Trash-basket epiphytes as secondary foundation species: a review of their distribution and effects on biodiversity and ecosystem functions

Background: Secondary foundation species (FS) are organisms that inhabit ecosystems structurally defined by a primary foundation species, providing additional structure to habitats and communities. Trash-basket epiphytes (TBE) are secondary FS that enhance arboreal soil accumulation, providing shelter to animals, and rooting sites for plants. While their importance may vary across biomes, TBE have been overlooked as drivers of biodiversity and ecosystem functions. Here, we discuss the prevalence of TBE across biomes, their effects on biodiversity and ecosystem functions, and future research directions. Methods: We performed a systematic literature review of articles, books and theses and collated and synthesised information about the taxonomic distribution of TBE, their effects on ecosystem functions, and reports of plant-animal and plant-plant interactions. Then, we analysed the global distribution of TBE using a generalized linear model and summarised two studies to assess their effects on soil invertebrates. Results: We identified 120 publications describing 209 species of TBE. Most TBE belong to Araceae (43%), Polypodiaceae (23%), and Orchidaceae (14%) and occur in all tropical and southern temperate forests. TBE richness peaks in the South-American Pacific mangroves, Eastern Cordillera Real, and the Napo moist forests. TBE effects on ecosystem functions include arboreal soil accumulation, water retention and temperature regulation in the canopy, and nutrient leaching through stem-flow. TBE provide shelter to species in more than 97 animal families, including from invertebrates to mammals, while 72 vascular plants have been reported to root in arboreal soil of TBE. Conclusions: TBE are a compelling group of model organisms that can be used to study ecological processes such as facilitation cascades, niche construction, extended phenotypes, or the effects of secondary FS on biodiversity and ecosystem functioning. TBE should also be included in forest management plans to enhance the availability of microhabitats in the canopy supporting its associated flora and fauna.

Water source and transmission in Haloxylon ammodendron in the desert margin of the Manas River Basin, China

Analysis of water source and moisture transfer characteristics of desert plants is of great significance for ecological restoration in arid areas. In this study, the water source utilized by the desert plant, Haloxylon ammodendron, was analysed using the stable isotope technique, and the water transportation characteristics were obtained based on the proportional heat balance method under different weather conditions. The results showed that (1) before raining, the moisture of H. ammodendron mainly relied on groundwater (the average contribution rate was 34.14%) and on soil water located at a depth of 120–180 cm (the average contribution rate was 29.87%). After the rain, H. ammodendron mainly absorbed soil water from a depth of 60–120 cm (the average contribution rate was 33.19%) and groundwater (the average contribution rate was 30.67%); (2) the stem flow of H. ammodendron showed an obvious diurnal variation, showing a “midday rest” phenomenon. The stem flow showed a peak value, and in sunny days, it was ~2 fold higher than that in cloudy days. (3) The stem flow rate of H. ammodendron varied regularly overtime as follows: August > July > September > June > May, and the meteorological factors affecting its stem flow were solar radiation (0.826) > atmospheric temperature (0.598) > humidity (-0.573). The results provide basic support for the ecological conservation of the desert plant H. ammodendron, while also having important implications for ecological restoration in arid regions.

INTERSEPSI DAN ALIRAN BATANG TANAMAN KOPI DENGAN BERBAGAI NAUNGAN DI SUMBERMANJING WETAN, MALANG

The current climate change has an impact on crop production, especially coffee plants. Rainfall is one of the climate elements that influences the process of crop cultivation, because of its role in the availability of water crops. Raindrops that fall on the vegetated land cover does not directly reach to ground, but will temporarily be accommodated by a canopy, stems and plant branch. Once those places saturated with water, the raindrops will drop to the soil surface through the canopy, stem flow and partially evaporated back into the atmosphere that called interception. The study aims to determine the effect of the shade of coffee plants on the interception, and stemflow of plant canopy. As well as knowing the relationship between rainfall with throughfall, stemflow, and interception. This research was conducted at smallholder coffee plantation in Sumbermanjing Wetan District on the use of gamal shade coffee grown, sengon shade coffee grown, and sun-grown coffee. The results showed that the value of canopy throughfall in the three land uses was not statistically significantly different, but there was a tendency for monoculture coffee plants which has a greater yield that is 66,38% of the total rainfall of 15,32 mm. The highest stemflow value is in the sengon shade coffee grown of 3,07% of the total rainfall of 15,32 mm. Interception in the gamal shade coffee grown is the highest compared to other land uses that results obtained are 36,92% of the total rainfall of 17,1 mm. Rainfall has a relationship with the value of stemflow, throughfall and interception. Based on the correlation analysis test the results were significantly correlated with strong relationship.

