Sự bẫy chất hữu cơ trong các vùng cây cỏ ở các kênh của Đồng bằng Okavango: một vấn đề về chất lượng

Schweizerische Zeitschrift für Hydrologie - Tập 79 - Trang 661-674 - 2017
Jonas Schoelynck1, Jörg Schaller2, Mike Murray-Hudson3, Patrick J. Frings4,5, Daniel J. Conley6, Dimitri van Pelt1, Keotshephile Mosimane3, Mangaliso Gondwe3, Piotr Wolski3, Patrick Meire1, Eric Struyf1
1Department of Biology, Ecosystem Management Research Group, University of Antwerp, Wilrijk, Belgium
2Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University Bayreuth, Bayreuth, Germany
3Okavango Research Institute, University of Botswana, Maun, Botswana
4Earth Surface Geochemistry, GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany
5Department of Geoscience, Swedish Museum of Natural History, Stockholm, Sweden
6Department of Geology, Lund University, Lund, Sweden

Tóm tắt

Vai trò của thực vật thủy sinh trong dòng chảy như những kỹ sư hệ sinh thái trong việc phân bố chất hữu cơ đã được nghiên cứu tại Đồng bằng Okavango, một trong những vùng đầm lầy oligotrophic lớn nhất thế giới. Các lòng kênh của Okavango được phủ tới 50% bằng các vùng cây cỏ ngập nước. Bằng cách tích lũy và tập trung chất hữu cơ trong trầm tích dưới các vùng cây cỏ, thực vật ngập nước có khả năng ngăn chặn tình trạng thiếu dinh dưỡng tại địa phương. Lượng N gấp 21 lần, C gấp 18 lần, P gấp 13 lần và Si gấp 6 lần có thể được tìm thấy trong các trầm tích có thực vật so với các trầm tích không có thực vật. Việc tích lũy dinh dưỡng riêng biệt liên quan đến mức độ khan hiếm tương đối của nó trong nước phía trên. Có sự suy giảm N hòa tan so với P, trong khi Si lại tương đối dồi dào. Nước ở Đồng bằng Okavango thường được đặc trưng là oligotrophic dựa trên thành phần loài thực vật (ví dụ: sự hiện diện của các loài thực vật ăn thịt và sự vắng mặt của các loài thực vật nổi), tỷ lệ N:P thấp của thực vật, và các nồng độ dinh dưỡng và nguyên tố thấp. Quy trình khoáng hóa tại địa phương và chu trình dinh dưỡng tăng cường trong các trầm tích được giả thuyết là rất quan trọng cho sự tồn tại của thực vật ngập nước vì nó cung cấp nguồn dinh dưỡng thiết yếu mà các thực vật không thể có được đủ từ nước nghèo dinh dưỡng. Bằng cách kỹ sư hệ sinh thái như vậy, thực vật ven kênh cũng làm chậm mất đi các nguyên tố và dinh dưỡng tới dòng nước ngầm trên đảo, góp phần vào một trong những quy trình chính thúc đẩy năng suất cao của Đồng bằng Okavango, làm cho nó trở nên độc đáo giữa các vùng tương tự.

Từ khóa

#thực vật thủy sinh #chất hữu cơ #đồng bằng Okavango #oligotrophic #chu trình dinh dưỡng #kỹ sư hệ sinh thái.

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