Introduction
Dispersal
limitation is the failure of a seed to reach all regeneration sites
suitable for its germination after leaving the parent. The failure
reasons include seed factors (i.e., seed dispersal mode, dispersal
ability, seed size, and yield) and environmental factors (i.e., wind,
water flow, and topography) (Han and Wang, 2002; Thomson, 2011).
Previous studies have shown that dispersal limitation played an
important role in Changbai Mountain forests for the Jaccard coefficient
of seed rain and neighboring mature trees decreased sharply with
increasing neighborhood radius (Li et al. , 2012) and in the
habitat fragmentation of tropical forest, where species diversity is
rich and seeds are mainly dispersed by animals (Cordeiro et al. ,
2009). Considering niche differentiation and dispersal limitation
simultaneously may better explain successional mechanisms in tropical
forests (Dalling et al. , 2002), and dispersal limitation may be
more important than ecological niche differentiation in determining
species composition in habitats where dispersers are scarce and forest
cover is low (Dent and Estrada-Villegas, 2021). For example, dispersal
limitation due to the disappearance of seed dispersers such as birds and
mammals in tropical forests has been a major factor in the inability of
later successional species to spread into young forests (Abbas et
al. , 2021). Therefore, birds and mammals are believed to play an
important role in seed dispersal (Willson, 1993; Glyphis et al. ,
1981). Previous studies suggested that mammals and birds were probably
the main dispersers of palm seeds (Zona & Henderson, 1989), and mainly
focused on the effects of large mammals and birds on seed dispersal
(Gosper et al. , 2005). Seeds from excrement or seeds dropped
during consumption by fruit-feeding primates could survive and germinate
(Corlett & Lucas, 1990), and these seedlings had a higher survival rate
(Pearson & Theimer, 2003). The composition and dynamics of large mammal
and bird communities have undergone significant alterations, primarily
attributable to pervasive overhunting and extensive habitat loss on a
global scale (Carpenter et al. , 2020; Fernández-Palacios et
al. , 2021). Furthermore, this has resulted in a significant reduction
in the population of these large herbivores, leading to extinctions in
certain cases, as well as a conspicuous reduction in the average body
weight of large mammalian species. Evidenced by a shift from an average
of approximately 14 kilograms at the 95th percentile to a mere 4
kilograms (Wenny & Levey, 1998), this trend underscores a substantial
change in mammalian community structure. Consequently, this
transformation has elevated the ecological significance of smaller
fauna, particularly rodent species, in the process of seed dispersal.
While feeding on plant seeds and fruits, rodents carry some seeds and
fruits to other places for storage to cope with food shortages (Zhanget al.et al. , 2015), and to help seeds escape predators,
ultimately leading to successful seed dispersal and regeneration (Hirschet al. , 2012). Therefore, dispersal hoarders, mainly rodents, are
prominent seed dispersers of plants (Roth & Vander Wall, 2005). These
rodents can spread viable seeds to different favorable environments
(Jansen & Forget, 2001), some seeds buried can be retrieved by animals
for food, while others would germinate successfully and achieve seedling
settlement to a large extent. This animal storage behavior, especially
decentralized storage, is profitable in reducing the competition for
resources and space between seedlings and mother trees, to promote seed
germination and seedling formation and to realize plant regeneration
(Xiao & Zhang, 2016; Yang et al. , 2020). Food storage animals
usually have an advantage over general foragers in finding storage food
(Stapanian & Smith, 1978), this may be related to not only the
difficulty of retrieval and the hidden conditions (Tamura et al. ,
1999), but also the directional dispersal preference of certain storage
animals. For example, scatter-hoarding rodents would transport seeds to
high-density microsites (such as the tree canopy) and redistribute them
for storage (Dimitri & Longland, 2017), resulting in the seed survival
rate and the dispersal pattern, and ultimately affecting the
regeneration pattern of vegetation (Yu et al. , 2017). The
repeated movement of seeds and the distance to the habitat as the two
main factors determining seed dispersal in rodents (Perea, 2011), and
chemosensory information from predators and parasitoids also influence
foraging decisions of storage rodents, and thus seed dispersal (Sunyeret al. , 2013).
Seed dispersal and seedling establishment are the key stages to the
mountain forest succession and regeneration, and their failure would
limit the recolonization of farmland (Standish et al. , 2007).
