Phenological patterns of neotropical lotic chironomids: Is emergence constrained by environmental factors?

Abstract In this paper we analyzed the emergence phenology of a highly diverse chironomid assemblage to test for association between emergence and some environmental variables and for the presence of synchrony in emergence. We used a time series of 48 weekly samples from a tropical low order forested stream (south‐eastern Brazil) to describe how this assemblage varied in an intra‐annual scale. An eigenvector‐based filtering approach was adapted to create temporal variables that could be used in our multiple regression analyses, trying to overcome the problems of temporal autocorrelation. Emergence of the Chironomidae, two subfamilies, concordant species, and of dominant species was not related to rainfall, temperature, moon phase or photoperiod. Taxonomic composition and species richness did not change across time. The number of emerging individuals of the subfamily Orthocladiinae was significantly related to temperature and to temporal filters. The inclusion of the temporal filters into the analyses almost eliminated autocorrelation in the regression residuals. We detected interspecific synchrony in a group of species, but an absence of trends and periodicity in chironomid emergence, which was not related to environmental variables. This suggests that unknown factors, differing from those known to control emergence in temperate regions, operate in the tropics. The erratic behaviour of the analyzed series raises the question of whether chaotic dynamics may generate this variability.     

A simple rearing chamber for lotic insect larvae

An effective rearing chamber for aquatic insects can be made from inexpensive commercially available products. An angled air line is attached to a round 400 ml Rubbermaid® dish with a snap-on lid to create a circular flow with bubbles. The lid included with the dish can be modified to accept a tube with fine mesh screen at one end for capturing emerging adults. This chamber is a reliable and effective technique for studying larval behavior and obtaining adults for species identification.     

Net biome production of managed forests in Japan

Net biome production (NBP) is considered as the most appropriate concept for analyzing long-term and large-scale changes of the carbon cycle induced by land use. We have estimated NBP potential of Japanese managed forests, based on their age structure, to be 16 Mt C/a. Fifty-nine percent of this sink is located in the warm-temperate broadleaf forest zone and the remaining 39% is located in the cool-temperate broadleaf forest zone. This potential of NBP could be achieved under a long rotation period (70 a) and may serve as a target for sink enhancement efforts with the potential to uptake up to 4% of current fossil fuel emissions.     

Nocturnal increases in the use of near-surface water by pond animals

We assessed diel animal habitat use in three shallow ponds, using unbaited funnel traps, a large column sampler, and sweep net collections in the upper stratum (0–0.3 m) of littoral and open habitats. In all three ponds, more animals were caught at night than during the day, indicating that use of near-surface waters was greatest at night, particularly in the fishless ponds. All methods yielded similar patterns. Our results demonstrate that nocturnal observations of pond animals are necessary to describe their ecology, even in fishless ponds where diel differences in habitat use or behavior might not be anticipated.     

呼和浩特市不同土地利用/覆盖类型对杨树春季物候的影响

城市化引起土地利用方式的变化,在局地、区域以及全球尺度上对环境造成了极为深刻的影响。局地尺度上,大面积的不透水地面以及较少的植被覆盖格局已经导致城郊物候的差异。在内蒙古呼和浩特城区选取新疆杨、青杨和毛白杨作为观测树种,通过定点定株的春季物候及温度的观测,探讨城市土地利用/覆盖对植物物候的影响。结果表明:1)各物候期发生当月(即4月)的平均气温、≥5℃积温、最低气温与各物候期之间呈显著负相关,而日平均最高气温与各物候期之间呈显著正相关。2)在4种不同的土地利用/覆盖类型中,绿地及裸土壤面积与4—6月的月平均气温、平均最低气温及≥5℃积温之间呈显著负相关,不透水面面积与各温度之间呈显著正相关。3)绿地及水体面积与展叶始期呈现显著负相关,而不透水面面积与展叶始期之间呈现显著正相关。研究表明,不同的土地利用/覆盖格局下,其温度之间存在差异,土地利用/覆盖显著地影响着温度的变化,进而影响了植物的春季物候。     

Description of the larva of Kempnyia colossica (Navás) (Plecoptera: Perlidae) with biological notes

In this paper, the larva of Kempnyia colossica (Navás 1934) is described based on material collected in Parque Estadual Intervales, São Paulo State, and biological notes are presented.