Ecological Factors Influencing the Occurrence of Macrofungi from Eastern Mountainous Areas to the Central Plains of Jilin Province, China

Macrofungi are essential in forest ecological functioning. Their distribution and diversity are primarily impacted by vegetation, topography, and environmental factors, such as precipitation and temperature. However, the composition and topographical changes of the macrofungi between the eastern mountainous area and central plains of Jilin Province are currently unknown. For this study, we selected six investigational sites representing three different topographical research sites in Jilin Province to assess macrofungal diversity, and applied a quadrat sampling method. Macro- and micro-morphological characteristics combined with the molecular method were used to identify the collected macrofungi. Meanwhile, selected meteorological data were obtained for statistical analysis. As a result, 691 species were identified, of which Agarics were the most common, accounting for 60.23%, while the Cantharelloid fungi were the least common (0.91%). Furthermore, most of the shared genera (species) were saprophytic. The α diversity showed that the species diversity and richness in Longwan National Forest Park (B2) were the highest at the genus level. The mycorrhizal macrofungi proportion revealed that Quanshuidong Forest Farm (A1) was the healthiest. Finally, species composition similarity decreased with the transition from mountainous to hilly plains. We concluded that the occurrence of macrofungi was most influenced by vegetation. The air humidity, precipitation, and wind velocity were also found to significantly impact the occurrence of macrofungi. Finally, the mycorrhizal:saprophytic ratios and species similarity decreased with the transition from the mountainous area to the plains. The results presented here help elucidate the macrofungi composition and their relationship with environmental factors and topography in Jilin Province, which is crucial for sustainable utilization and future conservation.


Introduction
Human beings have discovered and utilized macrofungi throughout history with an awareness of the essential role in forest ecology. Macrofungi form mycorrhizal symbioses with host plants to promote the absorbance of substances, such as mineral elements and water. They also improve the tolerance of host plants to heavy metals, promote the survival and growth of afforestation and seedlings, and improve the diversity and stability of plants in the forest ecosystem. The comprehensive effects of macrofungi on the forest ecosystem are mainly manifested by increasing the plant-soil connections, improving the soil structure, promoting soil microorganisms, enhancing the function of plant organs, resisting

Macrofungi Investigation
(1) Investigation In this study, four plots were selected at each investigation site in which three quadrats of 10 m × 10 m [35] were set in parallel at each plot, and each plot was numbered with a distance of 300 m, applied with a quadrat sampling method. (1) Quanshuidong Forest Farm (A1) Quanshuidong Forest Farm, located in Helong City, Jilin Province, belongs to the mid-temperate monsoonal semi-humid climate zone. The annual average temperature is 5.6 • C, and the effective accumulated temperature at 10 • C is 2534.0 • C. The average yearly precipitation is 573.6 mm, and the frost-free period is approximately 138 days [28].
(2) Lushuihe National Forest Park (A2) Lushuihe National Forest Park, located in Fusong County, Baishang City, Jilin Province, belongs to the temperate monsoon climate. The annual average temperature is 2.9 • C, and the effective accumulated temperature at 10 • C is 2606.9 • C. The average yearly precipitation is 894 mm, and the frost-free period is approximately 110 days [29].
(3) Laoyeling Branch-Shengli River Forest Farm (B1) Mt. Laoyeling belongs to the Mt. Changbai Systems and is in the northeast-southwest direction, 800-1000 m above sea level in Jilin Province, with a relative height of approximately 500 m. The landforms are mainly low and middle mountains, with narrow valleys between the mountains. Volcanoes and lava flows are widely distributed in this area [27].
Shengli River Forest Farm has a temperate continental climate with an average annual temperature of 3.8 • C, an average annual rainfall of 633.7 mm, and a frost-free period of 110-130 days. Longwan National Forest Park is in the middle section of Mt. Longgang in Huinan County, Jilin Province, with an average sea level of 880 m. It has a northern temperate continental monsoon climate. The annual average temperature is 4.8 • C, the minimum temperature is −17 • C, and the maximum monthly average temperature is 22.4 • C. The sufficient accumulated temperature at 10 • C is 2728 • C. The average annual precipitation is 837.9 mm, ranging from 436.5 to 987.2 mm. The maximum daily precipitation is 124.2 mm, concentrated from June to August, with an average yearly frost-free period of 138 days and an average sunshine time of 2296 h [30].