Some studies exploring seed dispersal constraints are currently
receiving increasing attention from naturalists, especially
topography-specific structures (Muscarella et al. , 2020; Wanget al. , 2014; Freitas et al. , 2010). The topography in
mountainous and hilly areas plays a significant role in regulating the
distribution of the solar radiation and precipitation, this can
effectively reveal the microclimatic state of the local environment and
showcases variations in the soil depth and nutrient content across
different locations (McDonald et al. , 1996). As an important
topographical factor, slope position directly affects vegetation through
geomorphic processes and controls the spatial redistribution of resource
factors through morphological changes, thus indirectly affecting the
distribution of vegetation (Kikuchi, 2001; Yang, 2005). Furthermore,
slope position also has an effect on vegetation cover and its ability to
recover after disturbance, with lower slopes having higher vegetation
cover and height, while upper slopes are more susceptible to
disturbances such as forest fire and deforestation (Pereira et
al. , 2016). The higher the slope of the mountain, the more spatially
isolated it is and the more susceptible it is to fire and logging
disturbances (Han et al. ,2018). Furthermore, crop yields are
generally lower in the upper slope than those in the lower slope due to
differences in soil types (McPhee, 1997), and acorns on the upper slope
are more susceptible to insects than those on the lower slope (Yu,
2003). Scatter hoarders also weigh the pros and cons of cache difficulty
against the risk of theft, with higher risk of predation often implying
higher seed establishment rates (Muñoz & Bonal, 2011; Steele et
al. , 2014). Compared to the hilltop area, there are usually many
exposed rocks and vegetation providing safe shelter for rodents in
midslope (Meliyo et al. , 2014), this may lead to better seed
storage and seedling regeneration. Treeline recruitment was seriously
affected by the high rate of seed theft by rodents (Pansing et
al. , 2007). Therefore, the dispersal limitation is more pronounced on
the upper slope than on the lower slope (Han et al. ,2018).
However, the relationship between food storage rodents and their
dispersal plants often changes depending on environmental conditions,
with mutual benefits and seed predation occurring (Vander Wall, 2010),
and there is no strict consistency.
As a result, differences in vegetation regeneration exist between
different slope positions, yet the reasons for these disparities remain
unknown. Could rodent-mediated seed dispersal serve as a critical factor
in explaining the regeneration variations among slope positions? To
quantitatively measure variations in seed dispersal across slope
positions, the current study explored rodent abundance and tracked seed
removal rate, seed fate, and seed dispersal distance by establishing
experimental plots at different slope positions of the Q.
wutaishanica -rodent ecosystem in the Dongling Mountains situated in the
North of Taihang Mountains. Thus, addressing the following questions: 1)
Do slope positions significantly influence rodent-mediated seed
dispersal? 2) What about the seed dispersal efficiency among different
slope positions? 3) Are there definite seed dispersal limitations among
slope positions? Based on the aforementioned inquiries, we formulate the
following preliminary hypotheses: 1) Concerning seed dispersal, in
accordance with the Mid-domain Effect (MDE) Model (Colwell and Lees,
2000), the dispersal rate is expected to exhibit a unimodal pattern as
slope position increases, characterized by an initial rise followed by a
subsequent decline. 2) In terms of faunal and floral abundance,
according to the Resource Availability Hypothesis (Coley, 1985), with
increasing slope position, an equilibrium point of resource utilization
is anticipated to exist, resulting in a pattern of initial abundance
escalation followed by a subsequent decline.
Materials and Methods
Study region
The Beijing Forest Ecosystem
Research Station (40°00’-40°03’N, 115°26’-115°30’ E) was located in
Dongling Mountains, the northern part of the Taihang Mountains. The
region belongs to warm temperate semi-humid continental monsoon climate,
and its average annual temperature is 5~10℃ and mean
annual precipitation is 500~600 mm, mainly precipitate
from July to August. The main soil type is brown soil and its depth is
about 50 cm. The zonal vegetation is warm temperate deciduous
broad-leaved and coniferous mixed forest, especially the Q.
wutaishanica forest, which is widely distributed and plays a
significant role in the conservation of water and soil, the maintenance
of biodiversity and the regulation of climate in the Taihang Mountains.
To minimize heterogeneity among forest types dominated by Q.
wutaishanica , ten transects were established from the foot to the top
of every mountain’s western slope (i.e., each transect occupied a
different elevation segment of the slopes), forming a single elevational
gradient of montane forests (1020 m-1770 m) (Xu et al. , 2017).
