Table 3 Calculation and meaning of space diversity indices of the Tunpu settlements

α diversity index

Shannon–Wiener index(H’)

\(H^{\prime} = - \sum\limits_{i = 1}^{s} {P_{i} \log_{2} p_{i} }\)

\(Pi = ni/N\)

p_i is the proportion of the ith spatial type in the overall space of the settlement

ni: the number of individuals of the ith species

N: the total number of spatial units in the village

Higher index represents more diversity of settlement space types

(1)

Pielou index (E)

\(E = H/H\max\)

H: space diversity index of actual observations,

H_max: Maximum possiblespace diversity index

E indicates the distribution of spatial types of different settlements in the overall settlement

Representing the allocation of the number of space types

(3)

Margalef index(R)

\(R = (S - 1)/InN\)

N: the total number of spatial patch units

ln: the natural logarithm based on e,

S: the number of space types

The higher the index, the richer the types of settlement spaces

(4)

β diversity index

Whittaker(βw)

\({\upbeta }w = {\text{s/ma}}{ - }1\)

S: the total number of spatial type units in the research system

ma: the average number of species in each plot or sample

Characterizing the degree of dissimilarity among different settlements

(5)

Jaccard (Cj)

\(Cj = j/(a + b - j)\)

j is the number of spatial types common in the two settlement study areas, a and b are the number of spatial types of settlement a and settlement b respectively

Representing the similarity of different settlement spaces

(7)

Bray–curtis(Cn)

\(Cn = 2jN/(aN + bN)\)

aN is the number of spatial types of settlement space a, bN is the number of spatial types of settlement b, jN is the sum of the smaller number of individuals in the common space of settlement a(jNa) and settlement b(jNb)(Taking the sum of the number of spatial individuals that are less than the average of the number of individuals in the common space)

Representing the spatial composition differences between different settlements

(9)