Species richness of boletes recorded in the Ouémé Supérieur forest reserves
The highest species richness (14) is obtained in 2016 while in 2015 and 2017 the lowest species richness (2) was recorded (2) (Fig. 2). The vegetation dominated by I. tomentosa is the most productive in species richness (14) and the least productive is the vegetation dominated by I. doka (Fig.2).
Descriptive analysis of the spatio-temporal variation in the fresh biomass and number of fruit bodies
A total of 105 kg / ha of fresh biomass and 7000 of boletes fruit bodies were recorded from 2015 to 2017 (Fig.3a, Fig.3b). The largest fresh biomass (70 kg / ha) (U. togoensis) was obtained in 2016 while the lowest fresh biomass (10 kg / ha) (I. tomentosa) in 2017 (Fig. 3a). The large number of fruit bodies (5000 fruit bodies / ha) while the lowest number of fruit bodies (1500 fruit bodies / ha) was recorded respectively in 2016 and 2017 (Fig.3b).
Effect of the year, the month and the vegetation on the fresh biomass, number of fruit bodies and species richness
The individual effect of the number of months and the year had a significant positive influence on the spatio-temporal variation of the fresh biomass (P <0.05, Table 3). However, the vegetation has no significant influence on the fresh biomass (P <0.05, Table 3). However, the combination of the year and the month has an influence on the number of fruit bodies (P <0.05, Table 3). On the other hand, the species richness remains fixed whatever the years (P> 0.05, Table 3).
Table.3. Analysis of variance on the models testing the effects of the year, month and the vegetation on the fresh biomass and the number of fruit bodies.
|
Fresh biomass
|
Number of fruit bodies
|
Species richness
|
|
|
F
|
Prob
|
Chisq
|
Prob
|
Chisq
|
Prob
|
Year
|
32.70
|
< 0.0001 ***
|
0.38
|
0.536 ns
|
0.04
|
0.843 ns
|
Month
|
26.58
|
< 0.0001 ***
|
2.83
|
0.093 ns
|
2.85
|
0.092 ns
|
Vegetation
|
1.28
|
0.279 ns
|
0.71
|
0.701 ns
|
3.15
|
0.207 ns
|
Year : Month
|
1.95
|
0.163 ns
|
5.72
|
0.017 *
|
4.8
|
0.305 ns
|
F.: Fisher statistic, Prob.: Probability value. Chisq. : Chi-square statistic. Asterisks represent the significance level for each term of the model: *** significant at 0.1%; ** significant at 1 %; * significant at 5 %; ns not significant.
Intra-annual variation in the number of fruit bodies and fresh biomass
We obtained the largest fresh biomass in July (2016) (Fig. 4a; Fig. 5b). However, the lowest is obtained in October (2017) (Fig. 4a; Fig. 5c). The highest number of fruit bodies (8000 fruit bodies / ha) in July (2016) (Fig. 4b; Fig. 6b). However, the lowest number (500 fruit bodies / ha) is obtained in October (2015) (Fig. 4b; Fig. 6a). Then, we observe a variation of the fresh biomass and the number of fruit bodies from one year to another (inter-annual variation) (Fig. 4a, b; Fig. 5a, b, c and Fig. 6a, b, c).
Spatial and temporal variability of microclimate parameters
The highest weekly mean air temperature and weekly mean soil temperature were recorded at the end of the season and at the start of the season, respectively (30 ° C; 29 ° C) and the lowest in July respectively and September (24.5 ° C; 25 ° C) (Fig. 7). However, the highest mean soil moisture and mean relative air humidity are obtained (0.30 m3 / m3; 100%) respectively in mid-season while the lowest respectively (0.1 m3 / m3; 75%) are recorded at the start of the season (Fig. 7, Fig. 8 and Fig. 9).
Influence of microclimatic parameters on the natural production of the boletes
Air temperature and soil temperature have no significant effect on fresh biomass and species richness (P> 0.05, Table 4). Only soil moisture significantly influences the number of boletes fruit bodies (P < 0.5, Table 4). We noticed a negative relationship between soil moisture and the number of fruit bodies (P <0.05, Table 4, Figure 13). When the soil moisture decreases by four units, the number of fruit bodies of boletes decreases, which leads to a negative correlation (Coef. = -0.04) between soil moisture and the number of fruit bodies. Then, above 0.25 m3 / m3 and below 0.05 m3 / m3 there is a decrease in the number of fruit bodies. Thus, the interval of soil moisture at which fruiting of boletes is possible is (0.05 m3 / m3; 0.25 m3 / m3). Hence, the appearance or not of the fruit bodies of boletes is conditioned by the soil moisture.
Table.4. Summary of the linear models testing the relationship between climatic variables the number of fruit bodies, the fresh biomass and the species richness
|
|
Number of fruit bodies
|
Fresh biomass
|
Species richness
|
Factors
|
Terms
|
Coef.
|
Prob.
|
Coef.
|
Prob.
|
Coef.
|
Prob
|
|
Intercept
|
2.38
|
< 2.00E-16 ***
|
5.77
|
b 0.144 ns
|
2.38
|
0.002 **
|
Covariates
|
Soil temperature
|
-
|
-
|
-
|
-
|
-0.06
|
0.192 ns
|
|
Air temperature
|
-
|
-
|
-
|
-
|
0.04
|
0.113 ns
|
|
Soil moisture
|
-0.04
|
0.000 ***
|
-0.09
|
0.338 ns
|
-0.14
|
0.015 ns
|
Coef. : Regression coefficient, Prob.: Probability value. “-“: term not present in the final model.
aThe probability of factors is derived from an ANOVA (Fisher test) to test the global significance of the factor. b The probability values relative to the terms are from the Student t test to test the significance of coefficients. Asterisks represent the significance level for each term of the model: *** significant at 0.1%; ** significant at 1 %; * significant at 5 %; ns not significant.