(5) Zuojia Region (C1)
The Zuojia area, Jilin Province, belongs to the hilly plain areas of Mt. Changbai. It has a continental climate with temperate monsoons and often experiences Siberian cold waves, with changeable weather and distinct seasons. The annual average temperature is 5.6 • C, and the effective accumulated temperature at 10 • C is 2779.8 • C. The average yearly precipitation is 679 mm, the average annual evaporation is 1200 mm, and the frost-free period is approximately 120 days [31][32][33].
(6) Jingyuetan National Forest Park (C2) Jingyuetan National Forest Park is in the transitional zone from the eastern mountain area to the western grasslands of Jilin Province. It belongs to the hill areas of Mt. Changbai. The elevation is between 245.8 and 371.6 m above sea level. The climate is temperate semi-dry, early, and semi-humid monsoon with four distinct seasons. The annual average temperature is 6.1 • C. The average annual precipitation is 577.3 mm. The rainy season is mainly concentrated in July and August, as it accounts for 67% of the annual precipitation, the annual evaporation is 1392.5 mm, and there is a frost-free period of 145 d [34].

Macrofungi Investigation
(1) Investigation In this study, four plots were selected at each investigation site in which three quadrats of 10 m × 10 m [35] were set in parallel at each plot, and each plot was numbered with a distance of 300 m, applied with a quadrat sampling method.
(2) Specimen collection and recording Specimens were mainly collected from July to September at every investigation site. The specimens were photographed in situ. The habitat, altitude, soil characteristics, and nearby trees were recorded. The size of basidiomata was measured when fresh, and features such as striations, hygrophanous, and squama were noted ( Figure 3). After examining and describing the fresh macroscopic characters, the specimens were dried in an electric drier at 45-50 • C. All the collected specimens had conspicuous basidiomata. (3) Specimen identification The dried specimens were rehydrated in 94% ethanol for microscopic examination, then mounted in 3% potassium hydroxide (KOH), 1% Congo red, and Melzer's reagent; they were then examined with a Zeiss Axiolab A1 microscope (Carl Zeiss, Jena, Germany) at magnifications up to 1000×. All measurements were taken from the sections mounted in 1% Congo red. A minimum of 40 spores, 20 basidia/asci, 20 cystidia, etc., were measured from at least two different fruiting bodies for each specimen [36]. When combined with the macroscopic characteristics, the classification status of the specimens was determined by referring to literature and monographs [37]. For some species, we also sequenced, and the sequences have been deposited in GenBank (GenBank accession numbers: ON683416-ON683495). The taxonomic status of all species is referenced in the Index Fungorum [38]. The specimens examined were deposited in the Herbarium of Mycology of Jilin Agricultural University (HMJAU).

(4) Data collection
The meteorological data-average temperature (T), average relative humidity (RH), average monthly precipitation (P), average wind speed, and accumulated temperature from July to September (AT)-were downloaded from the China meteorological data network [39]. The soil type and representative forest type data were obtained from the Chinese Academy of Sciences (Table 2) [40].

