Species Diversity, Growing Stock Variables and Carbon Mitigation Potential in the Phytocoenosis of Monotheca buxifolia Forests along Altitudinal Gradient across Pakistan

Abstract

The sub-tropical broadleaved forests in Pakistan are the main constituents of the ecosystem services playing a vital role in the global carbon cycle. Monotheca buxifolia (Falc.) A. DC. is an important constituent of these forests, encompassing a variety of ecological and commercial uses. To our best knowledge, no quantitative studies have been conducted in these forests across the landscape to establish a baseline for future monitoring. We investigated the forest structural attributes, growing stock characteristics and total biomass carbon stock and established relationships among them in the phytocoenosis of Monotheca forests along an altitudinal gradient in Pakistan to expand an eco-systemic model for assessment of the originally-implemented conservation strategies. A floristic survey recorded 4986 individuals of 27 species in overstory and 59 species in the understory stratum. Species richness (ANOVA; F = 3.239; p = 0.045) and Simpson’s diversity (ANOVA; F = 2.802; p = 0.043) differed significantly in three altitudinal zones, with a maximum value for lower elevations, followed by middle and higher elevations. Based on the importance values, Acacia modesta and Olea ferruginea are strong companions of M. buxifolia at lower and higher altitudes, whereas forests at mid elevation represent pure crop of M. buxifolia (IVI = ≥85.85%). A similar pattern in stem density, volume and Basal area were also recorded. The carbon stock in trees stratum (51.81 T ha−1) and understory vegetation (0.148 T ha−1) contributes high values in the lower elevation forests. In contrast, soil carbon had maximum values at higher elevation (36.21 T ha−1) and minimum at lower elevation (16.69 T ha−1) zones. Aboveground biomass carbon stock (AGB BMC) of woody trees, understory vegetation and soil organic carbon (SOC) were estimated higher (77.72 T ha−1) at higher and lower (68.65 T ha−1) elevations. Likewise, the AGB BMC exhibited a significant (p < 0.05) negative correlation with elevation and positive correlation with soil carbon. We concluded that lower elevation forests are more diverse and floristically rich in comparison to higher altitudinal forests. Similarly, the biomass carbon of Monotheca forests were recorded maximum at low altitudes followed by high and middle ranges, respectively.

Do environmental variables and overstory communities affect the spatial pattern of understory vegetation? Lessons from Monotheca buxifolia (Falc.) A. DC. forests in Pakistan

“…Among them, M. buxifolia is a wild, fruit yielding broadleaved tree species providing many services to the rural and urban inhabitants. So far, studies on different aspects of this commercially and ecologically important tree species have been conducted (Khan et al 2011;Ali et al 2022a), but no work has been carried out yet to investigate the understory diversity, composition, underlying structure, and its influential factors. Furthermore, the tree's canopy effects in these forests are still ignored.…”

“…1). Pakistan is a south Asian country spreads over 80,943 km 2 , spinning between 60° 55' to 75° 30' longitude and 23° 45' to 36° 50' latitude (Ali et al 2022a). Uneven topography, undulant valleys, diverse slopes, hillocks, huge mountains, plains, and many water streams joining main rivers are the basic structures of the studied area.…”

Ecosystem Services and Linkages of Naturally Managed Monotheca buxifolia (Falc.) A. DC. Forests with Local Communities across Contiguous Mountainous Ranges in Pakistan

“…A series of different elements including climatic, edaphic and anthropogenic factors collectively contribute to making the mountains a multilayered geosystem [ 3 ]. Mountains are generally characterised by an uneven relief, a unique variety of climatic conditions and water channels, conditioned by the altitude gradient and terrain exposure [ 4 ]. As a result, mountain ecosystems exhibit a great variety in the structure of services defined by the availability and rate of utilization by mountain inhabitants [ 5 ].…”

“…The most common services include medicinal products, hay for grazing animals, habitats for flora and fauna, wild edible fruits, timber for construction and burning purposes, tourism, and pastoral spots, which are often the only source of life for mountain inhabitants [ 7 , 8 ]. Mountainous areas are frequently subjected to land use change (e.g., deforestation) to allow the cultivation of cereal crops in order to fulfil the needs of the ever-growing population [ 4 , 9 ]. Due to a number of factors including environmental condition, geographical location, and anthropogenic pressure, the services, structure, and function of mountain ecosystems are currently undergoing widespread changes [ 10 ].…”

“…These forests are critical sources of food, timber, wildlife, and identity for local communities, which makes their exploitation (both for woody and non-woody products) an easy task. The current climate scenarios along with the aforementioned factors are the key elements responsible for the poor condition (structure and function) of the mountain ecosystems [ 4 ]. Although forest management policies such as Joint Forest Management (JFM) exist in Pakistan to raise awareness among the local inhabitants about the sustainable consumption of ecosystem services in high mountain areas [ 13 ], they have failed due to inappropriately conventional tactics and a failure to engage the local community [ 14 ].…”