1. Introduction
The rapidly decreasing numbers of wildlife species at local, regional, and global scales can largely be attributed to land-use and land-cover changes (LULCC). LULCC are structural modifications made by humans on Earth’s terrestrial surface [
1]. They can cause habitat destruction, alteration, and fragmentation. Land use is the utilization of land surface by humans to meet their needs, such as food procurement, pastoralism, agricultural development, construction of residential homes and economic zones, as well as industrial infrastructure. Land cover is the natural appearance, outlook, and biophysical characteristics of a land surface, such as forests, deserts, and grasslands. Several studies have concluded that LULCC activities are intensifying, and that wildlife habitat is increasingly being developed for agriculture and infrastructure [
2,
3]. Settlement development and the associated expansion of transportation networks are among the most influential LULCC affecting current species spatial distributions and habitat continuity [
4,
5]. Studies have also shown further expansion of already built-up areas into natural habitats [
6,
7]. This encroachment may ultimately impact conservation hotspots, even if they are located far from urban centers [
8].
The conversion of wildlife habitat to land for agriculture or infrastructure has contributed to global biodiversity loss [
3]. Humans have modified approximately 50% of natural land surfaces to artificial forms and shapes [
9]. The ever-growing needs of the rising human population has intensified the rate of LULCC, driving unprecedented shifts in ecosystems at local, regional, and global scales [
10,
11]. LULCC can impact a variety of factors including climate, precipitation, vegetation cover, land surface temperature and community structure and composition [
12,
13,
14,
15]. Terrestrial landscapes are increasingly subject to human alteration and associated LULCC changes, which has proven lethal to global biodiversity [
3,
16,
17,
18,
19,
20].
LULCC have been directly linked to altering wildlife species distributions, causing habitat modification and, ultimately, population decline or extinction [
21,
22,
23]. It can also affect the daily movement and seasonal migration of many species [
24]. [
25] reported that populations of forest dwelling species declined exponentially when their habitat was fragmented or reduced due to LULCC. The study suggested that alteration of native habitat into agricultural or infrastructural land not only caused a decline in species population, but also increased the intensity of conflicts between humans and wildlife [
25]. According to the IUCN Red List (IUCN 2017), 46% of species face extinction risks attributed to land-use change. The nature and intensity of LULCC effects vary from species to species, with some being more at-risk to its negative impacts than others [
13,
26,
27,
28]. For example, most species of the order Carnivora have slow population growth rates and low population sizes [
29]. They also require large areas to acquire food and shelter, and to find mates [
30]. These factors make the negative impacts of LULCC much more severe. In the previous two centuries, the population and diversity of terrestrial mammalian carnivores has declined by 95 to 99% in many parts of the world [
31]. This has largely been due to human related factors, of which LULCC ranks towards the top.
Snow leopards are one such carnivore species facing reduced distribution ranges because of human activities through direct habitat alteration and exploitation in the form of LULCC [
32]. Habitat thinning and loss is one of the major threats to this iconic, rare, and stunning species [
33]. The snow leopard meta-population is found sparsely distributed across the rugged mountains [
34] of 12 countries in Central Asia, including Afghanistan, Bhutan, China, India, Kazakhstan, Kyrgyzstan, Mongolia, Nepal, Pakistan, Russia, Tajikistan, and Uzbekistan [
35,
36,
37,
38]. A small area of potential snow leopard habitat was reported in Myanmar [
39] though presence of the species has yet to be confirmed [
37].
This remarkable and elusive species serves key roles in ecosystem function as a top predator and can serve as an indicator of overall high-altitude ecosystem health [
40]. As an umbrella species, if the snow leopard population thrives, so will countless other sympatric species [
41]. This includes humans, as millions of people depend on river systems tied to mountain ecosystems. Unfortunately, the low, sparsely distributed, and declining population of snow leopards suggest that the species is not thriving. The estimated global snow leopard population is approximately 2710 to 3386 mature individuals and decreasing [
37]. Among other threats, habitat loss, degradation, and fragmentation due to LULCC are depleting their future [
42]. Humans are exploiting available wildlife habitat and developing it for agriculture and infrastructure. Pastoralism and livestock numbers are also growing, with grazing grounds pushing further into snow leopard habitat as grassland degrades [
35,
43]. In recent decades, new roads and mines have encroached on their remaining range [
44]. Despite the clear threat of LULCC to the snow leopard, very little is known about the status of LULCC within species range.
To better understand the pattern, magnitude, and consequences of LULCC on a species, it is necessary to have accurate information regarding the previous (Past) and recent (Present) LULCC and land classes. LULCC can be assessed using various methods. Geographic information systems (GIS) and remote sensing have been introduced in the field of conservation to calculate the magnitude of LULCC of any surface of any size and shape. Remote sensing is the science of obtaining information about objects or areas from a distance, typically from an aircraft or a satellite. It involves a process in which the physical characteristics of an area are monitored and detected by measuring the radiation reflected and emitted by that area. The resulting multi spectral satellite images (MSI) have been used effectively by many researchers for detecting and measuring the spatial and temporal dynamics of forest cover change [
45]. GIS and remote sensing data across periodic intervals provide information for land use change analysis, modeling, and management. It is a cost-effective, rapid and an accurate method of LULCC measurement [
46].
