4.1 Spatial diversity analysis of Tunpu settlement in Qianzhong
4.1.1 Diversity characteristics α at different scales in the Tunpu settlement space
Table 5 shows that there are significant differences in spatial diversity between different Tunpu settlements in Qianzhong. The Margalef and Shannon indexes of military Tunpu and commericial Tunpu are relatively high, the Margalef and Shannon indexes of residential Tunpu are relatively low, and the Pielou index of each settlement is quite different. On the whole, the spatial diversity index of Vil8 in the core protected area is relatively high, and the spatial diversity index of Vil4 is relatively low; From the perspective of different scale ranges, there was a slight decrease in the diversity of military Tunpu and commercial Tunpu indicators. Residential Tunpu was characterized by an increase in the Margalef and Shannon indexes and a slight decline in the Pielou index, meanwhile, a relatively high spatial diversity in the coordinated control area as vil8 and vil1 as the lowest.
Table 5
α diversity of Tunpu settlement space (CPA is core protected area, CCA is coordinated control area.)
Tunpu’s
ID
|
Margalef
|
Simpson
|
Shannon
|
Pielou
|
CPA
|
CCA
|
CPA
|
CCA
|
CPA
|
CCA
|
CPA
|
CCA
|
Vil1
|
0.7453
|
1.2102
|
0.4343
|
0.3153
|
0.7702
|
0.6720
|
0.5556
|
0.3232
|
Vil2
|
1.6908
|
2.0237
|
0.5122
|
0.4398
|
1.0496
|
0.9368
|
0.4558
|
0.3652
|
Vil3
|
0.9262
|
1.2325
|
0.3948
|
0.4276
|
0.7297
|
0.8073
|
0.4073
|
0.3674
|
Vil4
|
0.8654
|
1.1870
|
0.2003
|
0.4260
|
0.4609
|
0.8760
|
0.2573
|
0.4213
|
Vil5
|
1.0178
|
1.2046
|
0.4437
|
0.4661
|
0.8863
|
0.9053
|
0.4947
|
0.4353
|
Vil6
|
1.2463
|
1.4583
|
0.5057
|
0.5371
|
0.9204
|
1.0155
|
0.4426
|
0.4410
|
Vil7
|
0.8461
|
1.2852
|
0.4760
|
0.4742
|
0.8849
|
0.9320
|
0.5498
|
0.4482
|
Vil8
|
2.2459
|
2.1621
|
0.6085
|
0.5658
|
1.4309
|
1.3279
|
0.5758
|
0.5344
|
Vil9
|
2.1493
|
2.0881
|
0.6157
|
0.5632
|
1.3765
|
1.2763
|
0.5539
|
0.5136
|
Vil10
|
1.8778
|
1.7941
|
0.5356
|
0.5153
|
1.1561
|
1.1237
|
0.4652
|
0.4522
|
4.1.2 Spatial types β diversity characteristics of Tunpu settlements
Based on the diversity results of the Tunpu settlement β classification as a difference gradient (Table 6), the Jaccard and Sorenson indexes between commercial Tunpu and military Tunpu were higher than those of other settlements, and the Whittaker and Bray-curtis indexes between residential Tunpu showed a relatively high performance, and the Cody index of military Tunpu/commercial-residential Tunpu showed a higher trend. The fluctuation of the β diversity index between settlements is relatively small, the β diversity of commertial Tunpu-commertial Tunpu and military Tunpu-military Tunpu at different scales is relatively stable, while the fluctuation range of military Tunpu-commertial Tunpu and commertial Tunpu-residential Tunpu is relatively large.
Table 6
Diversity of β between different types of Tunpu(MT is military Tunpu, CT is commercial Tunpu, RT is residential Tunpu).
SM
|
whittaker(βw)
|
Coday(βc)
|
Jaccard (Cj)
|
Sorenson (Cs)
|
Bray-curtis(Cn)
|
CPA
|
CCA
|
CPA
|
CCA
|
CPA
|
CCA
|
CPA
|
CCA
|
CPA
|
CCA
|
MT-RT
|
2.2726
|
2.2100
|
3.0833
|
2.3750
|
0.4665
|
0.6341
|
0.6293
|
0.7731
|
6.7528
|
6.2722
|
MT-MT
|
2.2000
|
2.2000
|
2.0000
|
2.0000
|
0.6923
|
0.6923
|
0.8182
|
0.8182
|
5.5455
|
5.5455
|
CT-CT
|
2.1818
|
2.1818
|
1.0000
|
1.0000
|
0.8462
|
0.8462
|
0.9167
|
0.9167
|
7.7500
|
9.4167
|
RT-RT
|
2.4205
|
2.2654
|
1.9000
|
1.4333
|
0.5112
|
0.7160
|
0.6736
|
0.8304
|
10.7021
|
10.0475
|
MT-CT
|
2.1885
|
2.1818
|
1.3750
|
0.5000
|
0.7953
|
0.9231
|
0.8794
|
0.9583
|
4.3696
|
6.5417
|
CT-RT
|
2.2503
|
2.2168
|
3.7083
|
2.4167
|
0.4187
|
0.6191
|
0.5857
|
0.7628
|
9.2184
|
8.9528
|
4.2 Spatial characteristics of The Tunpu settlement in Qianzhong
4.2.1 Characteristics of space network in Qianzhong Tunpu settlement
It can be seen from figure 3 that the overall level of military Tunpu and commercial Tunpu shows the characteristics of a space network with strong connections, and the spatial network connection of residential Tunpu is relatively weak, but there are different amplitudes of changes in the spatial network indicators of Tunpu settlements under artificial expansion. Among the spatial network indicators in the core area, Vil2 has the strongest spatial connection, and in the coordinated control area, Vil2 has the highest performance in road density and Vil8 has the highest performance in road connectivity and road circularity; On the whole, the expansion of the regional spatial network of residential Tunpu is characterized by a strengthening or slight decrease in ties, and most of the spatial relevance of military Tunpu and commercial Tunpu is weakened to a certain extent, while the slight increase in Vil8 may be related to the strengthening of external links with its original closed geographical conditions in the process of urbanization.
