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Worldwide, natural ecosystems have been replaced by intensive productive systems. This has led to an extreme simplification of habitat structure and loss of ecosystem heterogeneity but also might reduce the opportunities for species co‐occurrence.Anthropogenic disturbances offer an opportunity to explore how the functional diversity of spiders within a highly diverse ecosystem such as a subtropical forest change under intensive productive systems such as monoculture tree plantations. It allows to study the mechanisms underlying the community re‐assemblage process.Using a set of morphological and ecological traits of 259 species, the habitat filtering hypothesis was tested on spider communities inhabiting pine monocultures at different ages, where the stabilisation of habitat conditions such as vegetation complexity, maximum temperature/relative humidity and prey availability along the plantation cycle growth will promote spider colonisation of these productive areas.The conversion of native forest to pine monocultures decreased species and trait richness of spiders. Moreover, spiders from both communities differed in their identity but exhibited similar functional traits (low trait replacement). Variation in trait composition of spiders was explained by changes in vertical stratification complexity, tree density and relative humidity, rather than prey availability.The mechanistic processes structuring the spider community were not clear. Spiders from pine plantations might experience frequent changes in composition due to high species replacement levels in space and time. Because pine plantations harbour only a few species and exhibit low functional richness, the pressure for stabilisation of community composition can be low. [ABSTRACT FROM AUTHOR]

1. Fields such as ecology, macroecology, and conservation biology rely on accurate and comparable data. This is especially important for mostly unknown and megadiverse taxa such as spiders and regions such as the Mediterranean. Short-term sampling programmes are increasingly seen as the best option for sampling spiders. Comparability of results, however, demands standard procedures both in methodology and in sampling period. Cost-efficiency dictates that this period should be the most species rich. 2. Pitfall trapping was conducted in 23 sites from north to south Portugal, comprising three large-scale environmental zones and many different habitat types, during 10 months in each site. The annual richness pattern, differences in this pattern between areas and habitats, the complementarity between sampling periods and possible environmental correlates of richness were studied. 3. May and June present the optimal time for collecting spiders in Mediterranean areas. Northern areas have a later peak in richness and dense tree-cover sites offer more flexibility for sampling, with a higher proportion of species present at each period throughout the year. 4. Day length is the environmental factor most correlated with species richness. Maximum daily temperature may reduce richness, especially in southernmost areas, where summer temperatures can be extremely harsh. 5. It is recommended that short-term sampling programmes, intended to give a reasonable picture of spider communities in Portugal and in the Iberian Peninsula (and possibly extending to all the Mediterranean), should be conducted during May or June, with variable flexibility according to area and habitat. The proposed suggestions should appeal to everyone working in the field, given the cost-efficiency and comparability of results by adopting a common standardised approach. [ABSTRACT FROM AUTHOR]