Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A phenomenological spatial model for macro-ecological patterns in
  species-rich ecosystems   Over the last few decades, ecologists have come to appreciate that key
ecological patterns, which describe ecological communities at relatively large
spatial scales, are not only scale dependent, but also intimately intertwined.
The relative abundance of species, which informs us about the commonness and
rarity of species, changes its shape from small to large spatial scales. The
average number of species as a function of area has a steep initial increase,
followed by decreasing slopes at large scales. Finally, if we find a species in
a given location, it is more likely we find an individual of the same species
close-by, rather than farther apart. Such spatial turnover depends on the
geographical distribution of species, which often are spatially aggregated.
This reverberates on the abundances as well as the richness of species within a
region, but so far it has been difficult to quantify such relationships. Within
a neutral framework, which considers all individuals competitively equivalent,
we introduce a spatial stochastic model, which phenomenologically accounts for
birth, death, immigration and local dispersal of individuals. We calculate the
pair correlation function, which encapsulates spatial turnover, and the
conditional probability to find a species with a certain population within a
given circular area. Also, we calculate the macro-ecological patterns, which we
have referred to above, and compare the analytical formul{\ae} with the
numerical integration of the model. Finally, we contrast the model predictions
with the empirical data for two lowland tropical forest inventories, showing
always a good agreement.

1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
2
The categories of this paper are: math