Data Analysis
Two alpha diversity indices, the Simpson diversity index [41] and the Shannon-Wiener index [42], were calculated at the genus level for each investigation site to analyze the community composition of the macrofungi. The Shannon index (H ) reflected the diversity of the community species. The Simpson index (D) reflected the probability of two individuals being randomly selected from the same sample, and these two individuals are from the same class. The compositions of the macrofungi at Mt. Changbai (A), the transitional zone (B), and the plain hilly area (C) were compared by calculating the similarity coefficient (S) [43] and generating a complex heatmap [44]. The macrofungi compositions between Mt. Changbai and Mt. Laoyeling branch and Mt. Longgang Branch were also compared.
The diversity index formulae were as follows: where Pi is the proportion of species i to the total number of individuals of all species in the plot, a is the number of genera shared by the two places, and b and c are the genera that appear in the same place. According to the Atlas of Chinese Macrofungal Resources [37], identified species were divided into eight categories: Larger Ascomycete, Agarics, Polyporoid, Hyonaceous and Thelephoroid fungi (PHT fungi), Cantharelloid fungi, Gasteroid fungi, Jelly fungi, Coral fungi, and Boletes.
The identified genera were summarized in an Excel table. Then, we specified a value of 0/1 for each genus shown at each investigation site (0 means that the genus did not appear at the investigation site). Originpro 2019 (OriginLab, Northampton, USA) was used to analyze common genera. Dominant family (number of species more than ten of the family) and dominant genus (number of species more than five of the genera) of each investigation site were counted [45]. Moreover, the species numbers per family (genera) at all six investigation sites were statistics, the top ten families (genera) were shown, and the bubble matrix was drowned.
The software Canoco 5.0 (Micro-computer Power, Ithaca, NY, USA) [46] fits and analyzes the relationship between macrofungi species and the environmental factors at six investigation sites. Log (n + 1) was used to reduce meteorological data quality and balance the vast differences among the various factors. The quadrat × species matrix and the quadrat × environment matrix were established. Two-dimensional sorting and canonical correspondence analysis (CCA) of macrofungi and environmental factors in six different vegetation types were conducted.

Composition Characteristics of the Macrofungi
In this study, genera with more than four species were chosen from the six investigation sites for analysis. Site A1 included the most identified families and species among six investigation sites, while site B2 had the fewest (Figure 4). General overview, Russula Pers., Pholiota (Fr.) P. Kumm., and Mycena (Pers.) Roussel, etc., were the most common genera recorded. Taxa belonging to Russula and Mycena were the most common at site A1; Pholiota and Polyporus were the most common ones at site A2; Russula, Pholiota, and Hygrophorus Fr. were the most reported genera at site B1; Russula and Amanita Pers were the most recorded at site B2; Russula, Suillus Gray, and Pholiota were the most reported at site C1; Russula, Suillus, and Agaricus L., were the most common genera at site C2. Overall, the most reported one is Russula.

Shared Genera (Species) Analysis
A total of 691 species of macrofungi, belonging to 258 genera and 81 families, were identified (Table A1). There were 23 genera-including Ampulloclitocybe Redhead, Lutzoni, Moncalvo and Vilgalys, Cortinarius, and Pleurotus-identified at all six investigation sites ( Figure 5A). J. Fungi 2022, 7, x FOR PEER REVIEW 10 of 50 Furthermore, 11 species, such as Ampulloclitocybe clavipes (Pers.) Redhead, Lutzoni, Moncalvo and Vilgalys, Daldinia concentrica (Bolton) Ces. and De Not., and Ganoderma applanatum (Pers.) Pat., co-occurred at each survey site ( Figure 5B). Site A1 has the most endemic species, while site B2 has the fewest. Figure 5. The co-occurring genera and species were analyzed in six different investigation sites in Jilin Province. (A) Co-occurring genera analysis in six investigation sites; 23 genera co-occur in six investigation sites; site B2 has the fewest endemic genera and C2 has the most. (B) Co-occurring species analysis in six investigation sites; 11 species occur in all six investigation sites; site A1 has the most endemic species, while site B2 has the fewest. A1: Quanshuidong Forest Farm; A2: Lushuihe National Forest Park; B1: Shengli River Forest Farm; B2: Longwan National Forest Park; C1: Zuojia Region; C2: Jingyuetan National Forest Park.

