy to combat environmental deterioration and mitigate climate change effects. However, some authors have noted that worldwide large plantations in drylands (such as the Great Green Wall in Africa and Pakistan’s Billion Tree Tsunami) may unintentionally harm native ecosystems by altering water table levels, encroaching on natural habitats, disrupting local wetlands, introducing invasive species, and exhibiting allelopathic effects due to the selection of non-native species [139,140,141,142].

A global solution would involve the collaboration among researchers, policymakers, practitioners, and local communities, which is essential for adopting a socio-ecological framework to foster sustainable development in drylands [143]. Additionally, more ecologically suitable nature-based solutions must be considered.

4.3. Limitations of the Study and Gaps in Existing Research

Although our results are presented in two distinct sections—a bibliometric review and a classical review—they are deeply interrelated. The most representative research areas and journals are directly linked to the causes and consequences of biodiversity loss. The countries of origin for the majority of authors correlate with the main plant and animal species analyzed in the studies. The keywords commonly used in recent years align with the modern methods applied to mitigate the consequences of this phenomenon. Furthermore, the scientific results obtained from leading institutions aligns with the most effective management practices highlighted in the review.

The limitations of the review design of the article include the following:

Reliance on Bibliometric Analysis—The study heavily depends on bibliometric methods, which, while useful for identifying trends, may overlook nuanced qualitative insights into biodiversity conservation in arid regions.

Database Constraints—The literature search was restricted to the Web of Science Core Collection, potentially excluding relevant studies from other databases such as Scopus, or regional repositories.

Exclusion Criteria Impact—By excluding conference proceedings and non-peer-reviewed articles, the study might have missed emerging or region-specific conservation research not yet published in high-impact journals.

Potential Citation Bias—The clustering technique used to identify influential works may prioritize highly cited research, possibly overlooking newer or regionally significant studies with lower citation counts.

Temporal Bias—There is a risk that early studies supporting a particular hypothesis were more likely to be published first, while later research challenging or refining these findings might not have received equal attention. Additionally, the tendency to prioritize recent publications over older studies may lead to the oversight of foundational research, potentially perpetuating misinterpretations.

Publication Bias—The study may be affected by an inherent asymmetry in the likelihood of publishing different types of results. Statistically significant or positive findings are generally more favored for publication, while non-significant or negative results might be under-represented, skewing the overall conclusions of the review.

From a scientific perspective, we consider our inventory of articles on biodiversity conservation in arid areas to be a valuable resource for future researchers. It provides an overview of achievements in this domain, synthesizes the findings, and highlights existing gaps and future research directions. Aspects that remain underexplored include detailed studies of new plant and animal species in drylands impacted by biodiversity loss, comprehensive analyses of climatic factors driving this decline, the evaluation of biodiversity loss effects on ecosystem components, and the development of multidisciplinary restoration methods.

Additionally, the long-term effectiveness of conservation efforts remains an open question. More studies are needed to assess the ecological and socio-economic impacts of restoration programs, ensuring that interventions lead to sustainable biodiversity outcomes.

The conservation of biodiversity in arid regions requires a multifaceted approach, incorporating scientific research, traditional ecological knowledge, and policy interventions. Addressing the drivers of biodiversity loss and implementing effective restoration strategies can mitigate the adverse effects of desertification and climate change. Future research should prioritize filling existing knowledge gaps and promoting interdisciplinary collaborations to enhance conservation efforts in these fragile ecosystems.

5. Conclusions

This study provides a comprehensive bibliometric and classical review of biodiversity conservation in arid areas, offering critical insights into research trends, key contributors, and emerging themes.

Our bibliometric analysis revealed a steady increase in scientific interest in this field, with 947 publications spanning 58 research areas and involving contributions from 99 countries. The dominance of environmental sciences, biodiversity conservation, and plant sciences highlights the interdisciplinary nature of research in dryland ecosystems. Furthermore, the shifting focus of keywords over time—from fundamental biodiversity concepts to climate change, land use, and ecosystem services—reflects the evolving challenges and scientific priorities in this domain.

The classical review emphasizes that biodiversity loss in arid regions is primarily driven by climate change and human activities, with consequences that extend across entire ecosystems. The study highlights a range of conservation strategies, from agroforestry and tree plantations to grazing management and nature-based solutions. While large-scale afforestation projects have been widely adopted, their unintended ecological consequences underscore the need for balanced, ecologically appropriate approaches. Our findings reinforce the significance of integrating traditional knowledge with modern conservation strategies to enhance biodiversity resilience in drylands.

Beyond merely cataloging research efforts, this study underscores the pressing need for future investigations into underexplored aspects, such as new plant and animal species’ responses to biodiversity loss, the precise role of climatic drivers, and the long-term effectiveness of restoration methods. Strengthening global collaboration among researchers, practitioners, and policymakers is essential to developing sustainable, adaptive management strategies that address both the ecological and socio-economic dimensions of biodiversity conservation in arid areas.