According to Parker’s (1982) classification method widely used in
previous studies (Coppoletta et al. , 2016; Guarín et al. ,
2005; Clinton et al. , 1993) and the topographic characteristics
of Dongling Mountains, the transects were divided into three slope
positions: ridge, midslope, and valley, forming three continuous
sampling lines of oak forest at the different slope positions.
Seed marking
The seed of Q. wutaishanica was collected during the mature
period in 2020, and stored in the refrigerator at 4 ℃ for the
germination rate of the oak seeds stored for seven days only slightly
decreased and there was no significant difference compared to fresh
seeds (Chen and Yan, 2019). Therefore, fresh and healthy seeds were
selected within 48 hours by the water flotation and visual inspection
method. The seed marking was completed by referring to the original
method proposed by Zhang and Wang (2001) and made some necessary
changes. A micro-drill was used to drill a small hole with a diameter of
0.3 mm at the bottom of the seed to avoid damaging the core. Small
consecutively numbered plastic labels were made to track the seed fate,
and 10 cm thick wires were used to pass through the holes in the seeds
to connect the plastic labels with the seeds. Tags are generally exposed
to the surface of the ground in most cases, so there is a high chance of
finding them after the seeds have been buried by rodents. According to
Kempter’s (2018) research, labels have some influence on seed dispersal,
but would not change with slope position and other factors concerned.
Seed release
The seeds were released in 10
transects set along the elevation gradient in the Q. wutaishanicaforest in the Taihang Mountains from August 26 to October 14 in 2020.
According to the elevation
gradient, each transect line was
classified into three slope positions: ridge (the upper 1/3 of each
transect), midslope (the middle 1/3 of each transect), and valley (the
lower 1/3 of each transect). In total, there were 90 seed stations, 10
transects×3 slope positions×3 seed stations, and there were 10 seeds
released at each 1 m × 1 m seed station. For repeated experiments, the
scale of concern was the community and the factor of interest was the
slope position, with 30 seed stations set for each slope position.
Considering that seed fates changed little after 15 days, observations
were made only once a week. Therefore, it is observed two or three times
a week in the early stage and only once a week after 15 days, in order
to assess the harvest of the seeds and their removal by small rodents
(Fig.1). Seed fates were classified as six types: (1) intact in situ
(IIS), (2) eaten in situ (EIS), (3) eaten after removal (EAR), (4)
intact after removal (IAR), (5)
scatter hoarded (SH) or (6) missing
(M). We recorded the seed code numbers, measured the distance between
the tagged seed and its original seed station where the seed was
removed, and marked the specific cache locations. During March and May
of the following year, we investigated and identified the seedlings
established from seeds scattered by rodents according to the tagged
plastic labels.
Rodent composition structure
Trapping plots were set at about 500 m from the seed dispersal
experiment region at each transect and its three slope positions in the
Taihang Mountains to minimize interference. Three live traps, formed a
trapping plot, were placed at each slope position in August 2019 and
2020, respectively. Rodents were captured using 40 cm× 25 cm× 20 cm live
stell wire traps with peanuts as bait. The trapping experiment lasted
one week per transect and slope position, and the trapping period was
one month per year. From August to October 2020, an infrared camera was
set up in each seed dispersal area of each slope position to monitor
rodent activity.
Seedling surveys
We selected 10 transects to survey seedlings in the Taihang Mountains
from October 3 to October 6 in 2019 before seed release experiment.
Three slope positions (ridge, midslope and valley) were selected for
each transect to investigate the abundance of Q. wutaishanicaseedlings. The seedling survey experiment was repeated three times and a
total of 90 (3 slope positions × 10 sample strips × 3 replicates)
seedling data were obtained.
Data analysis
All statistical analysis were performed in R version 4.1.1 (R Core Team,
2021). The seed removal time of three slope positions was compared using
Cox Regression Analysis, and seed fate and dispersal distance were
analysed using seed tracking experiments. Differences in seed fate
(i.e., IIS, EIS, EAR, IAR, SH and M) among three slope positions and the
influence of the distance group on the removal distance were examined
using a Generalized Linear Model (GLM). Tukey’s HSD post hoc test was
applied for multiple comparisons of seed fates, seed removal rate, and
seed dispersal distance among three slope positions. The number of
seedlings was analysed using One-way analysis of variance (ANOVA) with
post hoc tests using the Least Significant Difference (LSD)method.