Macrofungi Composition Types Analysis
According to the Atlas of Chinese Macrofungal Resources [37], the macrofungi species were divided into eight statistical categories. Agarics were the most common, accounting for 60.23% of the total, followed by PHT fungi, accounting for 16.50%. In contrast, Jelly fungi and Cantharelloid fungi were rarely reported, accounting for 2.06% and 0.91%, respectively ( Figure 6A).
The statistical analysis of each investigation site ( Figure 6B) showed that Agarics and PHT fungi were predominant at sites A1, A2, B1, B2, C1, and C2, while Agarics and Jelly fungi were the most common at site B2. Coral fungi and Cantharelloid fungi were rarely reported at sites A1, A2, and B2. Jelly fungi and Cantharelloid fungi were seldom reported at sites B1, C1, and C2. In summary, Cantharelloid fungi were rare in all investigations, while the compositions of macrofungi at six investigation sites were vastly different. Furthermore, 11 species, such as Ampulloclitocybe clavipes (Pers.) Redhead, Lutzoni, Moncalvo and Vilgalys, Daldinia concentrica (Bolton) Ces. and De Not., and Ganoderma applanatum (Pers.) Pat., co-occurred at each survey site ( Figure 5B). Site A1 has the most endemic species, while site B2 has the fewest.

Macrofungi Composition Types Analysis
According to the Atlas of Chinese Macrofungal Resources [37], the macrofungi species were divided into eight statistical categories. Agarics were the most common, accounting for 60.23% of the total, followed by PHT fungi, accounting for 16.50%. In contrast, Jelly fungi and Cantharelloid fungi were rarely reported, accounting for 2.06% and 0.91%, respectively ( Figure 6A).
The statistical analysis of each investigation site ( Figure 6B) showed that Agarics and PHT fungi were predominant at sites A1, A2, B1, B2, C1, and C2, while Agarics and Jelly fungi were the most common at site B2. Coral fungi and Cantharelloid fungi were rarely reported at sites A1, A2, and B2. Jelly fungi and Cantharelloid fungi were seldom reported at sites B1, C1, and C2. In summary, Cantharelloid fungi were rare in all investigations, while the compositions of macrofungi at six investigation sites were vastly different.

Ecological Characteristics of Macrofungi
According to the reference [6] and FUNGuild [47], the numbers of mycorrhizal macrofungi and saprophytic macrofungi were counted. The proportion of mycorrhizal macrofungi at site A1 was the highest (0.47), indicating that the forest structure at this site was the healthiest and the most stable. While the proportion was the lowest at site C1 (Table 3).

Analysis of α Diversity
The α diversity at six investigation sites was analyzed ( Figure 7). The summary statistics from the Simpson diversity index for site B2 were significantly higher than those from the other five investigation sites. This result indicated that site B2 had the richest species diversity at the genus level and the most uniform distribution of species quantity ( Figure 7A). The Shannon-Wiener index results also indicated that the diversity at site B2 was the highest, and the species were the richest ( Figure 6B).

Ecological Characteristics of Macrofungi
According to the reference [6] and FUNGuild [47], the numbers of mycorrhizal macrofungi and saprophytic macrofungi were counted. The proportion of mycorrhizal macrofungi at site A1 was the highest (0.47), indicating that the forest structure at this site was the healthiest and the most stable. While the proportion was the lowest at site C1 (Table 3).

Analysis of α Diversity
The α diversity at six investigation sites was analyzed ( Figure 7). The summary statistics from the Simpson diversity index for site B2 were significantly higher than those from the other five investigation sites. This result indicated that site B2 had the richest species diversity at the genus level and the most uniform distribution of species quantity ( Figure 7A). The Shannon-Wiener index results also indicated that the diversity at site B2 was the highest, and the species were the richest ( Figure 6B).

