The phenology of an urban street flora: a transect study

Vascular plants in flower along a fixed 3.8 km route in eight streets in a primarily residential area of urban Cambridge, U.K., were recorded at monthly intervals between January 2016 and December 2019. There was a consistent annual pattern over the four years; the number of flowering species was greatest in June or July but there were still appreciable numbers of species flowering when totals were at their lowest in February or March. Five annuals (Capsella bursa-pastoris, Euphorbia peplus, Poa annua, Senecio vulgaris, Stellaria media) and one perennial (Parietaria judaica) were very frequent and flowered from January to December. Perennial species showed greater variation through the year than annual species. In most months the number of flowering British native species exceeded the combined number of archaeophytes and neophytes, but the native total peaked earlier in the summer and then declined more rapidly than that of the introductions. The transect method appeared to be effective in identifying the main annual phenological trends and also revealed the effects of extreme weather on the patterns in some seasons.

Revisiting Mt. Kilimanjaro: Do n-alkane biomarkers in soils reflect the δ²H isotopic composition of precipitation?

During the last decade compound-specific deuterium (δ2H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ2H of precipitation (δ2Hprec). Recently, several authors suggested that δ2H of n-alkanes (δ2H,sub>n-alkanes) can also be used as proxy in paleoaltimetry studies. Here we present results from a δ2H transect study (~1500 to 4000 m a.s.l.) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ2Hprec is present above ~2000 m a.s.l., i.e. δ2Hprec values become more negative with increasing altitude. The compound-specific δ2H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ2Hn-alkane results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro (Peterse et al., 2009, BG, 6, 2799–2807), a major re-interpretation is required given that the δ2Hn-alkane results do not reflect the δ2Hprec results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% at ~ 2000 m a.s.l. to 51% at 4000 m a.s.l.), strongly controls δ2Hleaf water. The modelled δ2H leaf water enrichment along the altitudinal transect matches well the measured 2H leaf water enrichment as assessed by using the δ2Hprec and δ2Hn-alkane results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ2Hprec but rather δ2Hleaf water, we conclude that care has to be taken not to over-interpret δ2Hn-alkane records from soils and sediments when reconstructing δ2H of paleoprecipitation. Both in paleoaltimetry and in paleoclimate studies changes in relative humidity and consequently in δ2Hn-alkane values can completely mask altitudinally or climatically-controlled changes in δ2Hprec.

Komposisi Jenis dan Kepadatan Sponge (Porifera: Demospongiae) di Kepulauan Spermonde Kota Makassar

Sponge is one of the components on the coastal and marine ecosystems, especially coral reefs and seagrass beds. Climate change and environmental conditions can affect the life of the sponge. The study is conducted to determine the distribution of the composition and density of sponge using belt transects (transect quadrant) with a size of 5x5 m, then count the number of each type of sponge contained in the transect. Study site divided into three (3) zones indicating different conditions of eutrophication. A total of 49 species were identified from 16 families of 8 orders. Composition and density of the sponge in inner zone as many as 11 families with a density of 0.96 ind/m2, and lower compared to the composition and density in the middle zone and outer zone. This is related to the difference in environmental conditions of the three zones based on eutrophication conditions.Keywords: Sponge, species composition, density, spermondeAbstrakSponge merupakan salah satu penyusun pada ekosistem pesisir dan laut, terutama pada ekosistem terumbu karang dan padang lamun. Perubahan iklim dan kondisi lingkungan dapat mempengaruhi kehidupan dari sponge. Maka dilakukan penelitian untuk mengetahui sebaran komposisi dan kepadatan sponge menggunakan metode transek belt (transek kuadran) dengan ukuran 5x5 m, kemudian menghitung jumlah dari setiap jenis sponge yang terdapat dalam transek. Lokasi penelitian terbagi atas 3 (tiga) zona eutrofikasi yang menunjukkan kondisi eutrofikasi yang berbeda. Sebanyak 49 spesies yang teridentifikasi berasal dari 16 famili 8 ordo. Komposisi dan Kepadatan sponge pada zona dalam sebanyak 11 famili dengan kepadatan 0,96 ind/m2,, lebih rendah dibandingkan dengan komposisi dan kepadatan pada zona tengah dan zona luar. Hal tersebut terkait dengan adanya perbedaan kondisi lingkungan dari ketiga zona yang terbagi berdasarkan kondisi eutrofikasi tersebut.Kata kunci: Sponge, komposisi jenis, kepadatan, spermonde