Results
Rodent species composition and abundance
There were 38, 32 and 3 captured rodents in valley, midslope, and ridge,
respectively, including Apodemus peninsulae , Apodemus
agrarius , Sciurotamias davidianus , Tamiops swinhoei , andSciurus vulgaris (Table 1). A. peninsulae was the most
common, accounting for 64.4% of the total, followed by S.
davidianus and T.s swinhoei , and their percentages were 17.8%
and 12.3%. Specifically, the first four rodent species mentioned above
were captured in midslope and their relative abundances in the midslope
were 68.6%, 3.1%, 9.4% and 18.8%, respectively. All five species of
rodents were captured in valley, and A. peninsulae and S.
davidianus were common, accounting for 63.2% and 26.3%, respectively.
Only three rodents were captured in ridge, including A.
peninsulae , A. agrarius , and T. swinhoei .
Seed removal rate
Most of the seeds released in valley and midslope, except the ridge,
were carried by rodents within 11 days (Fig.2). Cox regression analysis
showed that seed removal rates were significantly higher in midslope
(Z=10.69, P <0.001) and valley (Z=10.21,P <0.001) than that in ridge. Furthermore, the seed
removal rate was significantly higher in midslope (Z=2.24P =0.0252) than in valley. The seed removal rates in midslope and
valley almost had no change after 11 days and then became basically
stable after 22 days.
Seed fate
Almost all seeds were kept intact (ISS) in ridge, while half of the
seeds at valley and midslope were eaten by rodents (EAR, EIS) (Fig.3).
The ratios of IIS, EIS, EAR, IAR and M in valley (IIS: t =14.112,df =87, P <0.001; EIS: t =6.504,df =87, P <0.001; EAR: t =8.619,df =87, P <0.001; IAR: t =2.707,df =87, P =0.0220; M: t =8.800, df =87,P <0.001) and midslope (IIS: t =13.363,df =87, P <0.0001; EIS: t =5.488,df =87, P <0.001; EAR: t =9.328,df =87, P <0.0001; IAR: t =4.410,df =87, P =0.0001; M: t =4.470, df =87,P =0.0001) differed significantly from those in ridge. The
proportion of SH in ridge (t =1.892, df =87,P =0.1470) and midslope (t = 3.478, df = 87,P = 0.0023) had not significant difference with that in valley,
while there was significant difference in the proportion of SH between
ridge and midslope (t =3.379, df =87, P =0.0031).
Seed dispersal distance
The seeds dispersed by the rodent in ridge were all within 3 m and were
mainly concentrated in 1-3 m (Fig.4). The maximum dispersal distance of
midslope was almost 15 m, with a major concentration around 5 m.
The average seed dispersal distance
was significantly higher in midslope (t =3.449, df =207,P =0.002) than that in ridge, indicating that the seed was
dispersed farther in midslope. In contrast, the dispersal distance of
the seeds in ridge was finite.
Seedling survey
The mean value of seedling was 1.43 cm as a whole, while those in ridge,
midslope and valley were 1.13 cm, 1.83 cm and 1.33 cm. The variance test
statistic showed that the number of seedling in different slope
positions were significantly different (F=4.567, P =
0.013<0.05). The number of seedling was significantly less in
ridge than those in midslope (P =0.004, SE=0.239) and valley
(P =0.039, SE=0.239). There were no significant differences for
the number of seedling between
midslope and valley (P =0.404,
SE=0.239).
