珠海市山地森林及其植物多样性研究

珠海市是广东省最早建立的经济特区之一。由于长期的人类活动,珠海市原生森林早已破坏殆尽,现有的山地森林群落多为人工林和次生植被。应用样方法,在珠海面积较大、林相结构较完整的森林群落中设置了34个面积400m2的样方,调查和分析了这些山地森林群落的物种组成和植物多样性特点。研究结果表明,珠海市山地森林群落类型主要有风水林、沟谷林和早期次生林,以风水林和沟谷林的物种多样性较高,它们是珠海市宝贵的森林遗产。珠海市的森林群落以樟科、大戟科和山茶科植物最为丰富,茜草科、桃金娘科和桑科等热带植物种类也比较丰富。珠海市的天然林对维持当地生态平衡和区域性生物多样性的保护均具有重要的作用。     

Spatiotemporal changes in terrestrial water storage in the Beijing-Tianjin Sandstorm Source Region from GRACE satellites

The Sandstorm Source Control Project in and around the Beijing-Tianjin region was one of the most important ecological projects in China. Terrestrial water storage (TWS) has important impacts on the ecological construction, agriculture, industry, and resident’s lives. Based on the Gravity Recovery and Climate Experiment (GRACE) data, meteorological and Moderate Resolution Imaging Spectroradiometer (MODIS) data, etc., this paper analyzed spatiotemporal characteristics of TWS, groundwater storage, and precipitation, and explored the influencing factors of regional TWS combined with land use and land cover (LULC), social and economic data. The most important results were as follows: (1) From 2003 to 2016, TWS in the Beijing-Tianjin Sandstorm Source Region showed a decreasing trend with a rate of 3.14 mm yr⁻¹. (2) The TWS decline was caused mainly by groundwater overexploitation, but not precipitation variation. (3) Spatiotemporal variations of TWS were related to LULC. The area with the most serious decrease of TWS was mainly located in the southwestern part of the region, where farmland percentage and population density were greater. (4) Reducing the percent of farmland and tree planting, and adding the shrub and grass planting, could be a viable choice for the Beijing-Tianjin Sandstorm Source Control Project. These results provide a scientific basis for regional water resource and ecological management.     

基于地基激光雷达监测不同地表覆盖条件的土壤侵蚀试验研究

土壤侵蚀量是土壤退化风险评估的重要指标,地基激光雷达(TLS)为土壤侵蚀量动态监测提供新技术手段,但野外不同地表覆盖条件对监测精度的影响尚不明确。基于2019年11月和2021年7月在鹰潭红壤生态实验站获取的地表裸露、石块、稀疏象草、马尾松、马尾松+石块,马尾松+稀疏象草等不同地表覆盖条件的6个径流小区两期TLS数据,运用移动曲面拟合滤波和反距离加权插值方法估算土壤侵蚀量,结合实测侵蚀量数据评价TLS精度,并探讨不同地表覆盖条件下TLS的最小变化识别度(minLOD)。研究表明,TLS监测精度与土壤侵蚀量呈正相关关系,更适用于中等强度以上或长时间发生明显侵蚀的土壤侵蚀区监测。不同地表覆盖条件下minLOD为4～60 mm,TLS监测相对误差(RE)依次为：地表裸露(RE=–9.4%)<马尾松+石块(RE=12.6%)<石块(RE=15.5%)<稀疏象草(RE=–18.9%)<马尾松(RE=23.4%)<马尾松+稀疏象草(RE=–25.2%);地表覆盖条件不仅影响土壤侵蚀强度、地表粗糙度,也产生点云滤波及空间插值误差,进而影响TLS识别minLOD准确度和土...     