Analysis of Dominant Families (Genera)
According to the identification results, 81 families were recorded. The top ten families were Russulaceae, Tricholomataceae, Agaricaceae, etc., successively, containing 43.54% of the total species (Table 4). There were 24 families with only one species, accounting for 29.63%. The dominant families at each investigation site are shown in Figure 8A.
A total of 258 genera were reported in this study, among which the top ten genera were Mycena (Pers.) Roussel, Cortinarius (Pers.) Gray, Lactarius Pers., etc., accounting for 22.46% (Table 4). There were 137 genera with only one species, accounting for 53.10%. The dominant genera are shown in Figure 8B.

Analysis of Dominant Families (Genera)
According to the identification results, 81 families were recorded. The top ten families were Russulaceae, Tricholomataceae, Agaricaceae, etc., successively, containing 43.54% of the total species (Table 4). There were 24 families with only one species, accounting for 29.63%. The dominant families at each investigation site are shown in Figure 8A.
A total of 258 genera were reported in this study, among which the top ten genera were Mycena (Pers.) Roussel, Cortinarius (Pers.) Gray, Lactarius Pers., etc., accounting for 22.46% (Table 4). There were 137 genera with only one species, accounting for 53.10%. The dominant genera are shown in Figure 8B.

Relationships between Macrofungi and Environmental Factors
At first, the number of macrofungi collected from May to October at the three investigation sites was analyzed statistically. The results showed that they mainly arose from July to September, with minimal presence in May, June, and October ( Figure 9). Secondly, the relationship between macrofungi and environmental facts-air humidity, precipitation, and temperature were also analyzed. Macrofungi occurrence was positively correlated with air humidity ( Figure 10). When air humidity was higher, larger numbers of macrofungi were shown from July to September. Precipitation from May to October was positively correlated with macrofungi occurrence with a lag period ( Figure 11).
Then, the relationship between the average temperature from May to October and macrofungi occurrence was also analyzed. The results showed that macrofungi occurrence at sites A1 ( Figure 12A) and B2 ( Figure 12B) was positively correlated with air temperature, and there was a relative lag period. However, numerous macrofungi occurred in September at site C2 ( Figure 12C), while the monthly average temperature was significantly lower than from June to July. Further analysis of the meteorological data shows that the daily temperature difference at site C2 was significant in September, stimulating macrofungi formation.

Relationships between Macrofungi and Environmental Factors
At first, the number of macrofungi collected from May to October at the three investigation sites was analyzed statistically. The results showed that they mainly arose from July to September, with minimal presence in May, June, and October ( Figure 9). At last, a canonical correspondence analysis (CCA) was performed on the genera with the top 50% species numbers recorded at the six investigation sites. Five environmental factors-adequate accumulated temperature (AT), monthly mean air temperature from (T), mean humidity (RH), mean precipitation (P), and mean wind speed from July to September (S)-were selected for CCA. The results ( Figure 13) showed that all samples were roughly separated into six groups according to their corresponding locations. Eigenvalue axis 1 is higher than axis 2, with cumulative contributions of 32.70% and 28.50%, respectively. The selected environmental factors were found to impact the macrofungi occurrence. Of all the established ecological factors, the mean humidity from July to September, mean precipitation from July to September, and mean wind speed from July to September were the most significant factors. Secondly, the relationship between macrofungi and environmental facts-air humidity, precipitation, and temperature were also analyzed. Macrofungi occurrence was positively correlated with air humidity ( Figure 10). When air humidity was higher, larger numbers of macrofungi were shown from July to September. Precipitation from May to October was positively correlated with macrofungi occurrence with a lag period ( Figure  11).   Secondly, the relationship between macrofungi and environmental facts-air humidity, precipitation, and temperature were also analyzed. Macrofungi occurrence was positively correlated with air humidity ( Figure 10). When air humidity was higher, larger numbers of macrofungi were shown from July to September. Precipitation from May to October was positively correlated with macrofungi occurrence with a lag period ( Figure  11).  Then, the relationship between the average temperature from May to October and macrofungi occurrence was also analyzed. The results showed that macrofungi occurrence at sites A1 ( Figure 12A) and B2 ( Figure 12B) was positively correlated with air temperature, and there was a relative lag period. However, numerous macrofungi occurred in September at site C2 ( Figure 12C), while the monthly average temperature was significantly lower than from June to July. Further analysis of the meteorological data shows rence at sites A1 ( Figure 12A) and B2 ( Figure 12B) was positively correlated with air temperature, and there was a relative lag period. However, numerous macrofungi occurred in September at site C2 ( Figure 12C), while the monthly average temperature was significantly lower than from June to July. Further analysis of the meteorological data shows that the daily temperature difference at site C2 was significant in September, stimulating macrofungi formation. At last, a canonical correspondence analysis (CCA) was performed on the genera with the top 50% species numbers recorded at the six investigation sites. Five environmental factors-adequate accumulated temperature (AT), monthly mean air temperature from (T), mean humidity (RH), mean precipitation (P), and mean wind speed from July to September (S)-were selected for CCA. The results ( Figure 13) showed that all samples were roughly separated into six groups according to their corresponding locations. Eigenvalue axis 1 is higher than axis 2, with cumulative contributions of 32.70% and 28.50%, respectively. The selected environmental factors were found to impact the macrofungi occurrence. Of all the established ecological factors, the mean humidity from July to September, mean precipitation from July to September, and mean wind speed from July to September were the most significant factors.