Discussion
Seedling regeneration
According to our investigation, the
number of seedlings in ridge was lower than midslope and valley, this is
consistent with the results of Takahashi et al. (2010) and
O’Brien & Escudero (2022), supporting our hypothesis (2) as mentioned
above. The reason is that soil in ridge is shallower and drier than
other slope position, creating droughty and frost-prone conditions,
which can be detrimental to seedling germination and early establishment
(Fenner & Thompson, 2005; Takahashi et al. , 2010). Furthermore,
as the ridge slope increased near the top, airflow velocity increased,
increasing snow flux and snow transport, leading to an increase in snow
accumulation (Toloui-Semnani & Johnson, 2019) and intensifying
transpiration of pioneer seedlings (Renison et al. , 2015). This
further exacerbates the challenges faced by seedlings trying to
establish themselves in ridge. Seedlings at ridge showed wilting and
needle discoloration due to low photosynthetic carbon gain, reduced soil
water potential, low symbiotic infection of seedlings with mycorrhizal
fungi, limited root growth, and ultimately seedling dehydration, which
may explain the higher than ninety percent mortality rate of seedlings
in the ridge region (Smith et al. , 2009). As long as the
processes of freezing, tumbling, and burial persist at ridge, it will be
very difficult to establish seedlings in these areas (Butler et
al. , 2009). The ecosystem stability of mid-elevation zones at the
altitude between 500 and 2000 m were particularly stable, while
high-elevation zones (above 2000 m) and low-elevation zones (below
500 m) were comparatively vulnerable (Geng et al., 2019). This is, the
communities of middle region being more stable compared to the other two
regions (Jin et al., 2022). Furthermore, the forest litter layer may act
as a barrier, making it difficult for seeds to contact the soil, thus
affecting tree regeneration in the Taihang Mountains (Yang et al.,
2014). These natural challenges make ridge areas particularly
inhospitable for seedling regeneration and survival. Therefore,
topographic fragmentation, special climate and soil conditions lead to
poor vegetation regeneration in Taihang Mountains, with simple layers
and low coverage, especially at the ridge of the mountain.
Rodent abundance
Among the five recorded rodent species, the Apodemus peninsulaewas the most common in the Taihang Mountains, and the midslope and
valley had more rodents than ridge. According to the ’landscape of fear’
theory, vegetated habitats can provide shelter and improve survival
chances for animals, so animals prefer vegetated habitats over open
high-risk habitats (Laundré et al. , 2001), small rodents were
found in greater numbers in forested sparse grassland areas (Afonso,
2021), and nests around shrubs on the slopes could avoid the negative
effects of rainfall and uphill runoff on burrows (Jiang et al. ,
2017). Furthermore, plants generally exhibit better growth in midslope
compared to ridge and valley (Liao et al. , 2021; Ohsawa & Ide,
2008), and the vertical structure of vegetation distribution on the
mountain exhibits a central peak pattern (Lomolino, 2001). A similar
feature was also found that the distribution of alpha diversity of plant
community in the Taihang Mountains had unimodal distribution on the
elevational gradient, which was in line with the theory of ”diversity
peaked at the intermediate altitude” (Liang, 2022). Therefore, the
midslope and valley may have more rodents than the ridge. Significantly,
the distribution of small mammals exhibits a mid-elevation peak, i.e., a
single-peaked distribution at mid-elevation (McCain, 2010) according to
the MDE (Colwell and Lees, 2000), meaning that the midslope should have
more rodents than ridge and valley. Unfortunately, this study showed
that there were more rodents in the valley, which is inconsistent with
hypothesis (2), but there is little difference in rodent abundance
between the valley and the midslope. This may be due to the limitation
of plant growth by forest water sources as vegetation is primarily
driven by energy supply (Roebroek et al. , 2020). According to the
energy limitation hypothesis
(Colwell and Lees, 2000), light,
water and other conditions in mid-slope may be moderate, but not as
abundant as in valley, some rodent species may adapt to this medium
energy limitation environment, but other species may not adapt well,
reducing their diversity and quantity. Our results of rodent abundance
were obtained based on camera trap monitoring and traditional survey
methods, the applicability of the high resolution, the large breadth,
and the high sensitivity of infrared camera may allow better access to
animal behavioral data and may improve the results in future.
Seed removal rate and seed fate
The seed removal rate and the seed
collected proportion by rodents was lowest in ridges, which is
consistent with our hypothesis (1). On the contrary, we found that the
midslope had the highest seed removal rate and proportion
collected.
Seed removal rate is a critical metric for understanding the dynamics of
seed dispersal and regeneration within an ecosystem, reflecting a
composite of various ecological activities, including those of seed
predators, primary seed dispersers, and secondary seed dispersers
(Hambuckers et al. , 2020; Milotić et al. , 2018).
