荒漠植物囊果草生物学特性及其种群分布格局的生态适应意义

为明确荒漠植物囊果草生物学特性及其种群分布格局的生态适应意义,以北疆地区温性荒漠中的特有植物囊果草为研究对象,对其生物学特性、种子传播方式及野外种群的分布格局进行了观测。结果表明,囊果草具膀胱状膜质果囊和膨大的不规则块状根茎,每株平均具果囊8.29个,果囊底部和侧面具网状脉络,且底部脉络较粗,不易破裂,顶部无脉络但具蓝紫斑,成熟时易破裂,每个果囊内平均包含球形种子2.82个。囊果草的花具有暂时闭合特性。囊果草为风滚式传播植物,一方面,地上果囊随风滚动时释放内部种子完成远距离传播,随着果囊体积的增大,果囊在不同粗糙程度微地形条件下的移动距离呈线性递增趋势,随地面粗糙度的增加,果囊最短移动距离显著减小(P<0.05),散布的种子数量则显著增加(P<0.05),且果囊移动距离与散布种子数量之间显著负相关(r=0.30,P<0.05);另一方面,地下块状根茎以营养生殖的方式在原位萌发。囊果草种群的分布格局与其生殖方式密切相关。在小尺度范围内(0~50m),随着空间尺度的扩大,囊果草种群幼苗和成株的分布格局表现为从均匀分布到聚集分布再到随机分布的特点;在中等尺度范围内(3.0~17.5m),幼苗和成株的空间关联性表现为正关联,随着空间尺度的递增,二者之间的关联性逐渐减小且关联性不显著。

Ecological adaptability of biological traits and population distribution patterns for the ephemeral plant Leontice incerta in desert habitats

This study aimed to document the ecological adaptability of biological traits and the population distribution pattern of the ephemeral desert plant Leontice incerta in the northern Xinjiang region. Data gathered included biological characteristics, seed production traits, dispersal mechanisms and population distribution patterns in the natural habitat. L. incerta has membranous fruits that form bladders around the seeds and are dispersed by wind rolling, and a swollen irregular underground tuber. Flowers of L. incerta temporarily close in response to cool overnight temperatures in their desert environment. The number of fruits per plant was, on average, 8.29. Fruit have reticulate venation at the sides and base, with the bottom veins thicker and not easy broken, and the apex of the fruit is without veins and thin and paper-like with blue-purple spots. This fruit apex is easily punctured when the fruit matures. Each fruit on average had 2.82 spherical seeds. Long-distance dispersal is achieved through release of seeds from the fruits as they roll in the wind. Average plant height was 18.9 cm, and average tuber diameter was 3.5 cm, but tuber size increased with plant age. To understand seed dispersal characteristics in this species, laboratory simulation studies of capsule movement with variables capsule size, air speed, and surface roughness were carried out, and plant and seedling distribution in the field was studied and analyzed. In the laboratory study, the distance travelled by capsules increased with increasing capsule size and decreased with increasing surface roughness. Seeds were released as capsules travelled, so that total seeds dispersed per capsule increased with distance, while seeds dispersed per unit area of ground decreased with increasing distance. Increased surface roughness increased capsule puncture and seed release from capsules. In the field, correlation between position of adult plants and position of seedlings increased up to 18 m distance from the adult plant and decreased at greater distances, while plant distribution was uniform on a 0-2 m scale, aggregated on a 2.5-14.0 m scale, and random on sampling scales greater than 14 m.