黄河三角洲植被演替过程种群生态位变化研究

对黄河三角洲天然湿地陆生植被和水生植被两种演替序列的种群生态位宽度和生态位重叠进行了调查研究。结果表明: 陆生植被经过翅碱蓬群落、碱蓬柽柳群落、柽柳群落、白茅群落的演替过程, 每个阶段优势种的生态位宽度都较大。翅碱蓬群落阶段优势种翅碱蓬的生态位宽度达9.99, 碱蓬柽柳群落阶段碱蓬的生态位宽度为9.72, 柽柳群落阶段柽柳的生态位宽度为9.20, 白茅群落阶段白茅的生态位宽度为9.31。水生植被的演替序列为眼子菜金鱼藻群落(沉水植物)阶段、浮萍水鳖群落(浮水植物)阶段、芦苇水烛群落(挺水植物)阶段和杞柳芦苇群落(湿生植物)阶段, 沉水植物阶段优势种眼子菜的生态位宽度为8.62, 浮水植物阶段优势种浮萍生态位宽度为9.23, 挺水植物阶段优势种芦苇的生态位宽度为8.59, 湿生植物阶段优势种杞柳生态位宽度为7.45。生态位宽度计测结果较好地对应着各种群在群落中的地位和作用, 生态位宽度在演替系列中的动态也较好地反映了种群在群落演替过程的数量动态。各演替阶段生态位重叠计算结果表明, 各阶段种群间的生态位重叠值低, 每一阶段内种群间有较高的生态位重叠     

陆生植物对全球环境变化的适应

全球环境变化对陆地生态系统产生了深刻影响,而陆生植物对环境变化具有一定的适应机制。在生理过程中,信号物质能够对植物的生理过程进行调节,植物会主动积累或合成小分子物质以减轻逆境的伤害。在个体水平上,植物通过调节同化物在不同器官中的分配来适应环境条件的变化;植物对水氮资源的权衡利用可以使其适应不同的资源环境条件;由于对非结构碳水化合物的奢侈利用,植物生长不会受碳供应的限制。植物生理生态过程中的适应机制会影响陆地生态系统的碳收支。只有在综合分析的基础上建立整合植物适应机理的数学模型,才能准确预测环境变化对陆地生态系统的影响。     

Paralytic shellfish poison as an attractant for toxic snails

The attracting effect of paralytic shell poison (PSP) on eight toxic snail species (Polinices didyma, Natica lineata, N. vitellus, Zeuxis sufflatus, Niotha clathrata, Oliva miniacea, O. mustelina, O. hirasei) and two non-toxic species (Pomacea canaliculata, Satsuma bairdi) was investigated. Eight toxic species were reported to contain tetrodotoxin, and three out of these contained minor PSP. The minimum lethal dose of PSP in most toxic gastropods was estimated to be more than 150 MU PSP/20 g body weight, but in non-toxic gastropods was less than 15 MU PSP/20 g body weight. After the attracting test, all toxic gastropods showed significant positive linear relationship (Y=3.716X+0.363, r=0.8427) between comparative attracting variation and the toxicity reported. The relationship between PSP resistance ability and the toxicity also had a positive correlation (Y=0.91X+210.090, r=0.6803). However, the non-toxic species showed a negative response. This indicates that PSP is an attractant for toxic snails.     

Invasive rats alter assemblage characteristics of land snails in the Ogasawara Islands

Although a large number of studies have shown that rats have a serious effect on island ecosystems, questions remain regarding how their invasion alters native species diversity and assemblage patterns on islands. In particular, a long history of invasions makes it difficult to understand the impact of rat invasion. In the present study, I investigate how an increase in predation by black rats (Rattus rattus) alters the assemblage characteristics of land snails on the Ogasawara Islands in the West Pacific. Radical declines in many land snail species have occurred since 2006 due to increasing predation by black rats. The frequency of shells with predation scars was greater on larger species and on those living on the trees and in a shallower position in the litter, suggesting greater predation pressure on these species. As a result of this selective predation, large species living on trees and in shallower parts of the litter declined. Accordingly, when black rats increased on the island, small species and species with a burrowing microhabitat became dominant in the land snail assemblage. The present findings can be used to aid in predicting the effects of rat eradication and in estimating the assemblage patterns and diversity prior to rat invasion.     

地源热泵长期运行对生态环境的影响

基于解析解理论,得出垂直埋管周围土壤温度场分布解析表达式。分析当钻孔外传热达到稳态时,钻孔壁温度的变化,由此分析土壤温度变化,得出土壤温度持续变化对大地热流及土壤本身的物性参数的影响,并会造成对土壤中微生物环境、植物生存环境的影响,进而会影响到整个生态环境。最后,提出在地源热泵推广过程中应注意的问题及采取的相应措施。