So, this rate is not merely a
quantitative measure but also provides insights into the qualitative
aspects of seed dispersal mechanisms and their effectiveness under
different environmental conditions (Carlo & Morales, 2016). Seeds in
ridges exhibit limited dispersal, encountering challenges in germination
primarily attributed to restricted movement towards suitable germination
sites (Forget, 1990). The limitation in seed dispersal is chiefly due to
the diminished or absent role of key seed dispersers, particularly
rodents and birds. According to the niche limitation hypothesis (Romanuk
& Kolasa, 2002), the scarcity of resources and lower temperatures at
high elevations would increase the intensity of competition so that only
rodent species adapted to these conditions and survived in these
regions. Ecological niches at high altitudes may only be suitable for
some specific rodent species. Previous studies highlight the importance
of specific seed dispersers for large-seeded plants is underscored
(Moreira et al. , 2017). For example, the critical function of
various bird sizes in seed dispersal (Godínez-Alvarez et al. ,
2020), the interspecific interactions of rodents for enhancing seed
dispersal effectiveness in Japanese walnut (Okawa et al. , 2023),
and the dual reciprocal roles in pollination and seed dispersal of
dispersal-storage rodents (Xiao, 2021). These studies emphasize the
necessary contribution of vertebrates in overcoming the challenges of
seed dispersal, confirming the integrated part of these animals in
maintaining ecosystem balance and plant reproduction (La Mantia et
al. , 2019). Thus, the limiting effects of the absence of dispersers on
seed dispersal are evident, which not only hinders the movement of seeds
to suitable germination sites, but may also has long-term effects on the
balance of the ecosystem as a whole.
An interesting observation is that rodent-mediated seed dispersal was
more active in midslope, instead of the valley and ridge. Within our
study, the EIS of Q. wutaishanica on the mid-slope was found to
be lower than the average EIS rate (74%) reported in previous studies
(Li and Zhang, 2001). Midslope’s higher seed removal rate and
scatter-hoarding rate imply greater opportunities for seed dispersal and
establishment. This is inconsistent with the idea that seed release at
the top of the mountain was an order of magnitude greater than at the
bottom of the mountain (Katul, 2012). This is mainly because: 1) the
seeds are likely to roll downhill when they break away from the mother
tree, which can lead to superimposed seed shadows from different mother
trees (Ohsawa et al. , 2007; Schupp et al. , 2019) on
midslope and valley. Furthermore,
some valleys may accumulate seeds at
the bottom or in valley areas, as they may be natural meeting points for
wind or water. (Boland, 2017). 2) Rodents prefer to spread seeds
horizontally or downward because it consumes less energy
(Li and Zhang, 2003), but the
absence of rodents may limit seed dispersal and seedling regeneration in
ridge. Although birds are capable of dispersing and establishing seeds
in high mountainous or other high-altitude areas (Watanabe, 1994),
Quercus species are only moderately preferred as food by birds (Wright,
2022). Consequently, the impact of birds on the dispersal of Quercus
seeds is quite limited.
Seed dispersal distance
The dispersal distance reflects rodent foraging strategies and
dispersing effectiveness to some extent (Wang and Yan, 2017). We found
that the dispersal distances of the seeds were longer in midslope and
valley than those in ridge where the dispersal distance in ridge was
extremely limit (Fig.4). This phenomenon further validates the
reasonableness of our hypothesis (1). Although seeds would tend to
accumulate on lower slopes due to gravity and topography, and then
valley had a higher seed density (Yamase and Sekioka, 2006),
rodent-mediated seed dispersal is a central driver of horizontal seed
dispersal as it requires less energy (Wang et al. , 2018), while
in the vertical direction is just the opposite. Compared to the ridge
and valley, the better vegetation and less disturbance on midslope
attract more rodents to feed, and provide more diverse habitats for
rodents to meet their requirements of spreading over a longer distance
while avoiding predation (Bergstedt and Milberg, 2001). Furthermore,
long-distance dispersal increases reproduction rates by allowing seeds
to escape the high density of conspecifics in the vicinity of the mother
tree, reducing competition and predators, and providing them with the
opportunity to find suitable colonization sites (Novaes et al. ,
2020) according to the negative density-dependent hypothesis (Metzet al. , 2010; Jansen et al. , 2014). In our study, the
dispersal distance was concentrated within 15 m, which is consistent
with previous studies (Chen et al. , 2022). The dispersal distance
was mostly around and within 5 m, and the seed removal rate exhibited an
initial rapid decline followed by a gradual slowdown, indicating that
the rodents accelerated the possession of food, which might be caused by
competition (Jenkins and Peters, 1992).
These results, as mentioned above, were helpful in understanding the
dispersal of seeds mediated by rodents in the Q. wutaishanicapopulation at different slope positions. Further research still needs to
interpret the seed dispersal and vegetation regeneration pattern at a
larger temporal and spatial scale (Nathan and Muller-Landau, 2000). For
example, Q. wutaishanica interannual variation and its subsequent
effects on vegetation structure might have been overlooked (Wang and
Smith, 2002).