Search

The impacts of deforestation on edaphic mesostigmatid mites were investigated in oak forests of Lordegan, southwestern Iran, from April to October. A total of twenty-one species belonging to eighteen genera and ten families were collected and identified. The Shannon-Wiener, Simpson, Jaccard's and Margalef biodiversity indices were used for data analyses. Among the collected species, Antennoseius bacatus with 29% and Sessilunchus hungaricus with 16% relative abundance were the most abundant and dominant species in human-disturbed and natural forests, respectively. The estimated values were higher in natural oak forest than in disturbed and cultivated habitat. Significant differences were observed in soil nitrogen content and soil organic carbon between the two habitats, but not in pH values. Significant effects of sampling time and habitat were found on all four indices, but the effect of their interactions on these indices was not significant. It can be concluded that the changes in soil quality that resulted from deforestation may have a major role in reducing the soil mite density and related diversity indices in disturbed forests.

The impacts of deforestation on edaphic mesostigmatid mites were investigated in oak forests of Lordegan, southwestern Iran, from April to October. A total of twenty-one species belonging to eighteen genera and ten families were collected and identified. The Shannon-Wiener, Simpson, Jaccard's and Margalef biodiversity indices were used for data analyses. Among the collected species, Antennoseius bacatus with 29% and Sessilunchus hungaricus with 16% relative abundance were the most abundant and dominant species in human-disturbed and natural forests, respectively. The estimated values were higher in natural oak forest than in disturbed and cultivated habitat. Significant differences were observed in soil nitrogen content and soil organic carbon between the two habitats, but not in pH values. Signi- ficant effects of sampling time and habitat were found on all four indices, but the effect of their interactions on these indices was not significant. It can be concluded that the changes in soil quality that resulted from deforestation may have a major role in reducing the soil mite density and related diversity indices in disturbed forests. [ABSTRACT FROM AUTHOR]

In seasonally dry environments such as the Zagros woodlands (Iran), severe drought stress and lack of appropriate management practices can cause failure of oak afforestation or reforestation. We investigated the effect of soil properties and burial depth on Persian oak ( Quercus brantii Lindl.) establishment in different microhabitats resulting from traditional forest practices. Four microhabitats that were based on forest structure were considered for oak acorn seeding: (1) inside old sprout clumps (ISPC); (2) under the canopy of tall trees (UCTT); (3) outside the canopy of tall trees and sprout clumps; and (4) near recent stumps or sprout clumps. Acorns were seeded at two depths (2 and 5 cm), and seedling survival and growth variables were recorded for 4 years, together with soil chemical and biological attributes. Stepwise discriminant analysis showed that a combination of total soil nitrogen, cation exchange capacity, available phosphorus and potassium, litter depth, microbial quotient, metabolic coefficient, substrate-induced respiration and earthworm abundance was the best variables to characterise the microhabitats. With the exception of pH, bulk density and soil texture, these variables were higher in UCTT and ISPC than in the other microhabitats. Seedling emergence and survival were greater at a seed depth of 5 cm than at 2 cm. Seedling height and shoot, root and leaf biomasses were higher in the UCTT microhabitat compared to the other microhabitats and correlated positively with soil nutrients contents and most of the soil biological variables but negatively with soil bulk density. This study emphasised the role of microhabitats in creating a 'canopy effect' producing favourable physical, chemical and biological soil conditions. In particular, large oak trees form islands of fertility and therefore are of key importance for successful seedling establishment in forests subjected to intense human activities. [ABSTRACT FROM AUTHOR]

Coppicing is a common management strategy in oak woodlands; however, our knowledge is limited in the impacts of coppicing on spatial structure and growth dynamics of oak stands. In this study, we compared the spatial patterns of two adjacent high and coppice pure stands of Brant's oak (Quercus brantii Lindl.) in central part of Zagros semi-arid woodlands, western Iran. We used univariate form of scale-dependent summary statistics (nearest neighbour distribution function, L -function, pair- and mark correlation functions) and Analytical Global Envelopes under inhomogeneous Poisson process which allow detection of the intraspecific interactions of the individuals within the high and coppice stands. Our results indicated the aggregation of oak individuals at small spatial scales (i.e., 0-3 m) in the high stand, most likely as a result of aggregation in parts with environmentally benign conditions. The positive interactions of conspecifics had a marked effect on their size (e.g., larger height (5%), DBH (24%), and crown area (50%) than mean size at spatial scale of 2 m) inferred as growth stimulation and aggregation of young trees around their nurse or parent trees. However, the findings revealed the segregation of oak trees at short distances in the coppice stand (i.e., 0–5 m), probably due to strong competition of conspecific neighbors. The negative size correlation of oaks (e.g., smaller height, DRC, and crown area of oak individuals (15%) than mean size at distance of 2 m) was considered as the outcome of competition for scarce resources in the woodlands with unfavourable conditions. In general, it was concluded that the aggregated spatial structure of the high stand has changed to segregation of individuals within the coppice stand. Additionally, we found that environmental heterogeneity and intraspecific competition are the main drivers of the high and coppice stands, respectively. • We compared the structural properties of oak coppice and high stands in Zagros woodlands. • Higher competitive interactions between oak conspecifics in coppice parts. • Strong negative effects of neighbourhood density on oak size in coppice stands. • Environmental heterogeneity and competition are the main drivers of structure of oak stands. [ABSTRACT FROM AUTHOR]