Introduction
The
alpine meadows that occupy more than 35% of the total area of the
Qinghai-Tibet Plateau are the main location of alpine livestock
husbandry in the area, particularly because of their use as winter and
spring pastures (Zhang et al., 2003). The health of such alpine meadows
must be measured to enable estimation of the capacity of ecosystem
services, such as water and soil conservation and carbon sequestration
(Yang,
2002). In recent years, these alpine meadows have undergone succession
into multi-steady stages due to disturbances arising from climate change
and excessive human activity
(Meng
et al., 2014). Given the unique household contract system implemented on
family ranches on the Qinghai-Tibet Plateau, the landscape has
fragmented into multiple succession stages or steady states, resulting
in multi-steady stage coexistence within each topographical and climate
area
(Cao
et al., 2007).
Ecosystem
succession processes always proceed sequentially, such that the
corresponding plant communities organize into a series of hierarchical
structures or discrete levels
(Jørgensen
et al., 2016; Wellemeyer et al., 2019). Livestock grazing is the primary
form of disturbance that affects plant community structure, physical and
chemical soil
properties,
and the ability of alpine meadows to maintain ecological and productive
stability
(Proulx et al., 1998; Yang et al., 2001). In addition, the effects of
livestock grazing on plant-soil system organization are complex (Nicola
et al., 2010). For example,
long-term
and high-intensity grazing can affect plant community structure and
composition and even trigger the plant community to regime shift (Lin et
al., 2022). Such grazing can also alter the accumulation and
transformation of nutrients above and below the ground and
influence
the micro-climate and micro-geomorphology of mini-patches (Gonzalez et
al., 2010). Most prior studies have observed that the intensity of
livestock grazing and the reaction of a plant community to grazing are
coupled to various conditions (Wedin & Tilman, 1996; Klinerová &
Dostal, 2020; Lauren, 2018), which means that the examination of
mini-patches can be used to evaluate plant communities and predict the
trends of plant community
succession
(Wu et al.,
2012).
Compared
with other parts of ecosystems, mini-patches are more sensitive and
exhibit greater variations in response to disturbance and can thus be
considered as indicators of how ecosystems respond to disturbance.
Monitoring the characteristics of mini-patches can thus reveal the
organizational components of an ecosystem, the survival strategies used
by an ecosystem’s plant community to cope with disturbance, and the
mechanisms whereby an ecosystem maintains its stability. Mini-patches in
alpine meadows can therefore be considered as the basic units of the
plant–soil system at fine spatial scales, with their features isolated
in function but correlated in
space.
Consequently, the study of mini-patches in alpine meadows can provide
answers to many key questions. For example, are the same types of
mini-patches distributed across alpine meadow area of different grazing
intensities or only in areas of certain grazing intensities? What
factors mainly influence mini-patch distribution and determine the
direction of plant community succession in alpine meadows?
In this research, we aimed to improve understanding on the stabilization
mechanisms of alpine meadow ecosystems and strengthen theories on
restoration management in multi-steady-state coexistence conditions.
Therefore, we explored and examined the factors affecting alpine meadow
ecosystems under various grazing regimes by studying the characteristics
of plant functional groups and topography in mini-patches and grazing
intensity in typical alpine meadows on the Qinghai-Tibet Plateau.