Most of the snow leopard’s range in Pakistan lies in a climate change-sensitive, ecologically rich, and fragile area. Pakistan supports the third largest snow leopard population (250–400 individuals, tied with India) throughout its 12-country range with a total estimated area of about 80,000 km
2 [
47], half of which is considered prime habitat [
48]. However, a recently published study concluded that a large proportion of snow leopard range in Pakistan consists of very low-quality habitat [
49]. Pakistan is the sixth most populous country in the world [
50,
51] and is fifth on the list of countries most vulnerable to climate change according to the 2020 Global Climate Risk Index [
52]. The aim of this study was to identify and quantify LULCC across snow leopard range in Pakistan in an effort to better understand how these changes may impact snow leopard populations and their surrounding ecosystems. We hypothesized that increasing human populations within snow leopard habitat would be linked to changes in LULCC with climate change playing an additional role in LULCC.
4. Discussion
In this study, we calculated the LULCC across the entire snow leopard range in Pakistan. We used GIS and remote sensing to quantify LULCC for the years 2000, 2010, and 2020. Remote sensing has been extensively used to measure LULCC to gain useful information and insight into overall ecosystem health [
70]. The satellite data used in this study provided adequate spatial variability for LULCC [
71]. Our results provide concrete evidence of extensive LULC temporal changes in Pakistan’s snow leopard habitat. Assessing the magnitude and rate of these changes also helps to understand the driving factors of LULCC in the study area.
Built-up area and agricultural land expanded by 163% and 153%, from 2000 to 2020, respectively. Snow leopard range in Pakistan spans across GB, KP and AJK, with some areas being densely populated with humans. The observed increase in built-up area and agricultural land could be attributed to a growing human population. Pakistan is the sixth most populous country in the world with a population size of 207.8 million people [
50] with a current average annual population growth rate of 2%, it is projected to be the fifth most populous country in the world by 2050 [
51]. Human settlements are expanding, and new infrastructures are built deeper into species habitat as land procurement becomes more and more difficult. According to census data from the government of Pakistan, an increase of 36% was reported in the population of AJK (density: 302 people/km
2) from 1998 (2,972,523) to 2017 (4,045,366). Similarly, the human population in KP ((density: 300 people/km
2)) increased by 72% from 17,743,645 in 1998 to 30,523,371 in 2017 (
Figure 7). In GB, the human population (density: 17 people/km
2) increase by 43% from 1998 (870,347) to 2013 (1,249,000) (
Figure 8).
The growing demand of agricultural products for this increasing human population has intensified the rate of natural terrestrial land being shifted to agricultural land. The rise in this conversion has been exponential in recent decades [
72,
73]. The increase in agricultural land is typically coupled with an increase in livestock and expansion of grazing grounds deep into species habitat. A greater number of livestock may cause competition between wild and domestic ungulates over high-altitude grazing grounds. Moreover, the situation may make the livestock more vulnerable to snow leopard attacks, which could intensify conflicts between snow leopards and humans [
73,
74].
We also found that the rate of deforestation and forest loss was exponential [
25,
72]. Previous studies have concluded similar findings in that rapid urbanization and agricultural expansion are the major drivers of deforestation [
74,
75,
76]. Forests act as a carbon sink, and loss of forest area causes the release of more carbon into the environment [
77,
78]. The rise in carbon emissions due to deforestation and rapid urbanization can also cause subsequent rises in temperature, and a reduction of snow cover as seen in this study [
79,
80,
81,
82].
In this study a massive decrease in snow cover was observed from 2000 to 2020. This decrease could be attributed to climate change [
83,
84,
85,
86,
87], and LULCC [
88,
89]. Snow cover plays an important role in the overall health of an ecosystem [
90,
91]. It can affect glaciers and the overall hydrology of an area [
92]. Northern Pakistan currently has 5218 glaciers covering an approximate area of 15,040 km
2 [
93]. These glaciers not only feed into rivers but also play a vital role to stabilizing regional and global climates [
94]. Unfortunately, these glaciers are already melting at an alarming rate of 0.66 m/year [
94] due to human activities and global warming [
93]. The decrease observed in water bodies area may be attributed to fewer glaciers feeding into water bodies during the summer months coupled with reduced precipitation in winter months.
Land surface temperature (LST) in the Himalayas, Tibetan Plateau, and Central Asia at large are currently rising at a rate far faster than the global average [
95]. Subsequent habitat loss leading to fragmentation of the snow leopard’s range will present numerous conservation challenges [
96]. A recent study confirmed that parts of snow leopard range in Pakistan have very low habitat suitability for the species [
49]. However, this may increase as climate change threatens the mountain landscapes that snow leopards are found in. The Global Climate Risk Index has placed Pakistan fifth on the list of countries most vulnerable to climate change in its annual report for 2020 [
52]. Very little work on how climate change may impact ecosystems in Pakistan has been done [
97]. One study forecasted a mean temperature increase of 3.8 °C by 2100 [
98]. Another study claimed a potential increase of 1.4 °C to 3.7 °C by the 2060s, and a potential increase to 6.0 °C by the 2090s [
99]. In the last 50 years, the annual mean temperature in Pakistan has increased by roughly 0.5 °C [
100]. Species such as the snow leopard will likely face more dire consequences, as the northern high-altitude regions of the country are expected to warm faster and at a higher rate [
99].