Analysis of Flora Diversity
The six investigation sites were divided into three groups: Mt. Changbai area (A), containing Quanshuidong Forest Farm (A1) and Lushuihe National Forest Park (A2); Mt. Changbai Branch (B), comprising the Mt. Longgang Branch (Longwan National Forest Park, B1) and the Mt. Laoyeling Branch (Shengli Forest Farm, B2); and plain low hilly areas (C), encompassing the Zuojia Region (C1) and Jingyuetan National Forest Park (C2). The macrofungi composition was found to change when the mountainous region transited to the plains and low hills, and this was determined by calculating the similarity coefficient (s). The similarity decreased from 42.06% to 39.95% (Table 5). Simultaneously, the macrofungi compositions of Mt. Changbai, its Laoyeling Branch (B1), and the Mt. Longgang Branch (B2) were compared. The similarity between Mt. Changbai and Laoyeling Branch (B1) was 37.23%, higher than the Mt. Longgang Branch.
The top 30 genera were selected to analyze the speciation differences ( Figure 14). The composition of site C1 was the most similar to site C2, followed by site B2 and site B1, and site A was the least similar, which was consistent with the results for the similarity coefficient. The similarity of the species composition in Mt. Changbai Branch was lower than that in the plain low hilly area.
Substantial differences were seen in forming distinct genera among the six sites. The number of species in each genus was generally higher for area A and lower for site B2.   Table A2.

The Influence of Environmental Factors on Macrofungi Occurrence
CCA at the genus level of recorded macrofungi at six investigation sites showed that the mean humidity, mean precipitation, and mean wind speed from July to September