4.2.2 Spatial morphological characteristics of the Tunpu settlement in Qianzhong
It can be seen from figures 4 and 5 that the spatial morphological characteristics of the core area of tunpu settlement are manifested in four levels: high concentration, moderate concentration, moderate dispersion and high dispersion. The coordination area is characterized by the spatial morphological characteristics of three levels: high concentration, moderate concentration and moderate dispersion; The spatial formative indicators fluctuate by different amplitudes in the scale change, and according to the change of the degree of aggregation between different settlements, there is no obvious law between the spatial morphological changes of the Tunpu settlement and the type of the Tunpu settlement.
4.3 Analysis of influencing factors of spatial diversity in Qianzhong Tunpu settlement
4.3.1 The relationship between the internal influencing factors of the Qianzhong Tunpu settlement and the spatial diversity
Figure 6 is the correlation analysis results of the spatial network, spatial morphology and α, β diversity of the Tunpu settlement. The results showed that the internal influencing factors had no obvious correlation with the spatial diversity of the Tunpu settlement α, and there was a significant correlation between the whitttaker and Bray-curtis indices of β diversity, and the correlation with other indices was weak. Among them, the whittaker index has a very significant negative correlation with the road connectivity and road circularity indexes, a very significant positive correlation with the degree of connection and integration, and a significant negative correlation with the intelligibility, a very significant negative correlation between the Bray-curtis index and the road density, a significant negative correlation with the fractal dimension, and a significant positive correlation with the depth value and selectivity.
4.3.2 External influencing factors of spatial diversity in Qianzhong Tunpu settlement
Figure 7 shows that the indicators of α diversity and β diversity show different degrees of correlation with external influencing factors. The Margalef Index is significantly correlated with the type of Tunpu, and correlated with the degree of government support and religious. The Shannon index was significantly positively correlated with the Tunpu type; the whittaker index was significantly negatively correlated with altitude, significantly positively correlated with cultivated land per capita, and significantly negatively correlated with religion. The Bray-curtis index has a significant positive correlation with the distance from the urban area, per capita annual income, and infrastructure investment. It also has a significant negative correlation with water systems and customs, and a significant correlation with the amount of government support and education.
4.3.3 Analysis of control factors influencing spatial diversity in Tunpu settlement
It can be seen from figures 6 and 7 that the spatial richness of the Tunpu settlement is significantly related to the natural environment, cultural customs and government support. There is a significant correlation between the Shannon index and cultural customs; The whittaker and Bray-curtis indices were significantly correlated with the spatial characteristics and external influencing factors of the Tunpu settlement, as well as with the natural environment, socio-economic, policy support and cultural customs. Through stepwise linear regression, exclude variables that are not significant in spatial type α indexes and influencing factors, so as to conclude the regression equation for the spatial α diversity and influencing factors of the Tunpu settlement.
YR=0.905+0.385ST-2.016PCCL(R2=0.850)
YH=0.698+0.234ST-0.005MT(R2=0.802)
In the equation, ST is the Tunpu type, PCCL is the per capita cultivated land, and MT is the main transportation.
Through the stepwise linear regression equation, the regression equation for the spatial β diversity and influencing factors of the Tunpu settlement is obtained.
Yw=2.48—0.459Rc(R2=0.910)
Yn=1.508+6.639PCAI(R2=0.888)
In the equation, Rc is road connectivity and PCAI is annual per capita income.
Based on the above regression analysis and the integrated results and the value of R2, it can be concluded that when the R2 of the spatial type YR and YH of the Tunpu settlement is 0.85 and 0.802 respectively, then the degree of fitting is perfect. The Tunpu type has a strong influence on the richness and diversity of the Tunpu settlement space type. Arable land per capita and major traffic have a negative correlation effect on the spatial diversity of Tunpu settlements. When the R2 of the Yw and Yn spatial types of Tunpu settlement were 0.91 and 0.888 respectively, then the degree of fitting was relatively high. Per capita annual income has a large contribution rate to the spatial difference of Tunpu settlement, and road connectivity has a negative correlation with the spatial difference of Tunpu settlement. The above results also reflect from the side that the space network has an important responsible position for the spatial diversity of the Tunpu settlement, and the socio-economic and cultural customs are the main influencing factors for the spatial diversity of the Tunpu settlement.