Our finding of massive LULCC across snow leopard range in Pakistan is not an isolated occurrence. Snow leopard distribution has contracted across its entire range [
101]. Inside and near protected areas, the threat to snow leopards from habitat degradation and fragmentation is increasing due to livestock grazing, forest clearing for agriculture and pasture, and the collection of medicinal and aromatic plants [
102]. The observed expansion in built-up area and agricultural land could cause further habitat reduction and fragmentation. An increase in built-up area is usually associated with an increase in overall infrastructure, including new houses, settlements, residential and commercial buildings, pipelines, and roads. This causes a direct loss of species habitat. Roads can bisect populations and reduce gene flow and thus genetic diversity. In addition, roads provide easier access for humans to reach snow leopard habitat, which may escalate the rate of wildlife trafficking, illegal hunting, poaching, and pollution. Collisions of snow leopards with vehicles may also be fatal. While there is currently little research to suggest that roads at present are having negative impacts on snow leopards [
103] the construction of major throughways, such as the China–Pakistan Economic Corridor (CPEC) [
104,
105] will likely increase impact of roadways on wildlife. Projects like the CPEC will directly affect snow leopards by fragmenting and degrading their habitat. It will also contribute to localized warming, as it is estimated that approximately 7000 trucks will pass through this area daily during the operational phase, leading to the emission of up to 36.5 million tons of CO
2. These emissions could drastically reduce snow-covered area and will negatively impact glaciers [
106].
Given the potentially dire outcomes associated with LULCC observed in this study for snow leopards, we suggest several conservation actions. First, continuous and consistent long term monitoring of LULCC, their causes, and direct and indirect outcomes for wildlife like the snow leopard should be established. Consistent monitoring may help to better predict outcomes associated with LULCC and will aid in quickly addressing newly emerging conservation challenges. Monitoring should consist of a series of extensive surveys and open communication between administrative districts in Pakistan to share information and work collaboratively.
Second, creating protected areas is the best way to ensure the conservation of a species or ecosystem. Approximately, 24% of the snow leopard habitat is laying inside protected areas of different sizes. According to a recent study [
49] most of the suitable habitat of snow leopard in Pakistan has already been protected, however there are some areas presenting suitable habitat are outside of any declared protected area. The same study concluded that most of the national parks had weak links with regards to movement of snow leopard across different habitats. To mitigate or minimize LULCC, protected area networks should be strengthened throughout snow leopard range in Pakistan. In addition to managing pre-existing protected areas, new protected areas should be developed to protect currently suitable habitat from quickly expanding built-up area and agricultural land. The government should declare buffer zone areas for existing national parks and should strictly follow wildlife protection laws to ban developmental and agricultural practices in and outside of these zones. A model for this practice is the GB wildlife department, which is effectively protecting habitat in Khunjerab National Park (KNP). These same management strategies should be implemented in other protected areas. To ensure the implementation of wildlife laws, capacity building of forest and wildlife department staff is needed. In addition, staff should be logistically supported to protect species in this rough and rugged terrain.
Third, the government and NGOs should initiate projects on sustainable community based natural resource management, sustainable livelihood practices, and solutions to reduce human-wildlife conflicts. Literature suggests that formal and informal education helps to increase public understanding and acceptability of wildlife and is an effective solution to dilute people’s hatred for predators [
107,
108]. It increases public understanding and plays a key role in equipping people with pro-conservation attitudes and practices. Initiating community learning sessions, engaging youth in conservation, and organizing other awareness raising events will help to change the perception of locals towards snow leopard. Community-based surveillance that monitors snow leopard habitat and prevents wildlife crime should be implemented to protect the snow leopard from illegal hunting that may results as humans gain easier access to snow leopards.
Fourth, the government should implement forest protection laws to counteract illegal forest harvesting. Most of the communities living inside snow leopard range in Pakistan rely on the forest for their domestic and commercial needs. The government should provide alternative resources to locals that reduce their dependency on forest harvesting. The use of renewable and energy efficiency systems for cooking and heating should be introduced and encouraged to reduce pressure on forest and range land. Community based forest and land protection efforts could be very helpful to conserve and sustainably use natural resources within snow leopard range. Planting micro-forests at community levels should be practiced to combat rising CO2 levels that lead to an increase in land surface temperature and consequently loss of snow-covered area and snow leopard habitat.
Fifth, countries bordering the study area that are making large scale trans-boundary infrastructural changes should work with Pakistan in following national and international levels of environmental protection protocols. A comprehensive Environmental Impact Assessment study should be carried out before starting any developmental project in the area. The government should also monitor overall developmental projects inside the study area, so that adverse effects on snow leopard habitat can be minimized.