Building regression models to estimate tree traits influential to slope stability

<p><strong>ABSTRACT    </strong> The above-ground (shoot) system of trees can affect slope stability through effects of infiltration facilitation, surcharge and wind loading. The amount of stem flow that infiltrates into soils is determined by diameter at root collar (DRC) of trees. Tree weight (surcharge) is a function of their heights (H) and diameters at breast height (DBH). Wind loading is related to crown area (CA) of trees. To save efforts for measuring all of these traits, we aimed to build regression models which allow researchers to estimate the other three traits with DBH. The study site was located in the Lienhuachih Forest Dynamics Plot, central Taiwan. DBH, DRC, CA and H of 20-30 individuals for the 18 most dominant tree species were measures. Trees which have been snapped off were excluded. Results showed that the regression models between DRC and DBH were linear. The models of CA against DBH and H against DBH was best built with allometric models, indicating that CA and H stop to increase with DBH once DBH reach to a certain size. In terms of model performance, the models of DRC against DBH was best (r<sup>2</sup>= 0.48- 0.97), followed by those of H against DBH (r<sup>2</sup>= 0.32- 0.89). The relatively poor performance of CA against DBH models (r<sup>2</sup>= 0.15- 0.93), especially for light-demanding tree species, indicated the need of incorporating light environment (i.e. crown illumination index) into regression analysis.</p><p> </p><p>Key word：allomeric model, broad-leaved forest, diameters at breast height, landslide, Lienhuachih</p>

Evaluation of Sap Flow Sensors to Measure the Transpiration Rate of Plants during Canopy Wetting and Drying

Accurate measurement of transpiration is required to estimate the various components of evaporation losses during sprinkler irrigation. Among the methods, sap flow measurements have widely used for direct measurements of transpiration rate in plant. To evaluate the applicability of this method to field experiments involving canopy wetting (by sprinkler irrigation), stem flow measurements were compared with transpiration values estimated from successive mass measurements of small potted plants using pre-calibrated mini-lysimeters in a glasshouse at the University of Southern Queensland, during the period August–October 2010. From this study it was found that when the canopy was dry, the sap flow measurements mirrored the transpiration rate of plants with reasonable accuracy, overestimating the transpiration rate by about 11%. The measurements showed no evidence of time lag between sap flow and transpiration. Following wetting of the plant canopy the sap flow declined rapidly reflecting a decline in the transpiration rate transpiration and sap flow. Location of the sap flow gage on the stem was seen to be a factor with gages at different heights giving different sap flow rates again due to the buffering capacity of the stem.

Rain Fall Partition of the Forest Canopy beside Songhua River

Through field investigation and room experiment, the characteristics of the rainfall partition in the canopy layer of six forest types beside Songhua River were studied. The canopy interception of the rainfall was different in six forest types; from maximum to minimum was Quercus monglica forest, Pinus koraiensis plantation, Tilia mandshurica forest, Fraxinus mandshurica-Larix olgensis forest, Fraxinus mandshurica-Populus davidiana forest and Juglans mandshurica forest. There were significant linear correlation between through fall and precipitation and significant exponential correlation between canopy interception and precipitation in studied forest types; The stem flow ratio to gross rain fall ranged from 0.74% to 16.61% in six forest types, from maximum to minimum was Juglans mandshurica forest, Quercus monglica forest, Pinus koraiensis plantation, Fraxinus mandshurica-Larix olgensis forest, Fraxinus mandshurica-Populus davidiana forest and Tilia mandshurica Forest. In the same precipitation condition, the stem flow ratio to gross rain fall should be affected negatively by canopy size.