The Influence of Environmental Factors on Macrofungi Occurrence
CCA at the genus level of recorded macrofungi at six investigation sites showed that the mean humidity, mean precipitation, and mean wind speed from July to September were the most significant environmental factors influencing the occurrence and distribution of macrofungi.
The effect of wind speed on macrofungi is integrated and multifaceted. The most direct impact is an expansion of the dispersal of the spores range, promoting species dispersal and affecting the macrofungi's community structure by promoting the formation of dominant populations and reducing the macrofungi species richness within the same plant community [48]. Wind speed will also affect the oxygen content of the plant-macrofungi community. The high oxygen content will influence the oxygen content of soil [49], thus promoting hyphae respiration-the more energy released, the more promotion of mycelium growth [50]. Oxygen content will also affect the fruiting body morphogenesis, and elevated carbon dioxide will result in the formation of deformed mushrooms, thus affecting the macrofungi growth (e.g., the height of fruiting bodies lower than average) [51,52]. Wind speed will also affect soil moisture and air humidity [53]. From a positive perspective, water evaporation and transpiration will increase air humidity and adjust soil and air temperature, which benefits fruiting body formation. However, if the soil moisture evaporates excessively during spore germination and vegetative hyphal growth, excessive evaporation of the soil moisture will inhibit spore germination and promote hyphal reproductive growth or dormancy [54][55][56]. Furthermore, soil dryness caused by high winds may be a reason that macrofungi become gasteroid.
Precipitation will increase the soil water content, enabling resting spores to obtain sufficient water levels. For spores with thick walls, water immersion is essential. Sufficient soaking softens the walls, triggering enzymes hydrolysis of the spore's peptidoglycan cortex, enabling the mycelium to germinate more efficiently [57]. Water immersion will also dissolve the substances that inhibit spore germination into the water and release dormancy [58]. Furthermore, water can promote spore respiration and sugar decomposition, provide energy for growth activities, and stimulate spores to secrete various enzymes to destroy cell wall structures [59]. With the gradual temperature increase, the spores were found to absorb enough water to germinate gradually. The suitable temperature and humidity conditions were sufficient for the mycelium to grow in large quantities, laying the foundations for macrofungi occurrence [60,61]. However, this phenomenon depends on vital mechanisms of the spore, for dead spores do not swell, and absorption varies with the viability of the spore [62]. The swelling of spores is usually more than twice its original size [63], and with further germination, the protoplasm volume can sometimes increase more than ten times.
Relative humidity mainly affects the dispersal of spores. If the air humidity is too high, the weight/volume will also increase, thus reducing the dispersal range of spores [64]. The evidence shows that the RH had no direct influence on the growth of macrofungi [53]. If water is available on the surface, macrofungi may grow at deficient air humidity levels [65,66]. RH may also influence the growth of mycelia. Excessively high RH would slow down or inhibit mycelium growth [67].
Mushrooms also arise from primordia that their formation and differentiation are influenced by environmental factors such as precipitation and temperature. From 1993 to 2007, Krebs et al. [68] found that mushroom production could be predicted by summer rainfall, in Yukon, the mushroom production is positively correlated with precipitation. Low humidity will slow down the growth rate during primordia formation [69]. The temperature is also another critical factor. The formation of some mushroom's primordia requires low-temperature stimulation, such as Flammlina filiformis (Z.W. Ge, X.B. Liu, and Zhu L. Yang) P.M. Wang, Y.C. Dai, E. Horak, and Zhu L. Yang. The diverse climate types and environments allow different macrofungi to specialize and thrive [70].

The Influence of Vegetation on Macrofungi Occurrence
The Mt. Longgang and Mt. Laoyeling branches both belong to Mt. Changbai. However, the species richness in the Longwan National Forest Park (B2) was found to be higher than that at Mt. Changbai (A) and its Mt. Laoyeling branch (B1). This phenomenon may be due to the differences in their vegetation [71]. Mt. Changbai and its Mt. Laoyeling Branch are mainly covered by coniferous trees, including Pinus spp., Picea spp., etc. In contrast, Longgang Branch (Longwan National Forest Park, B2) is primarily covered with broadleaf mixed forests, such as Quercus mongolica and some pine forests. Macrofungi can show preferences for broadleaf or coniferous trees, vegetation, or substrate specificity might have contributed to the evolution of macrofungi [11,70]. Our result ( Figure 6) shows that the typical composition of recorded macrofungi varied in proportion across the six investigation sites. Jelly fungi, for example, at site B2 reached 13%; however, they were only 1-3% at the other investigation sites. Furthermore, deadwood fungi prefer different deadwood characteristics (host species, decay, etc.), and thus, species composition changes can occur about these characteristics [72]. It is evidenced that macrofungi species are usually more abundant in broadleaf forests than in coniferous forests [11]. According to our calculations, the wood and litter saprotroph macrofungi reached 51.7% at site B2, while sites A1, A2, and B1 were 50.3%, 47.9%, and 46.3%, respectively. In addition, plant community composition determines understory light availability, humidity, and litter composition [73]. At the same time, many macrofungal species have host associations with particular plant species; for example, Tuo et al. revealed that the quantity of EM fungi in Wunvfeng National Forest Park, China, was positively correlated with the amount of Q. mongolica [6]. Based on our results, site A1 had the highest proportion of EM fungi at 45.78% and site B2 had the lowest at 28.57% among Mt. Changbai and its branch sites. The balance between mycorrhizal macrofungi and saprophytic macrofungi is a reference to forest conditions [74][75][76][77]. In a healthy forest, the number of mycorrhizal macrofungi often exceeds the number of saprophytic macrofungi [78,79]. Moreover, the plant community constitutes an abiotic factor of crucial importance for fungal composition [80,81]. However, some studies have demonstrated that the contribution of plant communities to the impact of macrofungi communities is only 1-10% [82]. Therefore, the effects of plant communities on macrofungi require further investigation.

The Influence of Topography on Macrofungi Occurrence
The ratio of mycorrhizal macrofungi to saprophytic macrofungi decreased with the transition from the eastern mountains to the central plains. Unlike light or soil properties, the topography is an indirect environmental variable [83,84]. Topography is considered an essential driver of micro-habitat diversity in forest ecosystems [85,86], as different topographies result in various micro-habitats. Different micro-habitats can favor the occurrence of a wider variety of macrofungal species [84], thus leading to different macrofungi compositions, which we observed in our results. In our findings, the proportion of macrofungal composition types varied across six survey sites ( Figure 6). Moreover, the species numbers for each genus shifted with topography ( Figure 14). For example, the Lepiota and Geastrum species were most common at site C2; however, they were considered rare at the other sites.
Different macrofungi compositions eventually result in variations in species similarity. Species similarity decreased with the transition from the mountainous area to the plains area in this investigation. Furthermore, the similarity between Mt. Changbai and its Laoyeling Branch (Shengli Forestry Farm, B1) was higher than between Mt. Changbai and the Mt. Longgang branch (Longwan National Forest Park, B2). Based on the comparison of the representative vegetation and soil types of the three areas, the representative forest types and soil types in the Laoyeling Branch and Mt. Changbai area were highly similar, and it is speculated that the occurrence of macrofungi is not only related to vegetation but also closely related to soil types. Soil type influenced spore density and the percentage of mycorrhizal colonization of roots, where high spore density was not necessarily connected with intensive mycorrhizal development [87].

Conclusions
The occurrence of macrofungi is closely related to vegetation. By comparing sites B1 and B2, we found that the macrofungal abundance increased with increasing proportions of broadleaf trees, and specific genera were present at every survey site. Moreover, the nutritional patterns of co-occurring genera (species) were analyzed, most of which were saprophytic macrofungi.
The mycorrhizal:saprophytic ratios decreased with the transition from mountains to plains. The mycorrhizal:saprophytic ratios were consistently higher in the northeast than the southwest sites in the Mt. Changbai region and its branches.
Species similarity decreased with the transition from the mountainous area to the plains area; in addition, the species similarity between the Laoyeling Branch (B1) and Mt. Changbai (A) is higher than that between the Mt. Longgang Branch (B2) and Mt. Changbai (A).
The main environmental factors affecting macrofungi occurrence from the eastern mountains to the central plains of Jilin Province are the air humidity (RH), precipitation (P), and wind speed (S) from July to September. Our canonical correspondence analysis reveals the importance of wind speed in macrofungal occurrence.